Bioaccumulation of manganese in selected tissues of the freshwater crab,Potamonautes warreni (Calman), from industrial and mine-polluted freshwater ecosystems

Manganese concentrations in water and sediments of the Bronkhorstspruit River, Nooitgedacht Dam and especially in the Natalspruit River, did not fall within stated limits for the protection of aquatic life. Tissue manganese concentrations in Potamonautes warreni from the Natalspruit River were generally higher than those in the tissues of crabs from the other two aquatic ecosystems. The highest mean manganese tissue concentration in crabs from the three systems was detected in the carapace (587± 445 µg g^-1 wet weight). It appears that the carapace in these animals acts as a sink in which manganese can be deposited, thus also playing an important role in the detoxification of manganese in these crustaceans. No seasonal or sex-related variation was detected. Body size of the crabs, however, seems to be an important influencing factor in manganese bioaccumulation. A significant increase in carapace manganese concentrations was detected with an increase in body size. However, muscle manganese concentrations were higher in the smaller groups.The concentration factors (BF) calculated for the different tissues with respect to the water were highest in the carapace and ranged from 280.9 to 742.8. The BF with respect to the sediment was comparatively low for all the tissues (0.1 to 0.7). As the manganese concentration in the tissues reflects to some extent the degree of manganese contamination of the surrounding aquatic environment, it appears that P. warreni may be useful as a potential biomonitor of manganese pollution.     

不同营养状态下方斑东风螺的镉生物积累及毒性

采用室内模拟方式,研究了方斑东风螺在饥饿及摄食饵料分别为贻贝和沙蚕3种情况下暴露于水体镉(Cd2+,50 μg·L-1)10周后的存活、生长、螺体Cd蓄积及有关毒性效应参数的变化.结果表明:长期饥饿与同时水体Cd暴露降低了方斑东风螺的成活率,且螺体糖原被最大程度动用,摄食有助于螺体抵抗Cd毒性;方斑东风螺肝胰脏DNA受损伤后在摄食状态下随时间延长均有不同程度的自我修复能力,但长期禁食使螺的DNA完整性降低且不能恢复;饥饿引起方斑东风螺体组织萎缩,并导致Cd蓄积与金属硫蛋白(MT)含量升高,摄食螺因体质量增加的稀释作用而具有较低的Cd蓄积与MT含量;摄食贻贝的方斑东风螺较摄食沙蚕有更快的生长率和更低的Cd浓度.表明饥饿加剧了Cd对方斑东风螺的毒性;不同饵料对方斑东风螺的生长有显著影响,并间接影响螺体Cd蓄积、MT诱导和糖原消耗.应用方斑东风螺等海洋腹足类作为环境监测指示种时应考虑栖息地食物丰度和饵料类型等的影响.方斑东风螺高密度工厂化养殖中应注意合理投饵并定期监测海水Cd浓度.     

湘江藻类水华结构特征及对重金属的积累

2010年9月下旬,湘江中下游发生藻类水华,严重影响了沿线居民的生活.采集湘江上游永州、中游衡阳与下游株洲、湘潭、长沙段水样,对此次水华期间浮游植物群落结构、优势种类进行了调查分析,并测定其对湘江金属离子的积累,进行小鼠生物毒性实验,旨在评价此类水华是否将对湘江水生生态系统及人体健康构成威胁.结果表明：（1）光学显微镜与扫描电子显微镜分析,此次水华为硅藻门颗粒浮生直链藻（Aulacoseira granulata）水华.湘潭和长沙段水华最为严重,藻细胞数均达到1.3×105丝状体/L,长沙段叶绿素a含量达0.04mg/L;（2）湘江颗粒浮生直链藻对金属离子Al,Fe和Mn富集量分别达到4.4×103,768.4和138.7mg/kg干重,富集系数分别为4.0×105,7.7×105和3.2×103;其对高毒重金属Pb富集量为19.2mg/kg干重,富集系数为9.6×103;（3）小鼠生物毒性实验证实,湘江重金属污染条件下颗粒浮生直链藻水华存在一定生物毒性,全组份组LD50为384mg/kg,95%可信限介于228.5~646.3mg/kg之间,对湘江水生生态系统及沿线居民健康造成了威胁.     

三七对土壤中镉、铬、铜、铅的累积特征及健康风险评价

我国传统珍贵草本药用植物三七Panax notoginseng(Burk.)F.H.Chen重金属污染问题已引起广泛关注,但相关研究却非常有限。调查了三七种植区土壤重金属污染状况,揭示了三七对土壤中重金属的吸收转运规律及其健康风险。结果表明,三七种植区土壤镉(Cd)、铬(Cr)、铜(Cu)的超标率分别为75%、38%、50%,污染程度分布表现为丘北县文山县砚山县马关县;种植区三七存在较为严重的Cd、Cr、铅(Pb)污染,其不同部位的超标率范围分别为81%—100%、75%—100%、25%—63%;三七具有较强的Cd富集能力及Cd、Cu转运能力;三七不同部位Pb、Cd、Cr、Cu对人体的摄入风险贡献依次为13.46%—46.40%、8.67%—24.67%、1.90%—14.40%、0.38%—0.79%,其中主根中Cd、Cr、Cu对人体的健康风险与土壤中相应的重金属浓度呈线性正相关。研究可为解决三七种植区,乃至其他中草药种植区的重金属污染问题提供重要的科学依据。     

Metal ion accumulation by immobilised cells of Brevibacterium sp

This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised cells and challenged with influents containing 20 mg L⁻¹ of lead and 10 mg L⁻¹ of cadmium. The cells were able to accumulate lead (about 40 mg g⁻¹ dry biomass) and, to a lesser extent, cadmium (about 13 mg g⁻¹ dry biomass) from solutions. In the presence of 0.4 g L⁻¹ of glucose, the cells removed up to 53% of lead. Lead competed with cadmium for attachment to the binding sites when a solution containing both the metals was applied. Lead removal occurred by a combination of fast physico-chemical adsorption and prolonged low rate accumulation mediated by cell metabolism. The biosorptive capacity of the cells was sensitive to pH. Desorption of the metal with EDTA restored the binding capability of the cells. Received 07 July 1997/ Accepted in revised form 26 November 1997     

In vitro binding of the carcinogen N-[methyl-14C]-nitrosodimethylamine by algal dietary fibers and their role in reducing its bioaccumulation

The present study was initiated to determine if algal dietary fibers (DF) bind the carcinogen N-[methyl-¹⁴C]-nitrosodimethylamine (DMNA) in vitro and how bioaccumulation of orally-given carcinogen is affected by a diet containing algal DF. Eight kinds of algal DF, including powdered fronds of Laminaria religiosa (LRP) and agar (from Gracilaria verrucosa) were used in the in vitro test. Cellulose powder (CP) was used as a control DF. In vitro binding rates of DMNA by CP, LRP and agar were 0.28%, 0.65% and 0.21% of the initial dose, respectively. Rats fed a diet containing 2% LRP or 2% agar were examined at 3 or 24 h after dosing. There was reduced retention of the orally-ingested DMNA in the liver, possibly because of reduced DMNA-absorption from the intestinal tract earlier than 3 h after dosing. Binding rates of DMNA by algae were neither related to the DF values nor to the extent of reduction of DMNA-absorption from the intestinal tract.     

Uptake and distribution of chromium in Saccharomyces cerevisae exposed to Cr(III)-organic compounds

Abstract

The present study investigates the influence of different Cr(III)-organic compounds [Cr(III)-citrate and Cr(III)-histidine] in growth-nonsupportive exposure medium on the uptake and localisation of chromium in the cell structure of the yeast Saccharomyces cerevisae. The amount of total accumulated chromium in yeast cells and the distribution of chromium between the yeast cell walls and spheroplasts were determined by atomic absorption spectroscopy. Chromium accumulation potential was shown to depend on treatment time, metal concentration as well as the nature of the bound ligand. Chromium uptake was characterised by a time-dependent increase of total chromium which suggests that the amount of cell-accumulated chromium also tended to increase over time. Cellular chromium accumulation (mg g^?1 dry wt) of Cr(III)-histidine is higher than Cr(III)-citrate. The pH dependence pattern of chromium accumulation is similar for both of the Cr(III)-organic compounds: pH 6.5>pH 5>pH 8. Substantial differences were found between the two Cr(III)-organic compounds, in the total chromium accumulation as well as in the distribution in yeast cell walls and spheroplasts.     

Fractionation and bioaccumulation of copper and zinc in wetland soils of the Niger Delta determined by the oil palm

Abstract

The concentration, mobility, bioavailability, distribution and associations of two essential micronutrient elements (copper and zinc) to the oil palm in wetland soils of the Niger delta region of Nigeria was assessed by means of chemical fractionation analysis. The water soluble and plant available fractions were introduced into the sequential extraction scheme. Also assessed were the bioaccumulation (concentration and distribution) of these metals in the leaves and fruits of the oil palm of various ages found around the soil profiles. Copper was obtained more in the amorphous Fe-oxide fraction (151.05 mg kg^?1), but evenly distributed in the exchangeable component (16.16%) with a maximum value of 126.6 mg kg^?1. The water soluble and plant available fractions had 16.15 and 7.54% distribution of Cu respectively. Zinc had 2.35 and 30.42% distribution in the water soluble and plant available fractions respectively. The lowest mean amount of Cu (1.33 mg kg^?1) was determined in the leaves of palms of ages 15–32 years. Palms greater than 60 years had the highest mean concentration of copper (3.91 mg kg^?1) in the leaves while the endosperm (kernel) of palms between 2 and 10 years had concentration of 9.07 mg kg^?1. The fibrous oily mesocarp had the highest amount (16.78 mg kg^?1) of copper in the older palms (>60 years). Similarly, Zn was dominant in the older palms with a mean concentration of 187.14mg kg^?1 obtained in the endosperm (kernel). The bioaccumulation pattern of both metals by the palms irrespective of age and the fractionation analysis revealed sufficient bioavailable and reserved amounts of Zn and Cu in the wetland soils.     

Isolation of Arsenic-Resistant Bacteria from Bengal Delta Sediments and their Efficacy in Arsenic Removal from Soil in Association with Pteris vittata

The potential of arsenic-resistant bacteria in association with Pteris vittata to reduce the level of arsenic from soil was studied. The physicochemical characteristics of contaminated paddy soil were analyzed, and 3 bacterial isolates amongst 11 were screened and were selected for further study. These three isolates were characterized by 16S rDNA sequencing and identified as Bacillus altitudinis Strain SS8 (KJ432582), Bacillus megaterium Strain SS9 (KJ432583) and Lysinibacillus sp. Strain SS11 (KJ432584). Of these, Lysinibacillus sp. Strain SS11 displayed arsenic tolerance of 3256 mg L^?1 for arsenate and 1136 mg L^?1 for arsenite. Additionally, it showed bioaccumulation capacity of 23.43 mg L^?1 for arsenate and 5.65 mg L^?1 for arsenite. It also showed resistance to other heavy metals, especially towards iron, copper and chromium. It was also observed that Pteris vittata was able to take up more arsenic and iron from soil in the presence of these bacterial strains than in their absence, leading to contaminant-free soil. Thus, this system appears to be an effective bioremediating process to remove arsenic from contaminated soil.