Addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. Generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single-well experiment, dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased 1-2 orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from < 0.1 to > 25 nmol L(-1) hr(-1). A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 d(-1). Although collateral impacts such as reduced permeability were observed, overall results indicated the viability of manipulating biogeochemical processes to promote contaminant sequestration.

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Recent debates have suggested that increasing social diversity within Western economies is associated with adverse social consequences such as loss of community and decline of civic society, including an erosion of collective efficacy (ie shared expectations of and mutual engagement by residents in social control). In the UK and US, these debates have been given impetus by concerns about the effects of growing ethnic heterogeneity on community life. Here there is an assumption that heterogeneity undermines social cohesion and makes the established population less willing to share resources, trust fellow citizens, so that it eventually`hunkers down' and withdraws from collective life. To date there are few studies that have examined this in detail across England at the small-area level. The research presented here explores this terrain by exploiting information from the British Crime Survey on two recognised dimensions of collective efficacy: namely, social cohesion and trust, and informal social control. Multivariate, multilevel models were used to determine the importance of individual and area characteristics in the possible explanation of these outcomes, and particular attention was paid to the relative importance of neighbourhood disadvantage over and above neighbourhood diversity. Results suggest that both diversity and disadvantage are statistically associated with reduced levels of social cohesion and trust, and informal social control, but greater substantive importance is attached to neighbourhood disadvantage.