Metals in agricultural soils and plants in Egypt

Since analysis of both soil and plants are useful to assess contamination of a geographic area, concentrations of five representative metals: copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), and iron (Fe) in soil and associated plants were measured by atomic absorption spectroscopy. Samples were collected from four different Egyptian regions (El-mehala El-kobra, Kafr El-Sheikh, Kafr El-zayat, and Al-fayoum) during spring and summer 2010. Concentrations of the selected metals in agricultural soils were significantly different among locations and seasons. Concentrations of Cd and Fe in soils at the four locations exceeded the maximum allowable concentrations for Cd (8 mg/kg, dry mass (dm)) and Fe (1000 mg/kg, dm). Accumulation was different for clover and cotton. Clover blossoms grown in soil from Kafr El-zayat contained the greatest concentrations of Cu, Zn, Pb, and Fe. Cotton flowers from El-mehala El-kobra accumulated the highest levels of Cd. Concentrations of Cd and Pb in both clover and cotton flowers from the four locations exceeded maximum allowable concentrations (3 mg/kg, dm) for both Cd and Pb. Using such agricultural soils for cultivation of edible crops for consumption may result in chronic hazards to human health.     

The determination of partition coefficients of organic compounds in technical products and waste waters for the estimation of their bioaccumulation potential using reversed phase thin layer chromatography

Reversed phase thin layer chromatography (RPTLC) has been investigated for the estimation of octanol/water partition coefficients (P), an important parameter for the prediction of the environmental behaviour of organic chemicals. A strong correlation between P derived from the traditional octanol/water system and RPTLC has been established over five orders of magnitude. RPTLC data are likewise correlated to results obtained by high performance chromatography (HPLC). Due to the low costs, simplicity and separation power RPTLC is especially suited for the investigation and screening of mixtures of compounds before more complicated tests are involved.

Results from a round robin test on the determination of partition coefficients by HPLC, RPTLC and the batch method indicate the simplicity and accuracy of the RPTLC technique. Applications of the RPTLC‐technique on technical products and industrial waste waters are described.     

Bioaccumulation and adverse effects of trace metals and polycyclic aromatic hydrocarbons in the common onion Allium cepa as a model in ecotoxicological bioassays

The common onion Allium cepa can be easily used in ecotoxicological bioassays to evaluate the bioavailability and adverse effects of pollutants and complex mixtures like waste, industrial effluent or coal-mining drainage that contain elevated levels of trace metals and polycyclic aromatic hydrocarbons (PAHs). In this study, onions were exposed for 7 days to individual metals (1?µg?mL^?1), i.e., aluminium, copper, iron and manganese, or PAHs (1.5?ng?mL^?1), i.e., benzo[a]antracene and benzo[a]pirene. Biological effects, measured as growth inhibition of roots and leaves, were integrated with analysis of bioaccumulation in roots, bulbs and leaves. Copper, iron and benzo[a]pirene caused a significant inhibition in root development of newly formed tissues, whereas only slight variations were caused by other chemicals; the number of new root filaments and the length of the leaves did not show significant variations, thus not representing sensitive parameters to evaluate adverse effects of pollutants in A. cepa. Chemicals bioaccumulation was always significant in roots, whereas levels in bulbs and leaves exhibited increased levels only for manganese, and a decrease for aluminium. The overall results confirmed the sensitivity of the bioassays with A. cepa, suggesting their utility for future applications to evaluate the adverse effects of complex mixtures containing metals or PAHs.     

营养盐浓度对中肋骨条藻优势种群富集多溴联苯醚的影响

以中肋骨条藻（Skeletonema costatum）和东海原甲藻（Prorocentrum donghaiense）组成中肋骨条藻优势种群的海洋微藻为研究对象,以我国近海水体中存在的3种丰度较高的多溴联苯醚同系物为代表,包括2,4,4＇-三溴联苯醚（BDE-28）、2,2’,4,4’-四溴联苯醚（BDE-47）和2,2＇,4,4＇,5-五溴联苯醚（BDE-99）,研究了硝酸盐浓度（0、128、512μmol·L-1）和磷酸盐浓度（0、8、32μmol·L-1）对中肋骨条藻优势种群生化成分和富集3种多溴联苯醚的影响,分析了中肋骨条藻优势种群对多溴联苯醚的富集量与生化成分的关系。结果表明,随着营养盐浓度的升高,单位藻细胞的富集量呈现降低趋势,硝酸盐浓度为0μmol·L-1时,3种多溴联苯醚同系物每106cells的富集量为3.93-5.01 ng,而硝酸盐浓度为512μmol·L-1时,每106cells富集量为3.53-3.94 ng,降低了10%-23%;不同硝酸盐浓度下单位体积藻液富集量差异较小,随硝酸盐浓度的升高,BDE-99和47富集量分别从0.180和0.179 ng·mL^-1降低到0.167和0.150 ng·mL^-1,BDE-28没有出现明显差异。与硝酸盐相似,多溴联苯醚单位藻细胞富集量也随着磷酸盐浓度的升高而呈现出降低的趋势,每106cells的富集量从磷为0μmol·L-1的3.04-3.28 ng降低到32μmol·L-1时的2.27-2.73 ng;不同磷酸盐浓度下单位体积藻液的富集量差异不显著,其中BDE-99富集量范围在0.188-0.190 ng·mL^-1,随磷酸盐浓度的升高,BDE-47和28富集量略有降低,从0.20 ng·mL^-1降低到约0.16 ng·mL^-1。中肋骨条藻优势种群单位细胞对多溴联苯醚富集随着营养盐浓度的增加而降低,其原因是营养盐浓度影响了其细胞生化成分,其中脂类含量与富集量存在正相关关系。对3种同系物富集量的比较发现,随多溴联苯醚同系物的Kow降低,富集量总体上呈现降低的趋势。     

DDTs对水生哺乳动物的组织残留基准初步研究

作为一种曾经广泛使用的氯化烃杀虫剂,DDT及其主要代谢产物DDE和DDD(合称为DDTs)是一类典型的具有持久性和生物累积性的有毒污染物。亲脂性和持久性使得DDTs可以通过食物链进行生物放大,从而对处于高营养级的水生哺乳动物造成严重的毒害作用。在综述DDTs对哺乳动物的毒性研究基础上,采用物种敏感度分布(species sensitivity distribution,SSD)和毒性百分数排序法(toxicity percentile rank method,TPRM)推导DDTs保护水生哺乳动物的组织残留基准(Tissue Residue Guideline,TRG)。使用SSD和TPRM得到的TRG分别为23.9和22.7 ng·g-1食物(湿重)。相应的,DDTs保护水生哺乳动物的水质基准分别为188.2和178.7 pg·L-1。依据研究得到的DDTs的组织残留基准及其在鱼类体内的含量评估对水生哺乳动物的风险。研究结果可用于评估DDTs对水生哺乳动物的生态风险,并为DDTs的风险管理提供理论依据。     

中国环境基准理论与方法学研究进展及主要科学问题

环境基准是指环境介质中的环境要素对特定保护对象不产生不良或有害效应的最大限值,是环境标准制修订的科学依据。环境基准理论与方法学一直是国际环境科学和环境保护科学研究领域的前沿,也是国家环境管理的重大科技需求。本文在总结国际和我国环境基准研究成果的基础上,较为系统地阐述了环境基准的基本概况、理论方法学及重要进展。同时,结合学科特点和环境基准科技需求,综合分析了与环境基准理论方法学密切相关的系列关键科学问题。     

外源洛克沙胂对水生态系统砷蓄积及底泥微生物生长的影响

为探明洛克沙胂(ROX)对水生态系统的毒性效应,采用模拟水生态系统,研究了外源添加不同浓度洛克沙胂(0、10、20、40、80和160 mg·L-1)对水生态系统砷含量及底泥微生物生长的影响。结果表明,水体及底泥砷含量随外源ROX用量增加而增加,但随暴露时间延长水体砷含量降低的同时底泥砷含量逐渐增加。金鱼藻和鲫鱼体内均出现明显砷蓄积现象,且160 mg·L-1ROX处理的水生态系统鲫鱼毒害效应明显,暴露1 d的死亡率为100%。金鱼藻对砷具有较强的富集能力,暴露32 d后砷富集量达398.1~1 538.91 mg·kg-1。不同浓度ROX对底泥真菌、细菌和反硝化细菌生长均具有不同程度的抑制效应,而对放线菌和氨化细菌生长具有一定的促进作用,且低浓度ROX(10 mg·L-1)对放线菌生长的促进作用明显。总体上,外源ROX进入水生态系统导致水体砷污染的同时在生物及非生物媒介中再次迁移、分配和蓄积,进而对鲫鱼及部分底泥微生物生长产生毒害。     

Effects of sublethal concentrations of permethrin on bioaccumulation of cadmium in zebra cichlid (Cichlasoma nigrofasciatum)

The aim of this study was to evaluate the synergistic and antagonistic effects of permethrin on the bioaccumulation of cadmium in zebra cichlid (Cichlasoma nigrofasciatum). Zebra cichlid was exposed to various sublethal concentrations of permethrin combined with cadmium chloride for 15 days. Although at the lowest concentrations, permethrin (0.40 µg L^?1) decreased the bioconcentration potential of cadmium in fish, bioaccumulation of cadmium increased along with increasing concentrations of permethrin (0.80–1.20 µg L^?1). However, the magnitude of changes in the accumulation of cadmium in the fishes simultaneously exposed to 1.60 µg L^?1 permetrin and cadmium chloride was similar to the cadmium levels observed in fishes after exposure to the cadmium chloride alone. The results of this study suggest that the synergistic effects of permethrin on the bioaccumulation of cadmium highly depend on the concentrations of this pesticide in water.     

Mercury Accumulation in Periphyton of Eight River Ecosystems1

Abstract: In 2003, the U.S. Geological Survey (USGS) National Water‐Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface‐sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r² = 0.88, in log‐log space). Mean MeHg and THg concentrations in surface‐sediment periphyton were significantly higher (1,333 ng/m² for MeHg and 53,980 ng/m² for THg) than cobble (64 ng/m² for MeHg and 1,192 ng/m² for THg) or woody snag (71 ng/m² for MeHg and 1,089 ng/m² for THg) periphyton. Concentrations of THg in surface‐sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface‐sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems.     

淀山湖水生生物中有机氯化合物的浓度与富集特征

为研究淀山湖水生生物中有机氯化合物的浓度与富集特征,测定了该湖水生生物样品(铜锈环棱螺、日本沼虾、鱼类)中滴滴涕(DDTs)、六六六(HCHs)、六氯苯(HCB)、多氯联苯(PCBs)的浓度。研究结果显示,在所有生物样品中均检测到了DDTs、HCHs、HCB,各生物体内的有机氯农药含量有很大差异。在8种生物样品中,乌鳢体内的有机氯化合物含量最高,这可能与乌鳢处于较高营养级,且为肉食性鱼类,体内脂肪较多有关。∑DDTs、∑HCHs、HCB的含量范围分别是55~1 135、0.5~24、6.9~91ng/g lw,其中DDTs为最主要的有机氯农药。4,4’-DDE和α-HCH在各自同系物中所占比例最高,说明淀山湖历史上曾经使用过有机氯农药,而近期没有新的污染源输入。以铜锈环棱螺为参照,有机氯农药的生物放大系数(BMFs)范围是1.2(泥鳅)~23(乌鳢);PCBs的生物放大系数范围是5.9(河川沙塘鳢)~55(乌鳢)。亲脂疏水性、低生化降解速率导致有机氯化合物能在生物组织中富集并通过食物链逐级放大。研究结果表明,有机氯化合物会沿着食物链积累放大,可能会对人体健康存在潜在的威胁。