Atmospheric phenanthrene pollution modulates carbon allocation in red clover (Trifolium pratense L.)

The influence of atmospheric phenanthrene (PHE) exposure (160 μg m⁻³) during one month on carbon allocation in clover was investigated by integrative (plant growth analysis) and instantaneous ¹³CO₂ pulse-labelling approaches. PHE exposure diminished plant growth parameters (relative growth rate and net assimilation rate) and disturbed photosynthesis (carbon assimilation rate and chlorophyll content), leading to a 25% decrease in clover biomass. The root-shoot ratio was significantly enhanced (from 0.32 to 0.44). Photosynthates were identically allocated to leaves while less allocated to stems and roots. PHE exposure had a significant overall effect on the ¹³C partitioning among clover organs as more carbon was retained in leaves at the expense of roots and stems. The findings indicate that PHE decreases root exudation or transfer to symbionts and in leaves, retains carbon in a non-structural form diverting photosynthates away from growth and respiration (emergence of an additional C loss process).     

Sustainable management of transboundary river basins: a line of reasoning

This paper identifies a line of reasoning based on a number of concepts and tools to facilitate river basin management, which have been applied in a case study. For long-term sustainable river basin management, a balance is needed between the human use of the river and its basin, the ecological functioning of the river and receiving waters, and the river's capacity to supply goods and services. To find such a balance a framework is needed that illustrates and clarifies possible trade-offs between economic use and environmental supply by integrating scientific information on cause–effect chains on a catchment scale. A number of concepts and tools are proposed as a basis for this framework. The tools are: (1) indicators that describe the complex interactions and processes in rivers; (2) a suite of linked models that predict the economic, environmental and ecological effect of management measures; (3) an evaluation framework to rank different management alternatives on the basis of three objectives: economic efficiency, spatial equity in costs and benefits and environmental quality of the river and receiving lakes. The concept of environmental quality defines the potential of the river environment (i.e. natural capital) to contribute to human welfare. The concept of environmental functions is used to identify societal interest in natural capital. The concept and tools have been applied in a case study involving the evaluation of four management strategies on nutrient abatement in the Rhine basin. The result of the case study is that economic efficiency is in conflict with spatial equity and environmental quality. Spatial equity is in agreement with environmental quality. Electronic Publication     

Kriging for estimating spatial pattern of contaminants: Potential and problems

This paper discusses and illustrates the use of kriging techniques for estimating the spatial pattern of contaminants in environmental media, particularly soil. The assumptions underlying kriging are reviewed as are some advantages and disadvantages of the method. Lognormal kriging (kriging applied to logarithmic-transformed data) is illustrated using a set of radionuclide soil concentrations at a nuclear testing area on the Nevada Test Site. This example shows how lognormal kriging can be used to estimate average concentrations at points or for blocks of land, concentration contours over space, confidence bands about these contours, and radionuclide inventory in soil. The validity of kriging estimates depends on the accurate estimation and modeling of the spatial correlation structure of the phenomenon. Accuracy is especially important when lognormal kriging is used and estimates of means and their standard deviations are required in the original, untransformed scale. This paper illustrates the bias that can result when a changing correlation structure over space is ignored.Operated for the U.S. Department of Energy by Battelle Memorial InstituteWork supported by Nevada Applied Ecology Group, U.S. Department of Energy, Nevada Operations Office under Contract DE-AC06-76RLO 1830.     

Rethinking groundwater monitoring at the Hanford Site

Groundwater monitoring at Department of Energy's (DOE's) Hanford Site is a large, expensive undertaking serving multiple purposes, including compliance with regulations and DOE orders, remediation efforts under CERCLA, and sitewide risk evaluations. Like most large Federal facilities, the monitoring program currently in place has evolved and grown overtime as new requirements were established and groups were assigned to address them. DOE and its regulators simultaneously awakened to the fact that there was a need to reevaluate the monitoring activities at Hanford, to better integrate the program, to avoid duplicative sampling, to improve everyone's understanding of the performance of the network, and to evaluate whether adequate data could be collected for lower cost. This paper describes the approch that was developed to guide the rethinking effort with direct and extensive involvement of DOE, EPA, Washington Department of Ecology, Indian Tribes, and DOE Contractors, and how this approach was applied to a large portion of the site. Both the human element of the process (cultural change), as well as some of the technical details associated with the effort, including a flexible application of EPA's data quality objectives process, are discussed.     

Acute,chronic and biochemical effects of chlorothalonil on <Emphasis Type="Italic">Agalychnis callidryas</Emphasis>, <Emphasis Type="Italic">Isthmohyla pseudopuma</Emphasis> and <Emphasis Type="Italic">Smilisca baudinii</Emphasis> tadpoles

Declines of amphibian populations have been a worldwide issue of concern for the scientific community during the last several decades. Efforts are being carried out to elucidate factors related to this phenomenon. Among these factors, pathogens, climate change, and environmental pollution have been suggested as possible causes. Regarding environmental pollutants, some pesticides are persistent in the environment and capable of being transported long distances from their release point. In Costa Rica, some pesticides have been detected in protected areas, at locations where amphibian populations have declined. Information about toxicity of pesticides used in Costa Rican agriculture to amphibians is still scarce, particularly for native species.Toxicity tests with chlorothalonil, a fungicide intensively used in Costa Rica, were carried out exposing tadpoles of three Costa Rican native species: Agalychnis callidryas, Isthmohyla pseudopuma, and Smilisca baudinii in order to evaluate acute and chronic toxicity as well as the biomarkers cholinesterase activity (ChE), glutathione-S transferase activity (GST), and lipid peroxidation (LPO).96-h LC₅₀: 26.6 (18.9–35.8) μg/L to A. callidryas, 25.5 (21.3–29.7) μg/L to I pseudopuma and 32.3 (26.3–39.7) μg/L to S. baudinii were determined for chlorothalonil. These three species of anurans are among the most sensitive to chlorothalonil according to the literature. Besides, GST was induced in S. baudinii after exposure to sub-lethal concentrations of chlorothalonil while evisceration occurred in S. baudinii and A. callidryas tadpoles exposed to lethal concentrations of the fungicide. Chronic exposure to sub-lethal concentrations accelerated development in S. baudinii and caused lesions in tail of S. baudinii and I. pseudopuma tadpoles. Our results demonstrate that chlorothalonil is highly toxic to native amphibian species and that low concentrations can cause biochemical responses related to phase II of biotransformation and effects on development.     

Detecting and quantifying male sea urchin spawning with time-integrated fertilization assays

There has been much modeling and experimentation on factors affecting fertilization success in free-spawning marine invertebrates, but for many species spawning has rarely been observed in nature, if at all, and then mostly qualitatively. Understanding the dynamics of spawning and fertilization is especially important for species, such as the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), that have been widely depleted by harvesting. Time-integrated fertilization assays provide measures of sperm-availability adjacent to spawning populations for extended periods and with unprecedented temporal resolution. In such assays unfertilized eggs are held in baskets permeable to sperm and suspended in the water column as long as the eggs remain viable. In a consecutive series of 24- to 72-h assays the time course and spatial extent of sperm availability were measured near an aggregation of 250 sea urchins suspended in a cage at a field site in West Boothbay Harbor, Maine, USA. The assays were conducted in March and April, 2000, the spawning season of the green sea urchin. The distribution of embryonic stages within the assays revealed fine-scale temporal information on the timing of fertilization. The time series of multiple assays indicated that over a substantial portion of the spawning season there was an almost continuous low level of male spawning, a pattern consistent with a slow decline in gonad index observed in both male and female urchins. Fertilization rates averaged only 17% for the eggs in the basket nearest the spawning urchins (20 cm away), and the rates declined sharply over a distance of <1 m. Thus, despite the potential benefits of long egg life in integrating sperm supply over several days, the spatial effects on fertilization success were marked. Owing to the urchins' captivity and the lack of site replication, the generality of the observed spawning pattern must be confirmed. Nonetheless, the method lends itself to wider application among natural populations.     

RECOTOX,a French initiative in ecotoxicology-toxicology to monitor,understand and mitigate the ecotoxicological impacts of pollutants in socioagroecosystems

RECOTOX is a cross-cutting initiative promoting an integrated research to respond to the challenges of monitoring, understanding, and mitigating environmental and health impacts of pesticides in agroecosystems. The added value of RECOTOX is to develop a common culture around spatial ecotoxicology including the whole chain of pressure-exposure-impact, while strengthening an integrated network of in natura specifically equipped sites. In particular, it promotes transversal approaches at relevant socioecological system scales, to capitalize knowledge, expertise, and ongoing research in ecotoxicology and, to a lesser extent, environmental toxicology. Thus, it will open existing research infrastructures in environmental sciences to research programs in ecotoxicology of pesticides.     

Apparent segregation of null alleles ascribed to deletions of the ornithine transcarbamylase gene in congenital hyperammonaemia

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder of the urea cycle mapped to chromosome Xp21.1. Here, we show that apparent segregation of null alleles at the OTC locus and flanking polymorphic loci mimicked false maternity or false paternity in three affected families. Based on these observations, we suggest giving consideration to gene deletion when dealing with segregation of null alleles in OTC deficiency.