Influencing factors and a proposed evaluation methodology for predicting groundwater contamination potential from stormwater infiltration activities.

To offset the detrimental effects of urbanization on groundwater recharge, stormwater managers are focusing on infiltrating much of the runoff from a site that was generated because of development. For this to be effective, tools are required to predict the potential for contamination resulting from this infiltration for many site conditions, because infiltration should be stressed in areas where the least potential for causing groundwater contamination exists. Factors that influence contamination potential include the pollutant concentration in the runoff directed to the infiltration device and the ability of the underlying soil to remove the pollutant. The groundwater contamination potential of some pollutants, even those with high concentrations and moderate-to-high mobilities, can be reduced with proper pretreatment before infiltration. This paper presents a methodology that can be used to evaluate infiltration as an management option and introduces two different levels of models that could be used to evaluate contamination potential.     

MODEL PREDICTIONS OF WATERSHED HYDROLOGIC COMPONENTS: COMPARISON AND VERIFICATIION1

ABSTRACT: Model predictions of the relatively simple soil compartment model SESOIL are compared with those of the more data-intensive terrestrial ecosystem hydrology model AGTEHM. Comparisons were performed using data from a deciduous forest stand watershed, a grassland watershed, and two agricultural field plots. Good agreement was obtained between model predictions for annual values of infiltration, evapotranspiration, surface runoff, and groundwater runoff. SESOIL model predictions also compare well with empirical measurements at the forest stand and the grassland watersheds.     

Using Vegetation Analysis to Facilitate the Selection of Conservation Sites in Eastern Paraguay

This study demonstrates the use of vegetation analysis in the selection of priority areas for conservation. The analysis is based on field data derived from narrow rectangular sample plots and includes information from the database of Paraguay's Conservation Data Center. Ten 100-m² sample plots were laid out for each survey site. We compared three sites, Mbaracayú, Tarumá, and Parabel, all forests located in the ecoregion of Selva Central in eastern Paraguay. Subtropical and physiognomically similar, the sites are dominated by a single species, either Sorocea bonplandii or Actinostemon concolor , but differ in species richness. Vegetation analysis permitted us to calculate the total number of species, including liana species, the number of economic plants, and the number of rare, uncommon, and vulnerable species, and thus to quantify the conservation worthiness of the candidate sites. Our study pinpoints Mbaracayú as a mature, resource-rich forest with the highest habitat and plant species diversity and several local endemics. We maintain that it is the area of Paraguay's Selva Central most important for conservation.     

Histopathological alterations in hepatopancreas of Gafrarium divaricatum exposed to xylene, benzene and gear oil-WSF

Gafrarium divaricatum were exposed to xylene (4.25 and 8.50 mg l(-1)), benzene (4.35 and 8.70 mg l(-1)) and gear oil-WSF (1 and 2%) for 30 days. Chronic exposure of clams to the pollutants resulted in loss of bubbling epithelium, reduction in cytoplasm volume and density, fusion of cell membranes and nuclei forming darkly stained area at basal part of the cells. Disintegration of basement membrane due to damaged epithelial cells, disruption of inner lining of tubule, formation of necrotic spaces, separation of epithelial cells from basement membrane, increase in internal luminar area, complete necrosis of epithelial cells as well as occurrence of cell debris in between the tissue were also observed in the clams due to chronic exposure of the toxicants.