Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons

Oaks (Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination of contaminants. Additionally, a radial-growth decline began in these trees at approximately the same time that chloride became elevated. Growth did not decline in trees that contained smaller concentrations of chloride. The source of elevated chloride and the corresponding reductions in tree growth could not be explained by factors other than contamination. On the basis of tree-ring evidence alone, the release occurred in the late 1960s or early 1970s. Contaminant release at a second location apparently occurred in the mid- to late 1970s, suggesting that the area was used for disposal for at least 5 years and possibly longer.     

Contaminated sediments and bioassay responses of three macroinvertebrates, the midge larva Chironomus riparius, the water louse Asellus aquaticus and the mayfly nymph Ephoron virgo

Bioassays are widely used to estimate ecological risks of contaminated sediments. We compared the results of three whole sediment bioassays, using the midge larva Chironomus riparius, the water louse Asellus aquaticus, and the mayfly nymph Ephoron virgo. We used sediments from sixteen locations in the Dutch Rhine-Meuse Delta that differed in level of contamination. Previously developed protocols for each bioassay were followed, which differed in sediment pretreatment, replication, and food availability. The Chironomus bioassay was conducted in situ, whereas the other two were conducted in the laboratory. The measured endpoints, survival and growth, were related to contaminant levels in the sediment and to food quantity in water and sediment.

Only the response of A. aquaticus in the bioassay was correlated with sediment contamination. Food availability in overlying water was much more important for C. riparius and E. virgo, thereby masking potential sediment contaminant effects. We conclude that growth of A. aquaticus was depressed by sediment contamination, whereas growth of E. virgo and C. riparius was stimulated by seston food quantity. We discuss that the trophic state of the ecosystem largely affects the ecological risks of contaminated sediments.     

常熟河网区水污染物总量控制研究

基于常熟河网原型调水实验和水功能区划，建立了感潮地区河网水量水质模型，对常熟河道水质降解系数及水环境容量进行了计算，并按照点源和面源对区域内污染源进行统计，在此基础上进行了常熟河网水污染物总量控制值和现状削减量的计算，为该地区的水污染防控提供了科学依据。     

酸雨对污染环境中重金属化学行为的影响

综述了酸雨对污染环境中重金属化学行为的影响。在酸雨作用下 ,不同环境介质中重金属活性明显增强 ,化学形态转化明显 ,迁移能力和生态危害能力亦明显加强。探讨了控制酸雨发生、重金属污染环境修复技术以及开展复合污染环境化学风险评价的必要性     

叶面喷施2,3-二巯基丁二酸对水稻幼苗镉吸收转运及抗氧化系统的影响

稻米Cd超标问题已成为社会各界广泛关注的热点问题之一,探索降低Cd向地上部转运并缓解水稻Cd胁迫的新方法,对保障食品安全具有重要意义.本研究拟通过在水稻幼苗叶面喷施2,3-二巯基丁二酸(DMSA)评估利用该重金属螯合剂降低Cd向水稻地上部转运并缓解Cd胁迫的可行性.以我国南方水稻主栽品种之一中早35幼苗为研究材料,采用水培法研究了叶面喷施不同浓度DMSA对Cd在水稻幼苗体内吸收转运的影响,同时考察了对水稻幼苗丙二醛(MDA)、谷胱甘肽(GSH)含量以及对抗氧化酶过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性的影响.结果表明,叶面喷施DMSA 0.2、 0.4和1.0 mmol·L~(-1) 4次后,水稻幼苗地上部Cd含量随着DMSA喷施浓度增加呈显著降低趋势, 3种处理浓度与对照相比分别降低22.1%、 39.7%和43.5%,但是对水稻幼苗根部Cd含量无显著影响;对地上部及根中K、Ca、Mg、Fe、Zn和Mn这6种矿质元素含量无显著影响;喷施4次DMSA后显著降低了幼苗地上部MDA和GSH含量,同时使CAT和SOD活性显著增加,有效缓解了Cd对水稻幼苗造成的胁迫效应.DMSA能抑制Cd从水稻根部向地上部转运,同时不影响对人体必需矿质营养元素的吸收和转运,具备成为水稻降Cd叶面调理剂的潜力.     

巯基改性高岭土负载CeO2-CdS光催化降解结晶紫

为获得高效催化活性的光催化材料,实现偶氮类染料的高效降解,试验以巯基乙酸钠作为硫源和高岭土改性剂合成了巯基高岭土/CeO₂-CdS催化剂,并以降解结晶紫为模板反应,优化确定了巯基高岭土/CeO₂-CdS催化剂的制备条件.采用XRD（X射线衍射）、SEM（扫描电子显微镜）、TEM（透射电子显微镜）、FTIR（傅里叶红外光谱）和UV-Vis（紫外-可见光漫反射光谱）对催化剂进行了表征.结果表明:①催化剂是由巯基高岭土、立方相结构的CdS和萤石结构的CeO₂组成;②CdS和CeO₂的负载破坏了巯基高岭土的层状结构;③最优催化剂和巯基高岭土/CeO₂的可见光的响应范围分别为550和450 nm;④当CeO₂:CdS（摩尔比,下同）为4:6,巯基高岭土:CeO₂-CdS（质量比,下同）为1:3时,催化剂具有最优的光催化活性;⑤在50 mL结晶紫浓度为10 mg/L的溶液中,添加0.1 g最优催化剂后,采用350 W氙灯对其光照150 min时,结晶紫的降解率为95.1%;⑥最优催化剂具有良好的重复使用性能,重复使用5次时,对结晶紫的降解率为90.4%.研究显示,结晶紫降解的最终产物为CO₂和H₂O,催化剂对结晶紫的降解机理是以羟基自由基氧化为主和超氧基氧化为辅的共存氧化机理.      

One century record of contamination by polycyclic aromatic hydrocarbons and polychlorinated biphenyls in core sediments from the southern Yellow Sea

Sixteen polycyclic aromatic hydrocarbons (PAHs) and 28 polychlorinated biphenyls (PCBs) were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical variations in inflow and sources. The chronology was obtained using the 210Pb method. PAHs concentrations decreased generally with depth and two climax values occurred in 14–16 cm and 20–22 cm layers, demonstrating that the production and usage of PAHs might reach peaks in the periods of 1956–1962...     

Combined toxicity of copper and cadmium to six rice genotypes （Oryza sativa L.）

Accumulation of copper (Cu) and cadmium (Cd) in six rice cultivars (94D-22, 94D-54, 94D-64, Gui630, YY-1 and KY1360) was evaluated through exposure to heavy metal contamination (100 mg/kg Cu, 1.0 mg/kg Cd, and 100 mg/kg Cu + 1.0 mg/kg Cd) in a greenhouse. The dry weight of shoot and root, concentrations of Cu and Cd in plant tissues and the Cu, Cd, P, Fe concentrations in the root surface iron plaques were analyzed eight weeks later after treatment. The results indicated that the plant biomass was mainly determined by rice genotypes, not Cu and Cd content in soil. Separated treatment with Cu/Cd increased each metal level in shoot, root and iron plaques. Soil Cu enhanced Cd accumulation in tissues. In contrast, Cu concentrations in shoot and root was unaffected by soil Cd. Compared to single metal contamination, combined treatment increased Cd content by 110.6%, 77.0% and 45.2% in shoot, and by 112.7%, 51.2% and 18.4% in root for Gui630, YY-1 and KY1360, respectively. The content level of Cu or Cd in root surface iron plaques was not affected by their soil content. Cu promoted Fe accumulation in iron plaques, while Cd has no effect on P and Fe accumulation in it. The translocation of Cu and Cd from iron plaques to root and shoot was also discussed. These results might be beneficial in selecting cultivars with low heavy metal accumulation and designing strategies for soil bioremediation.     

红绒盖牛肝菌菌丝对Cu(Ⅱ)和Cd(Ⅱ)生物吸附的影响因子

在离体条件下,研究了外生菌根真菌红绒盖牛肝菌(Xerocomus chrysenteron)菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)生物吸附的影响因子,考察了X. chrysenteron菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)的吸附能力、去除率和平衡吸附量在不同初始质量浓度和不同温度下所受影响,并采用Freundlich和Langmuir线性化吸附等温线模型拟合X. chrysenteron菌丝的生物吸附热力学特性. 结果表明:当菌丝的质量浓度为10g/L, 30 ℃时,X. chrysenteron非活性菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)的最佳吸附量分别为47.11和11.72mg/g(以菌丝干质量计);X. chrysenteron非活性菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)的吸附能力、去除率、平衡吸附量均优于活性菌丝;X. chrysenteron菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)的吸附能力随其初始质量浓度的增加而增大,去除率随其初始质量浓度的增大而分别呈指数下降和线性下降;30 ℃时X. chrysenteron菌丝对 Cu(Ⅱ)和 Cd(Ⅱ)的吸附能力、去除率、平衡吸附量均比 25 ℃时大.     

密闭环境空调系统二次污染问题研究

密闭环境空调系统存在一系列特殊的室内空气品质问题.详细介绍了密闭空间空调系统二次污染的现状、对人员健康的影响、控制措施.提出2种解决空调系统二次污染问题的思路:终点控制和起点控制.终点控制措施和起点控制措各有其优点及缺点,适用范围也不一样.潜艇、深水工作船、宇宙飞船等密闭空间空调系统要根治二次污染问题,必须起点控制和终点控制相结合,在工程实践中逐步摸索出适用的方法.