Pollution and ecological risk assessment of antimony and other heavy metals in soils from the world's largest antimony mine area,China

Xikuangshan is located in Lengshuijiang City, Hunan province, China. With intensive mining and metallurgical activities, large amounts of tailing containing heavy metals (in this study, the term “heavy metals” is used for both metals and metalloids) were introduced to the soils around the mine area. Those heavy metals including antimony and other heavy metals would pose huge risk to human health and ecological environment. With a view to providing information on the extent of contamination and potential ecological risk of heavy metals in the soils of this mine area, the total contents of antimony (Sb), manganese (Mn), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb) in the soils were examined. The results revealed that the predominant pollutants in this area were Sb, Cd, and Zn with mean concentrations being 356.58, 9.98, and 486.42 mg kg^?1, 119.66, 117.41, and 5.17 times of the corresponding background values respectively. The pollution indices (Ps) indicated that the pollution levels of all sampling zones were serious including the control zones. The ecological risk levels of all heavy metals were very high on all the sampling zones except sampling zone 7 (as considerable), and Sb, Cd, and As were regarded as making great contribution to the risk indices (RI).     

Risk assessment of heavy metal and metalloid toxicity through a contaminated vegetable (Cucurbita maxima) from wastewater irrigated area: A case study for a site-specific risk assessment in Jhang,Pakistan

The present research was conducted in district Jhang, Pakistan, to evaluate the concentration of metals/metalloids in soil and pumpkin (Cucurbita maxima) irrigated with domestic wastewater. Data revealed that the levels of metals and metalloids in soil samples from two different sites were below the safe limits except Cd, whereas, in the vegetable, the concentrations of As, Se, Ni, Mo, Pb, Mn, and Cu were above the safe limits. The levels of 12 metals and metalloids in the soil were ranged between 0.14 to 22.76 mg/kg at site-I and 0.16 to 22.13 mg/kg at site-II. The levels of these metals in the vegetable were found 0.35 to 61.13 mg/kg at site-I and 0.31 to 53.63 mg/kg at site-II. The transfer factor at both sites was highest for As and Co. The pollution load index recorded for Se, Cu, Cd, Mo, Pb, and Co was greater than 1. The daily intake of As, Mn, and Mo was above the oral reference dose, which reflects that the intake of pumpkin is not safe for the inhabitants of the selected sites. The control measures should be taken to phytoextract heavy metals and metalloids from polluted sites so as to reduce the health risks.     

New insights into microbial oxidation of antimony and arsenic

Sb(III) oxidation was documented in an Agrobacterium tumefaciens isolate that can also oxidize As(III). Equivalent Sb(III) oxidation rates were observed in the parental wild-type organism and in two well-characterized mutants that cannot oxidize As(III) for fundamentally different reasons. Therefore, despite the literature suggesting that Sb(III) and As(III) may be biochemical analogs, Sb(III) oxidation is catalyzed by a pathway different than that used for As(III). Sb(III) and As(III) oxidation was also observed for an eukaryotic acidothermophilic alga belonging to the order Cyanidiales, implying that the ability to oxidize metalloids may be phylogenetically widespread.     

Regional distribution characteristics and ecological risk assessment of heavy metal pollution of different land use in an antimony mining area – Xikuangshan,China

Abstract

Mining activities have introduced various heavy metals and metalloids to surrounding soil environments, causing adverse impacts to the ecological environment system. The extremely high concentration of various heavy metals and metalloids make the Xikuangshan (Hunan, China) an excellent model to assess their ecological risk. In this study, the soil samples from 26 locations of different land use methods in four areas (smelting area, road nearby ore, mining area, and ore tailing area) in Xikuangshan with different levels of various heavy metals and metalloids (Sb, As, Pb, and Cd) were analyzed; in addition, the index of geo-accumulation and the potential ecological risk index were used to evaluate ecological risk. The results showed that the average contents of Sb, As, Pb, and Cd in all soil samples were 4368.222?mg·kg^?1, 40.722?mg·kg^?1, 248.013?mg·kg^?1, and 40.941?mg·kg^?1, respectively, implying serious contamination of compound pollution of heavy metals in soil. The concentration of heavy metals in soil among smelting area, road nearby ore, mining area, and ore tailing area showed significant distribution characteristics of region because different mining activities such as smelting, mining, transportation, and stacking caused different pollution intensity. Moreover, the contents of Sb in soil samples decreased successively in residue field, wasteland, forestland, sediment, grassland, and vegetable field, and the contents of Sb in vegetable-field and ecological restoration grassland were relatively low, which indicate that the method of grassland ecological restoration is an effective method to control antimony pollution in soil. The results of ecological risk assessment showed that the antimony mining area was seriously polluted by Sb, As, Pb, and Cd, and had strong ecological risk, and Sb and Cd were the most important pollution factors, which indicated that the pollution of Sb and Cd should be a major concern of relevant departments of environment and health.     

Evidence for cooperativity between the four binding sites of dimeric ArsD, an As(III)-responsive transcriptional regulator

ArsD is a trans-acting repressor of the arsRDABC operon that confers resistance to arsenicals and antimonials in Escherichia coli. It possesses two-pairs of vicinal cysteine residues, Cys(12)-Cys(13) and Cys(112)-Cys(113), that potentially form separate binding sites for the metalloids that trigger dissociation of ArsD from the operon. However, as a homodimer it has four vicinal cysteine pairs. Titration of the steady-state fluorescence of ArsD with metalloids revealed positive cooperativity, with a Hill coefficient of 2, between these sites. Disruption of the Cys(112)-Cys(113) site by mutagenesis of arsD, but not the Cys(12)-Cys(13) site, largely abolished this cooperativity, indicative of interactions between adjacent Cys(112)-Cys(113) sites within the dimer. The kinetics of metalloid binding were determined by stopped flow spectroscopy; the rate increased in a sigmoidal manner, with a Hill coefficient of 4, indicating that the pre-steady-state measurements reported cooperativity between all four sites of the dimer rather than just the intermolecular interactions reported by the steady-state measurements. The kinetics of Sb(III) displacement by As(III) revealed that the metalloid-binding sites behave differentially, with the rapid exchange of As(III) for Sb(III) at one site retarding the release of Sb(III) from the other sites. We propose a model involving the sequential binding and release of metalloids by the four binding sites of dimeric ArsD, with only one site releasing free metalloids.     

The uptake and detoxification of antimony by plants: A review

Many crops cultivated in mining areas have been found to accumulate high levels of antimony (Sb) in their edible parts, thereby causing potential risks to human health. Understanding the behaviours of Sb in plants is important, particularly the mechanisms involved in its uptake, toxicity, detoxification and accumulation in crops. Many factors affect the uptake of Sb in plants, including water management, Sb speciation and some coexisting ions in soils. At present, the mechanisms of Sb uptake by plants have not been fully elucidated so far. The uptake of Sb has been proposed to occur mainly through the passive pathway; however, it is possible that an active pathway exists as well. Antimony can damage plants, including growth retardation, inhibition of photosynthesis, decreases in the uptake of certain essential elements and decreases in the synthesis of certain metabolites. Plants often have defence mechanisms to alleviate Sb toxicity; e.g., a highly efficient antioxidative system and the ability to immobilise Sb in the cell wall or compartmentalise Sb in the cytosol. Such mechanisms have been widely reported in Sb-tolerant and Sb-accumulating plants. In view of the above knowledge, several questions remain: (1) What is the actual uptake pathway of Sb in plants? (2) Does Sb participate in redox reactions within plants? (3) What is the role of metabolic reactions of Sb in Sb toxicity to plants? (4) Can Sb be methylated, and if so, how? (5) How does Sb induce bursts of reactive oxidative species (ROS)?     

Antimony in the Soil-Plant System in an Sb Mining/Smelting Area of Southwest China

The distribution, bioavailability, and accumulation of antimony (Sb) at the interface of rhizospheric soils and indigenous plants from a large Sb mining/smelting area in Southwest China were explored. Results showed that the local soil was severely polluted by Sb, and the aluminum magnesium silicate minerals and the carbonate fraction may mainly contribute to bound Sb. The sequential extraction results of soil samples revealed that the portion of bioavailable Sb was low, but the bioavailable Sb concentration was up to 67.2 mg/kg, due to high total Sb concentrations in the soil. The Sb content in local plants showed a wide range, from 21 to 21148 mg/kg. The species of Chenopodium album Linn., Sedum emarginatum Migo, and Sedum lineare Thunb showed high accumulation of Sb at levels of above 1000 mg/kg. The Sb contents in the tissues for most plants decreased with the order of root > leaf > stem. The bioaccumulation coefficients and/or the biological transfer factors for most plants were less than 1. All of the studied plant species were not identified as Sb-hyperaccumulators, but the species of Chenopodium album Linn., Sedum emarginatum Migo, and Sedum lineare Thunb could be applied as alternative plants for phytoremediating Sb-polluted soils.     

Arsenic and antimony release from sediments in a Mediterranean estuary

An ancient realgar mine is responsible for the contamination of a riverine system in central Corsica. Nearby the mine, high As and Sb concentrations are found (up to 2–3 mg l^-1 and 2–3 g l^-1 respectively). A significant increase of the As and Sb concentrations in water is found in the water of the mixing zone of river and sea (Bravona estuary; chlorinity 7000–7800). In the same area, a decrease of As and Sb concentrations in sediments is observed. Fe and Mn exhibit the same behaviour. The possible involvement of redox processes is discussed. However, owing to insufficient reducing capacity and insignificant variation of redox potential values along the various estuarine sites (from 320 down to 280 mV), this scenario is rather doubtful. Desorption from FeOOH particles is the most likely process in the Bravona estuary. The impact of these contaminated waters on the marine environment is discussed. Owing to decrease by dilution, as well as the reduced water flow of the estuary, the net supply of As and Sb to the Tyrrhenian Sea is approximately 5 and 1.5 t y^-1 for As and Sb respectively. The possible harmful influence of the Bravona river should be of local concern only, and the emphasis of this study is, therefore, on a better knowledge of in situ processes.     

Antimony accumulation and antioxidative responses in four fern plants

Antimony (Sb) toxicity and contamination has become a growing concern in recent years. Remediation of Sb contamination using plants may be an effective approach. This study aimed to investigate the potential of antimony (Sb) tolerance and accumulation by plants, as well as to understand the antioxidative responses to Sb. One set of hydroponic trials was set up using four species of fern plants, including Pteris cretica (PCA), Microlepia hancei (MH), Cyrtomium fortunei (CYF) and Cyclosorus dentatus (CYD). Ferns were grown for 2 weeks in nutrient solution containing a medium (5 mg L^?1) and a high (20 mg L^?1) rate of Sb, with no Sb added as the control. The biomass of fern PCA remained constant with Sb addition, whereas the biomass of ferns CYF, MH and CYD at the high Sb rate exposure decreased by 12.5%, 35.0% and 38.3%, respectively as compared with their controls. This suggests a high to low Sb tolerance order for these four fern plants. For all of these fern plants, more Sb was accumulated in the roots than in the fronds. Antimony concentration in the roots at the high rate of Sb addition was recorded, on average, as 358 mg kg^?1 for fern PCA, 224 mg kg^?1 for fern CYF, 124 mg kg^?1 for fern CYD and 123 mg kg^?1 for fern MH. A high rate of addition of Sb increased the contents of malondialdehyde (MDA) by 41.3% and 171.6% for ferns MH and CYD, respectively, as compared with their controls. No changes for MDA contents were observed in ferns PCA and CYF with Sb addition, indicating no lipid peroxidation reaction in these two plants. At a medium rate of Sb addition, the activities of peroxidase, catalase and ascorbate peroxidase in fern PCA were much higher than those in ferns CYF, CYD and MH, demonstrating the important role of these three enzymes in resisting Sb toxicity. The consistency in unchanged biomass, high accumulation of Sb in roots, lower MDA contents, as well as high enzyme production in fronds, indicated that fern PCA was more tolerant to Sb than the other three fern plants. Antioxidative enzymes (peroxidase, catalase and ascorbate peroxidase) might be involved in Sb toxicity resistance of fern PCA.     

Leishmania donovani: Therapeutic and prophylactic action of antimony dextran glycoside (RL-712) in the golden hamster

Antimony dextran glycoside (RL-712, manufactured by Rosco A/S Pharmaceutical Taastrup, Denmark) produced a remarkable decrease in Leishmania donovani densities in hamster spleen and liver when administered in a single intraperitoneal (ip) dose of 500 mg Sb/kg body weight or in 600 mg Sb/kg body weight divided into two or three equal parts injected at weekly intervals beginning 15 days after intracardial inoculation of 10 million amastigotes, and also in a single ip dose of 300 mg Sb/kg body weight 14, 7, and 0 days before intracardial inoculation of 10 million amastigotes. No parasites were detected on using a single dose of 500 mg Sb/kg body weight followed by 100 mg Sb/kg body weight one week later.When the drug was administered in a dose of 500 mg Sb/kg body weight either 10 days before subcutaneous inoculation of 60 million promastigotes or eight days before intracardial inoculation of five million promastigotes, no parasites were recovered by smear or culture from the spleen and liver.Results show the prophylactic and therapeutic actions of this drug against L. donovani in the hamster.     

高原鼢鼠和高原鼠兔骨骼中非必需微量元素的测定

铅、镉、砷、汞、锑和铋等元素是人与动物生命活动非必需且有害的微量元素[1] 。哺乳类动物体内的这些微量元素主要由食物链传递所产生[2 ,3] 。本文对高原鼢鼠 (Ｍｙｏｓｐａｌａｘｂａｉｌｅｙｉ)和高原鼠兔(Ｏｃｈｏｔｏｎａｃｕｒｚｏｎｉａｅ)骨骼中非必需微量元素砷、锑、汞、铋、铅、镉的分布、种间含量差异及其相关性进行了分析和讨论 ,为高寒草甸生态系统研究小哺乳动物的营养生态学、化学生态学以及生态系统的物质循环[4 ,5] 等提供基础资料。1　材料与方法1 1　样品预处理1994年 5～ 6月在中国科学院海北高寒草甸生态系统定位站…     

Distribution of Cd, Pb, Zn, Mo, and S in juvenile and mature Brassica napus L. var. napus

The study was conducted at three locations in the Savinjska region of Slovenia, where soil is contaminated with heavy metals due to the zinc industry (Cinkarna Celje). In Ponikva the soil to a depth of 30 cm contains 0.8 mg kg(-1) Cd, 32.2 mg kg(-1) Pb, and 86 mg Zn kg(-1), in Medlog 1.4 mg kg(-1) Cd, 37.4 mg kg(-1) Pb, and 115 mg kg(-1) Zn and in Skofja vas 10.9 mg kg(-1) Cd, 239.7 mg kg(-1) Pb, and 1356 mg kg(-1) Zn. The pH at the selected sites was between 7.3 and 7.6. In the beginning of September 2006 two hybrids of Brassica napus L. var. napus, PR45 D01 and PR46 W31 suitable for production of biodiesel obtained from Pioneer Seeds Holding GmbH, were sown. After 96 days juvenile and after 277 days mature plants were collected. Parts of plants (root, shoot and seed) were separated and Cd, Pb, Zn, Mo, and S determined by ultra-trace ICP-MS. We compared the uptake of Cd, Pb, Zn, Mo and S in different parts of juvenile and mature plants of the two different hybrids, TF (translocation factor), BAF (bioaccumulation factor), and PP (phytoextraction potential) were calculated. The mature hybrid PR46 W31 had higher shoot/root ratio and higher PP for metals (Cd, Pb, and Zn) and lower PP for the micronutrient (Mo) and macronutrient (S) on the polluted site. The study demonstrated the potential use of oilseed rape on multiply polluted soils for production of 1st and 2nd generation biofuels. The potential restoration of degraded land could also disburden the use of agricultural land.     

Subcellular distribution and chemical forms of antimony in Ficus tikoua

Ficus tikoua (F. tikoua) was a potential species for antimony (Sb) phytoremediation due to its wide growth in the mining area. However, little was known about its tolerance mechanisms toward Sb. The determination of the distribution and chemical speciation of Sb in F. tikoua is essential for understanding the mechanisms involved in Sb accumulation, transportation, and detoxification. The present study investigated the subcellular distribution and chemical forms of Sb in F. tikoua. The plant was exposed to different Sb concentrations (0, 30, 90, and 180 μmol/L) for 30 days. The results showed that F. tikoua possessed a marked ability to tolerate and accumulate Sb. The proportional Sb increased with increasing Sb concentration in the solution, and the highest Sb concentration occurred in roots (1274.5–1580.9 mg/kg), followed by stems (133.5–498.9 mg/kg) and leaves (4.1–15.7 mg/kg). In the subcellular sequestration of Sb in F. tikoua, the largest accumulation of Sb occurred in cell walls (72.4–87.5%) followed by cytoplasmic organelles (8.2–18.6%) and cytoplasmic supernatant. The results suggested that cell walls act as important protective barriers against Sb toxicity in F. tikoua. Although Sb in all plant tissues found primarily in the fractions extracted by ethanol and distilled water, the current study found that the Sb amounts in the HAc-extractable fraction, HCl-extractable fraction, and residue fraction increased at the highest Sb level (180 μmol/L) compared to that under lower Sb levels. These results indicate that excessive Sb accumulated in F. tikoua under Sb stress is bound to non-dissolved or low-bioavailable compounds, a biochemical mechanism that benefits F. tikoua because it helps alleviate Sb toxicity.     

Effects of cadmium and arsenic on growth and metal accumulation of Cd-hyperaccumulator Solanum nigrum L

Remediation of heavy metal contaminated sites using hyperaccumulators presents a promising alternative to current environmental methodologies. In the pot-culture experiment, the effects of Cd, and Cd-As on the growth and its accumulation in the Cd-hyperaccumulator (Solanum nigrum L.) were determined. No reduction in plant height and shoot dry biomass was noted when the plants were grown at Cd concentration of 1.0. The plant can be classified as a Cd-hyperaccumulator. Growing in the presence of 10 mg/kg Cd and 50 mg/kg As, the plant height and shoot dry matter yields did not decrease significantly (p>0.05) compared to that at 10 mg/kg Cd, however the stem Cd content increased by 28%. It was also observed that S. nigrum used exclusion strategy to reduce As uptake in the roots and restricted translocation into the shoots, resulting in As contents of the plant being root>leaf>stem>seed. The Cd accumulation capacity coupled with its relatively high As tolerance ability could make it useful for phytoremediation of sites co-contaminated by Cd and As.     

Leishmania major LmACR2 is a pentavalent antimony reductase that confers sensitivity to the drug pentostam

Arsenicals and antimonials are first line drugs for the treatment of trypanosomal and leishmanial diseases. To create the active form of the drug, Sb(V) must be reduced to Sb(III). Because arsenic and antimony are related metalloids, and arsenical resistant Leishmania strains are frequently cross-resistant to antimonials, we considered the possibility that Sb(V) is reduced by a leishmanial As(V) reductase. The sequence for the arsenate reductase of Saccharomyces cerevisiae, ScAcr2p, was used to clone the gene for a homologue, LmACR2, from Leishmania major. LmACR2 was able to complement the arsenate-sensitive phenotype of an arsC deletion strain of Escherichia coli or an ScACR2 deletion strain of Saccharomyces cerevisiae. Transfection of Leishmania infantum with LmACR2 augmented Pentostam sensitivity in intracellular amastigotes. LmACR2 was purified and shown to reduce both As(V) and Sb(V). This is the first report of an enzyme that confers Pentostam sensitivity in intracellular amastigotes of Leishmania. We propose that LmACR2 is responsible for reduction of the pentavalent antimony in Pentostam to the active trivalent form of the drug in Leishmania.     

Interactive effects of selenium and antimony on the uptake of selenium, antimony and essential elements in paddy-rice

Aims

Selenium (Se) can be used to detoxify antimony (Sb); however, the associated mechanisms are not fully understood, in particular, the responses of essential elements to co-exposure to Se and Sb.

Methods

To resolve the above question, two nested hydroponic experiments based on a two-factor, five-level central composite design, were performed using a conventional indica rice (Fengmeizhan).

Results

The results showed that when the Se concentration was fixed at 0.8 mg L^-1, the addition of Sb, even at concentrations as low as 2.171 mg L^-1, could produce damages to this plant and significantly reduce both the aboveground and root biomasses, suggesting a high toxicity of Sb to this plant. However, when the Sb concentration was fixed at 5 mg L^-1, Se eliminated the negative effects of Sb on the aboveground growth of paddy-rice but did not noticeably affect the root biomass, suggesting a beneficial role of Se in conferring resistance to Sb toxicity in paddy-rice. Interestingly, when the Se concentration was fixed at 0.8 mg L^-1, the addition of Sb caused a consistent decrease in the Se concentration in the roots but a slight increase in the Se concentration in the aboveground, suggesting a dual effect of Sb on Se uptake. Furthermore, the addition of Sb could counterbalance the negative effects of 0.8 mg L^-1 Se on the uptake of most of the tested essential elements, significantly increased their concentrations in the different tissues of this plant.

Conclusions

The Se-mediated alleviation of Sb toxicity could be closely connected with (1) the direct inhibition of Sb uptake; and (2) the uptake regulation of some essential elements, such as calcium (Ca), magnesium (Mg) and potassium (K). This study contributes to the understanding of both the the interactions between Se and Sb and their effects on the uptake of essential elements in paddy-rice.     

渭河陕西段沉积物重金属空间分布及来源解析

为了了解渭河陕西段河道沉积物重金属空间分布特征,本研究对渭河陕西段干流及其支流17个采样点沉积物中的10种重金属元素(Cd、Sb、As、Co、Cu、Pb、Ni、Cr、Zn、Mn)含量进行测定及来源辨析。结果表明: 重金属元素Cd、Sb、As、Co、Cu、Pb、Ni、Cr、Zn、Mn的平均含量分别为0.10、1.24、11.73、11.95、24.90、24.91、29.31、54.18、72.74、626.85 mg·kg^-1, 除Cd的变异系数大于1以外,其他元素的变异系数均低于0.5。其中,Cd、Pb、Cr含量于灞河入渭处达到峰值,Co和Mn在黑河入渭处达到峰值,Cu和Zn在清姜河入渭处达到峰值, Sb、As和Ni分别于沙王渡、咸阳铁桥和林家村处达到峰值。相关性分析、主成分分析和聚类分析表明,Cd、Co、Cu、Pb、Ni、Cr、Zn、Mn主要来源于以工业源和生活源为主的污染源;Sb、As主要来源于农业和地球化学污染源。     

Characterizing the accumulation of various heavy metals in native plants growing around an old antimony mine

The objective of this study was to explore potential plant candidates to act as phytoremediators around the Xikuangshan mine, Hunan Province, China. Native plants including Imperata cylindrical (L), Rumex patientia L., Fagopyrum dibotrys (D.Don), Fagopyrum dibotrys (D.Don), Phytolacca americana L., Dryopteris erytbrosora, Pteriduum aquilinum var. latiusculum (Desv), Nephrolepiscordifolia (L) Presl, Oplismenus undulatifolius (A) Bea, Erigeron annuus (L) Pers, and soils samples were collected. As, Sb, Hg, Cd, Cr, Pb, and Zn levels were measured in soil and plant samples. The concentrations of As, Sb, Hg, and Cd in soils were above the corresponding background values for Hunan province. R. Patienti, P. aquilinum, and P. americana had large bioconcentration factors (BAFs) and high translocation factors (TFs) for Sb; and the same showed in D. erytbrosora for Hg, P. vittata for Cd, I. cylindrical for Cr, and D. erytbrosora for Pb and Zn. In general, perennial plants showed high heavy metal contents in roots, and TFs greater than 1 were only observed for Sb in E. annuus and Cr in O. undulatifolius. These results demonstrate that several native plants growing around Xikuangshan are potential phytoremediators for metal and metalloid contaminated soils.     

上海市小羽藓属植物重金属含量及其与环境的关系

应用原子吸收法对上海市13个样点的小羽藓植物体及相应土壤样品中的Cu、Pb、Cd、Zn、Cr 5种重金属元素含量进行了测定.通过对植物体内含量的聚类分析,将13个样点按重金属污染程度的轻重分为3个组：1)污染严重点,包括桂林公园、复兴公园、光启公园3个样点,均位于市区交通繁忙地带,其小羽藓体内重金属含量分别为：Cu 35.25～50.36 mg·kg^-1、Pb 55.50～65.00 mg·kg^-1、Cd 1.68～2.30 mg·kg^-1、Zn 829.63～1140.13 mg·kg^-1、Cr 7.41～16.41 mg·kg^-1;2)污染点,包括长风公园、古钟园、中山公园、和平公园、上海师范大学徐汇校区5个样点,均位于市区近郊,小羽藓体内重金属含量分别为：Cu 18.51～62.50 mg·kg^-1、Pb 14.38～34.25 mg·kg^-1、Cd 0.81～1.40 mg·kg^-1、Zn 354.25～671.75 mg·kg^-1、Cr 3.62～25.08 mg·kg^-1;3)相对清洁点,包括佘山、大观园、罗泾、植物园、崇明东平国家森林公园5个样点,位于上海市远郊,小羽藓体内重金属含量分别为：Cu 11.13～16.41 mg·kg^-1、Pb 4.63～27.25 mg·kg^-1、Cd 0.93～1.28 mg·kg^-1、Zn 489.25～1 086.75 mg·kg^-1、Cr 1.53～7.62 mg·kg^-1.结果表明,小羽藓属苔藓植物可作为监测上海地区环境重金属污染的良好指示植物.苔藓植物体内重金属含量水平与土壤重金属含量存在一定的相关性,而且也受其他因素的影响.     

The effect of some factors of polluted environment on catalase responses and resistance of microbial isolates against toxic oxidative stress

The properties of bacterial isolates from polluted environments which are characterized by increased levels of oxidative stress do not reflect only the level of contaminants, but also arise as a consequence of many permanently changed conditions. The survival rate of Comamonas terrigena N3H isolates from an environment with elevated levels of H(2)O(2) is correlated with stimulation of catalase. The response of bacterial catalase to the effect of phenol in exogenous conditions was affected by the presence of an additional contaminant, Cd(2+). An isolate of Aspergillus niger selected from river sediment containing 363?mg/kg As, 93?mg/kg Sb at pH 5.2-4.8 grew on Czapek-Dox agar ~1.6 times faster than an isolate of the same species from coal dust sediment with approximately the same level of pollution (400?mg/kg As) but somewhat lower pH (3.3-2.8). It also exhibited differences in the microscopic characteristics of its mycelial structures. Both isolates exhibited a higher tolerance to the exogenic toxic effects of metals (As(5+), Cd(2+), and Cu(2+) at 5, 25, or 50?mg/L) than a control culture, but the differences in tolerance between them were only slight. These laboratory results suggest that there are complicated relationships which may exist in the "in situ" environment.