Sampling distance, river

In the upper stream of the Meza River, including significant tributaries (e.g. Topla, Helenski potok, Musenik, Jazbinski potok, Juncarjev potok), the stream sediment samples were collected approximately 1 km apart. From Mezica to the Drava River the sampling distance was increased to 10 km. Additionally, two samples of the Drava River sediments were taken before and after its confluence with the Meza River (Fig. 1). 

Objects which are internally correlated for example volumes sampled from rivers, soils, or ambient air, can be treated by autocorrelation analysis or semivariogram analysis. The range up to a critical level of error probability is an expression of the critical spatial or temporal distance between sampling points. 

Surface-water samples are usually collected manually in precleaned polyethylene bottles (from a rubber or plastic boat) from the sea, lakes, and rivers. Sample collection is performed in the front of the bow of boats, against the wind. In the sea, or in larger inland lakes, sufficient distance (about 500 m) in an appropriate wind direction has to be kept between the boat and the research vessel to avoid contamination. The collection of surface water samples from the vessel itself is impossible, considering the heavy metal contamination plume surrounding each ship. Surface water samples are usually taken at 0.3-1 m depth, in order to be representive and to avoid interference by the air/water interfacial layer in which organics and consequently bound heavy metals accumulate. Usually, sample volumes between 0.5 and 21 are collected. Substantially larger volumes could not be handled in a sufficiently contamination-free manner in subsequent sample pretreatment steps. 

This stratified estuary has a depth of 40 m, with an upper fresh or brackish water layer of 0.2-4 m, depending on the river flow. The main source of pollution is untreated municipal wastewater, which is discharged into the estuary. Water samples were collected at different distances from these sewage outlets at two water depths from the fresh and the marine water layers. Furthermore, at one location, a vertical profile of the water column was made, including a sample of the water surface micro layer. Total A9PEOn, and individual AgPEOi, A9PEO2 and NP concentrations were determined with normal phase HPLC-FL analysis. 

The sampling conditions were described in detail in Section 8.2.1. Sediments were sampled from seven locations on the river WeiBe Elster in Thuringia (Germany) over a distance of 83 km (Fig. 8-9). The sediment samples were taken on both sides of the river for a better representativeness. 

Contamination of the Spring River in southwest Missouri by 2,3,7,8-TCDD is believed to have resulted from several well defined point-source waste disposal sites (Crunkilton et al. 1987). Analysis of 31 fish samples (11 different fish species) collected from 1981 to 1983 demonstrated a rapid decline in 2,3,7,8-TCDD concentrations in fish at increasing distances both upstream and downstream from the area of contamination. Mean concentrations of 2,3,7,8-TCDD 0.5 km downstream from the area of contamination were 38 ppt in whole fish and 20 ppt in fish fillets (wet weight basis). Mean concentrations in... 

Table VI shows the analytical data for the river water immediately after sampling. Although the sampling points were located within a distance of only about 30 km, the river water clearly showed different degrees of pollution. It seemed, therefore, very interesting to see how different bacterial populations and nutritive concentrations might affect the speed of biodegradation.

Soil samples collected from waste lands downwind and downhill from the Hood River orchard were analyzed for DDT and its analogs. The results indicated the extent to which spray drift during application and surface runoff during rainfall or irrigation had contaminated these areas with pesticides. The samples were collected at distances up to 200 yards from the edge of the orchard. The average DDT content of ten 0—6-inch samples was 2.64 p.p.m. (total of DDT plus isomers), with the range 0.36-8.3 p.p.m. On a pound per acre basis, this amounts to approximately 5 pounds of total pesticide per acre. 

Figure 1. Map of the lower Menominee River showing sampling sites. Transect numbers are distances from the mouth of the breakwater in hundreds of feet.

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