Current uses of the EPA lead model to assess health risk and action levels for soil

The EPA lead model predicts mean blood lead levels and risk of elevated blood lead levels in children based on lead uptake from multiple sources. In the latest model versions, environmental data from individual homes within a community can be used to predict the overall blood lead distribution and percent risk of exceeding a specific blood lead level (i.e. 10 g dl^–1). Recent criteria used by the EPA to evaluate this information include no more than 5% of houses with a greater than 5% lead risk, and a community weighted-average risk below 5%. Environmental (primarily soil) and blood lead data from a residential community near a smelter were used to illustrate recent uses of the model. Scheduled remediation in the community will remove soil for approximately 60% of the houses (i.e. those with lead levels > 1000 mg kg^–1). After remediation, the model results indicate a relatively low community risk (0.5–1.9%), although the percentage of houses with lead risks above 5% ranged from 3 to as high as 13%, depending on the variation in blood lead and assuming the model's 7 g dl^–1 increase in blood lead with each 1000 mg kg^–1 increase in soil lead level. A comparison of the limited blood lead data with soil lead levels below 1000 mg kg^–1, however, indicated no apparent relationship. Given these uncertainties, less invasive actions than additional soil removal (e.g. exposure intervention, monitoring conditions, and follow-up as necessary) may be appropriate under the new EPA guidance for lead in soil.     

淮河以南若干中小城市燃料煤硫品位的控制标准

采用国家二级标准（０．１５ｍｇ．ｍ＾－３）作为南方中小城市的环境标准值，硫品位标准应控制在１．３２％以下。对比南方各中小城市１９８７年使用的煤硫品位，在９８个城市中，有４４个城市符合标准，另有５４个城市应控制高硫煤使用量或应用脱硫技术，以减少大气中ＳＯ２浓度。     

Copper, Lead and Zinc Mobility and Bioavailability in a River Sediment Contaminated with Paint Stripping Residue

A river embankment sediment beneath a road bridge in South Australia had been surveyed on a previous occasion to a depth of 10 cm and found to contain high levels of copper, lead and zinc deposited during previous lead and zinc-based primer paint stripping operations prior to repainting the bridge. Since the river embankment is geologically different from the surrounding non-embankment soils, and a sufficient distance from the bridge along the river embankment could not be traversed, the geological background Cu, Pb and Zn fraction was established initially using a solid phase sequential extraction (SPSE) procedure. Assessment of the degree of contamination and extent of vertical mobility was then established. Copper was a minor contaminant and present predominantly as the geological background species. Lead was partitioned evenly between the oxalate soluble fraction and residual fraction to a depth of 30 cm with a decrease in total Pb concentration from 497 to 141 mg Pb kg^–1 while Zn was predominantly in the oxalate soluble fraction to a depth of 15cm with a decrease in concentration from 1013 to 150 mg Zn kg^–1. The reduced rate of nitrification and the lower total concentration of NO₃ ^–-N together with the higher respiratory quotient, combined with the lower microbial quotient, are indicative of microbial stress due to heavy metal toxicity. In the case of Pb and Zn paint stripping residues, these changes in indicators of microbial health are possibly the result of the greater abundance and hence possible bioavailabilty of organo- and chloro-Pb compared to organo- and chloro-Zn complexes.     

污泥与城市垃圾混合堆肥技术

本文介绍了城市污水处理厂污泥与城市生活垃圾混合堆肥技术,对温度、C/N、含水率、通风量等因素对堆肥的影响和物料平衡、无害化以及堆肥肥效等作了阐述.     

上海粮田锌和铅的生物地球化学

本文介绍了1990—1991年对上海粮田锌和铅的生物地球化学研究.阐述了锌和铅在上述地区的富集和迁移规律.研究了结累锌和铅的地球化学栅栏以及谷物对锌和铅的吸收与富集.     

高寒沙区两种典型固沙植物改良土壤的策略

植被恢复与重建是退化土地生态修复的重要途径,植物与土壤环境的关系一直是热点科学问题,但对高寒沙区尚缺乏系统性的研究。为探明不同沙生植物对高寒沙地土壤的改良策略,以青海共和盆地中间锦鸡儿(Caragana intermedia)和乌柳(Salix cheilophila)两种典型固沙植物为研究对象,通过对比细根分布规律分析其环境适应性,结合林地土壤物理性质、有机碳含量和土壤含水量等要素,分析两种植物对土壤的改良作用。结果表明,(1)两种植物的细根主要集中在0-60 cm土层,中间锦鸡儿水平方向分布更多,且细根平均生物量密度和有机碳含量都高于乌柳。(2)乌柳人工林各深度土壤有机碳密度均高于中间锦鸡儿,其累计百分比在0-40 cm土层较高,中间锦鸡儿在40-120 cm较高。(3)两种人工林的土壤容重、最大持水量和毛管持水量均值差异不显著。中间锦鸡儿林地土壤容重在0-40 cm土层大于乌柳,在40-120 cm小于乌柳;其最大持水量和毛管持水量在0-60 cm小于乌柳,在60-120 cm大于乌柳。(4)两种人工林土壤含水量和土壤温度都呈表层高,随土壤深度递减趋势。乌柳林地各深度土壤含水量均高于中间锦鸡儿,土壤温度均低于中间锦鸡儿。研究表明,中间锦鸡儿的环境适应性和固沙能力较强,倾向于深层土壤改良和固碳策略;乌柳人工林的固碳作用和涵养水源能力较强,倾向于表层土壤改良和固碳策略;同时,两种人工林都倾向于表层保水的策略。该文通过对比分析不同沙生植物改良土壤的策略,为长期研究高寒沙区生态修复与优良固沙植物筛选等工作提供理论依据。     

Reaction of spruce cells toward heavy metals and the influence of culture conditions

BACKGROUND: Plant cell cultures may serve as biosensors for the detection of heavy metals and other toxic substances. Standard culture media and protocols are frequently utilised, but in these media no care is usually taken to control the influence of hormones and nutrients on the reaction of the enzymes or m under consideration as parts of the sensor. The present paper investigates the influence of media composition on the reaction of spruce cells towards heavy metals. METHODS: Spruce cell cultures were grown in a standard medium, either i) alone, ii) containing 0.3% sucrose or iii) containing 3% sucrose and the hormones BAP and NAA. The cell cultures were then incubated in medium with fungal elicitor, H2O2, CdSO4 (50 to 500 microM), or, alternatively, with a standard heavy metal mixture containing 80 microM Na2HAsO4, 150 microM CdSO4 and 200 microM PbCl2. RESULTS: Depending on the nutrient status and hormone availability, large differences in glutathione contents and the GSH/GSSG ratio were observed. However, the cellular redox state seemed to remain more or less constant. Glutathione S-transferase activity was determined with four substrates, and high induction rates for the conjugation of three substrates were observed when hormones were omitted from the media. 1,2-epoxy-nitrophenoxy-propane conjugation was highest in starving cell in the presence of hormones, showing a transient GST induction, with highest rates occurring after 16 hrs following incubation; the induction effect was lost after 24 hrs. CONCLUSION: A medium containing 3% sucrose and both hormones (BAP and NAA) appears to be most favourable for cellular growth as well as the expression of a basis level of detoxification enzymes and antioxidants. With this combination, early responses towards heavy metals at low concentration can be monitored. RECOMMENDATIONS AND PERSPECTIVE: Plant cell cultures are valuable tools for the bioindication of heavy metals and toxic xenobiotics. If standard media and protocols are utilised, the influence of hormones and nutrients on the reaction of the biosensor have to be evaluated thoroughly.     

Regional monitoring of lead and cadmium contamination in a tropical grazing land site,Thailand

An investigation was carried out to monitor Pb and Cd contamination in grazing land located near a highway. Environmental media at different distances fromhighway (soil, grass, water, cow's forage, fertilizer,manure and milk samples) were collected from three samplinglocations. Soil and grass were characterized by high metalmobility (soil with Pb: 5.25±0.71–14.59±1.17 mgkg^-1, dry mass and Cd: 0.038–0.33±0.04 mg kg^-1, dry mass and grass with Pb: 0.76±0.05–6.62±0.18 mg kg^-1, dry mass and Cd: 0.17±0.01–0.73±0.09 mg kg^-1, dry mass). One-way analysis of variane (ANOVA) was applied to find out the correlation between metal (total and bioavailable) concentrationsin the soil and the distance from roadside. In most cases, the finding showed that plants growing nearer to the highway are usually exposed to more heavy metal accumulations than those awayfrom the highway. In addition, a correlation was established between plant available metal concentrations and plant metaluptake concentrations.Analysis of fertilizer and manure showed considerable amountof metals (fertilizer with Pb: 1.53±0.06 mg kg^-1 andCd: 0.038 mg kg^-1 and manure with Pb: 2.55–3.34 mgkg^-1 and Cd: 0.14–0.31 mg kg^-1). Long termsimultaneous application of fertilizer and manure on thecommercial farm showed higher metal accumulation in the soiland plants than those of co-operative farm Considerableconcentrations of metals (Pb: 1.60–2.94 mg kg^-1 andCd: 0.025–0.19 mg kg^-1) were observed in fodder. The finding clearly demonstrated that there are seasonalvariation in total daily metal intake by individual cow (Pb:109.37 mg day^-1 (dry), 273.47 mg day^-1 (rainy) andCd: 2.02 mg day^-1 (dry), 19.62 mg day^-1 (rainy)).The provisional tolerable weekly intake of heavy metals incows is 390 g Pb and 28 g Cd per kg bodyweight in the rainy season and 156 g Pb and 2 gCd per kg body weight in the dry season. The levels of metals (Pb: 0.014 mg L^-1 and Cd: not detectable) and bio-transferfactor (10^-5–10^-4) in raw milk were found to be well below the Codex Alimentarius Commissions Draft (1997). Ouranalysis revealed that improvements on farm management give significant reduction in elevated levels of Pb and Cdin soil and plants, and however leads to minimize the amountof Pb and Cd in consumed milk.     

双硫腙－醋酸丁酯萃取石墨炉原子吸收法测定海水中痕量铜、铅和镉

用双硫腙－醋酸丁酯萃取石墨炉原子吸收法测定海水中痕量Ｃｕ、Ｐｈ、Ｃｄ．试验选定了最佳测定条件．结果表明，在弱碱性介质（ｐＨ８－１０）中，能同时定量萃取Ｃｕ、Ｐｂ、Ｃｄ．方法的相对标准偏差＜３％，加标回收率９２％－１０２％，检出限（μｇ／Ｌ）分别为Ｃｕ０．０６，Ｐｂ０．１４，Ｃｄ０．００２．本法操作简便、快速，已应用于海水中Ｃｕ、Ｐｂ、Ｃｄ的分析，取得了令人满意的结果．     

Relationship between bioaccumulation, distribution of METand lipid content of aquatic organisms

Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｂｉｏａｃｃｕｍｕｌａｔｉｏｎ，ｄｉｓｔｒｉｂｕｔｉｏｎｏｆＭＥＴａｎｄｌｉｐｉｄｃｏｎｔｅｎｔｏｆａｑｕａｔｉｃｏｒｇａｎｉｓｍｓＬｉｕＺｈｅｎｇｔａｏ；ＺｈｏｕＦｅｎｇｆａｎ；ＪｉｎＨｏｎｇｊｕｎ（Ｄｅｐａｒ...