Atrazine dissipation in s-triazine-adapted and nonadapted soil from Colorado and Mississippi: implications of enhanced degradation on atrazine fate and transport parameters

Soil bacteria have developed novel metabolic abilities resulting in enhanced atrazine degradation. Consequently, there is a need to evaluate the effects of enhanced degradation on parameters used to model atrazine fate and transport. The objectives of this study were (i) to screen Colorado (CO) and Mississippi (MS) atrazine-adapted and non-adapted soil for genes that code for enzymes able to rapidly catabolize atrazine and (ii) to compare atrazine persistence, Q(10), beta, and metabolite profiles between adapted and non-adapted soils. The atzABC and/or trzN genes were detected only in adapted soil. Atrazine's average half-life in adapted soil was 10-fold lower than that of the non-adapted soil and 18-fold lower than the USEPA estimate of 3 to 4 mo. Q(10) was greater in adapted soil. No difference in beta was observed between soils. The accumulation and persistence of mono-N-dealkylated metabolites was lower in adapted soil; conversely, under suboptimal moisture levels in CO adapted soil, hydroxyatrazine concentrations exceeded 30% of the parent compounds' initial mass. Results indicate that (i) enhanced atrazine degradation and atzABC and/or trzN genes are likely widespread across the Western and Southern corn-growing regions of the USA; (ii) persistence of atrazine and its mono-N-dealkylated metabolites is significantly reduced in adapted soil; (iii) hydroxyatrazine can be a major degradation product in adapted soil; and (iv) fate, transport, and risk assessment models that assume historic atrazine degradation pathways and persistence estimates will likely overpredict the compounds' transport potential in adapted soil.     

Polybrominated diphenyl ethers (PBDE) in serum: findings from a US cohort of consumers of sport-caught fish

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in foams, fabrics and plastics, and are common contaminants of household air and dust and bioaccumulate in wildlife, and are detectable in human tissues and in fish and animal food products. In the Great Lakes Basin sport fish consumption has been demonstrated to be an important source of PCB and DDE exposure. PBDEs are present in the same sport fish but prior to our study the contribution to human PBDE body burdens from Great Lakes sport fish consumption had not been investigated. This study was designed to assess PBDE, PCB and 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE) serum concentrations in an existing cohort of 508 frequent and infrequent consumers of sport-caught fish living in five Great Lake states. BDE congeners 47 and 99 were identified in the majority of blood samples, 98% and 62% respectively. summation operatorPBDE levels were positively associated with age, hours spent outdoors, DDE, summation operatorPCB, years of sportfish consumption, and catfish and shellfish intake, and negatively associated with income and recent weight loss. Other dietary components collected were not predictive of measured summation operatorPBDE levels. In multivariate models, summation operatorPBDE levels were positively associated with age, years consuming sport fish, shellfish meals, and computer use and negatively associated with recent weight loss. Having summation operatorPBDE levels in the highest quintile was independently associated with older age, male gender, consumption of catfish and shellfish, computer use and spending less time indoors. summation operatorPCB and DDE were strongly associated suggesting common exposure routes. The association between summation operatorPBDE and summation operatorPCB or DDE was much weaker and modeling suggested more diverse PBDE sources with few identified multi-contaminant-shared exposure routes. In our cohort Great Lakes sport fish consumption does not contribute strongly to PBDE exposure.     

Municipal solid waste management challenges in developing countries--Kenyan case study

This paper provides an overview of the state of municipal solid waste management (MSWM) by local authorities in Kenya as a case study of a low-income developing country. Approaches of possible solutions that can be undertaken to improve municipal solid waste (MSW) services are discussed. Poor economic growth (1.1% in 1993) has resulted in an increase in the poverty level which presently stands at 56%. Migration from the rural areas to the urban areas has resulted in unplanned settlements in suburban areas accommodating about 60% of the urban population on only 5% urban land area. Political interference also hampers smooth running of local authorities. Vulnerability of pollution of surface and groundwater is high because local authorities rarely considered environmental impact in siting MSW disposal sites. Illegal dumping of MSW on the river banks or on the roadside poses environmental and economic threats on nearby properties. Poor servicing of MSW collection vehicles, poor state of infrastructure and the lack of adequate funding militate against optimization of MSW disposal service. The rural economy needs to be improved if rural-urban migration is to be managed. Involvement of stakeholders is important to achieve any meaningful and sustainable MSWM. The role of the informal sector through community-based organizations (CBOs), Non-Governmental Organizations (NGOs) and the private sector in offering solutions towards improvement of MSWM also is explored.     

Long-distance GM pollen movement of creeping bentgrass using modeled wind trajectory analysis.

The importance of understanding the role of atmospheric conditions in pollen dispersal has grown in recent years with increased field-testing of genetically modified (GM) crop plants. An atmospheric model was used to characterize wind trajectories at 10 m and 100 m above GM pollen source fields located within a 4452-ha "control" area north of Madras, Oregon, USA, designated by the Oregon Department of Agriculture (ODA). The area was used in 2003 for the growth of GM creeping bentgrass (Agrostis stolonifera) engineered to be resistant to glyphosate herbicide. The presence of the GM gene (CP4 EPSPS) provided a distinct selectable marker for pollen-mediated gene flow to sentinel and resident Agrostis spp. plants. Linkage of GM gene presence with wind flow characteristics over the "control" area became essential to understand the timing and processes leading to long-distance transport of this pollen. Wind trajectories showed a general pattern of northwest to southeast air movement. Trajectory travel distances calculated hourly from 06:00 hours to 15:00 hours during the 2003 pollination period (15 June-15 July) showed movement up to 15 km from the "control" area's center by the first hour. Maximum travel distances increased to 40 and 55 km after two and three hours from release, respectively. Calculated wind trajectory positions corresponded with observed long-distance pollen-mediated gene flow in the seedlings of sentinel and resident plants. The highest correlations were found during the late morning hours. Back-calculated wind trajectories from sentinel and resident locations with GM-gene-positive progeny suggested that most successful fertilizations occurred in the direction of prevailing winds during late June 2003. The occurrence of positive progeny from sentinel plants, upwind of the "control" area during this period, indicated the additional influence of local topography on pollen dispersal.     

Use of statistical methods in industrial water pollution control regulations in the United States

This paper describes the process for developing regulations limiting the discharge of pollutants from industrial sources into the waters of the United States. The process includies and surveys of the industry to define products, processes, wastewater sources and characteristics, appropriate subcategorization and control technologies in use. Limitations on the amounts of pollutants that may be discharged in treated wastewater are based on statistical analysis of physical and chemical analytical data characterizing the performance capability of technologies in use in the industry. A general discussion of the statistical approach employed is provided along with some examples based on work performed to support recently promulgated regulations. The determination of regulatory discharge limitations, based on estimates of percentiles of lognormal distributions of measured pollutant concentrations in treated wastewater, is presented. Modifications to account for different averaging periods and detection limit observations are discussed.     

A NUMERICAL ESTUARINE FLOW MODEL1

A novel estuarine flow model is proposed. It provides some two-dimensional features while using an essentially one-dimensional approach. The model is applied to the Upper Delaware Estuary, and is shown to match available field data with acceptable accuracy. The model is shown to be numerically stable and reasonably mass conservative.     

AGRICULTURAL CONSERVATION PROGRAM: AN EVALUATION1

The Agricultural Conservation Program (ACP), is undergoing a new, rigorous evaluation to determine its effectiveness in conserving the Nation's agricultural soils and waters. ACP deals with many types of conservation practices, but the focus here is on the evaluation of soil and water related practices. ACP has depended heavily on the State and private forestry services, Soil Conservation Service, and the Cooperative Extension Services, for technical expertise. Thus, the process is an evaluation of the effectiveness of a “team of agencies,” as well as of the program itself. Results of the evaluation have helped to develop new thrusts which have moved ACP further into the position of treating the total conservation problem. Phase I has its limitations. It did not address the impact of wind erosion, water quality, change in productive capacity, soil quality, wildlife habitat, off site and farm income impacts. It does show that ACP has and is doing a very good job in meeting its stated purposes. It is clear that ACP's effectiveness can be improved with more and better advanced planning and more intensive use of soil maps, the USLE, and other scientific tools. ACP is headed in this direction.     

Using Information on Spatial Variability of Small Estuaries in Designing Large-Scale Estuarine Monitoring Programs

In the early 1990s, EPA's Environmental Monitoring and Assessment Program (EMAP) documented the ecological condition of the overall population of small estuaries along the mid-Atlantic coast of the United States. However, the Program did not provide detailed information on the condition of individual estuaries less than 260 km² in surface area, a group of estuaries of concern to environmental managers. To address the needs of environmental managers, when EMAP returned to the region in summer 1997, it included a study of the spatial variability of ecological indicators within individual small estuaries. At 127 probability-based sites in 10 estuaries, EMAP measured a variety of parameters of water quality and sediments, including dissolved oxygen (DO), nutrients, grain size of sediments, contaminants in sediments, and community structures of benthic macroinvertebrates. From this information the ecological condition (e.g., percent area with DO concentrations below 5mg L^–1) for each estuary, along with 90% confidence interval, was determined. The width of the confidence interval was then recalculated for sample sizes ranging from two stations to the total number of stations sampled in that estuary. Confidence interval widths were then plotted against sample size. These plots can be useful in designing future regional monitoring programs with a goal of describing conditions in individual systems as well as broad geographic regions. Results illustrate that beyond five stations per estuary, the reduction in the width of the confidence interval with increasing sampling intensity is relatively small; however, individual program managers need to determine "how small is small enough."     

Scientific barriers

Whatever the appeal of extreme integrism or holism, science is necessarily more utilist and partial. We can only address our environmental problems scientifically if we identify the most pressing and attack them first. To do so, we must break with the monistic ideals and traditions of both theoretical and mechanistic ecology to pursue particular solutions instead of global models. Statistical analysis of empirically identified patterns has proven effective in providing such solutions, perhaps because empirical patterns are less valueladen than theoretical or mechanistic alternatives or because such patterns are closer to experience and easier to understand. Unfortunately, such simple analyses are often less valued by leading ecologists who seek intellectual content rather than predictive power and practicality. To overcome this barrier to actionable information, the body of scientists must reaffirm their commitment to environmental action through their work as journal referees, grant reviewers, scientific critics and teachers.