Comparison of manufactured and black carbon nanoparticle concentrations in aquatic sediments

In this paper, we show that concentrations of manufactured carbon-based nanoparticles (MCNPs) in aquatic sediments will be negligible compared to levels of black carbon nanoparticles (BCNPs). This is concluded from model calculations accounting for MCNP sedimentation fluxes, removal rates due to aggregation or degradation, and MCNP burial in deeper sediment layers. The resultant steady state MCNP levels are compared with BCNP levels calculated from soot levels in sediments and weight fractions of nanosized fractions of these soot particles. MCNP/BCNP ratios range from 10⁻⁷ to 10⁻⁴ (w:w). This suggests that the often acclaimed effect of MCNPs on organic pollutant binding and bioavailability will likely be below the level of detection if natural BCNPs are present, even if binding to MCNP is one to two orders of magnitude stronger than to BCNPs. Furthermore, exposure and toxic effects of MCNPs in sediments and soils will be negligible compared to that of BCNPs.     

建设项目竣工环境保护验收监测在环境管理中的任务与对策

建设项目竣工环境保护验收监测对于落实“三同时”制度、实现总量控制目标、为环境监督管理提供重要技术支持具有重要意义与作用。目前,验收监测在管理体制、收费标准、成果应用等方面存在的突出问题,可通过创新管理机制、健全管理制度、提高管理水平等具体措施解决。     

活性炭在膜生物反应器中的应用研究进展

活性炭是一种非常优良的吸附剂,具有物理吸附和化学吸附的双重特性。本文介绍了近年来向膜生物反应器中投加活性炭的应用研究进展,表明投加活性炭可以提高膜生物反应器的处理效果,同时对改善膜污染有很好的效果。     

Development and Use of a Sedimentation Risk Index for Unpaved Road‐Stream Crossings in the Choctawhatchee Watershed1

Abstract: Unpaved road‐stream crossings increase sediment yields in streams and alter channel morphology and stability. Before restoration and sedimentation reduction strategies can be implemented, a priority listing of unpaved road‐stream crossings must be created. The objectives of this study were to develop a sedimentation risk index (SRI) for unpaved road‐stream crossings and to prioritize 125 sites in the Choctawhatchee watershed (southeastern Alabama) using this model. Field surveys involved qualitative and quantitative observations of 73 metrics related to waterway conditions, crossing structures, road approaches, and roadside soil erosion. The road‐stream crossing risk analyses involved elimination of candidate metrics based on redundancy, skewness, lack of data, professional judgment, lack of nonzero values, unbalanced box plots, and limited ranges of values. A final selection of 12 metrics formed the SRI and weighed factors involving soil erodibility, road sedimentation abatement features, and stream morphology alteration. The SRI was organized into narrative categories (excellent, good, fair, poor, and very poor) based on the distribution of scores. No excellent sites (scores ≥55) were found in this study, 17 (20.7%) were good (low sedimentation risk), 37 (45.1%) were fair (moderate sedimentation risk), 26 (31.7%) were poor (high sedimentation risk), and two (2.5%) were very poor (high sedimentation risk). There was no significant difference in SRI scores among crossing structure type (round culverts, box culverts, and bridges) (H = 4.31, df = 2, p = 0.058). A future study of the Choctawhatchee watershed involving the same study sites could assess the success of restoration plans and activities based on site score improvement or decline.     

Development of a Quantitative Pasture Phosphorus Management Tool Using the SWAT Model1

Abstract: Assessment tools to evaluate phosphorus loss from agricultural lands allow conservation planners to evaluate the impact of management decisions on water quality. Available tools to predict phosphorus loss from agricultural fields are either: (1) qualitative indices with limited applicability to address offsite water quality standards, or (2) models which are prohibitively complex for application by most conservation planners. The purpose of this research was to develop a simple interface for a comprehensive hydrologic/water quality model to allow its usage by farmers and conservation planners. The Pasture Phosphorus Management (PPM) Calculator was developed to predict average annual phosphorus (P) losses from pastures under a variety of field conditions and management options. PPM Calculator is a vastly simplified interface for the Soil and Water Assessment Tool (SWAT) model that requires no knowledge of SWAT by the user. PPM Calculator was validated using 33 months of data on four pasture fields in northwestern Arkansas. This tool has been extensively applied in the Lake Eucha/Spavinaw Basin in northeastern Oklahoma and northwestern Arkansas. PPM Calculator allows conservation planners to take advantage of the predictive capacity of a comprehensive hydrologic water quality model typically reserved for use by hydrologists and engineers. This research demonstrates the applicability of existing water quality models in the development of user friendly P management tools.     

A Multilevel Model of the Impact of Farm‐Level Best Management Practices on Phosphorus Runoff1

Abstract: Multilevel or hierarchical models have been applied for a number of years in the social sciences but only relatively recently in the environmental sciences. These models can be developed in either a frequentist or Bayesian context and have similarities to other methods such as empirical Bayes analysis and random coefficients regression. In essence, multilevel models take advantage of the hierarchical structure that exists in many multivariate datasets; for example, water quality measurements may be taken from individual lakes, lakes are located in various climatic zones, lakes may be natural or man‐made, and so on. The groups, or levels, may effectively yield different responses or behaviors (e.g., nutrient load response in lakes) that often make retaining group membership more effective when developing a predictive model than when working with either all of the data together or working separately with the individuals. Here, we develop a multilevel model of the impact of farm level best management practices (BMPs) on phosphorus runoff. The result of this research is a model with parameters which vary with key practice categories and thus may be used to evaluate the effectiveness of these practices on phosphorus runoff. For example, it was found that the effect of fertilizer application rate on farm‐scale phosphorus loss is a function of the application method, the hydrologic soil group, and the land use (crop type). Further, results indicate that the most effective method for controlling fertilizer loss is through soil injection. In summary, the resultant multilevel model can be used to estimate phosphorus loss from farms and hence serve as a useful tool for BMP selection.     

Role of Alternative Electron Acceptors (AEA) to control methane flux from waterlogged paddy fields: Case studies in the southern part of West Bengal, India

The rice fields, depleted of O₂, contain large amount of moisture and organic substrates to provide an ideal anaerobic environment for methanogenesis and are one of the principal anthropogenic sources of methane. In order to mitigate this emission Alternative Electron Acceptors (AEA) were altered in the soil. The experiments were carried out in four seasons at the site of Balarampur, near Baruipur, South 24 Parganas, West Bengal, namely September–December, 2005 (Cultivar: Sundari), February–May, 2006 (Cultivar: Sundari), September–December, 2006 and February–May, 2007 (Cultivar: Swarna-Pankaj). The seasonal average methane flux (Fe treated), for the cultivar type “Sundari” (season: September–December, 2005), is 4.41 t ha⁻¹, as compared to the value of 6.40 t ha⁻¹ for the untreated soil. Similarly for February–May, 2006, the seasonal average methane flux (Fe treated) is 5.52 t ha⁻¹, whereas the untreated flux is 5.69 t ha⁻¹. In the third and fourth seasons we had two treatments with Ammonium Thiosulphate and Ferric Hydroxide. The seasonal average methane flux (treatment: Ammonium Thiosulphate) is 4.35 t ha⁻¹ and 5.41 t ha⁻¹ respectively, whereas for the ferric hydroxide treated soil it is 4.35 t ha⁻¹ and 6.14 t ha⁻¹ respectively. The properties related to the nutrient quality of the harvested paddy seeds supplement these results.     

Ru/γ-Al_2O_3和Ru/AC催化剂的制备及其对氨氧化反应的催化性能

分别以γ-Al_2O_3和活性炭(AC)为载体,采用浸渍法制备了Ru质量分数均为2.0%的Ru/γ-Al_2O_3和Ru/AC催化剂,并用X射线衍射仪和透射电子显微镜等方法对催化剂结构进行了表征.实验结果表明:Ru/AC中Ru沉积在AC表面,分散度较低;而Ru/γ-Al_2O_3中Ru进入到γ-Al_2O_3内部,形成了一种高度分散体系.Ru/γ-Al_2O_3对氨的催化活性高于Ru/AC,氨在Ru/γ-Al_2O_3和Ru/AC上的起活温度分别为200 ℃和266 ℃,T_(90)(氨去除率达90%时的反应温度)分别为267℃和320 ℃.随混合气体空速增大,Ru/γ-Al_2O_3催化剂的T_(90)逐渐升高,气体空速分别为3 600,4 800,5 400 h~(-1)时,T_(90)分别为235,266,303 ℃.随反应前混合气体中氨质量分数增加,氨的去除率降低.     

江河水源地突发性水污染事故风险评价

近年来,我国江河饮用水水源地突发性水质污染事故频发,成为我国面临的最严重的环境问题之一.江河水源地突发性水质污染事件的风险评价是确保饮用水源地水质安全的重要手段,对突发性水质污染事故,采取适当的应急处理措施.     

浅谈如何做好企业安全管理工作

从现代安全理论的角度,论述企业安全管理工作的主要内容、重点工作方面安全管理不到位可能发生的事故后果,以期达到保证企业的安全生产的目的。