Lead and Aroclor 1254 disrupt reproductive neuroendocrine function in Atlantic croaker     

I. A. Khan  P. Thomas 《Marine environmental research》2000,50(1-5):119-123

We have previously shown that lead (lead chloride) and a polychlorinated biphenyl (PCB) mixture (Aroclor 1254) can alter hypothalamic serotonin (5-hydroxytryptamine, 5-HT) content, and pituitary gonadotropin II (GTH II) release in vitro, in the Atlantic croaker (Micropogonias undulatus). In the present study we investigated whether impairment of the hypothalamic 5-HT pathway involves alterations in tryptophan hydroxylase (TPH), the rate-limiting enzyme in 5-HT biosynthesis, or monoamine oxidase (MAO), the catabolic enzyme. Aroclor 1254 (1 mg/kg body wt. for 30 days) significantly inhibited hypothalamic TPH activity without altering MAO activity, and caused a significant decline in 5-HT content. On the other hand, lead exposure (15 mg/kg body wt. for 30 days) only induced a slight decrease in hypothalamic 5-HT content and TPH activity, and a minor increase in MAO activity. However, both Aroclor 1254 and lead significantly inhibited the GTH II response to stimulation by a luteinizing hormone-releasing hormone analog (LHRHa) in vivo and caused reduced gonadal growth. These results demonstrate that impairment of hypothalamic serotonin metabolism by Aroclor 1254 involves inhibition of 5-HT synthesis, whereas lead does not exert a profound influence on 5-HT metabolism. The decline in 5-HT availability due to reduced 5-HT synthesis in the PCB-exposed fish may result in disruption of the stimulatory 5-HT-GnRH pathway controlling GTH II secretion leading to impairment of gonadal growth.  相似文献   

Reactive flow models of the Anarraaq Zn–Pb–Ag deposit,Red Dog district,Alaska     

Christian Schardt  Grant Garven  Karen D. Kelley  David L. Leach 《Mineralium Deposita》2008,43(7):735-757

The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200°C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS⁻ source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency).  相似文献   

Secondary mineral phases of metallic lead in soils of shooting ranges from Örebro County,Sweden     

Zhixun Lin 《Environmental Geology》1996,27(4):370-375

In some countries Pb-containing shotgun pellets have become one of the sources of soil contamination in shooting range areas. Pb pellets from eight shooting ranges in central Sweden were mineralogically analysed and the results show that when the Pb pellets come into contact with soil, about 10% of them are decomposed and transformed into secondary lead minerals as encrustations. The encrustation consists of two concentric rims: a 50 to 150 m wide outer rim of hydrocerussite (Pb₃(CO₃)₂(OH)₂) and a 10 to 30 m wide inner-rim of massicot (PbO). Anglesite (PbSO₄) occurs locally in the inner rim. The growing relationship between lead mineral phases suggests that replacement took place. The podzols of the shooting ranges studied are favorable for the formation of lead carbonate. Lead carbonate provides effective controls on the retention of lead in the upper soil layers.  相似文献   

Isotopic provenancing of Pb in Mitrovica,northern Kosovo: Source identification of chronic Pb enrichment in soils,house dust and scalp hair     

《Applied Geochemistry》2016

Mitrovica, northern Kosovo, is the site of some of the highest Pb concentrations reported in human populations; exemplified by Pb concentrations in scalp hair of up to 130 μg g⁻¹ and widely-publicized of Pb-related ill-health and mortality amongst internally displaced populations. High human Pb burdens are accompanied by elevated concentrations of potentially harmful elements (PHEs) in soils and house dust within the city, which has a long history of mining and metallurgy. In this study enrichment-levels for PHEs in soils are quantified and compared to environmental quality guidelines and a statistically-derived estimation of background concentration. In addition, Pb isotopes (²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb) are used to characterise the isotopic signatures of potential point sources of Pb and a mixing model employed to quantify the contribution of sources to Pb present in soils, house dust, and the scalp hair of children and young people. Pb isotopic evidence suggests that Pb in surface soils and house-dust is predominantly sourced from historical deposition of Pb-containing aerosols from metal smelting, with lower contributions from wind-blown dispersal of metalliferous waste. Pb present in scalp hair is interpreted as the result of non-occupational exposure and the ingestion and/or inhalation of Pb-enriched surface soil and house dust. This study represents one of the very few instances where this type of geochemical tracing technique has been successfully applied to definitively identify the source of Pb present within biological samples. The results of this study are of particular relevance to environmental management and highlight the human health risk posed by the legacy of now inactive mining and metallurgy in addition to the challenge posed in mitigating the risk posed by diffuse soil pollution.  相似文献   

交流电弧直读发射光谱法测定地球化学样品中银、硼、锡、钼、铅的方法研究   总被引：5，自引：0，他引：5  

郝志红  姚建贞  唐瑞玲  杨帆  李文阁  白金峰  张勤 《地质学报》2016,90(8):2070-2082

本文建立了交流电弧直读原子发射光谱法测定地球化学样品中银、硼、锡、钼、铅的分析方法。以K2S2O7、NaF、Al2O3、碳粉为缓冲剂,Ge为内标,优选了分析线对,曝光时间为25s,同时扣除分析线和内标线背景。选取国家一级地球化学标准物质（GBW07103、GBW07104、GBW07107、GBW07312、GBW07302a、GBW07304a、GBW07305a、GBW07307a、GBW07406、GBW07446、GBW07454、GBW07456）作为标准系列,以对数坐标二次曲线拟合标准曲线,并采取两次平行分析取平均值的计算方法。方法检出限为:Ag:0011×10-6、B:054×10-6、Sn:019×10-6、Mo:0034×10-6、Pb:066×10-6,精密度为:Ag:401%～833%、B:377%～786%、Sn:294%～817%、Mo:303%～1094%、Pb:201%～1111%。经岩石、水系沉积物、土壤国家一级标准物质验证,测定值与认定值符合。本方法操作简便、工作效率高,是一种新的测定地球化学样品中银、硼、锡、钼、铅的分析方法,可推广应用于大批量地球化学样品的分析测试。  相似文献   

土壤元素异常成因研究及生态风险评价     

胡省英  黄丹  邓凯文  杨力  李迪 《城市地质》2016,(4):59-65

山区岩石与水系沉积物,对山前平原土壤物质组成具有控制作用。土壤地球化学调查,查明北京某地区土壤存在着大面积同心圆状的镉、铜、铅等多金属元素异常。研究表明,西北侧山区分布着种类繁多的岩浆岩、变质与沉积岩,但与山前土壤具有高度正相关的元素组合特征的主要是燕山期中酸性岩浆杂岩体,而且杂岩体周边及其下游的BY沟水系沉积物中的多金属元素也呈现出明显的高背景含量特征。同时,铅同位素组成亦指示山前平原土壤铅与山区岩浆岩铅、沉积岩铅具有一致的物质来源,从而证实山前土壤多金属元素异常主要来源于山区岩浆杂岩体。由于山前平原土壤呈现为碱性且农田仅种植旱地作物,故富含多金属的土壤对农作物生长的生态风险程度低下。  相似文献   

长江口滨岸潮滩底栖泥螺受铅污染的急性毒理试验   总被引：4，自引：0，他引：4  

李丽娜  陈振楼  许世远  毕春娟 《海洋湖沼通报》2005,(2):88-92

为了评价长江口滨岸潮滩沉积物中重金属铅对底栖动物的影响，进行了底栖动物泥螺的24h急性毒理学试验研究。结果表明：泥螺的半致死剂量是0．275g／L，全致死剂量是11．5g／L；对泥螺体内重金属累积量的分析表明：泥螺体内Pb的含量随试验组浓度的增高而增多，试验组的Pb浓度和泥螺累积的Pb含量符合三次函数；泥螺体内Pb的增加对泥螺富集Cu、Zn的影响是使其富集量有所下降，在浓度为4g／L时稍有回升；Pb含量的增加对泥螺富集Cr的影响是在浓度为0．1 1 8g／L时出现富集较大量，说明底栖动物富集的重金属元素问具有一定的协同作用。  相似文献   

东海—图们江水中Zn,Cd,Pb,Cu的形式分析          下载免费PDF全文

张首临  李泽林 《海洋与湖沼》1993,24(6):609-615

用防吸附物理涂汞电极反向极谱进行了东海至图们江水中Ｚｎ，Ｃｄ，Ｐｂ，Ｃｕ（１９９１年５－６月）的形式分析研究。结果表明，该４种元素不稳定态的平均浓度分别为５．７，０．０６０，０．０３５，０．６２μｇ／Ｌ，分布较为均匀。该结果证实了痕量金属离子（自由离子及不稳定络离子）的均匀分布规律。有机结合态Ｚｎ，Ｐｂ，Ｃｕ和颗粒态的Ｚｎ，Ｃｕ的较高含量，位于长江口及东海水中。  相似文献   

长江口海域悬浮颗粒物中铜、铅、镉的化学形态及分布特征研究   总被引：9，自引：0，他引：9  

邵秘华  王正方 《海洋与湖沼》1992,23(2):144-149

研究了重金属Cu,Pb,Cd在长江口及其邻近海域悬浮颗粒中各化学形态间的含量,及其在长江内河段—河海混合界面—海区间的各形态间的迁移转化特征。结果表明,长江口海域中重金属以非残渣相为主要存在形式,其中铁锰氧化物为重要的清除载体;以铁锰氧化物和碳酸盐形式存在的重金属含量受水环境盐度和pH控制;通过多元回归计算求得重金属与pH值、盐度(X_s)、悬浮体(X_(s.s))的多元一次方程。  相似文献   

A first approach to study the mobility and behavior of lead in hypersaline salt marsh sediments: Diffusive and advective fluxes,geochemical partitioning and Pb isotopes     

M.F. Soto-Jiménez  F. Páez-Osuna 《Journal of Geochemical Exploration》2010

A geochemical study of interstitial water and solid phase sediment using bulk concentration and geochemical partitioning was undertaken in vertical sediment profiles to trace diagenetic processes of lead (Pb) in hypersaline salt marsh sediments. In addition, we measured the stable isotopic composition of Pb in order to distinguish its input sources. Concentrations of Pb increased from low or background values in the bottommost layer (< 60 cm depth), followed by fluctuations in the middle layer (20–60 cm) and peak values in the subsurface layer (3–5 cm). Pb associated to reactive fractions (e.g. OM, Fe–Mn oxyhydroxides and carbonates) accounted for 60% of that initially deposited. Stable Pb isotope data (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁷Pb/²⁰⁸Pb) suggested that most of the Pb in the upper sediments (1.204 ± 0.002 and 2.469 ± 0.007) is still derived from the leaded gasoline combustion (1.201 ± 0.006 and 2.475 ± 0.005). Profile of dissolved Pb was related to those for ammonium, phosphates and dissolve Fe and Mn, which reveals the influence of the diagenetic reactions on the Pb behavior. OM, Fe–Mn oxyhydroxides and the sulfide minerals play a significant role for mobilizing and trapping the Pb. Metal mobilization was calculated considering an advective–diffusive system. The advective process constitutes the dominant mechanism of Pb mobilization. A low diffusive outflux with respect to the Pb mobilization rate suggested that most of the released Pb is retained in the sediments. Authigenic oxides precipitated at the oxic–suboxic layers (0–4 cm depth) and authigenic sulfide minerals formed Pb in the anoxic layers (7–20 cm depth) constituting the main scavengers for Pb that is diagenetically released. This retention has significant environmental implications because it reduces the availability and toxicity of Pb to biota, including humans.  相似文献