DETERMINATION OF CROP PRODUCTION LOSS DUE TO INADEQUATE DRAINAGE IN A LARGE WATERSHED1

ABSTRACT Results of a field survey designed to assess the extent of crop production losses due to inadequate drainage in a large watershed of Iowa is presented. Information on the current status of drainage of the watershed, located in the Des Moines River basin, was collected through personal interviews with 256 farmers from 60 legal drainage districts. The results of the survey indicate that 95 percent of the area in upper Des Moines River basin has inadequate district mains or main outlet drains currently having a design capacity of ≤ 0.64 cm/day drainage coefficient. Outlet capacity of 1.27 cm/day d.c. would be required for full production. Inadequate drainage in the watershed is currently responsible for crop yield reduction equal to about one-third of the maximum yield potential for average weather conditions.     

Adaptive sampling and analysis programs for contaminated soils

Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application.     

Application of SMR to Modeling Watersheds in the Catskill Mountains

Very few hydrological models commonly used in watershed management are appropriate for simulating the saturation excess runoff. The Soil Moisture Routing model (SMR) was developed specifically to predict saturation excess runoff from variable source areas, especially for areas where shallow interflow controls saturation. A recent version of SMR was applied to two rural catchments in the Catskill Mountains to evaluate its ability to simulate the hydrology of these systems. Only readily available meteorological, topographical, and landuse information from published literature and governmental agencies was used. Measured and predicted streamflows showed relatively good agreement; the average Nash–Sutcliffe efficiency for the two watersheds were R ²=72% and R ²=63%. Distributed soil moisture contents and the locations of hydrologically sensitive areas were also predicted well.     

Organochlorine contamination in shorebirds from Washington state and the significance for their falcon predators

Arctic-breeding shorebirds collected in western Washington state during winter and spring, and a comparative sample collected in coastal California during the winter were analyzed for organochlorine contaminants to determine the potential impact of these residues on populations of peregrine falcons (Falco peregrinus) and merlins (F. columbarius) which prey upon shorebirds in western Washington. Dunlins (Calidris alpina), an important winter prey for falcons in western Washington, were collected between 1975 and 1981. During winter 1980–81, dunlins carried low organochlorine residues; DDE levels ranged from 0.01 to 1.2 ppm, and PCB levels ranged from 0.02 to 0.82 ppm (wet weight). Levels of other organochlorine contaminants (HCB, Chlordane compounds, Dieldrin, and Heptachlor Epoxide), analyzed in a subsample of dunlins, were consistently lower than DDE and PCB levels, and ranged from 0.001 to 0.22 ppm (wet weight). Dunlins in western Washington did not significantly increase their DDE or PCB burdens over the 1980–81 winter. A decline in DDE residues between 1978 and 1981 was noted, and declines in PCB residues from both 1975 and 1978 to 1980–81 were noted. Residues in other wintering shorebirds from western Washington were similar. Wintering sanderlings (Calidris alba) from California, revealed much higher DDE contamination than in Washington (up to 32 ppm, wet weight). Spring migrant shorebirds in western Washington contained both low and very high DDE residues (up to 417 ppm, wet weight). There is evidence suggesting these high DDE concentrations are accumulated along the Pacific coast of North America.     

Monitoring dissolved organic carbon in surface and drinking waters

The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.     

Effective monitoring of pollution by toxic trace elements in waters,sediment and biota of the Derwent River Estuary,Tasmania, through long-term retention of analytical facilities

This study considers the effectiveness of the monitoring of toxic trace elements in various media from a polluted river estuary over a period of 15 years, using the same analytical techniques, facilities and, in some cases, the same operators. It shows that reliable comparisons can be made for monitoring waters, sediment and biota from the Derwent River Estuary between 1975 data and that from 1990. Rigorous studies were undertaken before and during 1975 to ensure that reliable data was achieved at that time. Such studies are reviewed and included the evaluation of digestion techniques for a range of heavy metals, specific attention to the reliability of mercury determination in sediments between laboratories, a comparison of direct calibration and standard addition techniques for metals in seawater, recoveries of an organomercury compound from fish, and sources of error arising from sample preparation of biota for subsequent metal analysis. Comparative results for standard reference materials in both 1975 and 1990 show good agreement and are considered reliable except for lead at low concentrations. The long-term retention of the analytical facilities permits a direct comparison of data from 2 monitoring programmes over the space of 15 years.     

Microbiological and chemical characteristics of an acidic stream draining a disused copper mine

Water samples draining a disused copper mine (Parys Mountain) in Anglesey, North Wales, were analysed for distribution of acidophilic bacteria (iron oxidising and heterotrophic) and for changes in physicochemical composition along the length of the drainage stream. Ten samples were taken at regular distance intervals along a 1 km stretch from the source of the acid mine drainage. The stream remained highly acidic (pH < 2.8) although a slight decrease (0.6 pH unit) in acidity with distance from source was observed. Concentrations of most metals measured decreased with distance along the length of the stream, although some showed a gradual increase and others peaked at c. 200 m from source. Most dissolved iron was in the ferrous form in the upper reaches of the stream, but ferric iron became increasingly dominant downstream as a result of microbial oxidation. Although concentrations of nutrients such as nitrogen and phosphorus were low in the acid mine drainage, they were not limiting rates of bacterial iron oxidation, which appeared to be limited more by temperature. The iron oxidising bacteria Thiobacillus ferrooxidans and Leptospirillum ferrooxidans were both isolated from all sampling sites, although their relative abundances varied; L. ferrooxidans accounted for 57% of all iron oxidising isolates. Numbers of iron oxidising bacteria decreased with distance from drainage source, in contrast to those of acidophilic heterotrophic bacteria which increased. The diversity of heterotrophic isolates also increased with distance. The relationship between the chemistry and microbiology of the stream is discussed.     

Polychlorinated biphenyls in small mammals from contaminated landfill sites

PCBs in small mammals living in a contaminated landfill site varied in both concentration and congener composition, reflecting both the feeding strategy of each species and the chlorination of the congeners. Body concentrations of SigmaPCB on a 1:1:1 Arochlor (1242:1254:1260) basis gave a rank order of Sorex araneus > Apodemus sylvaticus > Microtus agrestis. Comparisons with data for other PCB-contaminated sites suggest that the SigmaPCB values in S. araneus from the landfill site may be of sufficient magnitude to inhibit reproductive capability and to cause other major organ dysfunction. There were also inter-specific differences in the whole body concentrations of the individually quantified congeners. For S. araneus, the rank order of concentrations of the selected ICES 7 marker PCB congeners was: No. 153>138>180>118>28>101>52. In M. agrestis the rank order was: No. 28>118>153>138>180, 52>101. The congener order for A. sylvaticus differed from both S. araneus and M. agrestis, but was more similar to the latter, being: No. 153>138>118>180>28>52, 101. The contribution of the different congeners to SigmaPCB in the mammals reflects the degree of chlorination of different congeners but varies with feeding strategy of the species. In the insectivorous S. araneus, heavily chlorinated congeners (Nos 153, 138 and 180) are most abundant, whereas the herbivore, M. agrestis showed congeners Nos 28 and 118 to be present in the highest amounts, whilst the equivalent pattern for the more omnivorous A. sylvaticus was intermediate between S. araneus and M. agrestis. The high concentrations of PCBs in S. araneus relative to the other species, suggests that it may serve as a useful biomarker of terrestrial environmental pollution by organochlorines.