构树修复对重金属污染土壤环境质量的影响

通过温室盆栽试验,研究构树（Broussonetia papyrifera）生长对重金属污染土壤酶活性和微生物群落结构的影响.结果表明,构树修复污染土壤中酶活性和微生物多样性明显提高.经270d培养后,构树生长土壤中蔗糖酶和酸性磷酸酶活性与种植土壤相比分别显著（P<0.05）提高3.12倍和2.29倍;土壤脱氢酶与有效态As、Cd、Pb、Zn和Cu含量,蔗糖酶与有效态Cd含量,以及磷酸酶与有效态Cd和Cu含量之间呈显著负相关（P<0.05）.根据16S和18S rDNA PCR-DGGE分析表明,构树修复可提高污染土壤中细菌和丛枝菌根真菌多样性.上述结果表明,构树修复可有效改善重金属污染土壤的环境质量.然而,污染土壤中重金属有效态含量下降不明显,必须辅助物理和化学措施来强化构树对重金属污染土壤的生态修复潜力.     

普伐他汀的光催化降解性能及机理研究

通过水热法合成Bi₂WO₆,并利用XPS,XRD,BET,UV-Vis和SEM等方法对样品进行了表征;通过光催化性能实验考察了Bi₂WO₆投加量,溶液pH值对普伐他汀（PR）降解效果的影响;通过自由基捕获实验及中间产物的鉴定探明了Bi₂WO₆光催化降解PR过程的主要活性自由基,中间产物及降解机理,并采用发光细菌急性毒性试验评估了PR降解前后的毒性.结果表明,所制备的Bi₂WO₆是由大量纳米片组成的正交晶系花瓣状微球,各元素物质的量比为Bi：W：O=2.5：1：6.7,比表面积为26.67m²/g,带隙能为2.74eV;光催化性能结果表明,对于10mg/L PR,当溶液pH=6.5,Bi₂WO₆投加量为0.4g/L时降解效果最佳,降解率可达80.6%,矿化度为40.2%;自由基捕获实验结果表明降解过程中h⁺起主要的氧化作用,·OH和·O₂^-的氧化起辅助作用.基于活性自由基和中间产物的鉴别结果提出了Bi₂WO₆光催化降解PR的机理,即以h⁺为主,·OH和·O₂^-为辅联合攻击PR分子中C－C键,C＝C双键,酯键等化学键,进而将其分解为易降解小分子有机物.另外,毒性测试结果表明PR经光催化降解后的小分子产物与PR原液相比毒性并没有增强.     

考虑边界条件不确定性的地下水污染风险分析

为分析边界条件不确定性对地下水污染质运移数值模拟模型输出结果的影响,运用Monte Carlo方法对一算例进行阐明,并从污染风险预报方面对模拟结果进行分析.为减少重复调用模拟模型产生的大量计算负荷,将边界条件（第一类边界条件-水头值）作为随机变量,建立地下水污染质运移数值模拟模型的Kriging替代模型,在保证较高精度的同时,实现了Monte Carlo模拟.结果表明：边界条件的不确定性,对地下水污染质运移数值模拟模型预报的结果有很大影响,考虑与未考虑边界条件不确定性得到的研究区污染羽分布差别较大.对地下水污染质运移数值模拟模型的Monte Carlo模拟结果进行统计与分析,可以评估研究区观测井1,2,3污染物浓度预报结果的可靠程度,并且可以预报出研究区观测井1,2,3遭受不同程度污染的风险.     

牛粪-化肥配施对水稻田氮磷迁移转化的影响

在控制外源N输入量相同的前提下,通过田间小区实验,探讨有机肥与化肥不同施用量（牛粪施用量：5,10,20t/hm²）对稻田田间土-水界面氮磷迁移转化特征的影响.结果表明：控制稻田水中NH₄⁺-N、NO₃^--N、TN和TP输出的最佳时期分别为施肥后的第5,30,7,20d,且TN和TP浓度随时间变化符合单指数衰减方程（0.7444≤R²≤0.9724;1.1×10^-6≤F≤0.0055）.采用牛粪部分代替化肥的施肥方式,在一定范围内能降低稻田退水中TN、TP输出负荷（41.8%、36.0%、64.3%;20.3%、39.1%、48.9%）,还可以降低稻田水中N/P,降低水体富营养化风险.同时,牛粪的施用可提高土壤中脲酶和磷酸酶的含量,促进氮磷向植物可吸收形态转化.综合经济成本和生态效益核算,采用10t有机肥代替无机肥的处理是相对经济环保的施肥方法,该施肥方式下,氮磷年输出负荷分别为17.70,1.26kg/hm².     

应用S-T模型对沉积物中PAHs的生态风险分级评价

本文构建S-T模型,运用集对分析理论（set pair analysis）构建基本模型,采用层次分析法并参考毒性当量因子确定各指标权重,应用三角模糊数（triangular fuzzy number）对差异度系数进行改进,基于加拿大沉积物环境质量标准,对沉积物中多环芳烃进行生态风险分级评价.结果表明,该模型考虑到化合物之间的相互作用因素并做模糊处理,对差异度系数进行改进体现沉积物中多环芳烃生态风险等级标准的模糊性,为持久性有机污染物生态风险分级评价提供了一种简便客观有效的方法.     

Mercury levels in human population from a mining district in Western Colombia

A biomonitoring study was carried out to examine the adverse impacts of total mercury in the blood(HgB), urine(Hg U) and human scalp hair(HgH) on the residents of a mining district in Colombia. Representative biological samples(scalp hair, urine and blood) were collected from volunteered participants(n = 63) to estimate the exposure levels of THg using a Direct mercury analyzer. The geometric mean of THg concentrations in the hair,urine and blood of males were 15.98 μg/g, 23.89 μg/L and 11.29 μg/L respectively, whereas the females presented values of 8.55 μg/g, 5.37 μg/L and 8.80 μg/L. Chronic urinary Hg(HgU)levels observed in male workers(32.53 μg/L) are attributed to their long termed exposures to inorganic and metallic mercury from gold panning activities. On an average, the levels of THg are increasing from blood(10.05 μg/L) to hair(12.27 μg/g) to urine(14.63 μg/L).Significant positive correlation was found between hair and blood urinary levels in both male and female individuals. Thus the present biomonitoring investigation to evaluate the Hg levels and associated health issues would positively form a framework for further developmental plans and policies in building an ecofriendly ecosystem.     

Suspended particulate mercury associated with tidal fluxes in a lagoon environment impacted by cinnabar mining activity (northern Adriatic Sea)

The Isonzo River has been demonstrated to be a continuing point source of mercury(Hg)in the Gulf of Trieste although the Idrija mine was last active in 1996. The present study aims to investigate the role of the suspended particulate matter(SPM) associated with tidal fluxes to disperse particulate Hg(PHg) into the Grado coastal lagoon system. PHg concentrations(avg. 3.11 ± 2.62 μg/g, d.w.), notwithstanding the ebb or flood tides, were significantly higher than the local sediment background(0.13 μg/g). The relative affinity of Hg for the particulate phase in surface waters was confirmed by higher average distribution coefficient(Kd) values(5.6–6.7). PHg contents showed the highest values in ebb tide conditions, thus suggesting their origin from the erosion of tidal flats and saltmarshes of the lagoon. When compared to river discharge, high PHg surface concentrations in flood tide are related to rainfall events occurring within the river basin. Results can be used to make an indicative assessment of the amount of Hg bound to SPM which is transported in and out of the lagoon basin following the action of tidal fluxes. A simple estimation provides a negative budget for the Grado lagoon sub-basin which loses between 0.14 and 1.16 kg of PHg during a tidal semi-cycle. This conclusion is in agreement with the evidence of morphological deterioration which has emerged from recent studies on the lagoon environment, and which testifies to a current sedimentary loss from the lagoon into the northern Adriatic Sea.     

Long-term effects of environmentally relevant concentrations of silver nanoparticles on microbial biomass, enzyme activity, and functional genes involved in the nitrogen cycle of loamy soil

The increasing production and use of engineered silver nanoparticles (AgNP) in industry and private households are leading to increased concentrations of AgNP in the environment. An ecological risk assessment of AgNP is needed, but it requires understanding the long term effects of environmentally relevant concentrations of AgNP on the soil microbiome. Hence, the aim of this study was to reveal the long-term effects of AgNP on soil microorganisms. The study was conducted as a laboratory incubation experiment over a period of one year using a loamy soil and AgNP concentrations ranging from 0.01 to 1?mg?AgNP/kg soil. The short term effects of AgNP were, in general, limited. However, after one year of exposure to 0.01?mg?AgNP/kg, there were significant negative effects on soil microbial biomass (quantified by extractable DNA; p?=?0.000) and bacterial ammonia oxidizers (quantified by amoA gene copy numbers; p?=?0.009). Furthermore, the tested AgNP concentrations significantly decreased the soil microbial biomass, the leucine aminopeptidase activity (quantified by substrate turnover; p?=?0.014), and the abundance of nitrogen fixing microorganisms (quantified by nifH gene copy numbers; p?=?0.001). The results of the positive control with AgNO3 revealed predominantly stronger effects due to Ag⁺ ion release. Thus, the increasing toxicity of AgNP during the test period may reflect the long-term release of Ag⁺ ions. Nevertheless, even very low concentrations of AgNP caused disadvantages for the microbial soil community, especially for nitrogen cycling, and our results confirmed the risks of releasing AgNP into the environment.     

泄漏检测与修复(LDAR)相关标准应用问题探讨

从LDAR项目建立、LDAR检测、泄漏维修、设备动静密封点泄漏VOCs排放量核算、第三方技术服务等方面,分析了目前泄漏检测与修复(LDAR)相关标准在实际应用中存在的问题和不足,并对下一步工作及标准制修订提出建议,以提升国内LDAR技术实施水平,满足石化企业实际需求。     

海水中阴极极化对X80钢应力腐蚀及氢脆敏感性的影响

目的研究不同p H值海水中阴极极化对X80管线钢应力腐蚀及氢脆的抑制作用。方法采用慢应变速率拉伸试验、电化学测试、微观组织观察等分析方法。结果 X80钢在天然海水中的析氢电位约为-940m V(vs.SCE,下同),海水p H为3.5时析氢电位发生正移。其应力腐蚀敏感性与极化电位有很大关系,随着极化电位负移,X80钢的氢脆敏感性增加。天然海水中当极化电位负于-950 m V时,断口出现准解理断裂特征形貌。在-1050 m V极化电位下,钢材进入氢脆断裂区发生脆性断裂。海水p H为3.5时,-900 m V钢材有发生氢脆的危险。结论与天然海水相比,X80钢在p H为3.5的酸性海水中具有较高的应力腐蚀敏感性,两种海水介质中X80钢的应力腐蚀敏感性均随极化电位负移而增加。