Small wonders, big future: the development of environmental nanotechnology

Nanotechnology--the engineering of atomic-scale devices and systems--is set to become one of the major industries of the 21st century. Environmental applications are emerging as a key area of interest. But alongside the benefits, there are concerns that nanotechnologies could bring new risks to the environment and human health. Are nanotechnologies friend or foe? And how can analysts contribute to the debate?     

Polychlorinated biphenyls in small mammals from contaminated landfill sites

PCBs in small mammals living in a contaminated landfill site varied in both concentration and congener composition, reflecting both the feeding strategy of each species and the chlorination of the congeners. Body concentrations of SigmaPCB on a 1:1:1 Arochlor (1242:1254:1260) basis gave a rank order of Sorex araneus > Apodemus sylvaticus > Microtus agrestis. Comparisons with data for other PCB-contaminated sites suggest that the SigmaPCB values in S. araneus from the landfill site may be of sufficient magnitude to inhibit reproductive capability and to cause other major organ dysfunction. There were also inter-specific differences in the whole body concentrations of the individually quantified congeners. For S. araneus, the rank order of concentrations of the selected ICES 7 marker PCB congeners was: No. 153>138>180>118>28>101>52. In M. agrestis the rank order was: No. 28>118>153>138>180, 52>101. The congener order for A. sylvaticus differed from both S. araneus and M. agrestis, but was more similar to the latter, being: No. 153>138>118>180>28>52, 101. The contribution of the different congeners to SigmaPCB in the mammals reflects the degree of chlorination of different congeners but varies with feeding strategy of the species. In the insectivorous S. araneus, heavily chlorinated congeners (Nos 153, 138 and 180) are most abundant, whereas the herbivore, M. agrestis showed congeners Nos 28 and 118 to be present in the highest amounts, whilst the equivalent pattern for the more omnivorous A. sylvaticus was intermediate between S. araneus and M. agrestis. The high concentrations of PCBs in S. araneus relative to the other species, suggests that it may serve as a useful biomarker of terrestrial environmental pollution by organochlorines.     

PREDICTING BASEFLOW ALKALINITY AS AN INDEX TO EPISODIC STREAM ACIDIFICATION AND FISH PRESENCE1

ABSTRACT: Regression models to predict baseflow alkalinity from basin hydrogeology were developed and verified for headwater streams on the Laurel Hill anticline in southwestern Pennsylvania. Predicted baseflow alkalinities were then used to estimate sensitivity to acidification and presence of trout (Salvelinus fontinalis) populations for 61 headwater streams. Sensitivity classifications were verified by surveying trout populations. Geologic variables relating to the carbonate rock burial depth, extent of carbonate rock recharge areas, and length of stream channel flowing through effluent carbonate rock outcrops were much more useful in predicting baseflow alkalinity than areal extent of carbonate rocks. Baseflow alkalinity was not well related to status of trout populations on these anticlinal basins, especially on noneffluent basins where bedrock dip exceeded surface slope.     

Ammonia volatilization from surface-applied poultry litter under conservation tillage management practices

Land application of poultry litter can provide essential plant nutrients for crop production, but ammonia (NH(3)) volatilization from the litter can be detrimental to the environment. A multiseason study was conducted to quantify NH(3) volatilization rates from surface-applied poultry litter under no-till and paraplowed conservation tillage managements. Litter was applied to supply 90 to 140 kg N ha(-1). Evaluation of NH(3) volatilization was determined using gas concentrations and the flux-gradient gas transport technique using the momentum balance transport coefficient. Ammonia fluxes ranged from 3.3 to 24% of the total N applied during the winter and summer, respectively. Ammonia volatilization was rapid immediately after litter application and stopped within 7 to 8 d. Precipitation of 17 mm essentially halted volatilization, probably by transporting litter N into the soil matrix. Application of poultry to conservation-tilled cropland immediately before rainfall events would reduce N losses to the atmosphere but could also increase NO(3) leaching and runoff to streams and rivers.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

Between resistance and resilience: a study of flood risk management in the Don catchment area (UK)

The river Don catchment area in Sheffield and Rotherham offers a good place for a case study of flood risk management, given the impact of a flooding event in 2007 and the way in which local events have become entwined with national and international policy shifts. To interpret local policy, a combination of systems-based and socio-cultural theory is used. Both the theories and the case study serve to disentangle the multiple meanings of resilience. Understood in opposition to flood resistance, resilience has only limited applicability in an area such as the case study where engineering works protect employment and infrastructure. Resilience as a policy discourse also lacks political transparency and a recognition of socio-cultural influences. Underlying the shift towards resilient styles of management is an appreciation of the importance of capacity, to learn and to act. The case study identifies blockages to the realisation of that capacity.