Review of Trace Element Blank and Replicate Data Collected in Ground and Surface Water for the National Water-Quality Assessment Program, 1991–2002
By Lori E. Apodaca1, David K. Mueller2 and Michael T. Koterba3
Scientific Investigations Report 2006-5093, published 2006.
Table 2
Upper 95-percent confidence limit by percentiles for contamination in trace elements from surface-water field-blank data.
[Bold faced values indicate contamination greater than the common reporting level. Al, aluminum; Ag, silver; As, arsenic; B, boron; Ba, barium; Be, beryllium; Cd, cadmium; Co, cobalt; Cr, chromium; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; Sb, antimony; Se, selenium; Sr, strontium; Tl, thallium; U, uranium; USEPA, U.S. Environmental Protection Agency; V, vanadium; Zn, zinc; na, not applicable; µg/L, microgram per liter; <, less than —, too few data to compute]
 AlSbAsBaBeBCdCrCoCuFePbLiMnMoNiSeAgSrTlUVZn
USEPA Drinking-Water Standard1²50–200³6³10³2,000³44600³5³100—51,300²300515—43004404100³50410044,000³2³30—42,000
Common Reporting Level (µg/L)1.01.01.01.014.01.01.01.01.03.01.00.31.01.01.01.01.00.10.11.01.01.0
Number of blanks11913086124138551391251261278311299875130124119142575412710124
Percentile95-percent Upper Confidence Limit (µg/L)
50th (median)2.0<1.0<1.0<1.0<1.0<4.0<1.0<1.0<1.0<1.0<3.0<1.0—<1.0<1.0<1.0<1.0<1.0<0.1<0.1<1.0—<1.0
75th 4.0<1.0<1.0<1.0<1.05.5<1.0<1.0<1.0<1.03.0<1.0—<1.0<1.0<1.0<1.0<1.0<0.1<0.1<1.0—3.0
85th5.0<1.0<1.0<1.0<1.09.4<1.0<1.0<1.0<1.05.0<1.0—<1.0<1.0<1.0<1.0<1.00.39<0.1<1.0—4.0
90th7.0<1.0<1.0<1.0<1.011<1.0<1.0<1.01.06.1<1.0—<1.0<1.0<1.0<1.0<1.00.65<0.1<1.0—4.3
91st7.0<1.0<1.0<1.0<1.014<1.0<1.0<1.01.07.0<1.0—<1.0<1.0<1.0<1.0<1.00.65<0.1<1.0—6.0
92nd10<1.0<1.0<1.0<1.014<1.0<1.0<1.01.08.0<1.0—<1.0<1.0<1.0<1.0<1.03.90.17<1.0—8.0
93rd15<1.0<1.01.0<1.014<1.0<1.0<1.01.08.0<1.0—<1.0<1.0<1.0<1.0<1.03.90.17<1.0—11
94th34<1.0<1.01.1<1.0—<1.0<1.0<1.01.010<1.0—1.0<1.01.0<1.01.03.90.17<1.0—11
95th45<1.01.251.1<1.0—<1.0<1.0<1.02.010<1.0—1.1<1.01.0<1.01.0——<1.0—13
96th45<1.01.252.0<1.0—<1.0<1.0<1.02.3201.8—1.6<1.01.0<1.02.0——<1.0—13
97th79<1.0—3.0<1.0—<1.0<1.0<1.02.7326.3—2.0<1.02.02.03.0——<1.0—13
98th——————————57——3.0—————————
99th——————————75——4.0—————————
                        
Common Reporting Level (µg/L)0.30.20.180.20.220.30.20.20.2na0.3na0.10.20.50.70.2nana0.20.210.5
Number of blanks4657646524455415151na52na8451501146nana55548
Percentile95-percent Upper Confidence Limit (µg/L)
50th (median)0.36<0.2na<0.2<0.2<2.0<0.3<0.2<0.2<0.2na<0.3na<0.1<0.2<0.5na<0.2nana<0.2na<0.5
75th 3.3<0.2na<0.2<0.23.5<0.3<0.2<0.20.34na<0.3na<0.1<0.2<0.5na<0.2nana<0.2na1.1
85th7.0<0.2na1.22<0.29.4<0.30.21<0.20.49na<0.3na0.12<0.2<0.5na<0.2nana<0.2na2.9
90th15<0.2na0.31<0.2110.420.34<0.20.75na<0.3na0.15<0.2<0.5na<0.2nana<0.2na11
91st34<0.2na0.9<0.2110.420.34<0.20.75na<0.3na0.15<0.2<0.5na<0.2nana<0.2na13
92nd34<0.2na0.9<0.2140.70.34<0.22.3na<0.3na0.20<0.2<0.5na<0.2nana<0.2na13
93rd34<0.2na0.9<0.2140.7—<0.22.3na<0.3na0.47<0.2<0.5na<0.2nana<0.2na13
94th—<0.2na—<0.2140.7—<0.22.3na<0.3na0.42<0.2<0.5na—nana<0.2na—
95th——na———————na—na0.92——na—nana—na—
96th——na———————na—na0.92——na—nana—na—
97th——na———————na—na———na—nana—na—
98th——na———————na—na———na—nana—na—
99th——na———————na—na———na—nana—na—
1U.S. Environmental Protection Agency, 2004. 2Secondary Drinking Water Regulation (SDWR): is a non-enforceable Federal guideline to address cosmetic or aesthetic effects of drinking water. 3Maximum Contaminant Level (MCL): the highest level of contaminant that is allowed in drinking water. 4Health Advisory (HA): is an acceptable drinking-water level for a chemical substance that is based on health effects information. HAs are not legally enforceable, but are a standard that serves as a guidance to assist Federal, state, and local officials. 5Action Level (AL): concentration of a contaminant that triggers treatment or other requirements that a water system must follow. For lead and copper, the action level is the level where 10 percent of the homes tested exceed the standard.