山东寿光农业利用方式对土壤砷累积的影响

对山东省寿光市不同农业利用方式下土壤砷的累积状况进行了调查.结果表明,寿光市农田土壤砷平均含量为9.63 mg·kg^-1,最高值为15.15 mg·kg^-1,以山东省当地的土壤背景值（9.3 mg·kg^-1）为基准,有53.1%的样本出现了砷富集现象.所调查地区土壤砷含量的空间分布为西、东、北部较高,中部居中,南部最低.不同农业利用方式下土壤砷含量呈现出明显差异,按由高到低顺序排列为小麦/玉米地＞棉花地＞设施菜地＞露天菜地,分析呈现这种规律的原因发现,土壤砷含量的差异除了受当地土壤砷背景值影响外,还不同程度地受农业活动的影响.随着设施菜地种植年限的增加,土壤砷含量呈增加趋势.猪粪和鸡粪中的砷可能是设施菜地土壤砷累积的重要来源,施用豆肥可在一定程度上减少土壤砷的累积.     

Mechanisms of arsenic trioxide induced apoptosis of human cervical cancer HeLa cells and protection by Bcl-2

It was recently reported that arsenic trioxide (As_2O_3) can induce complete remission in patients with acute promyelocytic leukemia (APL). In this present article, the biological effect of As_2O_3 on human cervical cancer HeLa cells and HeLa cells overexpressing Bcl-2 is studied. By MTT and colony forming ability assays, morphology alteration, flow cytometric analysis, DNA gel electrephoresis and in situ cell death detection (TUNEL), it was found that As_2O_3 inhibited the growth of HeLa cells and induced G2/M arrest and apoptosis of the cells. RT-PCR, Northern blot, Western blot analysis revealed that As_2O_3 induced HeLa cell apoptosis possibly via decreasing the expression of c-myc and viral genes. HeLa cells overexpressing Bcl-2 partly resist As_2O_3 induced apoptosis, which might be relative to preventing the cells from As_2O_3 caused G2/M block, downregulation of c-myc gene expression and inhibition of viral gene expression was also noted, However, it was found that As_2O_3 at a high concentratio     

三氧化二砷对鼻咽癌细胞Cx43表达的影响

目的:探讨三氧化二砷(As2O3)抑制鼻咽癌的作用机制。方法:采用流式细胞仪(FCM)、激光扫描共聚焦显微镜(LSCM)和荧光技术,检测人鼻咽癌细胞株(CNE1)经As2O3诱导后细胞连接蛋白43(Cx43)表达的变化。结果:FCM显示,经过浓度为4μmol L的As2O3处理后,其Cx43阳性细胞计数率明显升高,与未经As2O3处理和经2μmol L的As2O3处理的CNE1比较,其差异具有非常显著性意义(p<0.01);LSCM图像观察到,经4μmol LAs2O3处理后,标记Cx43的绿色荧光显著增强,集中分布于细胞膜。结论:较高剂量浓度的As2O3能提高鼻咽癌细胞Cx43的表达率,升高细胞膜Cx43的含量。As2O3抑制鼻咽癌细胞生长的作用机制之一,是通过恢复细胞间隙连接通讯功能来实现的。     

Arsenic-induced toxicity and the ameliorative role of antioxidants and natural compounds

Arsenic (As) poisoning has proven to be a major threat worldwide because of its toxic effects on the human body. As toxicity through drinking water is a global health concern. The toxicity of As is known to affect the liver, kidney, lungs, muscles, cardiovascular system, and nervous system and can even induce diabetes. Further As can cause skin lesions leading to notable diseases in the skin like Bowen's disease. Chronic exposure to As has caused many tragedies in Eastern, and several Southeast Asian and Latin American countries. Long-term exposure to As makes it an immediate threat that should be dealt with as a priority, and one of the ways to handle it may be with the use of antioxidants. In this review, we have discussed the natural and anthropogenic sources of As, its metabolism, pathophysiology, and mechanism of toxicity. Besides, we have also discussed some of the synthetic chelators and the ameliorative role of antioxidants and natural compounds in reducing As toxicity.     

Influences of the petroleum-recovering activity on the arsenic level in groundwater of Kuitun,Xinjiang, China

Increasing demands of groundwater in petroleum-recovering regions could elevate the level and mobility of arsenic in groundwater as a result of the enhanced dissolution of arsenic-bearing iron or manganese oxide due to the accelerated sulfate reduction by microorganisms in a reductive environment. To substantiate this possibility, groundwater samples were collected from 220 water wells in the nearby petroleum wells in Kuitun. Dissolved arsenic, iron, manganese, and sulfate levels and pH in groundwater samples were analyzed. The dissolved arsenic levels in groundwater varied from <2.3 to 789.4 μg·L^?1, in which approximately 96.4% of the measured values exceeded the allowed limits of the World Health Organization. An inverse relation existed between dissolved arsenic and sulfate levels. Most of the high arsenic-level samples (>300 μg·L^?1) were found in wells at close proximity to petroleum wells where a high iron or manganese level was also detected. The oil-exploring activity in the study region seemed to have enhanced the microbial reduction of sulfate in underground environment and hence the level of arsenic in groundwater. The microbial sulfate reduction coupled with the reduction of arsenic-bearing iron oxides in the groundwater environment may explain the spatial heterogeneity of the arsenic level in groundwater.     

Estimation of Multimedia Inorganic Arsenic Intake in the U.S. Population

Arsenic is widely distributed in the environment by natural and human means. The potential for adverse health effects from inorganic arsenic depends on the level and route of exposure. To estimate potential health risks of inorganic arsenic, the apportionment of exposure among sources of inorganic arsenic is critical. In this study, daily inorganic arsenic intake of U.S. adults from food, water, and soil ingestion and from airborne particle inhalation was estimated. To account for variations in exposure across the U.S., a Monte Carlo approach was taken using simulations for 100,000 individuals representing the age, gender, and county of residence of the U.S. population based on census data. Our analysis found that food is the greatest source of inorganic arsenic intake and that drinking water is the next highest contributor. Inhalation of airborne arsenic-containing particles and ingestion of arsenic-containing soils were negligible contributors. The exposure is best represented by the ranges of inorganic arsenic intake (at the 10^th and 90^th percentiles), which were 1.8 to 11.4 µg/day for males and 1.3 to 9.4 µg/day for females. Regional differences in inorganic arsenic exposure were due mostly to consumption of drinking water containing differing inorganic arsenic content rather than to food preferences.     

Human health risk from exposure to metals through fish and shellfish ingestion in Saudi Arabia

Abstract

In this study, human exposure and risks of metals through fish ingestion were predicted. Concentrations of 10 metals (Cd, As, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in 17 commonly eaten fish species in Saudi Arabia were characterized. Using the fish ingestion patterns, chronic daily intakes of metals among the Saudi and expatriate populations were predicted to be in the ranges of 8.89?×?10^?06–1.08?×?10^?02 and 6.59?×?10^?06–7.97?×?10^?03?mg/kg/day, respectively. The average cancer risks from inorganic arsenic were 2.76?×?10^?05 and 2.09?×?10^?05 for Saudi and expatriate, and the ranges were 1.61?×?10^?09–1.58?×?10^?03 and 2.64?×?10^?09–1.27?×?10^?03, respectively. The predicted risks were much lower than the previously reported risks. There were 47.4% and 42.4% chances that cancer risks would be higher than 1.0?×?10^?05 (10 per million) among Saudi and expatriate, respectively. The average cumulative hazard index (HI) for Saudi and expatriate were 0.324 and 0.239 with the ranges of 0.0142–7.26 and 0.017–6.43, respectively. Approximately 3.06% and 1.56% cases among Saudi and expatriate had HI greater than unity, indicating possible health concern, respectively. Through comprehensive understanding of exposure and risks, strategies can be adopted to protect human health.     

Identification of genes conferring arsenic resistance to Escherichia coli from an effluent treatment plant sludge metagenomic library

The majority of bacteria elude culture in the laboratory. A metagenomic approach provides culture-independent access to the gene pool of the whole bacterial community. A metagenomic library was constructed from an industrial effluent treatment plant sludge containing about 1.25 Gb of microbial community DNA. Two arsenic-resistant clones were selected from the metagenomic library. Clones MT3 and MT6 had eight- and 18-fold higher resistance to sodium arsenate in comparison with the parent strain, respectively. The clones also showed increased resistance to arsenite but not to antimony. Sequence analysis of the clones revealed genes encoding for putative arsenate reductases and arsenite efflux pumps. A novel arsenate resistance gene ( arsN ) encoding a protein with similarity to acetyltransferases was identified from clone MT6. ArsN homologues were found to be closely associated with arsenic resistance genes in many bacterial genomes. ArsN homologues were found fused to putative arsenate reductases in Methylibium petroleiphilum PM1 and Anaeromyxobacter dehalogenans 2CP-C and with a putative arsenite chaperone in Burkholderia vietnamiensis G4. ArsN alone resulted in an approximately sixfold higher resistance to sodium arsenate in wild-type Escherichia coli W3110.     

Screening Evaluation of the Ecological Risks to Terrestrial Wildlife Associated with a Coal Ash Disposal Site

Between 1955 and 1989, coal ash was deposited within an impounded watershed on the U.S. Department of Energy's Oak Ridge Reservation in Tennessee, creating the 3.6?ha Filled Coal Ash Pond (FCAP). The site has subsequently become vegetated wildlife habitat. To evaluate risks that metals in ash may pose to wildlife; ash, surface water, small mammal, and vegetation samples were collected and metal residues were determined. Metal concentrations, As and Se in particular, were elevated in ash, surface water, plant foliage, and small mammals relative to reference materials. Estimates of metal exposures were calculated for short-tailed shrews, white-footed mice, white-tailed deer, red fox, and red-tailed hawks. While shrews and mice were assumed to reside exclusively at and receive 100% exposure from the site, exposure experienced by deer, fox, and hawks was assumed to be proportional to the size of the site relative to their home range. Because deer had been observed to consume ash, presumably for its high sodium content, exposure experienced by deer consuming ash to meet sodium requirements was also estimated. Exposure estimates were compared to body-size adjusted toxicity data for each metal. These comparisons suggest that metals at the site may be detrimental to reproduction and survivorship of mice, shrews, and deer consuming ash for sodium; fox and hawks do not appear to be at risk