Soil arsenic surveys of New Orleans: localized hazards in children’s play areas

Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans soils revealed a median As content of 1.5 mg/kg (range <0.2–16.4) and no distinctive differences between the soils of the city core and outlying areas. Play area accessible soils associated with CCA-treated wood (N = 32) had a median As of 57 mg/kg and 78% of the samples were ≥12 mg/kg, the Louisiana soil As standard. The field survey of play areas for CCA-treated wood (N = 132 samples at 38 sites) was conducted with a portable energy-dispersive X-ray fluorescence (XRF) analyzer. Seventy-five of 132 wood samples (56.8%) were deemed CCA-treated wood. Of the 38 play areas surveyed, 14 (36.8%) had CCA-treated wood. A significant association (Fisher’s exact p-value = 0.348 × 10⁻⁶) was found between CCA-treated wood and soil As (N = 75). At one elementary school CCA-treated woodchips (As range 813–1,654 mg As/kg) covered the playgrounds. The situation in New Orleans probably exists in play areas across the nation. These findings support a precautionary program for testing soils and wood for hazardous substances at all play areas intended for children.     

Leachability of elements from sub-bituminous coal fly ash from India

Environmental concerns regarding the potential contamination of soil, surface and ground water due to the presence of soluble metal species in the ash pond leachate is of great importance. Serial batch leaching was carried out simulating the rainwater condition of the study area to understand the behaviour of elements during leaching. The leachates were analysed for the elements Al, Ca, K, Mg, Na, P, S, Si, As, Ba, Fe, Mn, Mo, Ti, V, Pb, Zn, Co, Cr, Cu, Ni and Cd by inductively coupled plasma optical emission spectrometer (ICP-OES). It was found that Cd, Co, Cr and Ni did not leach from the ash while Cu and Pb concentrations were insignificant in the leachate regardless of liquid to solid (L/S) ratio. Most of the elements showed maximum concentrations at lower L/S ratio and then decreased with increasing L/S. The total cumulative concentrations of As, Mn and Mo were found to be higher than the World Health Organization (WHO) recommended values for drinking water while the concentrations of Fe, Mn and As exceeded the maximum allowable concentrations prescribed by the United States Environmental Protection Agency (USEPA). The pre and the post leached ash samples were analysed for morphology, specific surface area and mineralogical changes. Analysis of post-leached fly ash indicated changes in the specific surface area and morphology but no change in mineralogy.     

Measuring the impact of rehabilitation services on the quality of life of disabled people in Cambodia

The present study aimed to measure the quality of life (QOL) of disabled people in Cambodia and the impact of rehabilitation services. The categories of services were: physical rehabilitation (prosthetics/orthotics with physiotherapy); community-based rehabilitation; and (3) labour market assistance. The 164 respondents were from a range of urban and rural settings. The results suggest that QOL was substantially lower among disabled Cambodians who had received no rehabilitation services compared to those who had received one of the three categories of rehabilitation services. QOL scores tended to be highest, however, among those who had received a combination of all three services. The results also highlighted the vulnerability of certain sub-groups who may need specific provision in planning, policy-making and service delivery. The present study suggests that an integrated approach may be the best way to maximise the impact of individual rehabilitation services in Cambodia.     

Management practice effects on phosphorus losses in runoff in corn production systems

Phosphorus losses in runoff from cropland can contribute to nonpoint-source pollution of surface waters. Management practices in corn (Zea mays L.) production systems may influence P losses. Field experiments with treatments including differing soil test P levels, tillage and manure application combinations, and manure and biosolids application histories were used to assess these management practice effects on P losses. Runoff from simulated rainfall (76 mm h(-1)) was collected from 0.83-m2 areas for 1 h after rainfall initiation and analyzed for dissolved reactive P (DRP), bioavailable P, total P (TP), and sediment. In no-till corn, both DRP concentration and load increased as Bray P1 soil test (STP) increased from 8 to 62 mg kg(-1). A 5-yr history of manure or biosolids application greatly increased STP and DRP concentrations in runoff. The 5-yr manure treatment had higher DRP concentration but lower DRP load than the 5-yr biosolids treatment, probably due to residue accumulation and lower runoff in the manure treatment. Studies of tillage and manure application effects on P losses showed that tillage to incorporate manure generally lowered runoff DRP concentration but increased TP concentration and loads due to increased sediment loss. Management practices have a major influence on P losses in runoff in corn production systems that may overshadow the effects of STP alone. Results from this work, showing that some practices may have opposite effects on DRP vs. TP losses, emphasize the need to design management recommendations to minimize losses of those P forms with the greatest pollution potential.     

The use of cluster sampling to determine aid needs in Grozny, Chechnya in 1995

War broke out in Chechnya in November 1994 following a three-year economic blockade. It caused widespread destruction in the capital Grozny. In April 1995 Medical Relief International--or Merlin, a British medical non-governmental organisation (NGO)--began a programme to provide medical supplies, support health centres, control communicable disease and promote preventive health-care in Grozny. In July 1995 the agency undertook a city-wide needs assessment using a modification of the cluster sampling technique developed by the Expanded Programme on Immunisation. This showed that most people had enough drinking-water, food and fuel but that provision of medical care was inadequate. The survey allowed Merlin to redirect resources earmarked for a clean water programme towards health education and improving primary health-care services. It also showed that rapid assessment by a statistically satisfactory method is both possible and useful in such a situation.     

浅谈污水设施运营的管理现状、发展方向及在云南的实践

通过对污水设施运营的实质内容、污水运营资质许可制度和污水设施运营管理现状及其发展方向的介绍,说明了污水设施运营在环境保护中的重要作用。     

Multimodel inference and adaptive management

Ecology is an inherently complex science coping with correlated variables, nonlinear interactions and multiple scales of pattern and process, making it difficult for experiments to result in clear, strong inference. Natural resource managers, policy makers, and stakeholders rely on science to provide timely and accurate management recommendations. However, the time necessary to untangle the complexities of interactions within ecosystems is often far greater than the time available to make management decisions. One method of coping with this problem is multimodel inference. Multimodel inference assesses uncertainty by calculating likelihoods among multiple competing hypotheses, but multimodel inference results are often equivocal. Despite this, there may be pressure for ecologists to provide management recommendations regardless of the strength of their study's inference. We reviewed papers in the Journal of Wildlife Management (JWM) and the journal Conservation Biology (CB) to quantify the prevalence of multimodel inference approaches, the resulting inference (weak versus strong), and how authors dealt with the uncertainty. Thirty-eight percent and 14%, respectively, of articles in the JWM and CB used multimodel inference approaches. Strong inference was rarely observed, with only 7% of JWM and 20% of CB articles resulting in strong inference. We found the majority of weak inference papers in both journals (59%) gave specific management recommendations. Model selection uncertainty was ignored in most recommendations for management. We suggest that adaptive management is an ideal method to resolve uncertainty when research results in weak inference.     

Experimental measurements and numerical simulations of the transport and retention of nanocrystal CdSe/ZnS quantum dots in saturated porous media: effects of pH,organic ligand,and natural organic matter

Environmental Science and Pollution Research - The risks of environmental exposures of quantum dot (QD) nanoparticles are increasing, but these risks are difficult to assess because fundamental...     

SNCR脱硝技术在循环流化床锅炉上的应用

分析了循环流化床锅炉特性和SNCR烟气脱硝技术的特点,通过CFD计算分析,对烟气和还原剂喷射混合过程进行了研究,得到了较理想的SNCR脱硝流场设计结果。在某75t/h循环流化床锅炉SNCR烟气脱硝工程上的初步应用结果表明,SNCR烟气脱硝效率可达55%以上,系统简捷、性能可靠,是循环流化床锅炉进行NOx控制的理想选择。     

层状半空间中凹陷地形对斜入射平面P波的2.5维散射

采用间接边界元法研究了层状半空间中凹陷地形对斜入射平面P波的2.5维散射问题。取无限长凹陷地形任一横截面,将边界以斜线单元离散,通过自由场反应分析,求得假想边界上各单元的应力响应。施加虚拟移动均布斜线荷载,求得应力格林函数。根据凹陷边界上的零应力边界条件确定虚拟移动均布斜线荷载密度,将自由场响应和虚拟移动均布斜线荷载产生的响应叠加起来,即得到问题的解答。通过与已有结果的对比,验证了本文方法的正确性。最后,以均匀弹性半空间和基岩上单一土层中凹陷地形对斜入射平面P波的2.5维散射为例,进行了数值计算分析,结果表明:凹陷地形的2.5维散射和二维散射之间存在明显差异;层状半空间中凹陷地形和均匀半空间中凹陷地形对波的散射作用存在显著差别。分析了造成差别的原因,并深入讨论了入射角度、覆盖层厚度和刚度对散射作用的影响。