Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted 14C ages of 20–30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in 18O and 2H relative to modern infiltration, with maximum enrichment in δ18O of approximately 2.0‰.
","language":"English","publisher":"Springer","doi":"10.1007/s100400000121","issn":"14312174","usgsCitation":"Plummer, N., and Sprinkle, C., 2001, Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA: Hydrogeology Journal, v. 9, no. 2, p. 127-150, https://doi.org/10.1007/s100400000121.","productDescription":"24 p.","startPage":"127","endPage":"150","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232133,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207299,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s100400000121"}],"volume":"9","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a93dfe4b0c8380cd81098","contributors":{"authors":[{"text":"Plummer, Niel 0000-0002-4020-1013 nplummer@usgs.gov","orcid":"https://orcid.org/0000-0002-4020-1013","contributorId":190100,"corporation":false,"usgs":true,"family":"Plummer","given":"Niel","email":"nplummer@usgs.gov","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":397772,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Sprinkle, C.L.","contributorId":10811,"corporation":false,"usgs":true,"family":"Sprinkle","given":"C.L.","email":"","affiliations":[],"preferred":false,"id":397771,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70023461,"text":"70023461 - 2001 - Formation and transport of the sulfonic acid metabolites of alachlor and metolachlor in soil","interactions":[],"lastModifiedDate":"2018-11-30T06:32:50","indexId":"70023461","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1565,"text":"Environmental Science & Technology","onlineIssn":"1520-5851","printIssn":"0013-936X","active":true,"publicationSubtype":{"id":10}},"title":"Formation and transport of the sulfonic acid metabolites of alachlor and metolachlor in soil","docAbstract":"Alachlor and metolachlor are dechlorinated and transformed into their corresponding ethane sulfonic acid (ESA) metabolites in soil. In a field-disappearance study, it was shown that alachlor ESA was formed at a faster rate and at concentrations 2−4 times higher than metolachlor ESA, conforming with the observed longer disappearance half-life of metolachlor (15.5 d) in the field as compared to alachlor (8 d). Runoff data also showed higher concentrations of alachlor ESA as compared to metolachlor ESA, even though they were applied at the same levels. Data from soil cores showed transport of the ESA compounds in soil to as far down as 75−90 cm below the surface, at concentrations ranging from less than 0.5 μg/L to about 50 μg/L. In contrast, no parent herbicide was detected at these depths. This observation correlates with the higher log Koc values for alachlor (3.33) and metolachlor (3.01) relative to their corresponding ESA metabolites, alachlor ESA (2.26), and metolachlor ESA (2.29).
Water fluxes were estimated and a water budget developed for the land surface and a surficial 10-m-deep section of the coastal sabkhas that extend from the city of Abu Dhabi, United Arab Emirates, west to the border with Saudi Arabia. The fluxes were estimated on the basis of water levels and hydraulic conductivities measured in wells and evaporation rates measured with a humidity chamber. In contrast with conceptual models proposed in earlier studies, groundwater inflow is estimated to be small, whereas the largest components of the water budget are recharge from rainfall and evaporation from the water table. Estimates within a rectilinear volume of sabkha, defined as 1 m wide by 10 km long by 10 m deep, indicate that about 1 m3/year of water enters and exits by lateral groundwater flow; 40–50 m3/year enters by upward leakage; and 640 m3/year enters by recharge from rainfall. Based on the water and solute fluxes estimated for the upward leakage into the sabkha, 7–8 pore volumes of brine have entered the sabkha from below since the time the sabkha became saturated (7,000 years ago) as a result of the last global sea-level rise.
","language":"English","publisher":"Springer","publisherLocation":"Berlin, Germany","doi":"10.1007/s100400100137","issn":"14312174","usgsCitation":"Sanford, W.E., and Wood, W., 2001, Hydrology of the coastal sabkhas of Abu Dhabi, United Arab Emirates: Hydrogeology Journal, v. 9, no. 4, p. 358-366, https://doi.org/10.1007/s100400100137.","productDescription":"9 p.","startPage":"358","endPage":"366","numberOfPages":"9","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":232285,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United Arab Emirates","city":"Abu Dhabi","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n 53.7506103515625,\n 24.046463999666567\n ],\n [\n 53.7506103515625,\n 25.055745117015316\n ],\n [\n 55.21728515625,\n 25.055745117015316\n ],\n [\n 55.21728515625,\n 24.046463999666567\n ],\n [\n 53.7506103515625,\n 24.046463999666567\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"9","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3765e4b0c8380cd60e52","contributors":{"authors":[{"text":"Sanford, Ward E. 0000-0002-6624-0280 wsanford@usgs.gov","orcid":"https://orcid.org/0000-0002-6624-0280","contributorId":2268,"corporation":false,"usgs":true,"family":"Sanford","given":"Ward","email":"wsanford@usgs.gov","middleInitial":"E.","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true},{"id":37778,"text":"WMA - Integrated Modeling and Prediction Division","active":true,"usgs":true}],"preferred":true,"id":397539,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wood, Warren W.","contributorId":47770,"corporation":false,"usgs":false,"family":"Wood","given":"Warren W.","affiliations":[{"id":6601,"text":"Michigan State University","active":true,"usgs":false}],"preferred":false,"id":397538,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70023380,"text":"70023380 - 2001 - Major herbicides in ground water: Results from the National Water-Quality Assessment","interactions":[],"lastModifiedDate":"2022-10-26T17:19:13.783285","indexId":"70023380","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2262,"text":"Journal of Environmental Quality","active":true,"publicationSubtype":{"id":10}},"title":"Major herbicides in ground water: Results from the National Water-Quality Assessment","docAbstract":"To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydrologic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides—atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis[ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N-[methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]- N-[2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxy-1-methylethyl]acetamide)— as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 μg L−1 at 98% of the sites with detections, but exceeded drinking-water criteria (for atrazine) at two sites. In urban areas, frequencies of detection (at or above 0.01 μg L−1) of atrazine, cyanazine, simazine, alachlor, and metolachlor in shallow ground water were positively correlated with their nonagricultural use nationwide (P < 0.05). Among different agricultural areas, frequencies of detection were positively correlated with nearby agricultural use for atrazine, cyanazine, alachlor, and metolachlor, but not simazine. Multivariate analysis demonstrated that for these five herbicides, frequencies of detection beneath agricultural areas were positively correlated with their agricultural use and persistence in aerobic soil. Acetochlor, an agricultural herbicide first registered in 1994 for use in the USA, was detected in shallow ground water by 1995, consistent with previous field-scale studies indicating that some pesticides may be detected in ground water within 1 yr following application. The NAWQA results agreed closely with those from other multistate studies with similar designs.
Advances in technology have resulted in a new instrument that is designed for in-situ determination of particle size spectra. Such an instrument that can measure undisturbed particle size distributions is much needed for sediment transport studies. The LISST-100 (Laser In-Situ Scattering and Transmissometry) uses the principle of laser diffraction to obtain the size distribution and volume concentration of suspended material in 32 size classes logarithmically spaced between 1.25 and 250 μm. This paper describes a laboratory evaluation of the ability of LISST-100 to determine particle sizes using suspensions of single size, artificial particles. Findings show the instrument is able to determine particle size to within about 10% with increasing error as particle size increases. The instrument determines volume (or mass) concentration using a volume conversion factor Cv. This volume conversion factor is theoretically a constant. In the laboratory evaluation Cv is found to vary by a factor of about three over the particle size range between 5 and 200 μm. Results from field studies in South San Francisco Bay show that values of mass concentration of suspended marine sediments estimated by LISST-100 agree favorably with estimates from optical backscatterance sensors if an appropriate value of Cv, according to mean size, is used and the assumed average particle (aggregate) density is carefully chosen. Analyses of size distribution of suspended materials in South San Francisco Bay over multiple tide cycles suggest the likelihood of different sources of sediment because of different size characteristics during flood and ebb cycles.
The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as ≈70‰) shifts in δ13C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70‰) occurs during oxidation of methyl halides by methylotrophic bacteria. We have demonstrated biological fractionation with whole cells of three methylotrophs (strain IMB-1, strain CC495, and strain MB2) and, to a lesser extent, with the purified cobalamin-dependent methyltransferase enzyme obtained from strain CC495. Thus, the genetic similarities recently reported between methylotrophs, and methanogens with respect to their pathways for C1-unit metabolism are also reflected in the carbon isotopic fractionations achieved by these organisms. We found that only part of the observed fractionation of carbon isotopes could be accounted for by the activity of the corrinoid methyltransferase enzyme, suggesting fractionation by enzymes further along the degradation pathway. These observations are of potential biogeochemical significance in the application of stable carbon isotope ratios to constrain the tropospheric budgets for the ozone-depleting halocarbons, methyl bromide and methyl chloride.
Methyl bromide (MeBr) and methyl chloride (MeCl) are, respectively, the most abundant volatile bromo- and chlorocarbons in the troposphere and are major contributors to stratospheric ozone destruction (1). Both compounds have natural and human-influenced sources and a predominant sink by reaction with OH in the troposphere (2–4). MeBr also has a bacterial soil sink (5) that represents about 20% of the estimated total removal from the troposphere, and it is likely that a soil sink of similar magnitude exists for MeCl (6). Hence, if an isotopic fractionation is associated with the soil sink, it will influence the isotopic compositions of MeBr and MeCl in the lower atmosphere (7). The δ 13C value of industrially produced MeBr ranges between −43.5‰ and −66.4‰ (7), but δ 13C values of tropospheric MeBr and natural sources are not yet known. The δ 13C of atmospheric MeCl has been measured from −22‰ to −45‰ (8, 9). If carbon isotope ratios are to be used to constrain the budgets of these methyl halides, it is essential to determine the extent of carbon isotope fractionation that occurs during biological degradation of these compounds.
Methylotrophic bacteria use C1 compounds, which are simple organic molecules that contain no carbon–carbon bonds. Strains IMB-1, CC495, and MB2 are as-yet-unnamed facultative methylotrophs isolated from agricultural soil, woodland leaf litter, and coastal seawater, respectively (10–13), environments where methyl halides are produced. They are members of the α subgroup of the Proteobacteria. On the basis of 16S rRNA gene sequences, strains IMB-1 and CC495 show some phylogenetic alignment with the genusRhizobium (10, 11) and are very closely related to the new genus Pseudoaminobacter (I. McDonald, personal communication). Strain MB2 aligns within the Ruegeria clade [J. K. Schaefer, K. D. Goodwin, I. R. McDonald, J. C. Murrell and R.S.O., unpublished work]. All of these aerobic bacteria are methylotrophs in that they can grow by using MeBr or MeCl as their sole carbon source, but they do not metabolize methane. They oxidize MeBr, MeCl, and methyl iodide (MeI) to CO2.
Soil bacteria are known to consume MeBr at the ambient tropospheric mixing ratio of around 10 parts per trillion by volume (5). Preliminary experiments with strain IMB-1 indicate that it can oxidize MeBr at these mixing ratios** and is therefore likely to be characteristic of bacteria associated with MeBr uptake by soils. We examined δ 13C of MeCl, MeBr, and MeI during oxidation by whole-cell suspensions of IMB-1 and CC495 and also the change in δ 13C values of the three methyl halides during oxidation by the marine strain MB2. In addition, we measured the fractionation of carbon isotopes during formation of methane thiol (MeSH) from MeCl by the purified cobalamin-dependent enzyme, halomethane:bisulphide/halide ion methyltransferase (11) from CC495, to determine whether this initial step in MeCl degradation could account for the observed fractionation by whole cells. Finally, we determined the fractionation associated with the degradation of MeBr during field studies with agricultural soil by monitoring MeBr concentration and δ 13C of MeBr in the headspace of flux chambers under fumigation conditions.
","language":"English","publisher":"PNAS","doi":"10.1073/pnas.101129798","issn":"00278424","usgsCitation":"Miller, L., Kalin, R.M., McCauley, S., Hamilton, J.T., Harper, D., Millet, D., Oremland, R., and Goldstein, A.H., 2001, Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria: Proceedings of the National Academy of Sciences of the United States of America, v. 98, no. 10, p. 5833-5837, https://doi.org/10.1073/pnas.101129798.","productDescription":"5 p.","startPage":"5833","endPage":"5837","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":478908,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1073/pnas.101129798","text":"Publisher Index Page"},{"id":232727,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207621,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1073/pnas.101129798"}],"volume":"98","issue":"10","noUsgsAuthors":false,"publicationDate":"2001-05-08","publicationStatus":"PW","scienceBaseUri":"505a4477e4b0c8380cd66b26","contributors":{"authors":[{"text":"Miller, L.G.","contributorId":32522,"corporation":false,"usgs":true,"family":"Miller","given":"L.G.","email":"","affiliations":[],"preferred":false,"id":397361,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kalin, Robert M.","contributorId":24133,"corporation":false,"usgs":true,"family":"Kalin","given":"Robert","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":397360,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"McCauley, S.E.","contributorId":47120,"corporation":false,"usgs":true,"family":"McCauley","given":"S.E.","email":"","affiliations":[],"preferred":false,"id":397362,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Hamilton, John T.G.","contributorId":53123,"corporation":false,"usgs":true,"family":"Hamilton","given":"John","email":"","middleInitial":"T.G.","affiliations":[],"preferred":false,"id":397363,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Harper, D.B.","contributorId":76506,"corporation":false,"usgs":true,"family":"Harper","given":"D.B.","email":"","affiliations":[],"preferred":false,"id":397365,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Millet, D.B.","contributorId":64425,"corporation":false,"usgs":true,"family":"Millet","given":"D.B.","email":"","affiliations":[],"preferred":false,"id":397364,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Oremland, R.S.","contributorId":97512,"corporation":false,"usgs":true,"family":"Oremland","given":"R.S.","email":"","affiliations":[],"preferred":false,"id":397366,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Goldstein, Allen H.","contributorId":7452,"corporation":false,"usgs":true,"family":"Goldstein","given":"Allen","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":397359,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70023352,"text":"70023352 - 2001 - Determination of the sources of nitrate contamination in karst springs using isotopic and chemical indicators","interactions":[],"lastModifiedDate":"2012-03-12T17:20:14","indexId":"70023352","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1213,"text":"Chemical Geology","active":true,"publicationSubtype":{"id":10}},"title":"Determination of the sources of nitrate contamination in karst springs using isotopic and chemical indicators","docAbstract":"The sources of nitrate (NO-3) in groundwater of the shallow karst aquifer in southwestern Illinois' sinkhole plain were investigated using chemical and isotopic techniques. The groundwater in this aquifer is an important source of potable water for about half of the residents of the sinkhole plain area. Previous work has shown that groundwater from approximately 18% of the wells in the sinkhole plain has NO-3 concentrations in excess of the USEPA's drinking water standard of 10 mg N/1. Relative to background levels, the NO-3 concentrations in water from 52% of the wells, and probably all of the springs in the study area, are anomalously high, suggesting that sources other than naturally occurring soil organic matter have contributed additional NO-3 to groundwater in the shallow karst aquifer. This information, and the dominance of agriculture in the study area, suggest that agrichemical contributions may be significant. To test this hypothesis, water samples from 10 relatively large karst springs were collected during four different seasons and analyzed for inorganic constituents, dissolved organic carbon, atrazine, and ??15N and ??18O of the NO-3 ions. The isotopic data were most definitive and suggested that the sources of NO-3 in spring water are dominated by N-fertilizer with some possible influence of atmospheric NO-3 and, to a much lesser extent, human and/or animal waste. Differences in the isotopic composition of NO-3 and some of the chemical characteristics were observed during the four consecutive seasons in which spring water samples were collected. Isotopic values for ??15N and ??18O of the NO-3 ranged from 3.2??? to 19.1??? and from 7.2??? to 18.7???, respectively. The trend of ??15N and ??18O data for NO-3 also indicated that a significant degree of denitrification is occurring in the shallow karst hydrologic system (within the soil zone, the epikarst and the shallow karst aquifer) prior to discharging to springs. ?? 2001 Elsevier Science B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Chemical Geology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0009-2541(01)00318-7","issn":"00092541","usgsCitation":"Panno, S., Hackley, K.C., Hwang, H., and Kelly, W., 2001, Determination of the sources of nitrate contamination in karst springs using isotopic and chemical indicators: Chemical Geology, v. 179, no. 1-4, p. 113-128, https://doi.org/10.1016/S0009-2541(01)00318-7.","startPage":"113","endPage":"128","numberOfPages":"16","costCenters":[],"links":[{"id":207599,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0009-2541(01)00318-7"},{"id":232683,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"179","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ffdae4b0c8380cd4f423","contributors":{"authors":[{"text":"Panno, S.V.","contributorId":102990,"corporation":false,"usgs":true,"family":"Panno","given":"S.V.","email":"","affiliations":[],"preferred":false,"id":397350,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hackley, Keith C.","contributorId":12166,"corporation":false,"usgs":true,"family":"Hackley","given":"Keith","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":397348,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hwang, H.-H.","contributorId":6981,"corporation":false,"usgs":true,"family":"Hwang","given":"H.-H.","email":"","affiliations":[],"preferred":false,"id":397347,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Kelly, W.R.","contributorId":74120,"corporation":false,"usgs":true,"family":"Kelly","given":"W.R.","email":"","affiliations":[],"preferred":false,"id":397349,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70023349,"text":"70023349 - 2001 - pH dependence of iron photoreduction in a rocky mountain stream affected by acid mine drainage","interactions":[],"lastModifiedDate":"2018-11-30T06:21:09","indexId":"70023349","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"pH dependence of iron photoreduction in a rocky mountain stream affected by acid mine drainage","docAbstract":"The redox speciation of dissolved iron and the transport of iron in acidic, metal‐enriched streams is controlled by precipitation and dissolution of iron hydroxides, by photoreduction of dissolved ferric iron and hydrous iron oxides, and by oxidation of the resulting dissolved ferrous iron. We examined the pH dependence of these processes in an acidic mine‐drainage stream, St Kevin Gulch, Colorado, by experimentally increasing the pH of the stream from about 4·0 to 6·5 and following the downstream changes in iron species. We used a solute transport model with variable flow to evaluate biogeochemical processes controlling downstream transport. We found that at pH 6·4 there was a rapid and large initial loss of ferrous iron concurrent with the precipitation of aluminium hydroxide. Below this reach, ferrous iron was conservative during the morning but there was a net downstream loss of ferrous iron around noon and in the afternoon. Calculation of net oxidation rates shows that the noontime loss rate was generally much faster than rates for the ferrous iron oxidation at pH 6 predicted by Singer and Stumm (1970. Science 167: 1121). The maintenance of ferrous iron concentrations in the morning is explained by the photoreduction of photoreactive ferric species, which are then depleted by noon.
Residence times of groundwater, discharging from springs in the middle Suwannee River Basin, were estimated using chlorofluorocarbons (CFCs), tritium (3H), and tritium/helium-3 (3H/3He) age-dating methods to assess the chronology of nitrate contamination of spring waters in northern Florida. During base-flow conditions for the Suwannee River in 1997–1999, 17 water samples were collected from 12 first, second, and third magnitude springs discharging groundwater from the Upper Floridan aquifer. Extending age-dating techniques, using transient tracers to spring waters in complex karst systems, required an assessment of several models [piston-flow (PFM), exponential mixing (EMM), and binary-mixing (BMM)] to account for different distributions of groundwater age. Multi-tracer analyses of four springs yielded generally concordant PFM ages of around 20±2 years from CFC-12, CFC-113, 3H, and 3He, with evidence of partial CFC-11 degradation. The EMM gave a reasonable fit to CFC-113, CFC-12, and 3H data, but did not reproduce the observed 3He concentrations or 3H/3He ratios, nor did a combination PFM–EMM. The BMM could reproduce most of the multi-tracer data set only if both endmembers had 3H concentrations not much different from modern values. CFC analyses of 14 additional springs yielded apparent PFM ages from about 10 to 20 years from CFC-113, with evidence of partial CFC-11 degradation and variable CFC-12 contamination. While it is not conclusive, with respect to the age distribution within each spring, the data indicate that the average residence times were in the order of 10–20 years and were roughly proportional to spring magnitude. Applying similar models to recharge and discharge of nitrate based on historical nitrogen loading data yielded contrasting trends for Suwanee County and Lafayette County. In Suwanee County, spring nitrate trends and nitrogen isotope data were consistent with a peak in fertilizer input in the 1970s and a relatively high overall ratio of artificial fertilizer/manure; whereas in Lafayette County, spring nitrate trends and nitrogen isotope data were consistent with a more monotonic increase in fertilizer input and relatively low overall ratio of artificial fertilizer/manure. The combined results of this study indicate that the nitrate concentrations of springs in the Suwannee River basin have responded to increased nitrogen loads from various sources in the watersheds over the last few decades; however, the responses have been subdued and delayed because the average residence time of groundwater discharging from springs are in the order of decades.
","language":"English","publisher":"Elsevier","doi":"10.1016/S0009-2541(01)00321-7","issn":"00092541","usgsCitation":"Katz, B., Böhlke, J., and Hornsby, H., 2001, Timescales for nitrate contamination of spring waters, northern Florida, USA: Chemical Geology, v. 179, no. 1-4, p. 167-186, https://doi.org/10.1016/S0009-2541(01)00321-7.","productDescription":"20 p.","startPage":"167","endPage":"186","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232521,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207515,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0009-2541(01)00321-7"}],"country":"United States","state":"Florida","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -87.36328125,\n 30.334953881988564\n ],\n [\n -86.98974609375,\n 30.278044377800153\n ],\n [\n -86.2646484375,\n 30.240086360983426\n ],\n [\n -85.6494140625,\n 29.935895213372444\n ],\n [\n -85.45166015624999,\n 29.592565403314087\n ],\n [\n -85.0341796875,\n 29.592565403314087\n ],\n [\n -84.19921875,\n 29.783449456820605\n ],\n [\n -84.17724609375,\n 29.99300228455108\n ],\n [\n -83.8916015625,\n 29.916852233070173\n ],\n [\n -83.49609375,\n 29.477861195816843\n ],\n [\n -83.03466796874999,\n 28.94086176940557\n ],\n [\n -82.9248046875,\n 29.075375179558346\n ],\n [\n -82.79296874999999,\n 28.671310915880834\n ],\n [\n -80.79345703125,\n 28.825425374477224\n ],\n [\n -81.2548828125,\n 29.6880527498568\n ],\n [\n -81.45263671875,\n 30.732392734006083\n ],\n [\n -82.02392578125,\n 30.86451022625836\n ],\n [\n -82.0458984375,\n 30.637912028341123\n ],\n [\n -84.83642578125,\n 30.789036751261136\n ],\n [\n -85.0341796875,\n 31.052933985705163\n ],\n [\n -87.64892578125,\n 31.034108344903512\n ],\n [\n -87.36328125,\n 30.334953881988564\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"179","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bb3e2e4b08c986b32604a","contributors":{"authors":[{"text":"Katz, B. G.","contributorId":82702,"corporation":false,"usgs":true,"family":"Katz","given":"B. G.","affiliations":[],"preferred":false,"id":397322,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Böhlke, J.K. 0000-0001-5693-6455","orcid":"https://orcid.org/0000-0001-5693-6455","contributorId":96696,"corporation":false,"usgs":true,"family":"Böhlke","given":"J.K.","affiliations":[],"preferred":false,"id":397324,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hornsby, H.D.","contributorId":91139,"corporation":false,"usgs":true,"family":"Hornsby","given":"H.D.","email":"","affiliations":[],"preferred":false,"id":397323,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70023340,"text":"70023340 - 2001 - Sulfate-reducing bacteria release barium and radium from naturally occurring radioactive material in oil-field barite","interactions":[],"lastModifiedDate":"2018-11-30T06:40:35","indexId":"70023340","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1800,"text":"Geomicrobiology Journal","active":true,"publicationSubtype":{"id":10}},"title":"Sulfate-reducing bacteria release barium and radium from naturally occurring radioactive material in oil-field barite","docAbstract":"Scale and sludge deposits formed during oil production can contain elevated levels of Ra, often coprecipitated with barium sulfate (barite). The potential for sulfate-reducing bacteria to release 226 Ra and Ba (a Ra analog) from oil-field barite was evaluated. The concentration of dissolved Ba increased when samples containing pipe scale, tank sludge, or oil-field brine pond sediment were incubated with sulfate-reducing bacteria Desulfovibrio sp., Str LZKI, isolated from an oil-field brine pond. However, Ba release was not stoichiometric with sulfide production in oil-field samples, and <0.1% of the Ba was released. Potential for the release of 226Ra was demonstrated, and the 226 Ra release associated with sulfate-reducing activity was predictable from the amount of Ba released. As with Ba, only a fraction of the 226Ra expected from the amount of sulfide produced was released, and most of the Ra remained associated with the solid material.","language":"English","publisher":"Taylor & Francis","doi":"10.1080/01490450120549","issn":"01490451","usgsCitation":"Phillips, E.J., Landa, E.R., Kraemer, T., and Zielinski, R., 2001, Sulfate-reducing bacteria release barium and radium from naturally occurring radioactive material in oil-field barite: Geomicrobiology Journal, v. 18, no. 2, p. 167-182, https://doi.org/10.1080/01490450120549.","productDescription":"16 p.","startPage":"167","endPage":"182","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232478,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9dc3e4b08c986b31da71","contributors":{"authors":[{"text":"Phillips, Elizabeth J.P.","contributorId":37475,"corporation":false,"usgs":true,"family":"Phillips","given":"Elizabeth","middleInitial":"J.P.","affiliations":[],"preferred":false,"id":397312,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Landa, E. R.","contributorId":100002,"corporation":false,"usgs":true,"family":"Landa","given":"E.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":397314,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kraemer, T.","contributorId":90040,"corporation":false,"usgs":true,"family":"Kraemer","given":"T.","affiliations":[],"preferred":false,"id":397313,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Zielinski, R. 0000-0002-4047-5129","orcid":"https://orcid.org/0000-0002-4047-5129","contributorId":7046,"corporation":false,"usgs":true,"family":"Zielinski","given":"R.","affiliations":[{"id":164,"text":"Central Energy Resources Science Center","active":true,"usgs":true}],"preferred":false,"id":397311,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70023328,"text":"70023328 - 2001 - Effect of canopy removal on snowpack quantity and quality, fraser experimental forest, Colorado","interactions":[],"lastModifiedDate":"2012-03-12T17:20:04","indexId":"70023328","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2342,"text":"Journal of Hydrology","active":true,"publicationSubtype":{"id":10}},"title":"Effect of canopy removal on snowpack quantity and quality, fraser experimental forest, Colorado","docAbstract":"Snowpack peak water equivalent (PWE), ion concentration, content, and spatial distribution of ion load data from spring 1987-1996 in a 1 ha clearcut and adjacent forested plots vegetated by mature Picea engelmannii and Abies lasiocarpa in the Fraser experimental forest (FEF), Colorado are presented. Our objectives were: (1) to see if a forest opening might redistribute snowfall, snowpack moisture, and snowpack chemical content, and (2) to examine the importance of canopy interception on snowpack quantity and chemistry. On an average, the canopy intercepted 36% of snowfall. Interception was correlated with snowfall amount, snowpack PWE beneath the canopy, and air temperature. Canopy removal increased snowpack PWE to >90% cumulative snowfall inputs. Snowpack K-, H-, and NH4+ concentrations on the clearcut were lower and NO3- higher than in the snowpack beneath the forested plots. Cu mulative snowfall K+ input was less than in the clearcut snowpack; H+ inputs were greater in snowfall than in the snowpack of any plot; and inorganic N (NO3- and NH4+) inputs from snowfall to the clearcut were greater than to the forested plots. Processes accounting for the differences between snowfall inputs and snowpack ion content were leaching of organic debris in the snowpack, differential elution of the snowpack, and canopy retention. There were significant trends by year in snowpack ion content at PWE without similar trends in snowfall inputs. This finding coupled with snowpack ion elution bring into question the use of snowpack chemistry as an indicator of winter atmospheric inputs in short-term studies. ?? 2001 Elsevier Science B.V.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Hydrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0022-1694(01)00351-1","issn":"00221694","usgsCitation":"Stottlemyer, R., and Troendle, C., 2001, Effect of canopy removal on snowpack quantity and quality, fraser experimental forest, Colorado: Journal of Hydrology, v. 245, no. 1-4, p. 165-176, https://doi.org/10.1016/S0022-1694(01)00351-1.","startPage":"165","endPage":"176","numberOfPages":"12","costCenters":[],"links":[{"id":207377,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0022-1694(01)00351-1"},{"id":232280,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"245","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a05c6e4b0c8380cd50f54","contributors":{"authors":[{"text":"Stottlemyer, R.","contributorId":44493,"corporation":false,"usgs":true,"family":"Stottlemyer","given":"R.","email":"","affiliations":[],"preferred":false,"id":397270,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Troendle, C.A.","contributorId":103820,"corporation":false,"usgs":true,"family":"Troendle","given":"C.A.","email":"","affiliations":[],"preferred":false,"id":397271,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70023325,"text":"70023325 - 2001 - Applying the scientific method to small catchment studies: Areview of the Panola Mountain experience","interactions":[],"lastModifiedDate":"2012-03-12T17:19:59","indexId":"70023325","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"Applying the scientific method to small catchment studies: Areview of the Panola Mountain experience","docAbstract":"A hallmark of the scientific method is its iterative application to a problem to increase and refine the understanding of the underlying processes controlling it. A successful iterative application of the scientific method to catchment science (including the fields of hillslope hydrology and biogeochemistry) has been hindered by two factors. First, the scale at which controlled experiments can be performed is much smaller than the scale of the phenomenon of interest. Second, computer simulation models generally have not been used as hypothesis-testing tools as rigorously as they might have been. Model evaluation often has gone only so far as evaluation of goodness of fit, rather than a full structural analysis, which is more useful when treating the model as a hypothesis. An iterative application of a simple mixing model to the Panola Mountain Research Watershed is reviewed to illustrate the increase in understanding gained by this approach and to discern general principles that may be applicable to other studies. The lessons learned include the need for an explicitly stated conceptual model of the catchment, the definition of objective measures of its applicability, and a clear linkage between the scale of observations and the scale of predictions. Published in 2001 by John Wiley & Sons. Ltd.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1002/hyp.255","issn":"08856087","usgsCitation":"Hooper, R.P., 2001, Applying the scientific method to small catchment studies: Areview of the Panola Mountain experience: Hydrological Processes, v. 15, no. 10, p. 2039-2050, https://doi.org/10.1002/hyp.255.","startPage":"2039","endPage":"2050","numberOfPages":"12","costCenters":[],"links":[{"id":479048,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1002/hyp.255","text":"Publisher Index Page"},{"id":207338,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.255"},{"id":232203,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"15","issue":"10","noUsgsAuthors":false,"publicationDate":"2001-07-11","publicationStatus":"PW","scienceBaseUri":"5059ecd1e4b0c8380cd494ec","contributors":{"authors":[{"text":"Hooper, R. P.","contributorId":26321,"corporation":false,"usgs":true,"family":"Hooper","given":"R.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":397263,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70023324,"text":"70023324 - 2001 - A look inside 'black box' hydrograph separation models: A study at the hydrohill catchment","interactions":[],"lastModifiedDate":"2012-03-12T17:19:59","indexId":"70023324","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"A look inside 'black box' hydrograph separation models: A study at the hydrohill catchment","docAbstract":"Runoff sources and dominant flowpaths are still poorly understood in most catchments; consequently, most hydrograph separations are essentially 'black box' models where only external information is used. The well-instrumented 490 m2 Hydrohill artificial grassland catchment located near Nanjing (China) was used to examine internal catchment processes. Since groundwater levels never reach the soil surface at this site, two physically distinct flowpaths can unambiguously be defined: surface and subsurface runoff. This study combines hydrometric, isotopic and geochemical approaches to investigating the relations between the chloride, silica, and oxygen isotopic compositions of subsurface waters and rainfall. During a 120 mm storm over a 24 h period in 1989, 55% of event water input infiltrated and added to soil water storage; the remainder ran off as infiltration-excess overland flow. Only about 3-5% of the pre-event water was displaced out of the catchment by in-storm rainfall. About 80% of the total flow was quickflow, and 10% of the total flow was pre-event water, mostly derived from saturated flow from deeper soils. Rain water with high ??18O values from the beginning of the storm appeared to be preferentially stored in shallow soils. Groundwater at the end of the storm shows a wide range of isotopic and chemical compositions, primarily reflecting the heterogeneous distribution of the new and mixed pore waters. High chloride and silica concentrations in quickflow runoff derived from event water indicate that these species are not suitable conservative tracers of either water sources or flowpaths in this catchment. Determining the proportion of event water alone does not constrain the possible hydrologic mechanisms sufficiently to distinguish subsurface and surface flowpaths uniquely, even in this highly controlled artificial catchment. We reconcile these findings with a perceptual model of stormflow sources and flowpaths that explicitly accounts for water, isotopic, and chemical mass balance. Copyright ?? 2001 John Wiley & Sons, Ltd.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1002/hyp.245","issn":"08856087","usgsCitation":"Kendall, C., McDonnell, J.J., and Gu, W., 2001, A look inside 'black box' hydrograph separation models: A study at the hydrohill catchment: Hydrological Processes, v. 15, no. 10, p. 1877-1902, https://doi.org/10.1002/hyp.245.","startPage":"1877","endPage":"1902","numberOfPages":"26","costCenters":[],"links":[{"id":207337,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.245"},{"id":232202,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"15","issue":"10","noUsgsAuthors":false,"publicationDate":"2001-07-11","publicationStatus":"PW","scienceBaseUri":"5059e441e4b0c8380cd46520","contributors":{"authors":[{"text":"Kendall, C. 0000-0002-0247-3405","orcid":"https://orcid.org/0000-0002-0247-3405","contributorId":35050,"corporation":false,"usgs":true,"family":"Kendall","given":"C.","affiliations":[],"preferred":false,"id":397261,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"McDonnell, Jeffery J. 0000-0002-3880-3162","orcid":"https://orcid.org/0000-0002-3880-3162","contributorId":62723,"corporation":false,"usgs":false,"family":"McDonnell","given":"Jeffery","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":397262,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gu, W.","contributorId":6629,"corporation":false,"usgs":true,"family":"Gu","given":"W.","affiliations":[],"preferred":false,"id":397260,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70023302,"text":"70023302 - 2001 - Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata","interactions":[],"lastModifiedDate":"2018-12-03T08:55:15","indexId":"70023302","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2663,"text":"Marine Ecology Progress Series","active":true,"publicationSubtype":{"id":10}},"title":"Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata","docAbstract":"A laboratory bioassay determined the relative contribution of various pathways of Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata exposed to moderately contaminated sediments. Juvenile worms were exposed for 25 d to experimental sediments containing 5 different reactive sulfide (acid volatile sulfides, AVS) concentrations (1 to 30 ??mol g-1), but with constant Ag, Cd, and Zn concentrations of 0.1, 0.1 and 7 ??mol g-1, respectively. The sediments were supplemented with contaminated food (TetraMin??) containing 3 levels of Ag-Cd-Zn (uncontaminated, 1?? or 5??1 metal concentrations in the contaminated sediment). The results suggest that bioaccumulation of Ag, Cd and Zn in the worms occurred predominantly from ingestion of contaminated sediments and contaminated supplementary food. AVS or dissolved metals (in porewater and overlying water) had a minor effect on bioaccumulation of the 3 metals in most of the treatments. The contribution to uptake from the dissolved source was most important in the most oxic sediments, with maximum contributions of 8% for Ag, 30% for Cd and 20% for Zn bioaccumulation. Sediment bioassays where uncontaminated supplemental food is added could seriously underestimate metal exposures in an equilibrated system; N. arenaceodentata feeding on uncontaminated food would be exposed to 40-60% less metal than if the food source was equilibrated (as occurs in nature). Overall, the results show that pathways of metal exposure are dynamically linked in contaminated sediments and shift as external geochemical characteristics and internal biological attributes vary.","language":"English","publisher":"Inter-Research","doi":"10.3354/meps216129","issn":"01718630","usgsCitation":"Lee, J., Lee, B., Yoo, H., Koh, C., and Luoma, S., 2001, Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata: Marine Ecology Progress Series, v. 216, p. 129-140, https://doi.org/10.3354/meps216129.","productDescription":"12 p.","startPage":"129","endPage":"140","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":478950,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.3354/meps216129","text":"Publisher Index Page"},{"id":232519,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"216","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3b6de4b0c8380cd62513","contributors":{"authors":[{"text":"Lee, J.-S.","contributorId":15787,"corporation":false,"usgs":true,"family":"Lee","given":"J.-S.","email":"","affiliations":[],"preferred":false,"id":397204,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lee, B.-G.","contributorId":11777,"corporation":false,"usgs":true,"family":"Lee","given":"B.-G.","email":"","affiliations":[],"preferred":false,"id":397203,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Yoo, H.","contributorId":46725,"corporation":false,"usgs":true,"family":"Yoo","given":"H.","email":"","affiliations":[],"preferred":false,"id":397205,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Koh, C.-H.","contributorId":9797,"corporation":false,"usgs":true,"family":"Koh","given":"C.-H.","email":"","affiliations":[],"preferred":false,"id":397202,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Luoma, S. N.","contributorId":86353,"corporation":false,"usgs":true,"family":"Luoma","given":"S. N.","affiliations":[],"preferred":false,"id":397206,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70023297,"text":"70023297 - 2001 - Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons","interactions":[],"lastModifiedDate":"2012-03-12T17:20:14","indexId":"70023297","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2233,"text":"Journal of Contaminant Hydrology","active":true,"publicationSubtype":{"id":10}},"title":"Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons","docAbstract":"Oaks (Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination of contaminants. Additionally, a radial-growth decline began in these trees at approximately the same time that chloride became elevated. Growth did not decline in trees that contained smaller concentrations of chloride. The source of elevated chloride and the corresponding reductions in tree growth could not be explained by factors other than contamination. On the basis of tree-ring evidence alone, the release occurred in the late 1960s or early 1970s. Contaminant release at a second location apparently occurred in the mid- to late 1970s, suggesting that the area was used for disposal for at least 5 years and possibly longer. Copyright ?? 2001 Elsevier Science B.V.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Contaminant Hydrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0169-7722(01)00117-6","issn":"01697722","usgsCitation":"Yanosky, T., Hansen, B.P., and Schening, M., 2001, Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons: Journal of Contaminant Hydrology, v. 50, no. 3-4, p. 159-173, https://doi.org/10.1016/S0169-7722(01)00117-6.","startPage":"159","endPage":"173","numberOfPages":"15","costCenters":[],"links":[{"id":207462,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0169-7722(01)00117-6"},{"id":232435,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"50","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bbfa9e4b08c986b329cbe","contributors":{"authors":[{"text":"Yanosky, T.M.","contributorId":42263,"corporation":false,"usgs":true,"family":"Yanosky","given":"T.M.","email":"","affiliations":[],"preferred":false,"id":397184,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hansen, B. P.","contributorId":45332,"corporation":false,"usgs":true,"family":"Hansen","given":"B.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":397185,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Schening, M.R.","contributorId":103707,"corporation":false,"usgs":true,"family":"Schening","given":"M.R.","email":"","affiliations":[],"preferred":false,"id":397186,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70023296,"text":"70023296 - 2001 - Evaluation of flash-flood discharge forecasts in complex terrain using precipitation","interactions":[],"lastModifiedDate":"2012-03-12T17:20:14","indexId":"70023296","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2341,"text":"Journal of Hydrologic Engineering","active":true,"publicationSubtype":{"id":10}},"title":"Evaluation of flash-flood discharge forecasts in complex terrain using precipitation","docAbstract":"Operational prediction of flash floods produced by thunderstorm (convective) precipitation in mountainous areas requires accurate estimates or predictions of the precipitation distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds are generally small in size, and small position errors in the forecast or observed placement of the precipitation can distribute the rain over the wrong watershed. In addition to the need for good precipitation estimates and predictions, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the precipitation-rate input data. Different techniques for the estimation and prediction of convective precipitation will be applied to the Buffalo Creek, Colorado flash flood of July 1996, where over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the precipitation was exacerbated by the fact that a significant fraction of the watershed experienced a wildfire approximately two months prior to the rain event. Precipitation estimates from the National Weather Service's operational Weather Surveillance Radar-Doppler 1988 and the National Center for Atmospheric Research S-band, research, dual-polarization radar, colocated to the east of Denver, are compared. In addition, very short range forecasts from a convection-resolving dynamic model, which is initialized variationally using the radar reflectivity and Doppler winds, are compared with forecasts from an automated-algorithmic forecast system that also employs the radar data. The radar estimates of rain rate, and the two forecasting systems that employ the radar data, have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the radar data and forecasts from the dynamic model and the automated algorithm could be operationally useful for input to surface-hydrologic models employed for flood warning. Precipitation data provided by these various techniques at short time scales and at fine spatial resolutions are employed as detailed input to a distributed-parameter hydrologic model for flash-flood prediction and analysis. With the radar-based precipitation estimates employed as input, the simulated flood discharge was similar to that observed. The dynamic-model precipitation forecast showed the most promise in providing a significant discharge-forecast lead time. The algorithmic system's precipitation forecast did not demonstrate as much skill, but the associated discharge forecast would still have been sufficient to have provided an alert of impending flood danger.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Hydrologic Engineering","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1061/(ASCE)1084-0699(2001)6:4(265)","issn":"10840699","usgsCitation":"Yates, D., Warner, T., Brandes, E., Leavesley, G., Sun, J., and Mueller, C., 2001, Evaluation of flash-flood discharge forecasts in complex terrain using precipitation: Journal of Hydrologic Engineering, v. 6, no. 4, p. 265-274, https://doi.org/10.1061/(ASCE)1084-0699(2001)6:4(265).","startPage":"265","endPage":"274","numberOfPages":"10","costCenters":[],"links":[{"id":232397,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207444,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1061/(ASCE)1084-0699(2001)6:4(265)"}],"volume":"6","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0c75e4b0c8380cd52b62","contributors":{"authors":[{"text":"Yates, D.","contributorId":42391,"corporation":false,"usgs":true,"family":"Yates","given":"D.","email":"","affiliations":[],"preferred":false,"id":397181,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Warner, T.T.","contributorId":7459,"corporation":false,"usgs":true,"family":"Warner","given":"T.T.","email":"","affiliations":[],"preferred":false,"id":397178,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Brandes, E.A.","contributorId":22534,"corporation":false,"usgs":true,"family":"Brandes","given":"E.A.","email":"","affiliations":[],"preferred":false,"id":397179,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Leavesley, G.H.","contributorId":93895,"corporation":false,"usgs":true,"family":"Leavesley","given":"G.H.","email":"","affiliations":[],"preferred":false,"id":397183,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sun, Jielun","contributorId":33443,"corporation":false,"usgs":true,"family":"Sun","given":"Jielun","email":"","affiliations":[],"preferred":false,"id":397180,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Mueller, C.K.","contributorId":47944,"corporation":false,"usgs":true,"family":"Mueller","given":"C.K.","email":"","affiliations":[],"preferred":false,"id":397182,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70023289,"text":"70023289 - 2001 - Possible environmental factors underlying amphibian decline in eastern Puerto Rico: Analysis of U.S. government data archives","interactions":[],"lastModifiedDate":"2018-12-03T09:38:49","indexId":"70023289","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1321,"text":"Conservation Biology","active":true,"publicationSubtype":{"id":10}},"title":"Possible environmental factors underlying amphibian decline in eastern Puerto Rico: Analysis of U.S. government data archives","docAbstract":"The past three decades have seen major declines in populations of several species of amphibians at high elevations in eastern Puerto Rico, a region unique in the humid tropics because of the degree of environmental monitoring that has taken place through the efforts of U.S. government agencies. I examined changes in environmental conditions by examining time-series data sets that extend back at least into the 1980s, a period when frog populations were declining. The data include forest cover; annual mean, minimum, and maximum daily temperature; annual rainfall; rain and stream chemistry; and atmospheric-dust transport. I examined satellite imagery and air-chemistry samples from a single National Aeronautics and Space Administration aircraft flight across the Caribbean showing patches of pollutants, described as thin sheets or lenses, in the lower troposphere. The main source of these pollutants appeared to be fires from land clearing and deforestation, primarily in Africa. Some pollutant concentrations were high and, in the case of ozone, approached health limits set for urban air. Urban pollution impinging on Puerto Rico, dust generation from Africa (potential soil pathogens), and tropical forest burning (gaseous pollutants) have all increased during the last three decades, overlapping the timing of amphibian declines in eastern Puerto Rico. None of the data sets pointed directly to changes so extreme that they might be considered a direct lethal cause of amphibian declines in Puerto Rico. More experimental research is required to link any of these environmental factors to this problem.","language":"English","publisher":"Wiley","doi":"10.1046/j.1523-1739.2001.015004943.x","issn":"08888892","usgsCitation":"Stallard, R., 2001, Possible environmental factors underlying amphibian decline in eastern Puerto Rico: Analysis of U.S. government data archives: Conservation Biology, v. 15, no. 4, p. 943-953, https://doi.org/10.1046/j.1523-1739.2001.015004943.x.","productDescription":"11 p.","startPage":"943","endPage":"953","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232279,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207376,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1046/j.1523-1739.2001.015004943.x"}],"volume":"15","issue":"4","noUsgsAuthors":false,"publicationDate":"2002-03-21","publicationStatus":"PW","scienceBaseUri":"505a7e20e4b0c8380cd7a35e","contributors":{"authors":[{"text":"Stallard, R.F.","contributorId":30247,"corporation":false,"usgs":true,"family":"Stallard","given":"R.F.","email":"","affiliations":[],"preferred":false,"id":397159,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70023286,"text":"70023286 - 2001 - Long-term changes in consentrations and flux fo nitrogen in the Mississippi River Basin, USA","interactions":[],"lastModifiedDate":"2018-11-30T05:43:56","indexId":"70023286","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"Long-term changes in consentrations and flux fo nitrogen in the Mississippi River Basin, USA","docAbstract":"Current and historical data show that nitrogen concentrations and flux in the Mississippi River Basin have increased significantly during the past 100 years. Most of the increase observed in the lower Mississippi River has occurred since the early 1970s and is due almost entirely to an increase in nitrate. The current (1980-99) average annual nitrogen (N) flux from the Mississippi Basin to the Gulf of Mexico is about 1 555 500 t year-1, of which about 62% is nitrate-N. The remaining 38% is organic nitrogen and a small amount of ammonium. The current (1980-99) average nitrate flux to the Gulf is almost three times larger than it was during 1955-70. This increased supply of nitrogen to the Gulf is believed to be partly responsible for the increasing size of a large hypoxic zone that develops along the Louisiana-Texas shelf each summer. This zone of oxygen-depleted water has doubled in areal extent since it was first measured in 1985. The increase in annual nitrate flux to the Gulf can be largely explained by three factors: Increased fertilizer use, annual variability in precipitation and increased streamflow, and the year-to-year variability in the amount of nitrogen available in the soil-ground water system for leaching to streams. The predominant source areas for the nitrogen transported to the Gulf of Mexico are basins draining southern Minnesota, Iowa, Illinois, Indiana, and Ohio. Basins in this region yield 1801 to 3050 kg N km-2 year-1 to streams, several times the N yield of basins outside this region.","language":"English","publisher":"Wiley","doi":"10.1002/hyp.210","issn":"08856087","usgsCitation":"Goolsby, D.A., and Battaglin, W., 2001, Long-term changes in consentrations and flux fo nitrogen in the Mississippi River Basin, USA: Hydrological Processes, v. 15, no. 7, p. 1209-1226, https://doi.org/10.1002/hyp.210.","productDescription":"18 p.","startPage":"1209","endPage":"1226","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232240,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207351,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.210"}],"volume":"15","issue":"7","noUsgsAuthors":false,"publicationDate":"2001-05-25","publicationStatus":"PW","scienceBaseUri":"505a497ce4b0c8380cd6864d","contributors":{"authors":[{"text":"Goolsby, D. A.","contributorId":50508,"corporation":false,"usgs":true,"family":"Goolsby","given":"D.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":397152,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Battaglin, W.A.","contributorId":16376,"corporation":false,"usgs":true,"family":"Battaglin","given":"W.A.","email":"","affiliations":[],"preferred":false,"id":397151,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70023271,"text":"70023271 - 2001 - Quantifying contributions to storm runoff through end-member mixing analysis and hydrologic measurements at the Panola Mountain research watershed (Georgia, USA)","interactions":[],"lastModifiedDate":"2012-03-12T17:20:14","indexId":"70023271","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"Quantifying contributions to storm runoff through end-member mixing analysis and hydrologic measurements at the Panola Mountain research watershed (Georgia, USA)","docAbstract":"The geographic sources and hydrologic flow paths of stormflow in small catchments are not well understood because of limitations in sampling methods and insufficient resolution of potential end members. To address these limitations, an extensive hydrologic dataset was collected at a 10 ha catchment at Panola Mountain research watershed near Atlanta, GA, to quantify the contribution of three geographic sources of stormflow. Samples of stream water, runoff from an outcrop, and hillslope subsurface stormflow were collected during two rainstorms in the winter of 1996, and an end-member mixing analysis model that included five solutes was developed. Runoff from the outcrop, which occupies about one-third of the catchment area, contributed 50-55% of the peak streamflow during the 2 February rainstorm, and 80-85% of the peak streamflow during the 6-7 March rainstorm; it also contributed about 50% to total streamflow during the dry winter conditions that preceded the 6-7 March storm. Riparian groundwater runoff was the largest component of stream runoff (80-100%) early during rising streamflow and throughout stream recession, and contributed about 50% to total stream runoff during the 2 February storm, which was preceded by wet winter conditions. Hillslope runoff contributed 25-30% to peak stream runoff and 15-18% to total stream runoff during both storms. The temporal response of the three runoff components showed general agreement with hydrologic measurements from the catchment during each storm. Estimates of recharge from the outcrop to the riparian aquifer that were independent of model calculations indicated that storage in the riparian aquifer could account for the volume of rain that fell on the outcrop but did not contribute to stream runoff. The results of this study generally indicate that improvements in the ability of mixing models to describe the hydrologic response accurately in forested catchments may depend on better identification, and detailed spatial and temporal characterization of the mobile waters from the principal hydrologic source areas that contribute to stream runoff. Copyright ?? 2001 John Wiley & Sons, Ltd.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1002/hyp.246","issn":"08856087","usgsCitation":"Burns, D.A., McDonnell, J.J., Hooper, R.P., Peters, N., Freer, J., Kendall, C., and Beven, K., 2001, Quantifying contributions to storm runoff through end-member mixing analysis and hydrologic measurements at the Panola Mountain research watershed (Georgia, USA): Hydrological Processes, v. 15, no. 10, p. 1903-1924, https://doi.org/10.1002/hyp.246.","startPage":"1903","endPage":"1924","numberOfPages":"22","costCenters":[],"links":[{"id":207572,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.246"},{"id":232634,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"15","issue":"10","noUsgsAuthors":false,"publicationDate":"2001-07-11","publicationStatus":"PW","scienceBaseUri":"505a91c5e4b0c8380cd8044d","contributors":{"authors":[{"text":"Burns, Douglas A. 0000-0001-6516-2869","orcid":"https://orcid.org/0000-0001-6516-2869","contributorId":29450,"corporation":false,"usgs":true,"family":"Burns","given":"Douglas","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":397098,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"McDonnell, Jeffery J. 0000-0002-3880-3162","orcid":"https://orcid.org/0000-0002-3880-3162","contributorId":62723,"corporation":false,"usgs":false,"family":"McDonnell","given":"Jeffery","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":397101,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hooper, R. P.","contributorId":26321,"corporation":false,"usgs":true,"family":"Hooper","given":"R.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":397097,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Peters, N.E.","contributorId":33332,"corporation":false,"usgs":true,"family":"Peters","given":"N.E.","email":"","affiliations":[],"preferred":false,"id":397099,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Freer, J.E.","contributorId":18930,"corporation":false,"usgs":true,"family":"Freer","given":"J.E.","email":"","affiliations":[],"preferred":false,"id":397095,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Kendall, C. 0000-0002-0247-3405","orcid":"https://orcid.org/0000-0002-0247-3405","contributorId":35050,"corporation":false,"usgs":true,"family":"Kendall","given":"C.","affiliations":[],"preferred":false,"id":397100,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Beven, K.","contributorId":25320,"corporation":false,"usgs":true,"family":"Beven","given":"K.","email":"","affiliations":[],"preferred":false,"id":397096,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70023269,"text":"70023269 - 2001 - Carbon and nitrogen isotopic compositions of particulate organic matter in four large river systems across the United States","interactions":[],"lastModifiedDate":"2018-11-30T05:27:37","indexId":"70023269","displayToPublicDate":"2001-01-01T00:00:00","publicationYear":"2001","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"Carbon and nitrogen isotopic compositions of particulate organic matter in four large river systems across the United States","docAbstract":"Riverine particulate organic matter (POM) samples were collected bi‐weekly to monthly from 40 sites in the Mississippi, Colorado, Rio Grande, and Columbia River Basins (USA) in 1996–97 and analysed for carbon and nitrogen stable isotopic compositions. These isotopic compositions and C : N ratios were used to identify four endmember sources of POM: plankton, fresh terrestrial plant material, aquatic plants, and soil organic material. This large‐scale study also incorporated ancillary chemical and hydrologic data to refine and extend the interpretations of POM sources beyond the source characterizations that could be done solely with isotopic and elemental ratios. The ancillary data were especially useful for differentiating between seasonal changes in POM source materials and the effects of local nutrient sources and in‐stream biogeochemical processes.
Average values of δ13C and C : N for all four river systems suggested that plankton is the dominant source of POM in these rivers, with higher percentages of plankton downstream of reservoirs. Although the temporal patterns in some rivers are complex, the low δ13C and C : N values in spring and summer probably indicate plankton blooms, whereas relatively elevated values in fall and winter are consistent with greater proportions of decaying aquatic vegetation and/or terrestrial material. Seasonal shifts in the δ13C of POM when the C : N remains relatively constant probably indicate changes in the relative rates of photosynthesis and respiration. Periodic inputs of plant detritus are suggested by C : N ratios >15, principally on the Columbia and Ohio Rivers. The δ15N and δ13C also reflect the importance of internal and external sources of dissolved carbon and nitrogen, and the degree of in‐stream processing. Elevated δ15N values at some sites probably reflect inputs from sewage and/or animal waste. This information on the spatial and temporal variation in sources of POM in four major river systems should prove useful in future food web and nutrient transport studies.
","language":"English","publisher":"Wiley","doi":"10.1002/hyp.216","issn":"08856087","usgsCitation":"Kendall, C., Silva, S.R., and Kelly, V., 2001, Carbon and nitrogen isotopic compositions of particulate organic matter in four large river systems across the United States: Hydrological Processes, v. 15, no. 7, p. 1301-1346, https://doi.org/10.1002/hyp.216.","productDescription":"46 p.","startPage":"1301","endPage":"1346","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232595,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207550,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.216"}],"volume":"15","issue":"7","noUsgsAuthors":false,"publicationDate":"2001-05-25","publicationStatus":"PW","scienceBaseUri":"5059f35be4b0c8380cd4b747","contributors":{"authors":[{"text":"Kendall, C. 0000-0002-0247-3405","orcid":"https://orcid.org/0000-0002-0247-3405","contributorId":35050,"corporation":false,"usgs":true,"family":"Kendall","given":"C.","affiliations":[],"preferred":false,"id":397091,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Silva, S. R.","contributorId":27474,"corporation":false,"usgs":true,"family":"Silva","given":"S.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":397090,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kelly, V.J.","contributorId":14009,"corporation":false,"usgs":true,"family":"Kelly","given":"V.J.","email":"","affiliations":[],"preferred":false,"id":397089,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ]}