Study Design and Data Collection

Stream Chemistry

Basic and Intensive Fixed Sites were selected primarily to assess the occurrence and distribution of dissolved compounds in streamwater (Gilliom and others, 1995). Basic Fixed Sites were sampled less frequently and for fewer compounds than Intensive Fixed Sites. Intensive Fixed Sites were sampled to evaluate the seasonal effects of land uses on water quality and to determine the occurrence of dissolved pesticides. Stream synoptic studies extended the range of sampling beyond the fixed sites to provide an overview of dissolved compounds in relation to land resource provinces (Berndt and others, 1996). Sampling of streambed sediments was done to assess concentrations of trace elements and the occurrence and distribution of organic compounds.

(9,753 bytes)

Stream Ecology

Ecological assessments were done at three of the four basic sites and all five of the intensive sites. The assessments were repeated over 2 years to determine spatial or temporal variations in the community structure of aquatic biota. Synoptic samplings were done to define spatial variability in stream ecology by sampling clam or other macroinvertebrate communities at a number of sites in a short period of time.

(6,238 bytes)

Ground-Water Chemistry and Special Studies

Surveys of background water quality and effects of agricultural land use were done in the surficial aquifer in the Southern Coastal Plain and the eastern parts of the Coastal Flatwoods. Urban water-quality studies were done in Ocala and Tampa, Fla. A ground-water/surface-water interaction study was done in a karst area where ground water from the Upper Floridan aquifer interacts with water from the Suwannee River. Pesticides and nutrients were evaluated in a ground-water seepage study in the surficial aquifer downgradient from citrus groves in central Florida.

(7,066 bytes)

Stream chemistry

Basic Fixed Sites --
general water
chemistry

Streamflow, nutrients, major ions, suspended sediment, water temperature, specific conductance, organic carbon, alkalinity, dissolved oxygen, and pH; to describe concentrations, loads, and seasonal variations.

Large rivers with prior long-term nutrient sampling and continuous streamflow measurements.

Streams with continuous streamflow measurements, that drain forested, and agricultural basins.

2

3

Quarterly, 3/93-6/96

Monthly, 3/93-6/96

Intensive Fixed
Sites --
pesticides

In addition to the above constituents, 85 pesticides; to describe concentrations and seasonal variations.

Streams with continuous streamflow measurements, that drain urban and agricultural basins.

3

1

Weekly, 3/93-10/93

Monthly, 11/93-6/96
Biweekly, 3/93-10/93
Monthly, 11/93-6/96

Synoptic studies --
water chemistry

Nutrients, pesticides, suspended sediment, organic carbon, and streamflow; to describe spatial distribution.

Tributaries draining subbasins in two intensive sites.

Streams draining forested, agricultural, and urban basins.

36

36

Twice in 1993

Twice in 1994

Contaminants in bed sediments

Total PCBs, 32 organochlorine pesticides, 63 semi-volatile organic compounds, and 44 trace elements to determine presence of potentially toxic compounds attached to sediments in major streams.

Sites representing depositional zones of basic and intensive sites and selected tributaries.

59

Once

Contaminants in
benthic inverte-
brates

Total PCBs, 30 organochlorine pesticides, and 24 trace elements in Corbicula fluminea (a clam) to determine presence of contaminants that can accumulate in Corbicula fluminea tissues.

Streams with continuous streamflow measurements.

30

Once

Stream ecology

Intensive assessments

Fish, macroinvertebrates, and algae; to assess biological communities and habitat in streams representing primary ecological regions.

Sites at or near a stream-chemistry station.

7

Once per year,
2 years

Synoptic studies

Fish, macroinvertebrates and algae; to determine spatial distribution and community structure of aquatic species and habitat.

Sites at or near stream-chemistry stations and in representative streams across the study area.

17

Once

Ground-water chemistry

Aquifer survey -- surficial

Major ions, nutrients, pesticides, volatile organic compounds, and radon; to describe the overall water quality and natural chemistry in surficial aquifers.

Domestic wells in selected sub-regions across the study area.

38

Once in 1993

Land-use effects -- row crop
agriculture

Major ions, nutrients, pesticides, volatile organic compounds and radon; to determine the effects of land use on the quality of shallow ground water.

Newly drilled monitoring wells completed near water table in surficial aquifer beneath cropland.

23

Once in 1994

(14 wells sampled twice)

Land-use effects --urban

Major ions, nutrients, pesticides, volatile organic compounds, radon, and trace elements; to determine the effects of land use on shallow ground water.

Existing monitoring wells in surficial and Upper Floridan aquifers beneath urban areas.

32

Once in 1995

Special studies

Suwannee River ground-water/
surface-water interaction and springs study

Ground water samples collected and analyzed for major ions, nutrients, trace elements, and age-
dating constituents to describe chemistry and hydrology of ground-water interaction with the river.

Springs sampled for nutrients and major ions.

Clusters of wells of various depths (in the Upper Floridan aquifer), springs and the river.

Springs discharging to Suwannee River.

15

11

Quarterly, 1995-96

Once in July 1995

Ground-water
seepage --
citrus grove area in central Florida

Pesticides, nutrients and tritium; to determine the effects of citrus agriculture on the quality of ground water discharging to streams.

Drive-point wells to sample ground water discharging to small creeks and lakes downgradient from citrus groves. Wells were approximately 1 to 4 ft deep.

8

Once in June 1994