砷中毒易感性与基因多态性的关系研究进展

无机砷是一种确认的人类致癌物,但其致癌机制至今仍不很清楚.人类的大多数肿瘤是环境与遗传因素共同作用的结果.砷中毒在不同种属(族)和个体之间存在着明显的差异,除年龄、性别、砷暴露量、营养状况等因素外,近年来研究发现,个体间砷中毒易感性的不同可能与某些基因多态性密切相关,这些基因包括谷胱苷肽-S-转移酶基因、5,10-亚甲基四氢叶酸还原酶基因、着色性干皮病D基因、髓性过氧化物酶基因、过氧化氢酶基因以及p53基因等.只有充分考虑遗传因素的作用,才能深入阐明砷中毒的机制.     

砷与农药草甘膦、敌敌畏对秀丽隐杆线虫的联合毒性

农田常遭受砷和农药污染,这2种污染会产生联合毒性,影响生物体健康。利用野生型秀丽隐杆线虫进行砷、草甘膦和敌敌畏的24h单一毒性和联合毒性实验。结果表明,砷、草甘膦和敌敌畏对秀丽隐杆线虫24h-LC50分别为130.5mg·L-1、18.5mg·L-1、3.3μL·L-1;通过等效毒性相加法实验,发现砷与草甘膦对秀丽隐杆线虫的联合毒性为协同作用,砷与敌敌畏对秀丽隐杆线虫的联合毒性为拮抗作用。     

Toxic effects of realgar transforming solution on the reproduction of Caenorhabditis elegans

Realgar transforming solution is an arsenic formulation which has shown anticancer effects with low toxicity both in vivo and in vitro. In this study, Caenorhabditis elegans was used to evaluate its reproductive toxicity and its possible mechanisms. Realgar transforming solution decreased the brood size and induced proliferation arrest and apoptosis significantly only at an elemental concentration of 37.5 mg/L, while arsenic trioxide reduced the brood sizes and induced proliferation arrest and apoptosis of both the wild type N2 and let-60 ras(gf) mutant worms in an arsenic concentration dependent manner. Mitogen-activated protein kinase and protein p53 pathways may be involved in reproductive toxicity as evidenced by real-time quantitative polymerase chain reaction, RNA interference, and inhibition experiments with mitogen-activated protein kinases and p53. In conclusion, realgar transforming solution at the low arsenic (As) concentrations showed lower reproductive toxicity than arsenic trioxide, and a different molecular mechanism of reproductive toxicity is suggested.     

碳纳米管影响无机砷(As(III)和As(V))对大型蚤毒性的研究：特定砷形态的作用

作为一种新兴的纳米材料,羟基多壁碳纳米管(OH-MWCNTs)可能与其他污染物在水环境中共存,并进一步影响它们的毒性、输移和归趋。因此,评价碳纳米管存在下砷的毒性变化需要得到更多的关注。该试验探索了在不同pH值条件下,OH-MWCNTs诱导砷(As(III)和As(V))对水生生物大型蚤的毒性变化的潜在机制。发现了H₂AsO₃^-和H₂AsO₄^-是对大型蚤毒性最大的As(III)和As(V)。比较As(III)和As(V)的结果,发现pH值是影响砷毒性最重要的因素。此外,OH-MWCNTs影响砷对大型蚤毒性的结果表明,OH-MWCNTs的存在可以提高砷的毒性。通过吸附实验进一步研究了砷与OH-MWCNTs的相互作用。OH-MWCNTs 对As(V)吸附容量高于As(III)。总而言之, OH-MWCNTs对某些形态砷的吸附是解释砷毒性增强的可靠证据。
精选自Xinghao Wang, Ruijuan Qu, Ahmed A. Allam, Jamaan Ajarem, Zhongbo Wei, Zuoyao Wang. Impact of carbon nanotubes on the toxicity of inorganic arsenic [As(III) and As(V)] to Daphnia magna: the role of the certain arsenic species. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1852–1859, July 2016. DOI: 10.1002/etc.3340
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3340/full
     

硅促进水稻种子萌发及缓解幼苗砷毒性的效应研究

通过As~(Ⅲ)胁迫下水稻种子的发芽试验和幼苗毒性试验,研究了外源硅对水稻种子发芽率、幼苗生长的影响及其缓解幼苗砷毒性的效应。外源硅的2种处理方式为种子萌发时添加外源硅(Si1)和采用硅处理液浸种(Si2)。结果表明,发芽时介质中As浓度达到10 mg·L~(-1)时显著抑制水稻种子萌发(P0.05),发芽率仅为80%,但是Si1和Si2处理下发芽率则提高到97%和100%,这说明外源硅可促进砷胁迫下水稻种子萌发;砷浓度≥5 mg·L~(-1)时,Si1和Si2处理均可提高水稻的相对幼苗高度和根耐性指数,提高幅度分别为6.00%~16.8%和57.9%~77.0%、7.10%~23.5%和54.2%~61.2%,并且降低了水稻幼苗砷含量,降低幅度分别为17.8%~21.4%和31.0%~49.1%。这说明外源硅处理可促进砷胁迫下水稻幼苗的生长;不同砷浓度处理与水稻芽长、根长及幼苗干重之间存在"S"型的剂量-效应关系,且外源硅显著提高了相应的EC50,缓解了砷对水稻幼苗生长的毒性。综上所述,砷胁迫下水稻种子萌发时添加外源硅或采用硅处理液浸种均可促进水稻种子萌发和幼苗生长,并降低了幼苗砷累积和缓解砷对水稻幼苗的毒性。     

Arsenic toxicity in crop plants: physiological effects and tolerance mechanisms

Heavy metals are toxic substances released into the environment, contributing to a variety of toxic effects on living organisms in food chain by accumulation and biomagnifications. Certain pollutants such as arsenic (As) remain in the environment for an extensive period. They eventually accumulate to levels that could harm physiochemical properties of soils and lead to loss of soil fertility and crop yield. Arsenic, when not detoxified, may trigger a sequence of reactions leading to growth inhibition, disruption of photosynthetic and respiratory systems, and stimulation of secondary metabolism. Plants respond to As toxicity by a variety of mechanisms including hyperaccumulation, antioxidant defense system, and phytochelation. Arbuscular mycorrhizae symbiosis occurs in almost all habitats and climates, including disturbed soils. There is growing evidence that arbuscular mycorrhizae fungi may alleviate metal/metalloid toxicity to host plant. Here, we review (1) arsenic speciation in the environment and how As is taken up by the roots and metabolised within plants, and (2) the role of arbuscular mycorrhizae in alleviating arsenic toxicity in crop plants.     

Arsenic in groundwater in six districts of West Bengal,India

Arsenic in groundwater above the WHO maximum permissible limit of 0.05 mg l^–1 has been found in six districts of West Bengal covering an area of 34 000 km² with a population of 30 million. At present, 37 administrative blocks by the side of the River Ganga and adjoining areas are affected. Areas affected by arsenic contamination in groundwater are all located in the upper delta plain, and are mostly in the abandoned meander belt. More than 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people show arsenical skin lesions. Thousands of tube-well water in these six districts have been analysed for arsenic species. Hair, nails, scales, urine, liver tissue analyses show elevated concentrations of arsenic in people drinking arsenic-contaminated water for a longer period. The source of the arsenic is geological. Bore-hole sediment analyses show high arsenic concentrations in only few soil layers which is found to be associated with iron-pyrites. Various social problems arise due to arsenical skin lesions in these districts. Malnutrition, poor socio-economic conditions, illiteracy, food habits and intake of arsenic-contaminated water for many years have aggravated the arsenic toxicity. In all these districts, major water demands are met from groundwater and the geochemical reaction, caused by high withdrawal of water may be the cause of arsenic leaching from the source. If alternative water resources are not utilised, a good percentage of the 30 million people of these six districts may suffer from arsenic toxicity in the near future.     

不同分子量的腐殖酸存在下2种无机砷的生物毒性效应研究

水环境中天然有机质会与砷形成络合物,进而影响砷的迁移、转化和生物毒性。研究利用超滤方法将腐殖酸(humic acid, HA)分为5个不同分子量的组分,以大型溞为受试生物,探究了不同分子量HA存在下砷对大型溞的毒性效应。结果表明,不同分子量的HA均缓解了As(Ⅲ)和As(Ⅴ)对大型溞的氧化应激损伤和细胞膜损伤,并降低了砷对MT的诱导量。其中1～30 k Da的HA对砷的缓解效果最好,1 k Da的HA毒性缓解效果最差,可能的原因是HA与砷的络合增加溶液中络合态砷的含量,而络合态砷难以进入细胞并被生物利用。不同分子量的HA对砷毒性的缓解差异与其跟砷的络合比例不同有关。     

中国关于砷的研究进展

综述了近年来有关中国的砷污染状况、相关的分析监测技术及砷化合物毒性的研究进展.在中国部分地区,长期砷暴露导致了严重的区域性的砷中毒,主要的暴露途径是饮用水、食物和煤炭的燃烧.样品前处理、砷的富集和形态分析技术的丰富和发展,为环境科学、毒理学和流行病学的研究提供了可靠的技术支持.生物检测是一种直接有效的污染物健康风险评估...     

抗氧化系统在蜈蚣草细胞砷解毒机制中的作用

砷超富集植物——蜈蚣草体内可以富集高浓度的砷且不表现出受害症状,暗示蜈蚣草细胞具有较强的砷解毒机制.为探讨抗氧化系统在蜈蚣草砷解毒机制中的作用,测定了0、0.5、1和2mmol/L的砷酸盐[As(Ⅴ)]、亚砷酸盐[As(Ⅲ)]和二甲基胂酸盐(DMA)处理下蜈蚣草愈伤组织的丙二醛(Malonyldiadehyde,MDA)含量、非酶类抗氧化物质含量和酶类抗氧化物质的活性.结果表明,0.5mmol/L As(Ⅴ)和DMA就可以诱导氧化胁迫的产生,浓度越高胁迫程度也越严重.而1mmol/L的As(III)仍未使蜈蚣草愈伤组织产生氧化胁迫.在As(Ⅲ)处理下,酸溶性巯基含量增加,叶绿素和类胡萝卜素含量不变,过氧化氢酶(Catalase,CAT)和过氧化物酶(Peroxidase,POD)活性增加.在As(Ⅴ)处理下,酸溶性巯基含量减少,叶绿素和类胡萝卜素含量略有上升;CAT和POD活性先增加后减少.在DMA处理下,酸溶性巯基含量减少,叶绿素含量降低而类胡萝卜素含量增加,CAT和POD活性先增加后减少.与As(Ⅴ)和DMA相比,As(Ⅲ)处理下高酸溶性巯基含量、高氧化酶活性和低MDA含量暗示As(Ⅲ)对蜈蚣草的毒性可能比As(Ⅴ)和DMA要小.这些结果表明,酸溶性巯基和酶类抗氧化物质(CAT和POD)在蜈蚣草细胞砷解毒机制中发挥着重要作用.图4参22     

Anomalous arsenic concentrations in groundwaters of an island community, Bowen Island, British Columbia

Recently, occurrences of elevated arsenic concentrations in bedrock groundwaters used for individual and municipal water supplies have been recognised along the mainland coast of southern British Columbia, Canada. An area on Bowen Island (Queen Charlotte Heights community) was chosen to investigate the source(s) of arsenic, geochemical processes controlling its aqueous uptake, the role of geology and structure in the formation of these waters, and the use of hydrogeochemical survey methods for detecting arsenious groundwater regions. Pyrite- arsenopyrite-Cu mineralisation in the Queen Charlotte Heights area is present as veins associated with NE-trending fault zones and as disseminations in marginal breccia and stockwork zones of a ryhodacite porphyry stock. Near surface mineralisation was later altered by supergene events to form minor pyrite- arsenopyrite in a matrix of limonite and clay. Geochemical factors that control the concentration and mobility of arsenic in these groundwaters include: (a) anion exchange of arsenic from clay minerals during cation divalent/univalent exchange processes (water softening) which leads to waters of high pH and high anion exchange capacities; (b) desorption of arsenic from Fe and Al oxyhydroxide minerals during pronounced shifts in pH from acid to alkaline conditions brought on by the water softening process; and (c) stepwise oxidation of arsenopyrite mineralisation to form arsenious sulphate-bearing groundwaters. The inconsistent behaviour of the As3+ and As5+ ions during the complex waterrock interaction processes described above, precludes the use of detailed chemical analyses to predict relative abundances of the more toxic As3+ species. For a full appreciation of the toxic impact of groundwaters containing total arsenic concentrations that are above regulatory guidelines an arsenic speciation analysis is required.     

Arsenic bioaccumulation in rice and edible plants and subsequent transmission through food chain in Bengal basin: a review of the perspectives for environmental health

Arsenic (As) is a metalloid that poses serious environmental threats due to its behemoth toxicity and wide abundance. The use of arsenic-contaminated groundwater for irrigation purpose in crop fields elevates arsenic concentration in surface soil and in the plants. In many arsenic-affected countries, including Bangladesh and India, rice is reported to be one of the major sources of arsenic contamination. Rice is much more efficient at accumulating arsenic into the grains than other staple cereal crops. Rice is generally grown in submerged flooded condition, where arsenic bioavailability is high in soil. As arsenic species are phytotoxic, they can also affect the overall production of rice, and can reduce the economic growth of a country. Once the foodstuffs are contaminated with arsenic, this local problem can gain further significance and may become a global problem, as many food products are exported to other countries. Large-scale use of rainwater in irrigation systems, bioremediation by arsenic-resistant organisms and hyperaccumulating plants, and the aerobic cultivation of rice are some possible ways to reduce the extent of bioaccumulation in rice. Investigation on a complete food chain is urgently needed in the arsenic-contaminated zones, which should be our priority in future researches.     

Arsenic uptake by plants and possible phytoremediation applications: a brief overview

This review focuses the behaviour of arsenic in plant?Csoil and plant?Cwater systems, arsenic?Cplant cell interactions, phytoremediation, and biosorption. Arsenate and arsenite uptake by plants varies in different environment conditions. An eco-friendly and low-cost method for arsenic removal from soil?Cwater system is phytoremediation, in which living plants are used to remove arsenic from the environment or to render it less toxic. Several factors such as soil redox conditions, arsenic speciation in soils, and the presence of phosphates play a major role. Translocation factor is the important feature for categorising plants for their remediation ability. Phytoremediation techniques often do not take into account the biosorption processes of living plants and plant litter. In biosorption techniques, contaminants can be removed by a biological substrate, as a sorbent, bacteria, fungi, algae, or vascular plants surfaces based on passive binding of arsenic or other contaminants on cell wall surfaces containing special active functional groups. Evaluation of the current literature suggests that understanding molecular level processes, and kinetic aspects in phytoremediation using advanced analytical techniques are essential for designing phytoremediation technologies with improved, predictable remedial success. Hence, more efforts are needed on addressing the molecular level behaviour of arsenic in plants, kinetics of uptake, and transfer of arsenic in plants with flowing waters, remobilisation through decay, possible methylation, and volatilisation.     

An assessment of sampling,preservation, and analytical procedures for arsenic speciation in potentially contaminated waters

This study was undertaken to ascertain optimal methods of sampling, preserving, separating, and analyzing arsenic species in potentially contaminated waters. Arsenic species are readily transformed in nature by slight changes in conditions. Each species has a different toxicity and mobility. The conventional field sampling method using filters of 0.45 μm in size could overestimate the dissolved arsenic concentrations, as passing suspended particles that can act as a sink or source of arsenic depending on the site condition. For arsenic species in neutral pH and iron-poor waters, the precipitation can be stable for up to 3 days without any treatment, but for longer periods, a preservative, such as phosphoric acid, is required. Also, the analytical procedure must be selected carefully because the levels and hydride generation efficiencies of arsenic in different species can vary, even for the same amount of arsenic. For arsenic speciation in samples that also include organic species, a hybrid high-performance liquid chromatography (HPLC) column and inductively coupled plasma mass spectrometry (ICP-MS) gave the best resolution and lowest detection limits. However, the procedure using a solid phase extraction (SPE) cartridge can be used economically and conveniently for analyzing samples containing only inorganic arsenic species, such as groundwater, especially that related to mine activity.     

Toxicology of arsenic in fish and aquatic systems

Arsenic (As) is found in waters such as seawater, warm springs, groundwater, rivers, and lakes. In aquatic environments, As occurs as a mixture of arsenate and arsenite, with arsenate usually predominating. The unrestricted application of As pesticides, industrial activities, and mining operations has led to the global occurrence of soluble As above permissible levels of 0.010 mg/L. Continuous exposure of freshwater organisms including fish to low concentrations of As results in bioaccumulation, notably in liver and kidney. As a consequence As induces hyperglycemia, depletion of enzymatic activities, various acute and chronic toxicity, and immune system dysfunction. Here we review arsenic chemistry, the occurrence of arsenic in aquatic system, the transformation and metabolism of arsenic; arsenic bioaccumulation and bioconcentration; behavioral changes; and acute and other effects such as biochemical, immunotoxic, and cytogenotoxic effects on fish.     

Improving arsenopyrite oxidation rate laws: implications for arsenic mobilization during aquifer storage and recovery (ASR)

Aquifer storage and recovery (ASR) and aquifer recharge (AR) provide technical solutions to address water supply deficits and growing future water demands. Unfortunately, the mobilization of naturally present arsenic due to ASR/AR operations has undermined its application on a larger scale. Predicting arsenic mobility in the subsurface during ASR/AR is further complicated by site-specific factors, including the arsenic mobilization mechanisms, groundwater flow conditions, and multi-phase geochemical interactions. In order to ensure safe and sustainable ASR/AR operation, a better understanding of these factors is needed. The current study thus aims to better characterize and model arsenic remobilization at ASR/AR sites by compiling and analyzing available kinetic data on arsenic mobilization from arsenopyrite under different aqueous conditions. More robust and widely applicable rate laws are developed for geochemical conditions relevant to ASR/AR. Sensitivity analysis of these new rate laws gives further insight into the controlling geochemical factors for arsenic mobilization. When improved rate laws are incorporated as the inputs for reactive transport modeling, arsenic mobilization in ASR/AR operations can be predicted with an improved accuracy. The outcomes will be used to guide groundwater monitoring and specify ASR/AR operational parameters, including water pretreatment requirements prior to injection.     

Health risk assessment for arsenic contaminated soil

This paper describes risk assessment methods for two chronic exposure pathways involving arsenic contaminated soil, namely inhalation of fugitive dust emissions over a lifetime, and inadvertent soil/house dust ingestion. The endpoint in the first case is assumed to be lung cancer and in the second case skin cancer. In order to estimate exposures, inhalation rates and soil/dust ingestion rates are estimated for different age groups; indoor/outdoor time budgets for different age groups are developed; and indoor surface dust and air arsenic concentrations are estimated based on outdoor concentration measurements. Differences observed in indoor/outdoor ratios and arsenic containing dust particle size among different types of communities are noted, as well as possible relationship of particle size to bioavailability. Calculations of risk are presented using cancer potency factors developed by the U.S. Environmental Protection Agency, and uncertainties in these toxicity estimates are described based on: (1) evidence that arsenic may be neither a cancer initiator nor promotor, but may act instead as a late stage carcinogen and (2) evidence that the arsenic dose-response relationship for ingestion may be nonlinear at low doses due to increasing methylation of inorganic arsenic. The first of these considerations influences the relative importance ascribed to arsenic doses in different age groups. The latter consideration indicates that the risk estimates described here are probably very conservative.     

外源洛克沙胂对水生态系统砷蓄积及底泥微生物生长的影响

为探明洛克沙胂(ROX)对水生态系统的毒性效应,采用模拟水生态系统,研究了外源添加不同浓度洛克沙胂(0、10、20、40、80和160 mg·L-1)对水生态系统砷含量及底泥微生物生长的影响。结果表明,水体及底泥砷含量随外源ROX用量增加而增加,但随暴露时间延长水体砷含量降低的同时底泥砷含量逐渐增加。金鱼藻和鲫鱼体内均出现明显砷蓄积现象,且160 mg·L-1ROX处理的水生态系统鲫鱼毒害效应明显,暴露1 d的死亡率为100%。金鱼藻对砷具有较强的富集能力,暴露32 d后砷富集量达398.1~1 538.91 mg·kg-1。不同浓度ROX对底泥真菌、细菌和反硝化细菌生长均具有不同程度的抑制效应,而对放线菌和氨化细菌生长具有一定的促进作用,且低浓度ROX(10 mg·L-1)对放线菌生长的促进作用明显。总体上,外源ROX进入水生态系统导致水体砷污染的同时在生物及非生物媒介中再次迁移、分配和蓄积,进而对鲫鱼及部分底泥微生物生长产生毒害。     

Ableitung ökotoxikologisch begründeter Bodenqualitätskriterien am Beispiel Arsen

Background

A vast amount of data on the concentration of substances in soils is being generated in environmental monitoring programmes. This data has to be assessed in terms of effects on terrestrial biota. Benchmarks for such an assessment have been missing up to now. This gap has been filled by the development of a concept for the derivation of ecotoxicologically based soil quality criteria (SQC) and the application of this concept to environmentally relevant substances.

Objectives

The derivation method was applied to arsenic. The derivation process was described in detail from the compilation of data regarding effects on microbial processes, plants, and soil invertebrates to the formulation of a recommendation for an SQC.

Methods

The conceptual framework for the derivation of ecotoxicologically based SQC was developed after reviewing national and international concepts for the assessment of the effects of substances on terrestrial communities. For the assessment of arsenic effects, all relevant biotic processes and trophic levels have been taken into account. Moreover, soil characteristics that may affect the toxicity to biota have been reviewed.

Results

Effects of arsenic on biota may occur at soil background concentrations or slightly above. There are only a few studies in which the influence of soil characteristics, such as soil pH, soil texture, and soil organic carbon, on the effects of arsenic has been investigated systematically. That is why the SQC was oriented on soil background concentrations for sandy soils (5 mg As/kg soil dw). A comparison of the SQC derived in this work with ecotoxicologically based soilquality values from Canada, Denmark, the Netherlands, and the United States shows an average value of 16 mg As/kg, with a range between 5 and 34 mg/kg. The variations in the soil quality values are mainly due to differences in the derivation approaches.

Conclusions and Outlook

The concept applied is considered suitable for the derivation of SQC designed to protect terrestrial communities against direct effects of substances in soils. Therefore, its use is planned to derive SQC for other environmentally relevant substances. In addition to compensation factors, statistical methods should be taken into account to compensate for risks which cannot be quantified. Furthermore, there is the need for an assessment of indirect effects of soil contaminants on birds and mammals.     

不同价态无机砷对罗非鱼肝脏砷积累及GSH/GST解毒代谢的影响

低剂量中长期暴露下的氧化胁迫是砷对水生生物致毒的重要机制之一。本文通过对罗非鱼进行32 d的食物相砷暴露,测定不同时间点罗非鱼肝脏中谷胱甘肽(glutathione,GSH)含量和谷胱甘肽巯基转移酶(glutathione S-transferase,GST)活性,揭示不同价态无机砷对罗非鱼肝脏中GSH/GST的影响机制。经三价砷(As(III))暴露后,砷含量在2 d内显著增加而在随后的30 d内无显著性差异; 0～2 d内GSH含量显著增加,后降低,13 d后GSH含量均低于空白组; 0～6 d GST活性均大于空白组,6～8 d GST活性降低,8 d后活性高于空白组,且32 d达到最大值。经五价砷(As(V))暴露后,罗非鱼肝脏中砷含量逐渐增加,在20 d时达到最大值而后无显著性差异; 0～2 d时GSH含量降低,随后逐渐增加,在16 d达到最大值,16 d后GSH含量均低于空白组; 0～8 d时GST被大量诱导合成,8～20 d时GST合成被抑制,20 d后活性增加,在32 d达到最大值。As(III)和As(V)对罗非鱼GSH/GST的不同影响与其在罗非鱼体内的积累量有关。As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GSH含量呈统计学正相关,而As(V)暴露无明显相关性。这是因为As(V)进入罗非鱼肝脏后会还原为As(III),进而GSH作为可提供巯基的还原剂而被大量消耗。另外,As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GST活性呈显著负相关,而As(V)暴露却呈现出很强的滞后性,这是由于进入生物体内的As(V)需转化为As(III)后,才可直接作用于酶系统。可见,不同形态砷对水生生物的致毒机制需进一步深入研究。