BETR-World: a geographically explicit model of chemical fate: application to transport of alpha-HCH to the Arctic

The Berkeley-Trent (BETR)-World model, a 25 compartment, geographically explicit fugacity-based model is described and applied to evaluate the transport of chemicals from temperate source regions to receptor regions (such as the Arctic). The model was parameterized using GIS and an array of digital data on weather, oceans, freshwater, vegetation and geo-political boundaries. This version of the BETR model framework includes modification of atmospheric degradation rates by seasonally variable hydroxyl radical concentrations and temperature. Degradation rates in all other compartments vary with seasonally changing temperature. Deposition to the deep ocean has been included as a loss mechanism. A case study was undertaken for alpha-HCH. Dynamic emission scenarios were estimated for each of the 25 regions. Predicted environmental concentrations showed good agreement with measured values for the northern regions in air, and fresh and oceanic water and with the results from a previous model of global chemical fate. Potential for long-range transport and deposition to the Arctic region was assessed using a Transfer Efficiency combined with estimated emissions. European regions and the Orient including China have a high potential to contribute alpha-HCH contamination in the Arctic due to high rates of emission in these regions despite low Transfer Efficiencies. Sensitivity analyses reveal that the performance and reliability of the model is strongly influenced by parameters controlling degradation rates.     

The possible origin of Zostera noltii in the Canary Islands and guidelines for restoration

Seagrasses and their habitat are declining worldwide. Zostera noltii in the Canary Islands has been drastically reduced, mainly by anthropogenic disturbance, to three small surviving patches in a single harbor in Lanzarote. A previous genetic study, using neutral microsatellite markers, revealed that these patches consist of a single clonal individual. Here, an assignment test, using microsatellite data, was used to locate the most likely population of origin from a set of possible donor populations. Our results show that the Moulay Bousselham population in northern Morocco is assigned as the most likely population of origin (88%), although the probability of being at one generation time distance is low (2.7%). This result, however, allows locating the most closely related stands that may be the most successful donor populations for future restoration based on shoot or seed transplantation.     

Overstory mortality as an indicator of forest health in California

The interagency Forest Health Monitoring Program involves a network of about 4200 forest plots on a triangular grid across the United States. We present data on recent mortality of trees 27.9 cm diameter from the first three years of measurements in California (1992–1994). Three plot designs were used to collect data representative of a 1-ha stand at each site; the designs differed primarily in total area sampled (0.067, 0.4 and 1.0 ha). Approximately 50 sites were visited each year yielding a total of about 150. Field tallies showed few cases of recent mortality in the smallest plot size. Cumulative distribution functions of recent dead tree densities in the 0.067-ha plots differed significantly from those generated by tallies from entire 1-ha stands. We conclude that an area of 0.067 ha is unsuitable to assess and monitor overstory mortality in Pacific Coast forests.The U.S. government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Spatial and seasonal distribution of nitrate-N in groundwater beneath the rice�Cwheat cropping system of India: a geospatial analysis

Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)?Cwheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO₃-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO₃-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5?C10 mg l^???1) and high (>10 mg l^???1) risk categories, respectively. The results revealed that NO₃-N was 10?C50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r ²?=?0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO₃ ^? enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO₃ in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO₃ enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.     

Rainwater toxicity and contamination study from São Paulo Metropolitan Region, Brazil

Wet deposition is an important process that removes pollutants from the atmosphere and transfers them to waters and soil. The goal of this study was to assess the biological effects of the atmospheric contamination of rainwater in the metropolitan area of São Paulo (MASP) using Daphnia similis, Ceriodaphnia dubia, and Vibrio fischeri. Experimental assays were carried out according to standard toxicity methodology. Twenty-three rainwater samples were collected from October 2007 to December 2008, at the Nuclear Research Institute (IPEN), in MASP. Major ions were determined by ionic chromatography, which showed NH₄ ⁺ and NO₃ ^? as prevalent ions. Ecotoxicological results confirmed toxic potential of rainwater, as all samples were toxic to D. similis and C. dubia. The V. fischeri luminescence reduction confirmed those negative effects of rainwater and percentage inhibition of relative luminescence ranged from 0.2 to 0.9 for 16 samples. Worse conditions were observed during the rainy season, suggesting convective rains are more effective in transferring contaminants and toxicity from atmosphere to surface.     

Examples of the role of analytical chemistry in environmental risk management research

Analytical chemistry is an important tier of environmental protection and has been traditionally linked to compliance and/or exposure monitoring activities for environmental contaminants. The adoption of the risk management paradigm has led to special challenges for analytical chemistry applied to environmental risk analysis. Namely, methods developed for regulated contaminants may not be appropriate and/or applicable to risk management scenarios. This paper contains examples of analytical chemistry applied to risk management challenges broken down by the analytical approach and analyte for some selected work in our laboratory. Specific techniques discussed include stable association complex electrospray mass spectrometry (cESI-MS), gas chromatography-mass spectrometry (GC-MS), split-flow thin cell (SPLITT) fractionation and matrix-assisted laser desorption time of flight mass spectrometry (MALDI-ToF-MS). Specific analytes include haloacetic acids (HAA9), perchlorate, bromate, triazine degradation products, metal-contaminated colloids and Cryptosporidium parvum oocysts.     

Water chemistry in 179 randomly selected Swedish headwater streams related to forest production,clear-felling and climate

From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.     

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 μg L(-1), a linear range from 4 to 400 μg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.     

Effect of Trivalent and Hexavalent Chromium on Carbohydrate Metabolism of a Freshwater Field Crab, Barytelphusa guerini

The in vivo toxic impact of chromium in its two forms(trivalent and hexavalent) on glycogen metabolism in the tissuesof freshwater field crab Barytelphusa guerini was studied.In a sublethal long-term exposure of 30, 60 and 90 days, thedepletion of glycogen and glucose levels reflected in theactivity of glycogenphosphorylases `a' and `ab'. A tissuespecific and time-dependent variation in tissue glucose reservesparelleled the progressive accumulation of haemolymph sugars.Trivalent and hexavalent chromium induced alterations in metabolite levels and in enzyme activities in the tissues. Themagnitude of responses were found more in the hexavalent formthan in trivalent form.