不同覆盖材料对沉积物P、N释放的抑制效果

以百花湖沉积物为实验对象,选取沸石、粘土、生物炭、褐铁矿和高岭土等5种覆盖材料开展模拟柱静态实验,研究上覆水中总氮(TN)、总磷(TP)和氨氮变化规律。在静态模拟柱90 d实验过程中,第45天时上覆水中TN、氨氮浓度最高,分别为8.79和6.10 mg/L。第45天时氨氮浓度最低的是生物炭组,为1.62 mg/L, 第45天时TN浓度最低的是粘土组,为1.92 mg/L。第45天后上覆水TN、氨氮浓度下降,实验结束时生物炭组TN和氨氮浓度均最低,其浓度分别为0.74和0.42 mg/L。实验过程中TP浓度不断上升,到实验结束时空白组TP浓度0.42 mg/L,高岭土组TP浓度最低为0.027 mg/L。百花湖水质主要超标指标为TP,而高岭土覆盖对沉积物中P释放的抑制优于其他4种材料,且在百花湖地区易获得、无污染,故建议以高岭土为百花湖原位覆盖材料。     

厌氧氨氧化颗粒污泥EPS的作用、成分及影响因素研究进展

厌氧氨氧化是一种新型自养生物脱氮反应,具有节能、脱氮负荷高、无需外加碳源、污泥产生量小等优势,因而对低碳高氮废水的处理具有应用价值。然而,厌氧氨氧化菌生长速率低,常通过污泥颗粒化提升反应器的生物量。胞外聚合物(EPS)在颗粒污泥的形成和稳定方面起着至关重要的作用。为此,综述了EPS在anammox颗粒形成过程中,促进污泥聚集和维持稳定的作用,并阐明了EPS主次要成分及作用,分析了anammox颗粒污泥自身粒径大小、水质条件(有机物、氮浓度和负荷),以及外加介体(矿物质或金属离子等)对EPS含量及成分的影响,并提出未来应在anammox颗粒污泥EPS结构和成分的微观解析、强化EPS分泌以促进颗粒污泥快速形成等方面进一步开展研究,旨在为anammox颗粒污泥的大规模工程化应用提供参考。     

External benefits of environmental regulation: Resource recovery and the utilisation of effluents

Summary Since 1977, stringent environmental regulation has been progressively imposed on Malaysia's most polluting industry, the palm oil mills. The impact of the regulation on international trade and producer welfare has been quite small compared to the relative benefits to society in terms of changes in the levels of dissolved oxygen in the industrial effluents. External benefits from pollution abatement have been derived. This paper presents a preliminary evaluation of the derived benefits which have a long- term potential of recycling valuable resources while maintaining competitiveness in the international palm oil trade.Dr Khalid Abdul Rahim is a member of faculty in the Department of Natural Resource Economics at the Universiti Pertanian Malaysia. Wan Mustafa Wan Ali is a research assistant in the Department. This paper is based on part of the "Intensification of Research in Priority Areas" (IRPA) project 1991–95, funded by the Government of Malaysia.     

湘西沅麻盆地的干旱与对策

笔者以无雨日数、旱期内降水量和干旱对农业生产的影响确定干旱等级指标,分析了沅麻盆地干旱的特征,特别指出当地干旱频率在加快、旱区在扩大。文中的观点可供湘西山区开发,乃至我国东部亚热带丘陵山区开发参考。     

Mercury in dental amalgam: Are our health care workers at risk?

Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann–Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann–Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612–64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

Implications: Exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers. Nationwide chronic mercury exposure among dental personnel was assessed through urinary mercury levels. Findings suggest low urinary mercury levels of these health care workers. Exposure to dental amalgam is not associated with high mercury exposure. However, the usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.     

Bioremediation of diesel-contaminated soil with composting

The major objective of this research was to find the appropriate mix ratio of organic amendments for enhancing diesel oil degradation during contaminated soil composting. Sewage sludge or compost was added as an amendment for supplementing organic matter for composting of contaminated soil. The ratios of contaminated soil to organic amendments were 1:0.1, 1:0.3, 1:0.5, and 1:1 as wet weight basis. Target contaminant of this research was diesel oil, which was spiked at 10,000 mg/kg sample on a dry weight basis. The degradation of diesel oil was significantly enhanced by the addition of these organic amendments relative to straight soil. Degradation rates of total petroleum hydrocarbons (TPH) and n-alkanes were the greatest at the ratio of 1:0.5 of contaminated soil to organic amendments on wet weight basis. Preferential degradation of n-alkanes over TPH was observed regardless of the kind and the amount of organic amendments. The first order degradation constant of n-alkanes was about twice TPH degradation constant. Normal alkanes could be divided in two groups (C10-C15 versus C16-C20) based on the first order kinetic constant. Volatilization loss of TPH was only about 2% of initial TPH. Normal alkanes lost by volatilization were mainly by the compounds of C10 to C16. High correlations (r=0.80-0.86) were found among TPH degradation rate, amount of CO2 evolved, and dehydrogenase activity.     

青藏高原及邻近区域的大震危险性分析和探讨

用青藏高原及周边区域的历史地震和近代地震的分布特征来分析本区域的地震危险性。通过用1889年以来的7级以上大震的面波震级对印度块体推挤作用所积累的能量进行了分析和计算,结果表明每年在该区域将会积累的地震波能量在2.09×1016J左右。分析认为,由于应力的不均匀分布,能量得不到全面释放,所以大的地震将会在一些断层带上重复发生。     

Prediction of Soil and Nutrient Losses in A Highland Catchment

Highland catchments in tropical regions are frequently subjected to soil erosion and the transport of chemicals downstream. Any drastic changes in land use will increase the severity of these processes of land degradation. A simulation study using GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) was conducted at a catchment presently under tea farming in Cameron Highlands, Malaysia. Soil, water and nutrient transport associated with several alternative land uses was studied. In addition, the effect of a disruptive form of land clearing on soil, water and nutrient losses was also investigated. Modelling with GLEAMS required information from field measurements and observations, laboratory analyses, guide tables, industry records, maps and reports published by soil survey and meteorological departments. The most critical step in simulating soil and water movement using GLEAMS is the identification of a representative flow sequence. In the catchment under study, the representative flow sequence was overland flow–channel 1–channel 2. Input data on soil erodibility, porosity and surface roughness were manipulated to represent various degrees and forms of disturbance to the surface soil layer. For all land uses studied, the highest soil loss was predicted for the overland flow area where slope gradient is high and the soil friable. The variations in soil loss, runoff and nutrient loss between landscape elements and between land uses were consistent with soil erosion features observed in the field. Soil and nutrient losses were substantial for crops such as cabbage that required land shaping activities and frequent ploughing of the soil. Predicted data on enrichment ratio of specific surface (ERSS) are consistent with nutrient enrichment processes in the field and could prove to be useful in studies on chemical transport in highland catchments.     

江苏省自然资源利用时空变化特征及驱动力分析

基于改进的三维生态足迹模型测度江苏省2009—2016年的人均生态足迹、足迹深度与足迹广度,定量分析江苏省自然资源利用状况的时空变化特征;用改进的T型关联分析探讨江苏省人均生态足迹的驱动因子,并利用灰色预测模型GM(1,1)预测江苏省2019—2022年生态足迹与生态承载力的演变趋势。结果表明:1)2009—2016年,江苏省人均生态足迹、人均生态赤字、足迹深度与足迹广度均呈上升趋势,人均生态承载力略有下降。除建设用地外,耕地、林地、牧草地、水域与化石能源用地均处于生态赤字状态,其中,化石能源用地的生态足迹占全省生态足迹的主要部分;牧草地与水域的足迹深度较高,资源存量透支较为严重;耕地的足迹广度占全省足迹广度的主要部分,其在研究期内略有下降。省内各城市间足迹深度与足迹广度的差异较大,足迹深度表现为苏南＞苏中＞苏北,足迹广度为苏北＞苏中＞苏南。2)引导第三产业发展,提高能源利用效率,增强区域贸易交流能够缓解人均生态足迹的增长;人均GDP的增长、城市化水平以及人口规模的提高促进了生态足迹的增长。3)2019—2022年,江苏省人均生态足迹将进一步增加,人均生态承载力将小幅下降,生态赤字现象将继续存在且总量不断增加,生态环境压力进一步加剧。