Editorial: Effects of metal contamination on ammonia-oxidizing microorganisms in a freshwater reservoir

<正>Ammonia-oxidizing microorganisms, including ammoniaoxidizing bacteria (AOB) and archaea (AOA), are important to the global nitrogen cycle. These microbes catalyze the oxidization of ammonia (NH_3) to nitrite (NO_2~-), the ratelimiting step in the biogeochemical cycling of nitrogen (Stahl and de la Torre, 2012). Effects on the activity of the ammoniaoxidizing microbes could ultimately influence the global     

背景离子类型和浓度对聚苯乙烯微塑料/铅在饱和石英砂中共运移的影响

为阐明水化学条件对微塑料和重金属运移的影响,初步明确两种环境污染物共运移过程中的耦合效应及其对环境条件的响应机制,研究了背景电解质离子不同价态和浓度组成条件下1μm聚苯乙烯微塑料(PS-MPs)和Pb²⁺在饱和一维砂柱中的单独及共迁移行为.结果表明:背景离子浓度的增加或价态的升高均会抑制PS-MPs的单独运移能力,当Na⁺浓度从1mmol/L增加到100mmol/L,PS-MPs和石英砂之间的排斥势垒下降了1348kT;当Ca²⁺浓度从1mmol/L增加到100mmol/L,PS-MPs和石英砂之间的排斥势垒下降了956kT.PS-MPs/Pb²⁺二元体系中Pb²⁺能降低PS-MPs的迁移能力,背景离子浓度和价态的提升可削弱Pb²⁺对PS-MPs运移能力的抑制性.当Na⁺浓度从1mmol/L增加到100mmol/L,PS-MPs和石英砂之间的排斥势垒下降了1100kT;当Ca²⁺浓度从1mmol/L增加到100mmol/L,PS-MPs和石英砂之间的排斥势垒下降了543kT.背景离子浓度的增加或价态的升高能促进Pb²⁺的单独运移能力.PS-MPs/Pb²⁺二元体系中,PS-MPs能够促进Pb²⁺的运移,背景离子浓度较低时,PS-MPs负载Pb²⁺的迁移率较高,反之亦然.对于PS-MPs和Pb²⁺单运移体系,背景阳离子浓度和价态的提升可进一步屏蔽PS-MPs及石英砂表面负电荷,竞争吸附石英砂表面结合位点,抑制PS-MPs运移,促进Pb²⁺运移;对于PS-MPs和Pb²⁺共运移体系,背景离子浓度和价态的提升可通过调节Pb²⁺与PS-MPs及石英砂表面的相互作用,削弱Pb²⁺对PS-MPs迁移能力的抑制作用.背景离子对PS-MPs表面位点的竞争吸附及对电荷的屏蔽效应影响PS-MPs对Pb²⁺的负载迁移能力.     

土壤-苦丁茶树系统中铅的GF-AAS测定及其分布特性

采集不同苦丁茶树的根、茎、叶及对应的土壤样品,经过清洗、烘干、研磨等预处理后,采用高压密封罐加热消解,加入磷酸氢二铵作为基体改进剂,通过氘灯扣除背景,以石墨炉原子吸收光谱法(GF-AAS)测定样品中的铅,铅浓度在0.000—60.000ng.ml-1时与吸光度呈现良好的线性关系,相关系数r=0.9999,检出限为0.200ng.ml-1,方法精密度RSD5%,回收率93%—107%.用上述方法研究土壤-苦丁茶树系统中铅的分布表明,各种苦丁茶树及土壤中铅的分布具有类似规律,即土壤中铅含量远高于茶树中,茶树的地下部分含量分布为:吸收根主根,地上部分为:枯叶茎老叶嫩叶,其中嫩叶中铅含量远低于限量指标(Pb≤5.0μg.g-1),对茶叶服用的安全性有利.     

基于土壤酶活性变化的铅污染土壤修复基准

近年来,污染土壤修复技术发展很快,而污染土壤修复标准的建立则相对迟缓。为了推进我国该领域的工作,对铅胁迫下土壤酶活性（如过氧化氢酶,磷酸酶,脲酶）随时间的变化进行了研究,以确定棕壤土中铅的土壤修复基准。结果表明：土壤中的铅能够刺激土壤中过氧化氢酶活性的增加,但随着土壤铅浓度的增加,这种刺激作用逐渐减小。土壤过氧化氢酶活性不宜作为铅污染土壤的生物标记物。土壤磷酸酶活性没有一致的变化规律,土壤磷酸酶活性不能作为铅污染土壤的生物标记物。在整个实验时间范围内,土壤脲酶活性与土壤中铅的浓度具有明显的剂量-效应关系（P〈0.01）,土壤脲酶活性可以作为铅污染土壤生物标记物。以土壤脲酶抑制率降低25%为依据,确定棕壤中铅的土壤修复基准为94mg·kg-1,以土壤脲酶抑制率降低45%为依据,确定棕壤中铅的土壤修复基准为178mg·kg-1。     

贵阳市城市道路灰尘重金属铅污染及评价

对贵阳市城市道路灰尘重金属铅污染进行了研究。结果表明：2008年贵阳市各行政区道路灰尘中铅的含量按南明区、乌当区、白云区、花溪区、云岩区、小河区顺序分别为81.19～174.94mg/kg、54.33～177.62mg/kg、59.75～275.93mg/kg、59.45～143.41mg/kg、61.32～106.05mg/kg、57.84～115.53mg/kg,平均含量分别为110.94mg/kg、78.49mg/kg、105.35mg/kg、96.87mg/kg、81.51mg/kg、88.11mg/kg,分别为环境背景值的3.0倍、2.1倍、2.8倍、2.6倍、2.2倍、2.4倍;不同行政区铅含量存在较大差异,铅在空间分布上也存在较大差异,其中白云区差异最大,云岩区差异最小。地积累指数及铅污染指数评价表明：贵阳市城市道路灰尘中铅污染总体上处于轻度污染水平,但局部区域处于偏中度至中度污染水平。     

轮叶黑藻对铅的吸附特征及生物吸附机理研究

研究了轮叶黑藻对重金属铅的吸附特征,同时对吸附机理进行探讨.动力学研究结果表明,轮叶黑藻对铅有较快的吸附能力,10min后铅的去除率达到74.54%;20min后,吸附达到平衡.整个吸附过程符合伪二级动力学方程(R2=0.9910).Sips和Langmuir模型相比Freundlich而言,有着较好的拟合效果,表明轮叶黑藻对重金属铅的吸附属于单层吸附,相邻铅离子间的相互干扰可以忽略不计.红外光谱分析表明:轮叶黑藻叶片富含多种活性基团,羟基、羰基和羧基、C–O及C–N为主要作用基团.吸附铅后,轮叶黑藻叶片内K、Na、Ca、Mg含量明显下降,表明铅离子因产生离子交换而被吸附,且铅离子更易与二价的Ca和Mg产生离子交换.     

Chelating resin immobilized sawdust packed chromatographic column: Application to separation and preconcentration of lead ion

Naturally abundant rubber sawdust has been utilized as a stationary support, which after immobilization with a chelating polyelectrolyte (xylenol orange as counterion) gets converted into a suitable column packing material for isolation and enrichment of trace level target analyte, accurately detectable by the technique of differential pulse anodic stripping voltammetry. The sorbent is robust and re-usable in column-chromatography without showing any leaching and interference complications. Its unique lead ion selectivity from multielemental complex matrices (synthetic water sample, blood serum) at optimized column conditions (pH 2.5 and flow rate 0.5?mL?min^?1) mitigates the usual problems of intermetallic and readsorption effects. Effects of flow rate, pH, equilibration time, and other variables are reported. The system has advantageous feature to be used in a single-column ion chromatography with satisfactory performance. A modest attempt has been made to determine lead fractions in human blood serum samples on the bases of selective retention of ionic and labile fractions on complexing resin.     

Blood lead level in the children of western Uttar Pradesh,India

The objective of this study was to determine the blood lead levels (blls) of children under an age of 5 years living in western Uttar Pradesh, India. A total of 100 blood samples, 100 drinking water samples, and 21 vegetable samples were assessed for lead contamination. Blood levels in the range of 30–116?µg?L^?1 were observed at Kazipur village. The levels of lead in water samples were reported to be in the range of 0.006–0.095?ppm and identified at up to 9.5 times the stated permissible limit. A significant positive correlation (+0.679) was obtained between blls and water lead levels. All vegetable samples were also contaminated with lead up to 12 times higher than the permissible limit of 2.5?mg?kg^?1 of Prevention of Food Adulteration Act (PFA) 1954. The cottage lead battery industry, industrial effluents, and lead paints were identified as possible factors for lead incidence in the study area. Lead may be associated with increased antisocial activities of the children living in western Uttar Pradesh. Children with elevated blls had poorer nutritional status than those with normal levels, and parents did not know that lead causes health problems. A national population-based study is recommended to determine the prevalence of elevated blls.     

Risk assessment of children's blood lead level in some rural habitations of western Uttar Pradesh,India

The objective of this study was to determine the blood lead level (BLL) of children aged under 5 living in western Uttar Pradesh, India. A total of 100 blood samples, 100 drinking water samples, and 21 vegetable samples were assessed for lead (Pb) contamination. BLL was observed in the range of 3–11.58?µg?dL^?1 with a maximal level of 11.58?±?0.05?µg?dL^?1 in Kazipur village. Lead in water samples was detected in the range of 0.006–0.095?ppm and identified at upto 9.5-fold higher than the stated permissible limit. A significant positive correlation (+0.679) was obtained between BLL and water Pb levels. All vegetable samples were also contaminated with Pb upto 12-fold higher than the permissible limit of 2.5?µg?g^?1 of Prevention of Food Adulteration Act (PFA) 1954. Untreated industrial effluents were identified as the responsible factors for Pb occurrence in the study area. The presence of lead may be associated with the increased antisocial activities of children living in western Uttar Pradesh. Children with elevated BLL had poorer nutritional status than those with background Pb levels. There is an urgent need for a national campaign to monitor the BLL of children in India.     

The effects of developmental lead (Pb) exposure on the expression of the CTGF and TGF-β1 in hippocampus of pups

Pregnant mice were exposed to control (0%), low (0.1%), moderate (0.5%), and high (1%) lead (Pb) acetate in deionized drinking water from the first day of gestation to postnatal day (PND) 21. Pb concentration was determined in blood and the hippocampus at the 7th, 14th, or 21st day of neonatal mice pups. The expression of connective tissue growth factor (CTGF) and TGF-β1 mRNA and protein was also measured in the hippocampus using RT-PCR and immunohistochemistry assays. The expression of CTGF and TGF-β1 mRNA was up-regulated in hippocampus in Pb-exposed groups. These results were further confirmed by immunohistochemistry staining. Data suggest that CTGF and TGF-β1 genes are differentially regulated and are affected by Pb.