Contamination of groundwater and risk assessment for arsenic exposure in Ha Nam province, Vietnam

The characteristics of arsenic-contaminated groundwater and the potential risks from the groundwater were investigated. Arsenic contamination in groundwater was found in four villages (Vinh Tru, Bo De, Hoa Hau, Nhan Dao) in Ha Nam province in northern Vietnam. Since the groundwater had been used as one of the main drinking water sources in these regions, groundwater and hair samples were collected in the villages. The concentrations of arsenic in the three villages (Vinh Tru, Bo De, Hoa Hau) significantly exceeded the Vietnamese drinking water standard for arsenic (10 microg/L) with average concentrations of 348, 211, and 325 microg/L, respectively. According to the results of the arsenic speciation testing, the predominant arsenic species in the groundwater existed as arsenite [As(III)]. Elevated concentrations of iron, manganese, and ammonium were also found in the groundwater. Although more than 90% of the arsenic was removed by sand filtration systems used in this region, arsenic concentrations of most treated groundwater were still higher than the drinking water standard. A significant positive correlation was found between the arsenic concentrations in the treated groundwater and in female human hair. The risk assessment for arsenic through drinking water pathways shows both potential chronic and carcinogenic risks to the local community. More than 40% of the people consuming treated groundwater are at chronic risk for arsenic exposure.     

Accumulation of Pb, Cd, Cu and Zn in plants and hyperaccumulator choice in Lanping lead-zinc mine area, China

A field survey of higher terrestrial plants growing on Lanping lead-zinc mine, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Cd, Cu and Zn of 20 samples of 17 plant species. Concentrations of Pb and Zn in soil and in plant were higher than that of Cu and Cd. Significant difference was observed among the average concentrations of four heavy metals in plants (except Cd and Cu) and in soil (except Pb and Zn) (P<0.05). For the enrichment coefficient of the four heavy metals in plant, the order of average was Pbtree>herbaceous, and herbaceous grew in soil with the highest concentrations of four heavy metals. In different areas, the concentrations of Pb, Cd, Cu and Zn in plants and soils and enrichment coefficient were different. Plants in Paomaping had more accumulating ability to Pb, Cd and Zn, and plants in Jinfeng River had more accumulating ability to Cu. Six plant species, i.e. S. cathayana, Lithocarpus dealbatus, L. plyneura, Fargesia dura, Arundinella yunnanensis and R. annae in Paomaping, had high accumulation capacity. R. annae in Paomaping had hyperaccumulating capacity to Pb, Cd and Zn, L. plyneura to Pb and Cd, and S. cathayana to Cd, respectively.     

Selection of a suitable mobile phase for the speciation of four arsenic compounds in drinking water samples using ion-exchange chromatography coupled to inductively coupled plasma mass spectrometry

The performance of two mobile phase buffers, phosphate and TRIS, were compared for the speciation of four arsenic species: arsenate (As(V)), arsenite (As(III)), mono methylarsonic acid (MMA), and dimethyl arsinic acid (DMA) in drinking water, using ion-exchange chromatography inductivelycoupled plasma mass spectrometry (IEC-ICP-MS). The mobile phase containing TRIS acetate buffer ("TRIS") demonstrated superior perfomance in baseline separation of all four arsenic species and the internal standard. It is also applicable to high-throughput sample analysis as it minimized the frequency required to clean the sampling interface due to salt build-up when compared to the phosphate mobile phase. The method was evaluated for its precision, accuracy, linearity and detection limits. The method was successfully applied for the analysis of drinking water samples.     

Hyperaccumulation of Pb, Zn and Cd in herbaceous grown on lead-zinc mining area in Yunnan, China

A field survey of herbaceous growing on lead-zinc mining area in Yunnan, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Zn and Cd in shoots. In total, 220 plant samples of 129 species of 50 families and 220 soil samples in which the plants were growing were collected. According to accumulation concentration in plant shoots and the concentration time levels compared to plants from non-polluted environments, 21 plant samples of 16 species were chosen as best-performing specimens, 11 plant samples of 10 species for Pb, 5 plant samples of 4 species for Zn and 5 plant samples of 5 species for Cd. Sonchus asper (L.) Hill in Qilinkeng had hyperaccumulation capacity to Pb and Zn. Corydalis pterygopetala Franch in Paomaping had hyperaccumulation capacity to Zn and Cd. All 5 Cd hyperaccumulators came from Lanping lead-zinc mining area. Out of 11 Pb hyperaccumulators, 7 came from Minbingying of Huice lead-zinc mining area. The average of the concentration time levels compared to plants from non-polluted environments were higher than 10 times in all plant samples, the concentration time levels changed from 203 times to 620 times for Pb, from 50 times to 70 times for Zn and from 145 times to 330 times for Cd. Out of 21 plant samples, translocation factor changed from 0.35 to 1.90, only translocation factor of 7 plant samples were higher than 1. Enrichment coefficients of all samples were lower than 1. These plant species were primarily heavy metal hyperaccumulator, and will be used in phytoremediation of the metallic pollutants in soils after further research in accumulation mechanism.     

Effect of soil properties on arsenic fractionation and bioaccessibility in cattle and sheep dipping vat sites

Historical use of high arsenic (As) concentrations in cattle/sheep dipping vat sites to treat ticks has resulted in severe contamination of soil and groundwater with this Group-A human carcinogen. In the absence of a universally applicable soil As bioaccessibility model, baseline risk assessment studies have traditionally used the extremely conservative estimate of 100% soil As bioaccessibility. Several in-vitro, as well as, in-vivo animal studies suggest that As bioaccessibility in soil can be lower than that in water. Arsenic in soils exists in several geochemical forms with varying degree of dissolution in the human digestive system, and thus, with highly varying As bioaccessibility. Earlier batch incubation studies with As-spiked soils have shown that As bioaccessibility is a function of soil physicochemical properties. We selected 12 dipping vat soils collected from USA and Australia to test the hypothesis that soil properties exert a significant effect on As bioaccessibility in As-contaminated sites. The 12 soils varied widely in terms of soil physico-chemical properties. They were subject to an As sequential fractionation scheme and two in-vitro tests (IVGS and IVGIA) to simulate soil As bioavailability in the human gastrointestinal system. Sequential As fractionation results showed that the majority of the As measured in the dipping vat soils resided either in the Fe/Al hydroxide fraction, or the Ca/Mg fractions, or in the residual fraction. Water-extractable As fraction of the 12 soils was typically <10% of the total, reaching values up to 23%, indicating minimal leaching potential, and hence, lower risk of As-contamination from exposure to groundwater, typically used as drinking water in many parts of the world. Partial individual correlations and subsequent multiple regression analyses suggested that the most significant soil factors influencing As bioaccessibility were total Ca+Mg, total P, clay content and EC. Collectively, these soil properties were able to explain 85 and 86% of the variability associated with the prediction of bioaccessible As, using IVGS and IVGIA in-vitro tests, respectively. This study showed that specific soil properties influenced the magnitude of soil As bioaccessibility, which was typically much lower than total soil-As concentrations, challenging the traditional risk assessment guideline, which assumes that soil As is 100% bioaccessible. Our study showed that total soil As concentration is unlikely to provide an accurate estimate of human health risk from exposure to dipping vat site soils.     

Recent advances in the bioremediation of arsenic-contaminated groundwater

The biological treatment of groundwater is used primarily to remove electron donors from water sources, providing (biologically) stable drinking water, which preclude bacterial regrowth during subsequent water distribution. To the electron donors belong also the dissolved metal cations of ferrous iron and manganese, which are common contaminants found in most (anaerobic) groundwater. The removal of iron and manganese is usually accomplished by the application of chemical oxidation and filtration. However, biological oxidation has recently gained increased importance and application due to the existence of certain advantages, over the conventional physicochemical treatment. The oxidation of iron and manganese is accelerated by the presence of certain indigenous bacteria, the so-called "iron and manganese oxidizing bacteria." In the present paper, selected long-term experimental results will be presented, regarding the bioremediation of natural groundwater, containing elevated concentrations of iron and arsenic. Arsenic is considered as a primary pollutant in drinking water due to its high toxicity. Therefore, its efficient removal from natural waters intended for drinking water is considered of great importance. The application of biological processes for the oxidation and removal of dissolved iron was found to be an efficient treatment technique for the simultaneous removal of arsenic, from initial concentrations between 60 and 80 microg/l to residual (effluent) arsenic concentrations lower than the limit of 10 microg/l. The paper was focused on the removal of As(III) as the most common species in anaerobic groundwater and generally is removed less efficiently than the oxidized form of As(V). To obtain information for the mechanism of As(III) removal, X-ray photoelectron spectroscopy (XPS) analyses were applied and it was found that As(III) was partially oxidized to As(V), which enabled the high arsenic removal efficiency over a treatment period of 10 months.     

Levels of metals in soils of Alcalá de Henares,Spain: human health risks

The concentrations of aluminium (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), vanadium (V), and zinc (Zn) were determined in soil samples collected in Alcalá de Henares (Madrid, Spain). Human health risks derived from metal inhalation and ingestion of soils were also assessed. For noncarcinogenic risks, the current levels of metals were usually lower than those considered as safe for the general population. With respect to the potentially carcinogenic elements As, Be, Cd, and Cr, the concentrations of Be, Cd, and Cr were lower than the reference values, while the average As concentration (3.4 microg/g) was higher than the safety limit for risk cancer. In general terms, the potential human health impact of ingestion/inhalation through soils of the analyzed elements seems to be rather small.     

Plants against the global epidemic of arsenic poisoning

Due to the growing current trend around the world of drinking water from underground sources, in an attempt to replace heavily polluted surface water supplies, arsenic is causing a global epidemic of poisoning with hundreds of millions of people now being thought at serious risk in many countries. Phytoremediation (bioremediation mediated by plants) has been proposed as an effective tool in arsenic cleanup. Actually, some plants (most notably, the Chinese brake fern Pteris vittata) have been reported to be suitable for arsenic phytoremediation. In this respect, transgenic plants are being developed to improve their capacity to accumulate arsenic. Most interestingly, rhizofiltration (use of plants to absorb or adsorb pollutants from water) is being considered for the ex situ and in situ remediation of arsenic-contaminated water. Similarly, some plants show great potential to remove arsenic from polluted soil.     

Toxicological responses in Laeonereis acuta (annelida, polychaeta) after arsenic exposure

Several environmental pollutants, including metals, can induce oxidative stress. So, the objective of this study was to evaluate the effects of arsenic (As(III), as As(2)O(3)) on the antioxidant responses in the polychaete Laeonereis acuta. Worms were exposed to two environmentally relevant concentrations of As, including the highest previously allowed by Brazilian legislation (50 microg As/l). A control group was kept in saline water (10 per thousand) without added metal. It was observed that: (1) a peak concentration of lipid peroxide was registered after 2 days of exposure to 50 microg As/l (61+/-3.2 nmol CHP/g wet weight) compared to the control group (43+/-4.5 nmol CHP/g wet weight), together with a lowering of the activity of the antioxidant enzyme catalase (-47 and -48%, at 50 or 500 microg As/l respectively) and a higher superoxide dismutase activity (+305% at 50 microg As/l with respect to the control group); (2) a lower conjugation capacity through glutathione-S-transferase activity was observed after 7 days of exposure to 50 microg As/l (-48% compared to the control group); (3) a significant increase in As concentration was verified after 1 week of exposure to both As concentrations (50 and 500 microg/l); (4) worms exposed to As showed a limited accumulation of related methylated As species and the levels of non-toxic As species like arsenobetaine (AsB) and arsenocholine (AsC) remained unchanged during the exposure period when compared with the controls. Overall, it can be concluded that As interfered in the antioxidant defense system of L. acuta, even at low concentrations (50 microg/l) that Brazilian legislation previously considered safe. The fact that worms exposed to As showed high levels of methylated As species indicates the methylation capability of L. acuta, although the high levels of inorganic As suggest that not all the administered As(III) (as As(2)O(3)) is completely removed or biotransformed after 7 days of exposure.     

Assessment of arsenic and heavy metal concentrations in water and sediments of the Rio Grande at El Paso-Juarez metroplex region

The Rio Grande located along the US-Mexico border is affected by anthropogenic activities along its geographical course. Runoff and wind deposition of smelting residues may contribute to the pollution of the Rio Grande in the El Paso-Ciudad Juarez area. Few studies have addressed the presence or impacts of heavy metals or arsenic in this ecosystem. This study reports a survey of heavy metals (Cr, Cu, Cd, Ni, Pb, and Zn) and arsenic (As) in water and sediments of the Rio Grande collected from seven sites in the El Paso-Juarez region. Since water quality influences metal content in water, physical (temperature, flow and conductivity), and chemical (pH, dissolved oxygen, nitrates, alkalinity, and water hardness) parameters were measured at each site. Arsenic and heavy metal levels were determined using Inductively Couple Plasma (ICP) emission spectroscopy following EPA procedures. Zinc and lead were found as both total and dissolved metals in most of the samples, with concentrations of total recoverable metals reaching up to 105 and 70 microg/l, respectively. Most metals were found in sediment samples collected from four of seven sites. The highest Cu concentration (35 mg/l) was found at the American Dam site. Concentrations of metals found through this survey will be used as a reference for future studies in monitoring arsenic, heavy metals, and their impacts in the Rio Grande.     

Effect of copper-tolerant rhizosphere bacteria on mobility of copper in soil and copper accumulation by Elsholtzia splendens

The role of rhizosphere bacteria in facilitating the solubility of copper (Cu) in contaminated soil and Cu accumulation in plant were studied. The bacteria strains were isolated from the rhizosphere of Elsholtzia splendens, a Cu accumulator growing on Tonglu Mountain copper mines. After the sandy soils containing 237 mg kg(-1) were incubated with the bacteria strains, it was indicated that rhizosphere microbes played an important role in influencing the availability of water-soluble Cu in soils. Soils had greater concentrations of water-extractable Cu compared with axenic soils inoculated with different bacterial strains. Further evidence for bacterial facilitation of increased solubility of Cu in the soil was obtained using the antibiotic ampicillin (0.1 mg g(-1)). There were 36% decreases in Cu concentration in the presence of bacterial strain MS12 and ampicillin together compared with bacterial inoculation alone. Different bacterial strains had different abilities on soil water-soluble Cu. To achieve the highest rates of plant Cu accumulation, it was necessary for bacteria to be present in the rhizosphere of E. splendens. Inoculated plants supplied with 20 micromol L(-1) CuSO4 had significantly greater concentrations of Cu in shoots and roots than uninoculated plants and bacterial strain MS2 was the most effective strain in promoting plant Cu uptake. There were 2.2-fold and 2.5-fold increases in Cu accumulation in the shoots and roots of plants inoculated with strain MS2 compared to axenic controls. Furthermore, when ampicillin and the bacterial strains were added together to the nutrient solution, the Cu concentrations in roots and shoots of ampicillin-treated plants were lower than those in inoculated plants. When ampicillin was added to the nutrient solution, Cu accumulation was inhibited by about 24-44% in shoots and 20-44% in roots. The above results provided a new insight into the phytoremediation of Cu-contaminated soil.     

Arsenic concentrations in rice, vegetables, and fish in Bangladesh: a preliminary study

Arsenic contaminating groundwater in Bangladesh is one of the largest environmental health hazards in the world. Because of the potential risk to human health through consumption of agricultural produce grown in fields irrigated with arsenic contaminated water, we have determined the level of contamination in 100 samples of crop, vegetables and fresh water fish collected from three different regions in Bangladesh. Arsenic concentrations were determined by hydride generation atomic absorption spectrophotometry. All 11 samples of water and 18 samples of soil exceeded the expected limits of arsenic. No samples of rice grain (Oryza sativa L.) had arsenic concentrations more than the recommended limit of 1.0 mg/kg. However, rice plants, especially the roots had a significantly higher concentration of arsenic (2.4 mg/kg) compared to stem (0.73 mg/kg) and rice grains (0.14 mg/kg). Arsenic contents of vegetables varied; those exceeding the food safety limits included Kachu sak (Colocasia antiquorum) (0.09-3.99 mg/kg, n=9), potatoes (Solanum tuberisum) (0.07-1.36 mg/kg, n=5), and Kalmi sak (Ipomoea reptoms) (0.1-1.53 mg/kg, n=6). Lata fish (Ophicephalus punctatus) did not contain unacceptable levels of arsenic. These results indicate that arsenic contaminates some food items in Bangladesh. Further studies with larger samples are needed to demonstrate the extent of arsenic contamination of food in Bangladesh.     

Metal levels in sugar cane (Saccharum spp.) samples from an area under the influence of a municipal landfill and a medical waste treatment system in Brazil

In July 2003, duplicated samples of roots, stems and leaves of sugar cane (Saccharum spp.) were collected in 25 points of an area under direct influence of the municipal landfill site (MLS) and medical waste treatment system (MWTS) of Ribeirao Preto, S?o Paulo, Brazil. Cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), lead (Pb) and zinc (Zn) were determined by atomic absorption spectrophotometry. The following concentrations (mg/kg) were found in roots: Cd, 0.22+/-0.12; Cr, 64.3+/-48.7; Cu, 140.6+/-27.7; Hg, 0.04+/-0.02; Mn, 561.6+/-283.3; Pb, 7.9+/-2.1 and Zn, 177.4+/-64.9. For some metals, these levels are higher than the concentrations previously reported for different plants, reaching, in some cases, values that might be considered toxic for vegetables. Metal levels in stems were 80-90% of those found in roots, while the concentrations detected in leaves were significantly lower than those in roots. The present results suggest that MLS and MWTS activities might have been increasing metal concentrations in edible tissues of sugar cane grown in the area under their influence. Moreover, the traditional agricultural practices in the production of sugar cane could be also another determinant factor to reach the current metal levels. The results of this study indicate that sugar cane is a crop that is able to grow in areas where metals in soils are accumulated.     

Effect of arsenic contamination on microbial biomass and its activities in arsenic contaminated soils of Gangetic West Bengal, India

A study was conducted to see the effect of arsenic contamination on soil quality indicators, viz., microbial biomass, soil respiration, fluorescein diacetate and dehydrogenase (DHG) activity in arsenic contaminated soils of West Bengal. All the parameters were significantly and negatively correlated with all the form of arsenic (bioavailable and total) but the microbial metabolic quotient was significantly and positively correlated with all forms of arsenic, indicating arsenic induced stress to the soil microbial community. This may be due to part of the microbial biomass, which is located in the inner parts of the micro-aggregates of soil, which is affected by arsenic accumulates present in soil particles. Linear regression analysis revealed that the bioavailable arsenic exerted greater inhibitory effect on the soil microbial population than the total arsenic content of soils. Water-soluble arsenic showed more inhibitory effect than NaHCO(3) extractable form, in their association with biological properties of the contaminated soils. Water-soluble form of arsenic was much more toxic than insoluble forms. This signified that with increase in bioavailability, the arsenic exerted more inhibitory effect on these parameters. It is thus suggested that the microbial biomass, fluorescein diacetate and dehydrogenase activity alone and expressed on a soil organic matter basis along with the soil respiration parameters can be helpful in assessing the effects of arsenic on the size and activity of microbial biomass in soils.     

Plant community tolerant to trace elements growing on the degraded soils of São Domingos mine in the south east of Portugal: environmental implications

The selection of trace element tolerant species is a key factor to the success of remediation of degraded mine soils. Mining activities generate a large amount of waste rocks and tailings, which get deposited at the surface. The degraded soils, the waste rocks and tailings are often very unstable and will become sources of pollution. The direct effects will be the loss of cultivated land, forest or grazing land, and the overall loss of production. The indirect effects will include air and water pollution and siltation of rivers. These will eventually lead to the loss of biodiversity, amenity and economic wealth. Restoration of a vegetation cover can fulfil the objectives of stabilization, pollution control, visual improvement and removal of threats to human beings. Thus, remediation of mine spoils/tailings and biogeochemical prospecting would rely on the appropriate selection of plant species. Plant community responds differently on their ability to uptake or exclude a variety of metals. In this work, plant species were sampled from all populations established in an abandoned copper mine of S?o Domingos, SE Portugal. Plants belonging to 24 species, 16 genera and 13 families were collected from the degraded copper mine of S?o Domingos. Plant samples were analysed for total Ag, As, Cu, Ni, Pb, and Zn. The highest concentrations of metals in soils dry matter were 11217.5 mg Pb kg(-1), 1829 mg Cu kg(-1), 1291 mg As kg(-1), 713.7 mg Zn kg(-1), 84.6 mg Cr kg(-1), 54.3 mg Co kg(-1), 52.9 mg Ni kg(-1) and 16.6 mg Ag kg(-1). With respect to plants, the higher concentrations of Pb and As were recorded in the semi-aquatic species Juncus conglomeratus with 84.8 and 23.5 mg kg(-1) dry weight (DW), Juncus efusus with 22.4 and 8.5 mg kg(-1) DW, and Scirpus holoschoenus with 51.7 and 8.0 mg kg(-1) DW, respectively. Thymus mastichina also showed high content of As in the aboveground parts, 13.6 mg kg(-1) DW. Overall, the results indicate accumulation of various metals by different plant species, with some of these metals being partitioned to the shoots. Environmental implications of these observations are discussed.     

性腺发育及年龄对养殖中华鲟抗氧化力的影响

以养殖的子一代（n=21）中华鲟为对象,研究了性腺发育及年龄对其抗氧化力的影响。结果表明：（1）1998年生子一代雌性(未达性成熟,性腺处于慢速发育阶段)和雄性(接近性成熟,性腺处于开始快速发育阶段)的睾酮和雌二醇/睾酮差异显著,雌性血清丙二醛水平显著低于雄性,而超氧化物歧化酶和谷胱甘肽过氧化酶的活力及超氧化物歧化酶/丙二醛值虽高于雄性,但二者间不存在显著性差异,雌性和雄性的丙二醛与超氧化物歧化酶/丙二醛之间相关性极显著（r=-0915,-0818,P＜001);（2）雌二醇/睾酮值与丙二醛显著负相关,与超氧化物歧化酶/丙二醛显著正相关（r=-0635,r=0709,P＜005）,与超氧化物歧化酶、谷胱甘肽过氧化酶无显著相关性;（3）4个年龄组（4、8、11、12龄,未达性成熟）的超氧化物歧化酶和丙二醛无显著性差异,12龄组的谷胱甘肽过氧化酶显著低于其余3组,而超氧化物歧化酶/丙二醛显著高于其余3组,谷胱甘肽过氧化酶和丙二醛与年龄呈负相关（r=-0547,P＜001;r=-0519,P＜005）,超氧化物歧化酶/丙二醛与年龄呈正相关（r=0569,P＜001）。这表明进入性腺快速发育阶段的雄性氧化应激水平明显高于处于性腺慢速发育阶段的同龄雌性;随着年龄增长,未达性成熟中华鲟的抗氧化力水平逐渐增强;使用以上指标作为亚健康群体的筛选指标和氧化应激的生物标志物时,应充分考虑监测群体性腺发育和年龄因素,以使参考指标更准确     

铜绿微囊藻对有机毒物菲的生理生态响应研究

选取富营养化湖泊蓝藻水华常见优势种铜绿微囊藻（Microcystis aeruginosa,M. aeruginosa）为研究对象,采用室内暴露培养实验考察多环芳烃（Polycyclic aromatic hydrocarbons,PAHs）化合物菲（Phenanthrene,Phe）对铜绿微囊藻生长及生理特性的影响效应和作用机制。研究结果表明,低浓度Phe（0.05~0.2 mg/L）对铜绿微囊藻细胞生长有不同程度的促进作用,0.2 mg/LPhe促进作用最为显著（P＜0.05）;高浓度Phe（0.5~1.0 mg/L）显著抑制铜绿微囊藻生长（P＜0.05）。铜绿微囊藻典型生理指标细胞光合作用率（Fv/Fm）、超氧化物歧化酶（SOD）、谷氨酰胺还原酶（GR）酶活性以及丙二醛（MDA）含量同步分析结果显示,低浓度Phe通过增强SOD、GR酶活性,降低铜绿微囊藻细胞内MDA含量,提高藻细胞光合作用率,进而促进细胞增殖;高浓度Phe则通过降低SOD、GR酶活性,增加藻细胞内MDA产量,减弱细胞光合作用,从而抑制细胞生长。对不同暴露时刻藻细胞的生长抑制率进行回归分析可得EC50（半抑制浓度）随着污染暴露时间增加而减低,1day EC50为1.27 mg/L,12day EC50降至0.65 mg/L,即高剂量Phe（0.5~1.0 mg/L）对微囊藻细胞生长的抑制作用随时间延长逐渐增强。结合低剂量浓度下Phe对铜〖JP+2〗绿微囊藻生长的促进作用分析,湖泊生态系统Phe污染长期暴露对铜绿微囊藻生长生理特性及优势种的形成和维持具有不可忽视的作用。其中,铜绿微囊藻细胞主要生理指标SOD与GR对Phe污染胁迫反应灵敏,可用作评价PAHs等有机毒物对浮游藻类生理生态影响的生物标记物     

A cultural practice of drinking realgar wine leading to elevated urinary arsenic and its potential health risk

Toasting friends and family with realgar wines and painting children's foreheads and limbs with the leftover realgar/alcohol slurries is an important customary ritual during the Dragon Boat Festival (DBF); a Chinese national holiday and ancient feast day celebrated throughout Asia. Realgar is an arsenic sulfide mineral, and source of highly toxic inorganic arsenic. Despite the long history of realgar use during the DBF, associated risk to human health by arsenic ingestion or percutaneous adsorption is unknown. To address this urine samples were collected from a cohort of volunteers who were partaking in the DBF festivities. The total concentration of arsenic in the wine consumed was 70 mg L?1 with all the arsenic found to be inorganic. Total arsenic concentrations in adult urine reached a maximum of ca. 550 μg L?1 (mean 220.2 μg L?1) after 16 h post-ingestion of realgar wine, while face painting caused arsenic levels in children's urine to soar to 100 μg L?1 (mean 85.3 μg L?1) 40 h after the initial paint application. The average concentration of inorganic arsenic in the urine of realgar wine drinkers on average doubled 16 h after drinking, although this was not permanent and levels subsided after 28 h. As would be expected in young children, the proportions of organic arsenic in the urine remained high throughout the 88-h monitoring period. However, even when arsenic concentrations in the urine peaked at 40 h after paint application, concentrations in the urine only declined slightly thereafter, suggesting pronounced longer term dermal accumulation and penetration of arsenic. Drinking wines blended with realgar or using realgar based paints on children does result in the significant absorption of arsenic and therefore presents a potentially serious and currently unquantified health risk.     

Differences in U root-to-shoot translocation between plant species explained by U distribution in roots

Accumulation and distribution of uranium in roots and shoots of four plants species differing in their cation exchange capacity of roots (CECR) was investigated. After exposure in hydroponics for seven days to 100 μmol U L⁻¹, distribution of uranium in roots was investigated through chemical extraction of roots. Higher U concentrations were measured in roots of dicots which showed a higher CECR than monocot species. Chemical extractions indicated that uranium is mostly located in the apoplasm of roots of monocots but that it is predominantly located in the symplasm of roots of dicots. Translocation of U to shoot was not significantly affected by the CECR or distribution of U between symplasm and apoplasm. Distribution of uranium in roots was investigated through chemical extraction of roots for all species. Additionally, longitudinal and radial distribution of U in roots of maize and Indian mustard, respectively showing the lowest and the highest translocation, was studied following X-ray fluorescence (XRF) analysis of specific root sections. Chemical analysis and XRF analysis of roots of maize and Indian mustard clearly indicated a higher longitudinal and radial transport of uranium in roots of Indian mustard than in roots of maize, where uranium mostly accumulated in root tips. These results showed that even if CECR could partly explain U accumulation in roots, other mechanisms like radial and longitudinal transport are implied in the translocation of U to the shoot.     

Secondary arsenic minerals in the environment: A review

Information on arsenic (As) speciation in solid materials is critical for many environmental studies concerned with As stability and/or mobility in natural As-impacted soils and mining or industrial sites contaminated by As. The investigation of these systems has provided evidence for a number of secondary As minerals that have often played a significant role in As mobility in the solid phase–water system. This paper presents a list of environmentally important secondary As minerals in contaminated soil and waste systems, summarizes the information about their origin, occurrence, environmental stability and thermodynamics, and proposes several important avenues for further investigation.