Drainage sampling sediment collection

Figure 4.7 A flow chart summarising the procedures at a drainage site for the collection of stream water, sediment and heavy mineral concentrate. Note Certain procedures are repeated when duplicate samples are collected.

Mirex was identified in sediment samples collected in 1979 from Bloody Run Creek, which is a drainage ditch for the Hyde Park landfill in Niagara Falls, New York. Mirex levels in the sediment ranged from 0.5 to 2 mg/kg (ppm) (detection limit, 0.5 mg/kg [ppm]) (Elder et al. 1981). 

Samples of drainage sediments and pan concentrates of heavy minerals were collected. Chemical analysis was undertaken on the fine fraction (-270 and... 

Running stream water was collected from the small, second-order, drainage basins (<100 km2) at the same site as the active stream sediment. In dry terrains, such as southern Europe, streams have no running water for most of the year. Hence, the sampling, whenever possible, was carried out during the winter and early spring months. Four subsamples of stream water were separately collected from each site. 

On arrival at site, samples should be collected in the order of stream water, stream sediment and panned heavy mineral concentrate. A flow chart of procedures is shown in Fig. 4.7 which demonstrates the team effort of a sampling pair to efficiendy sample a site in a strictly prescribed order. Time spent at each site will vary according to the experience of the samplers and the ease of collecting and sieving fine sediment. On average a drainage site should take 30-40 min to sample. 

The availability of other sample media at a drainage site has been briefly mentioned previously. The dirty water filters with the >45 im suspended sediment captured on the filter discs could be very useful in studies of the suspended-sediment load. The Fe and Mn coatings on pebbles and other chemical precipitates (e.g., insoluble Fe hydroxides) could also be collected as these are known to have good scavenging properties for certain trace elements. 

Subsequent studies90 focused on the population structure of fish presenting tumors as well as the role of heavy metals. Overall neoplasm prevalence appears to be stable at about 22% of the population. No juvenile fish, out of 2000 + examined, exhibited tumors. Likewise, tumor prevalence did not appear to be seasonal or site specific within the Lake of the Arbuckles. Water, sediment and fish tissues were collected from the Lake of the Arbuckles, a reference lake outside the drainage, and were analyzed for total recoverable metals (cadmium, chromium, copper, nickel and lead) by graphite furnace atomic absorption. Chromium, copper and nickel were found in the water samples at concentrations of > 1 — 8.6 /xg/1. Low concentrations (>1-13.6 /xg/g wet weight) of all the metals were found in the sediment and liver tissues from both sites. Based on these concentrations, heavy metal contamination does not appear linked to neoplasm occurrence. 

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