松花江流域生物完整性时空变化分析

采用大型底栖动物生物完整性指数(B-IBI)法对松花江流域的水生态环境质量进行研究分析。结果表明,2015年松花江流域各点位水生态环境质量17.24%为优、10.34%为良好、24.14%为一般、41.38%为较差、6.90%为很差。与2012年松花江流域水生态环境质量的比较和趋势分析表明,松花江干流下游、第二松花江、松花江支流的水生态质量均出现不同程度的改善,松花江干流下游改善尤为显著,松花江干流上游生态质量基本保持不变,嫩江水生态质量有下降迹象。流域总体水生态环境质量得到进一步改善,总物种数和清洁指示类群EPT丰度均有增加。     

Effect of the ecological water conveyance project on environment in the Lower Tarim River, Xinjiang, China

The dynamic response of groundwater level is examined in traverse and lengthways directions. Take the Yinsu section for an example, we have simulated groundwater levels before and after water-conveyance every time and calculated the incidence of groundwater on the both sides of the river. It is noted that the effect keeps growing with the water-delivery times increasing, from 570 m after the first times to 3,334 m after the eighth times. In addition, this paper involves the temporal response of the natural vegetation to water conveyance, vegetation coverage, planted-species number, dominant position and species diversity from 2002 to 2006. The findings indicate that the positive influence of ecological water conveyance project (EWCP) on the ecosystem in the Lower Tarim River is a long-term process. In this paper, we try to calculate water required for recovery of damaged ecosystem by using data available. This project is likely the base of research on water demand and the reference of measures for research on ecological water conveyance effect.     

Nitrogen enrichment in runoff sediments as affected by soil texture in Beijing mountain area

Enrichment ratio (ER) is widely used in nonpoint source pollution models to estimate the nutrient loss associated with soil erosion. The objective of this study was to determine the ER of total nitrogen (ER_N) in the sediments eroded from the typical soils with varying soil textures in Beijing mountain area. Each of the four soils was packed into a 40 by 30 by 15 cm soil pan and received 40-min simulated rainfalls at the intensity of 90 mm h^?1 on five slopes. ER_N for most sediments were above unity, indicating the common occurrence of nitrogen enrichment accompanied with soil erosion in Beijing mountain area. Soil texture was not the only factor that influenced N enrichment in this experiment since the ER_N for the two fine-textured soils were not always lower. Soil properties such as soil structure might exert a more important influence in some circumstances. The selective erosion of clay particles was the main reason for N enrichment, as implied by the significant positive correlation between the ER of total nitrogen and clay fraction in eroded sediments. Significant regression equations between ER_N and sediment yield were obtained for two pairs of soils, which were artificially categorized by soil texture. The one for fine-textured soils had greater intercept and more negative slope. Thus, the initially higher ER_N would be lower than that for the other two soils with coarser texture once the sediment yield exceeded 629 kg ha^?1.     

灰色模型理论在环境空气质量趋势分析中的应用

根据泰州市保护局公布的2006 ～ 2010泰州市环境空气的监测数据,利用灰色系统GM(1,1)残差修正模型,分析预测未来5年的环境空气质量.预测结果显示,泰州市未来5年环境空气质量将持续好转,这表明,泰州市近年来采取的产业结构调整和清洁能源战略实施卓有成效.     

Role of cosubstrate and bioaccessibility played in the enhanced anaerobic biodegradation of organochlorine pesticides (OCPs) in a paddy soil by nitrate and methyl-β-cyclodextrin amendments

The present study was conducted to investigate the anaerobic biodegradation potential of biostimulation by nitrate (KNO₃) and methyl-β-cyclodextrin (MCD) addition on an aged organochlorine pesticide (OCP)-contaminated paddy soil. After 180 days of incubation, total OCP biodegradation was highest in soil receiving the addition of nitrate and MCD simultaneously and then followed by nitrate addition, MCD addition, and control. The highest biodegradation of chlordanes, hexachlorocyclohexanes, endosulfans, and total OCPs was 74.3, 63.5, 51.2, and 65.1 %, respectively. Meanwhile, MCD addition significantly increased OCP bioaccessibility (p?<?0.05) evaluated by Tenax TA extraction and a three-compartment model method. Moreover, the addition of nitrate and MCD also obtained the highest values of soil microbial activities, including soil microbial biomass carbon and nitrogen, ATP production, denitrifying bacteria count, and nitrate reductase activity. Such similar trend between OCP biodegradation and soil-denitrifying activities suggests a close relationship between OCP biodegradation and N cycling and the indirect/direct involvement of soil microorganisms, especially denitrifying microorganisms in the anaerobic biodegradation of OCPs.     

Integration of cerium chemical forms and subcellular distribution to understand cerium tolerance mechanism in the rice seedlings

Environmental Science and Pollution Research - Rare earth elements (REEs) accumulate in the soil and ecosystem. Cerium (Ce) is one of the main additives in REE-containing fertilizers. However,...     

Effects of leachate accumulation on landfill stability in humid regions of China

Leachate levels are important to landfill stability and safety. High leachate or water levels often lead to landfill instability, which can cause accidents. Here a case study of a landfill located in a humid region of southern China is presented. Leachate distribution and quality were systematically analyzed, and the effect of leachate level on waste-mass stability was assessed. Boreholes were drilled in the field, samples were analyzed in the laboratory, and a simulation was performed. In addition, the safety and stability of the landfill was evaluated. The leachate level in the landfill was 9–19 m, which was higher than the top of the dam crest (8–20 m). Leachate accounted for more than 1/4 of the total landfill storage capacity. The contaminant concentration of the leachate samples collected directly from the waste body was very high, with large variation among the samples. The mean concentrations of NH₃–N, BOD, and COD from the waste body were 5404, 14,136, and 22,691 mg/L, nearly 2.7, 2.4, and 1.8 times the mean concentrations in the leachate pond, respectively. Three series of shear strength parameters were used in a slope stability analysis, and a limit equilibrium method was used to calculate the factor of safety (Fs). The analysis showed that Fs could be affected by potential anisotropy in the shear strength of the waste. The minimum values of Fs corresponding to series I were 1.84 and 1.17 for units ? and II, respectively. The Fs value of unit II was significantly lower than the safe design value (1.25). In addition, Fs decreased with increase in the normalized height of the leachate level, h/H, where h is the height of the leachate mound and H is the maximum thickness of the landfill. If the h/H values of units I and II are kept below 50% and 40%, respectively, a safe design value of 1.25 for Fs can be guaranteed. Therefore, some measures to prevent risk should be considered.     

Optimization of hydrogen distribution systems with pressure constraints

Hydrogenation units are often operated at high pressure, requiring the use of compressors which are one of the most expensive chemical processing equipment. Optimizing a hydrogen network should therefore take into consideration not only purity and flowrate constraints but also pressure requirements. In this paper, based on the hydrogen surplus diagram approach, the average pressure profiles of hydrogen sources and sinks are proposed through the introduction of a system’s minimum pressure drop Δp. Combined with the traditional purity profiles, whether a source can meet a sink either for hydrogen concentration or for pressure requirements can be determined intuitively. In cases where the pressure of a source is not sufficient for a sink, installing a hydrogen compressor or using another source with higher purity and pressure could be potential solutions. A cost equation is established to determine which of the two solutions is economically more viable. For different matching situations between sources and sinks, strategies for optimum placement of compression equipment within a given hydrogen network are proposed. A case study is used to illustrate the application and effectiveness of the proposed method.     

试用模糊数学方法对电焊作业防护措施进行综合评价

选择北京市四家锅炉厂的电焊工５６名，即从事手把焊、氩弧焊、ＣＯ２气体保护焊、电弧气爆等特种工种作业人员。通过调查，提出单项四级评分标准，再依模糊数学模型，进行综合评价。按Ｂ＝Ａ·Ｒ，求得Ｂ中最大元为０．７０７。最后总评为甲级。此结果与权数分配有关。此方法，可为劳动卫生管理（防护措施评级）提供依据。     

钻井废水的处理

本文针对钻井废水的处理，综述了现有的处理方法、处理药剂以及处理装置，并对钻井废水的处理、排放提出了一些意见和建议。