Sea-to-land transfer of technetium-99 through the use of contaminated seaweed as an agricultural soil conditioner

The use of seaweed as an agricultural soil conditioner gives rise to a potential pathway for the transfer of Technetium-99 ((99)Tc) from marine to terrestrial ecosystems and thence to man. However, to date there is little information on the extent of the release of (99)Tc from seaweed into soil and the mechanisms involved. This pot experiment has shown that (99)Tc is released fairly rapidly from Fucus vesiculosus into a sandy coastal soil. Despite low temperature conditions, 60% of the (99)Tc added with the seaweed had accumulated in the soil 15 weeks after addition. Concurrent CO(2) monitoring (used as a measure of microbial decomposition or catabolism) suggested that the initial (99)Tc release (up to 40% in the first 8 weeks) was due to leaching from the seaweed and that microbial decomposition was responsible for the release of the remaining (99)Tc in the latter phase (12-15 weeks).     

POTENTIAL EFFECTS OF CLIMATE CHANGE ON GROUND WATER IN LANSING,MICHIGAN1

ABSTRACT: Computer simulations involving general circulation models, a hydrologic modeling system, and a ground water flow model indicate potential impacts of selected climate change projections on ground water levels in the Lansing, Michigan, area. General circulation models developed by the Canadian Climate Centre and the Hadley Centre generated meteorology estimates for 1961 through 1990 (as a reference condition) and for the 20 years centered on 2030 (as a changed climate condition). Using these meteorology estimates, the Great Lakes Environmental Research Laboratory's hydrologic modeling system produced corresponding period streamflow simulations. Ground water recharge was estimated from the streamflow simulations and from variables derived from the general circulation models. The U.S. Geological Survey developed a numerical ground water flow model of the Saginaw and glacial aquifers in the Tri‐County region surrounding Lansing, Michigan. Model simulations, using the ground water recharge estimates, indicate changes in ground water levels. Within the Lansing area, simulated ground water levels in the Saginaw aquifer declined under the Canadian predictions and increased under the Hadley.     

Protecting endangered species under future climate change: From single-species preservation to an anticipatory policy approach

Anthropogenic climate climate change presents a unique challenge for endangered species policy and an opportunity for policy makers to develop a more predictive and robust approach to preserving the nation's biological resources. Biological and ecological reactions to shifting climate conditions and the potential feedbacks and synergistic effects of such changes may threaten the well-being of many species, particularly of those already in jeopardy of extinction. The United States Endangered Species Act of 1973 will fail to keep pace with increasing numbers of species needing protection as long as it remains focused on protecting species individually. The actmust not be abandoned, however; it holds tremendous promise for preserving biological diversity through a more proactive, anticipatory perspective. The current Endangered Species Act should be reinforced and improved by better integration of scientific expertise into habitat and community preservation listing decisions and recovery plan devlopment. Given the uncertainties surrounding long-term environmental consequences of human activities and resource use, a longer-term perspective must be integrated into all efforts to protect our biotic resources. Under appointment from the Graduate Fellowships for Global Change administered by the Oak Ridge Institute for Science and Ecducation for the US Department of Energy.     

The use of regression equations for quality control in a pesticide physical property database

Quality control is a crucial aspect of database management, particularly for physicochemical parameters that are widely used in modeling environmental fate processes. Complete rechecking of original studies to verify environmental fate parameters is time consuming and difficult. This paper evaluates an alternative, more efficient approach to identifying database errors. The approach focuses verification efforts on a targeted subset of entries by making use of the relationship between water solubility (S) and soil organic carbon partition coefficient (K _oc ). Two regression equations, one selected from the literature and one calculated from entries in the database, were used to evaluate the reasonableness of (S, K _oc ) pairs among control compared to the targeted outlier group from a total of 59 pesticides. Our hypothesis was that (S, K _oc ) pairs that lay far from the regression line were more likely to be in error than those that fit the regression. Database values were checked against original studies. Identified errors in the database included coding mistakes, miscalculations, and incorrect chemical identification codes. The error rate in outlier (S, K _oc ) pairs was about twice that of pairs that conformed to the regression equation; however, the error rate differential was probably not large enough to justify the use of this quality control method. Through our close scrutiny of database entries we were able to identify administrative practices that led to mistakes in the data base. Resolution of these problems will significantly decrease the number of future mistakes.     

An analysis for the causes of accidents of repair,maintenance, alteration and addition works in Hong Kong

This study unveils causes of accidents in repair, maintenance, alteration and addition (RMAA) work. RMAA work is playing an increasingly important role in developed societies, including Hong Kong. Safety problems associated with RMAA work in Hong Kong has reached an alarming level. In view of rapid expansion of the RMAA sector and rising proportion of accidents in the construction industry, there is a pressing need to investigate causes of RMAA accidents. Structured interviews were conducted with RMAA contractors to explore causes of accidents in the RMAA sector. A two-round Delphi method with 13 safety experts was subsequently employed to verify the interview findings and rank the relative degree of importance for various causes of accidents. Accidents happen in RMAA work due to intersection of reasons. One of the root causes of accidents in RMAA works is low safety awareness of RMAA workers; however, wider organizational and industrial factors are not negligible. This study sheds light on why accidents happen in the RMAA sector. Only when the factors leading to accidents are identified can effective measures be made.     

WALNUT CREEK WATERSHED MONITORING PROJECT,IOWA MONITORING WATER QUALITY IN RESPONSE TO PRAIRIE RESTORATION1

ABSTRACT: Land use and surface water data for nitrogen and pesticides (1995 to 1997) are reported for the Walnut Creek Watershed Monitoring Project, Jasper County Iowa. The Walnut Creek project was established in 1995 as a nonpoint source monitoring program in relation to watershed habitat restoration and agricultural management changes implemented at the Neal Smith National Wildlife Refuge by the U.S. Fish and Wildlife Service. The monitoring project utilizes a paired‐watershed approach (Walnut and Squaw creeks) as well as upstream/downstream comparisons on Walnut for analysis and tracking of trends. From 1992 to 1997, 13.4 percent of the watershed was converted from row crop to native prairie in the Walnut Creek watershed. Including another 6 percent of watershed farmed on a cash‐rent basis, land use changes have been implemented on 19.4 percent of the watershed by the USFWS. Nitrogen and pesticide applications were reduced an estimated 18 percent and 28 percent in the watershed from land use changes. Atrazine was detected most often in surface water with frequencies of detection ranging from 76–86 percent. No significant differences were noted in atrazine concentrations between Walnut and Squaw Creek. Nitrate‐N concentrations measured in both watersheds were similar; both basins showed a similar pattern of detection and an overall reduction in nitrate‐N concentrations from upstream to downstream monitoring sites. Water quality improvements are suggested by nitrate‐N and chloride ratios less than one in the Walnut Creek watershed and low nitrate‐N concentrations measured in the subbasin of Walnut Creek containing the greatest amount of land use changes. Atrazine and nitrate‐N concentrations from the lower portion of the Walnut Creek watershed (including the prairie restoration area) may be decreasing in relation to the upstream untreated component of the watershed. The frequencies of pesticide detections and mean nitrate‐N concentrations appear related to the percentage of row crop in the basins and subbasins. Although some results are encouraging, definitive water quality improvements have not been observed during the first three years of monitoring. Possible reasons include: (1) more time is needed to adequately detect changes; (2) the size of the watershed is too large to detect improvements; (3) land use changes are not located in the area of the watershed where they would have greatest effect; or (4) water quality improvements have occurred but have been missed by the project monitoring design. Longer‐term monitoring will allow better evaluation of the impact of restoration activities on water quality.