In South West England, more than two hundred years of intensive exploitation of metalliferous ore deposits, combined with the natural processes of pedogenesis from mineral-rich parent rocks, has resulted in the creation of a aignificant area of arsenic-contaminated wastes and soils. The scale of arsenic dispersion by natural and anthropogenic processes is such that 722 km(2) of land contains concentrations of arsenic in excess of 110 μg g(-1), more than twice the maximum that might be expected in a normal soil.The general rationale for the clean-up of derelict and contaminated mining sites often includes aesthetic factors and the desirability of preventing the dispersion of contaminants beyond the site boundaries. Only in extreme cases is public health directly invoked as justification for remediation. In South West England, if arsenic constitutes a genuine threat to the public, an increased rate of site remediation would be justified. The primary purpose of this review is to establish whether or not widespread arsenic contamination (principally of soils) has any measurable effects on public health in South West England, and how this might affect current contaminated site remediation policy. The review is based on data from previous research in the region, and other relevant international studies of mining and smelting communities, and other populations exposed to elevated arsenic concentrations. The literature reviewed also includes the determination of the extent and sources of contamination, and pathways between source and man.While the contamination of potable waters in some countries has led to measurable health effects, this scenario has not yet been identified in South West England, and there is little reason to believe that significantly contaminated potable water supplies would escape detection for extended periods of time under the current monitoring regime.In relative terms (based on both globaland local data), one of the most significant links between contaminated soils and humans appears to be contaminated food stuffs. In absolute terms, such exposure is low due to the natural constraints on arsenic uptake by herbage, cereal crops and vegetables, and the food chain does not appear to have been significantly compromised in South West England. Chronic health effects are unlikely as excessive arsenic concentrations in locally grown food crops remain rare.With the problems of confounding medical and social factors, it is not surprising that studies in South West England have failed to identify chronic exposure to arsenic at very low concentrations as a significant health risk. Those studies that indicate otherwise do not stand up to close scrutiny. It appears that the number of additional deaths arising from the widespread arsenic contamination in South West England is small. The relative benefits of a costly statistical study to actually determine the number of additional deaths might be considered minimal, but one major area could benefit from further studies: the sensitivity of certain population sub-...

Evapotranspiration (ET) is a key component limiting groundwater recharge past the root zone in semiarid regions. Vegetation management may alter groundwater recharge if ET is altered due to changes in vegetation type or cover. This study quantifies changes in groundwater recharge following vegetation cover change from native woodland to pasture in a semiarid region of southwest Texas. The Carrizo-Wilcox aquifer is a valuable groundwater resource in this area, where overuse by dependent farming practices has lowered aquifer levels significantly in the last 85 yr. Combining data from short-term (30 mo) monitoring of the changes in soil moisture and long-term (5-30 yr) changes in total soil chloride indicated deep drainage increased slightly where land had been cleared of vegetation. Annual recharge rates below rooting depths (standardized to 155 cm) averaged only 0.72 6 0.2 mm ? yr 21 (mean 6 SE) in areas not cleared of woody vegetation, as estimated by chloride mass balance. Upon clearing, 72% of the total chloride naturally occurring in the soil profile was flushed away within 30 yr, leading to an estimated 2.59 6 1.7 mm ? yr 21 additional recharge. Deep soil moisture in recently cleared land increased by up to 17% during the growing season of wet years (double the average rainfall) but did not increase in dry or normal precipitation years, providing supporting evidence that more water penetrated below the roots under certain environmental conditions. These results demonstrate that brush management can increase recharge by modest, but measurable, amounts depending on site-specific soil characteristics and degree of reduction in vegetation. Resumen La evapotranspiración (ET) es un componente clave que limita la recarga de agua subterránea más allá de la zona radicular en regiones semiáridas. El manejo de la vegetación puede alterar la recarga de las aguas subterráneas si se altera la ET por los cambios en la cubierta o el tipo de vegetación. Este estudio midió los cambios de la recarga del agua subterránea despue´s de los cambios en la cubierta de la vegetación de un bosque nativo a un pastizal en una región semiárida del suroeste de Texas. El acuífero de Carrizo-Wilcox es un recurso valioso de las aguas subterráneas en esta zona, donde el uso excesivo debido a las prácticas dependientes de la agricultura ha bajado significativamente los niveles acuíferos en los últimos 85 añ os. Combinando los datos de seguimiento a corto plazo (30 meses) de los cambios en la humedad del suelo y a largo plazo (5-30 añ os) en los cambios del total del cloruro de suelo indicaron que el drenaje profundo aumentó ligeramente en áreas donde la vegetación se había aclarado. Las tasas anuales de recarga debajo de la profundidad de la raíz (estandarizado a 155 cm) promedió sólo 0.72 6 0.2 mm ? añ o 21 en áreas no esclarecidas de vegetación leñ osa, estimado por el balance de masa de cloruro. Despue´s del aclareo el 72% del total del cloruro que ocurre naturalmente en el perfil del suelo fue removido entre 30 añ os, conduciendo a una estim...

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