A ten-year study of chlorinated hydrocarbon insecticide residues in bovine milk in Illinois, 1972 - 1981

Milk supplies in Illinois were monitored for chlorinated hydrocarbon insecticide residues from 1972 through 1981. The percentage of milk samples that were contaminated with aldrin/dieldrin, DDT and its analogs, and BHC/lindane decreased during the 10-year sampling period. The percentage of samples contaminated with aldrin/dieldrin decreased from 98.7% in 1978 to 5.9% in 1981. The amount of aldrin/dieldrin residues found in contaminated samples also decreased from an average of 0.077 ppm (1972-79) to 0.001 ppm in 1980-81. The levels of chlordane and heptachlor/heptachlor epoxide residues in milk did not decrease, but residues of BHC and DDT decreased gradually over the 10-year period. The percentage of samples that had less than 0.1 ppm of all chlorinated hydrocarbon residues combined ranged from 10.6% to 25.7% during 1972 through 1978 and increased to 36.2% in 1979, 71.1% in 1980, and 61.4% in 1981.     

Response of Fish and Macroinvertebrate Bioassessment Indices to Water Chemistry in a Mined Appalachian Watershed

Multimetric indices based on fish and benthic macroinvertebrate assemblages are commonly used to assess the biological integrity of aquatic ecosystems. However, their response to specific stressors is rarely known. We quantified the response of a fish-based index (Mid-Atlantic Highlands Index of Biotic Integrity, MAH-IBI) and a benthic invertebrate-based index (West Virginia Stream Condition Index, WV-SCI) to acid mine drainage (AMD)-related stressors in 46 stream sites within the Cheat River watershed, West Virginia. We also identified specific stressor concentrations at which biological impairment was always or never observed. Water chemistry was extremely variable among tributaries of the Cheat River, and the WV-SCI was highly responsive across a range of AMD stressor levels. Furthermore, impairment to macroinvertebrate communities was observed at relatively low stressor concentrations, especially when compared to state water quality standards. In contrast to the WV-SCI, we found that the MAH-IBI was significantly less responsive to local water quality conditions. Low fish diversity was observed in several streams that possessed relatively good water quality. This pattern was especially pronounced in highly degraded subwatersheds, suggesting that regional conditions may have a strong influence on fish assemblages in this system. Our results indicate that biomonitoring programs in mined watersheds should include both benthic invertebrates, which are consistent indicators of local conditions, and fishes, which may be indicators of regional conditions. In addition, remediation programs must address the full suite of chemical constituents in AMD and focus on improving linkages among streams within drainage networks to ensure recovery of invertebrate and fish assemblages. Future research should identify the precise chemical conditions necessary to maintain biological integrity in mined Appalachian watersheds.     

Monitoring Contrasting Land Management in the Savanna Landscapes of Northern Australia

We compared measures of ecosystem state across six adjacent land-tenure groups in the intact tropical savanna landscapes of northern Australia. Tenure groups include two managed by Aboriginal owners, two national parks, a cluster of pastoral leases, and a military training area. This information is of relevance to the debate about the role of indigenous lands in the Australian conservation estate. The timing and frequency of fire was determined by satellite imagery; the biomass and composition of the herb-layer and the abundance of large feral herbivores by field surveys; and weediness by analysis of a Herbarium database. European tenures varied greatly in fire frequencies but were consistently burnt earlier in the dry season than the two Aboriginal tenures, the latter having intermediate fire frequencies. Weeds were more frequent in the European tenures, whilst feral animals were most abundant in the Aboriginal tenures. This variation strongly implies a signature of current management and/or recent environmental history. We identify indices suitable for monitoring of management outcomes in an extensive and sparsely populated landscape. Aboriginal land offers a unique opportunity for the conservation of biodiversity through the maintenance of traditional fire regimes. However, without financial support, traditional practices may prove unsustainable both economically and because exotic weeds and feral animals will alter fire regimes. An additional return on investment in Aboriginal land management is likely to be improved livelihoods and health outcomes for these disadvantaged communities.     

An Evaluation of Selenium Concentrations in Water, Sediment, Invertebrates, and Fish from the Republican River Basin: 1997–1999

The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L^-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L^-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g^-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g^-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin.     

An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Solomon River Basin

The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production. Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium. Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery resources in the Basin. The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged.     

Comparison of a novel passive sampler to standard water-column sampling for organic contaminants associated with wastewater effluents entering a New Jersey stream

Four water samples collected using standard depth and width water-column sampling methodology were compared to an innovative passive, in situ, sampler (the polar organic chemical integrative sampler or POCIS) for the detection of 96 organic wastewater-related contaminants (OWCs) in a stream that receives agricultural, municipal, and industrial wastewaters. Thirty-two OWCs were identified in POCIS extracts whereas 9-24 were identified in individual water-column samples demonstrating the utility of POCIS for identifying contaminants whose occurrence are transient or whose concentrations are below routine analytical detection limits. Overall, 10 OWCs were identified exclusively in the POCIS extracts and only six solely identified in the water-column samples, however, repetitive water samples taken using the standard method during the POCIS deployment period required multiple trips to the sampling site and an increased number of samples to store, process, and analyze. Due to the greater number of OWCs detected in the POCIS extracts as compared to individual water-column samples, the ease of performing a single deployment as compared to collecting and processing multiple water samples, the greater mass of chemical residues sequestered, and the ability to detect chemicals which dissipate quickly, the passive sampling technique offers an efficient and effective alternative for detecting OWCs in our waterways for wastewater contaminants.     

Modular containers for microcosm and process model studies on the fate and effects of aquatic contaminants

Container modules are described for the laboratory simulation of selected processes and ecosystems that are representative of lentic environments. Emphasis is placed on design features permitting mass balance accountability of contaminant residues and procedural cautions required for the proper use of the described systems in environmental simulations. Experiments on the efficiency of container modules for microbial mineralization studies were conducted using ¹⁴CNaHCO₃, and acidification resulted in a ¹⁴CCO₂ recovery of $\text{97.3 ± 4.7\% (}\text{x}\text{?}\text{± SD}\text{)}$. The trapping efficiency of pesticides volatilized from water and glass surfaces was investigated using the same module and the mean recoveries of ¹⁴C-fonofos and ¹⁴C-trifluralin were 114.2 ± 3.2% and 95.2 ± 3.5%, respectively. The mass balance capabilities of the system was also demonstrated for extended microcosm exposures to ¹⁴C-trifluralin.     

Streamflow Hydrology Estimate Using Machine Learning (SHEM)

Continuity and accuracy of near real‐time streamflow gauge (streamgage) data are critical for flood forecasting, assessing imminent risk, and implementing flood mitigation activities. Without these data, decision makers and first responders are limited in their ability to effectively allocate resources, implement evacuations to save lives, and reduce property losses. The Streamflow Hydrology Estimate using Machine Learning (SHEM) is a new predictive model for providing accurate and timely proxy streamflow data for inoperative streamgages. SHEM relies on machine learning (“training”) to process and interpret large volumes (“big data”) of historic complex hydrologic information. Continually updated with real‐time streamflow data, the model constructs a virtual dataset index of correlations and groups (clusters) of relationship correlations between selected streamgages in a watershed and under differing flow conditions. Using these datasets, SHEM interpolates estimated discharge and time data for any indexed streamgage that stops transmitting data. These estimates are continuously tested, scored, and revised using multiple regression analysis processes and methodologies. The SHEM model was tested in Idaho and Washington in four diverse watersheds, and the model's estimates were then compared to the actual recorded data for the same time period. Results from all watersheds revealed a high correlation, validating both the degree of accuracy and reliability of the model.     

Analytical Performance of Four Portable Gas Chromatographs Under Field Conditions

A field evaluation of the performance of four portable gas chromatographs was conducted at two field sites, one in the Pacific Northwest (chlorinated solvent contamination) and one in the Desert Southwest (primarily jet fuel contamination). The purpose of the study was to compare the performance of four portable GCs under the same conditions. The gas chromatographs had either electron-capture detectors or photoionization detectors. The study evaluated instrument linearity, instrument detection limits, retention time stabilities, response factor stability, and chromatographic performance. Standards and samples contained 1, 1, 2, 2-tetrachloroethane, trichloroethene, tetrachloroethane, 1, 1, 1-trichloroethane, benzene, toluene, and ethylbenzene. In order to ensure data comparability, the same model wide-bore column and computing integrator were used with each instrument, where possible. Significant differences in the performance of the four models were detected under the specific conditions used for this study. The results indicate the need to fully characterize the performance of portable instruments before field use so that appropriate quality control measures can be planned and implemented based on the performance of a specific analytical system.