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991.
992.
珠三角城市群典型城市土壤邻苯二甲酸酯污染特征 总被引:21,自引:1,他引:20
选择了经济相对发达的珠江三角洲城市群中的典型中小城市的菜园和果园表层土壤(0~20 cm)进行调查取样,采用气相色谱法,对土壤样品中的16种邻苯二甲酸酯(PAEs)进行了测定,分析了其分布特征,并初步探讨了本区域的PAEs的污染控制问题.结果表明:在珠三角城市中,东莞土壤的PAEs含量最高,各地土壤中的PAEs均值高低顺序依次为东莞>深圳(珠海)>中山(惠州);菜园土壤中的平均PAEs含量比果园高37%左右;从珠三角城市菜地和果园的平均PAEs分布来看,东莞和深圳的菜地PAEs明显高于果园;珠海、中山和惠州菜地的平均PAEs与果园基本持平.16种PAEs类化合物在珠江三角洲不同城市的分布的差异非常大,不同城市所受到的主要PAEs化合物污染的种类不同;与美国土壤PAEs控制标准相比,珠三角城市果园和菜地土壤的PAEs主要为DEP和DnBP超标,这两类PAEs化合物应该成为重点的污染控制对象. 相似文献
993.
广西南部地区坡地桉树生长与气象因子的关系 总被引:1,自引:0,他引:1
采用偏相关、典型相关分析等方法,对广西南部地区2.5万hm2 2~8 a生桉树(Eucalyptus)的平均胸径、平均树高、单位蓄积量等生长指标与该地区的气象因子的关系进行分析,研究制约坡地桉树生长的主要因素.结果表明:(1)该地区桉树生长与气候因子间存在着较密切的相关关系,其中成年桉树的树高和单位蓄积量生长主要受最冷月平均气温、年平均气温和年降雨量的影响;(2)胸径生长受气象因子的影响较小;(3)4 a生桉树受最冷月气温、年平均气温影响较大;(4)2 a生桉树幼林平均胸径与最冷月平均气温呈极显著正相关,而与年平均气温、年降雨量呈显著正相关关系; (5)尽管降水量丰富,但由于坡地特殊的地形,年降水量仍然是制约广西南部坡地桉树人工林的主要限制因子;(6)广西南部地区太阳辐射较大,不是制约桉树生长的主要因素,故在采用3-PG模型预测桉树生长状况时,太阳辐射不是关键参数. 相似文献
994.
M. Burkhardt M. Junghans S. Zuleeg M. Boller U. Schoknecht X. Lamani K. Bester R. Vonbank H. Simmler 《Environmental Sciences Europe》2009,21(1):36-47
Background, aim and scope Sources of organic micropollutants occuring in surface waters are often unknown. Regarding environmental risk assessments for surface waters, construction materials have as till now, not been given much consideration, although biocides used as preservatives are known to reach urban storm water runoff. The study focused on biocides for facades coatings and aimed (1) to determine ecotoxicological effect values, (2) to quantify the leaching behaviour and (3) to assess the environmental risk for surface waters using a dynamic transport model. Materials and methods Eight biocides used in resin based facade coatings were investigated. Some biocides are substances known as pesticides for agricultural purposes like diuron, carbendazim and terbutryn. Ecotoxicological effect values for aquatic organisms were determined for every biocide. Leaching of four biocides from a render under UV-irradiation has been investigated in the laboratory including the influence of varying temperatures. Using 80 irrigation intervals over 28 days, facade runoff was sampled and followed by biocide chemical analysis. The total losses were calculated based on the concentration patterns. These data were used for modelling the transport of cybutryn from facades to surface waters. Biocide specific effect values and leaching characteristics have been taken into consideration. Results Acute and chronic effect values as well as predicted no effect concentrations for the investigated biocides indicate their high potential to affect aquatic organisms. The leaching of four biocides (diuron, terbutryn, cybutryn, carbendazim) from the facade render under the experimental conditions delivers high concentrations in the beginning followed by an exponential decrease. Rising temperature increased the concentration of biocides in the runoff. The total losses were between 7?% and 29?% depending on the substances. More than half of the losses occur in the runoff within the first 15 min of runoff from a 60 min irrigation cycle. The modelling result for cybutryn underlines its high environmental risk for small surface waters. Discussion The leaching of the biocides, their potential ecotoxic effects and persistence show clearly that the environmental risk for surface waters and soils seems to be high for certain biocides; whereas for others the risk seems to be significantly lower. With respect water quality criteria, polluted facades runoff has to be diluted before runoff can enter the discharge. Diuron and carbendazim are however also used as pesticides and preservatives for other materials and cybutryn is also used as an antifouling agent. All pathways have to be evaluated in order to identify relevant sources and to act more efficiently with respect to water and soil protection. Conclusions Concentrations with high environmental risk are expected at new facades, especially at facades with thermal insulation. With the given low predicted no effect concentrations in a range of a few ng/L and large amounts of biocides applied in paints and renders, the environmental risk for common biocides used in facade coatings has to be investigated in laboratory and field scale. It seems plausible that source control measures as the most efficient and sustainable precautionary principle need to be evaluated. Recommendations and perspectives Biocides and additives applied in construction materials have to be taken into consideration as relevant sources when evaluating the quality of storm water runoff, discharge into urban areas and the impact to soil and surface waters. A sustainable construction material management and storm water management are required. It is expected that ongoing laboratory and field studies with exterior paints, renders and flat sheets for waterproofing containing biocides and additives will give further insight into their environmental impact. 相似文献
995.
The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700 m3 chicken-manure continuous stirred tank reactor (CSTR). A 12.3 L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35 ± 1 °C was employed for the investigation. With a corresponding organic loading rate of 1.5-3.5 kg-COD/m3 d over a hydraulic retention time of 1.5 d, a maximum volumetric biogas production rate of 1.2 m3/m3 d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250 mg/L) at an influent pH of 8.5-9. 相似文献
996.
采用大孔树脂吸附—Fenton试剂氧化法预处理含邻苯二甲酸二异丁酯(DIBP)废水。大孔树脂吸附工段的最佳实验条件为:以树脂NDA88为吸附剂,废水pH为2。NDA88经过10批次的连续使用,COD去除率基本稳定在58%左右,脱附率可达96%以上,吸附后废水COD为12 000 mg/L左右。Fenton试剂氧化工段的最佳实验条件为:H2O2加入量70 mL/L,n(H2O2):n(Fe2+)=4,废水pH 4。在此最佳条件下进行实验,Fenton试剂氧化工段COD去除率达65%,处理后废水COD为4 200 mg/L。 相似文献
997.
998.
移动电话的电磁辐射对人体伤害及其预防措施的探讨 总被引:1,自引:0,他引:1
随着移动电话的迅速普及 ,由其产生的电磁辐射对人体健康的影响已成为人们关心的热门话题。笔者就移动电话的电磁辐射对人体的伤害及其有关预防措施进行探讨。旨在提醒人们正确使用手机 ,尽量减少手机辐射对人体健康的影响 ,起到宣传教育和指导作用 相似文献
999.
逻辑是一门工具性基础学科 ,在职业安全卫生领域占有重要位置并得到广泛应用 ,从而出现了安全逻辑。笔者概要分析并阐述了安全逻辑所涉及的理论和方法 ;指出安全逻辑学已成为安全科学的一个重要组成部分 ;强调安全逻辑的推广及应用对安全生产有着重要的实用价值和指导意义 ,具有良好的发展前景。笔者通过对安全逻辑的长期研究 ,认为我国“安全逻辑学”的框架及学科理论已基本形成 相似文献
1000.
Optimising the preparation of activated carbon from digested sewage sludge and coconut husk. 总被引:18,自引:0,他引:18
Preparation of activated carbon from sewage sludge is a promising way to dispose of sewage sludge as well as to produce a low-cost adsorbent for pollutant removal. This research work aimed to optimise the condition for activated carbon preparation from anaerobically digested sewage sludge with the additive coconut husk. The sewage sludge sample was mixed with the additive coconut husk. The preparation condition variables investigated involved the concentration of the ZnCl2 solutions, heating temperature, dwell time and heating rate in pyrolysis and the mixing ratio of coconut husk to sewage sludge. Surface area, pore size distribution, aqueous phenol adsorption capacity and the production yield of the final products were determined and compared. Experimental results revealed that low concentrations of ZnCl2 solution tended to improve the microporosity of the final product. Heating temperature had a considerable impact on the surface area, pore size distribution and phenol adsorption capacity of the final products, whereas dwell time and heating rate performed comparatively insignificantly. The effect of increasing the mixing ratio of coconut husk to sewage sludge was principally to increase the microporosity of the final products. The activated carbon with the highest BET surface area was produced with the activation of 5 M ZnCl2 solution and, thereafter, pyrolysis at a heating temperature of 500 degrees C for 2 h with a heating rate of 10 degrees C/min. The mixing ratio of 1:4 in terms of coconut husk to sewage sludge based on their dried weights was found to be most cost effective. 相似文献