The Tolerance Index and Translocation Factor were Used to Identify the Barley Genotypes with High Arsenic Stress Tolerance

Ninety-four barley genotypes were used to investigate the genotypic differences in arsenic (As) uptake and translocation and their relationships with As tolerance index (TI) and translocation factor (TF). Two As treatments (300 µM and 500 µM) were applied in the initial screening and the confirmatory experiments, respectively. The results showed significant (p < 0.05) differences in tissue biomass, shoot height, root length, As TI and TF among genotypes. Based on As TI, 11 barley genotypes were selected and divided into 3 groups, i.e. tolerant, mildly tolerant and sensitive. There was more As uptake in the roots of the As tolerant genotypes, while the As sensitive genotypes contained more As in shoots, which was further proved by the greater TF. Significantly negative correlation was observed between shoot and root As concentration. The results showed that As tolerant genotypes are able to restrict the upward movement of As, thus developing their tolerance.     

Interactions between arbuscular mycorrhizal fungi and fungivorous nematodes on the growth and arsenic uptake of tobacco in arsenic-contaminated soils

The effects of inoculation with two AM fungi (M1, Glomus caledonium; M2, Glomus spp. and Acaulospora spp.) and a fungivorous nematode Aphelenchoides sp. on growth and arsenic (As) uptake of Nicotiana tabacum L. were investigated in soils contaminated with a range of As. The reproduction of Aphelenchoides sp. was triggered by the co-inoculation of AM fungi regardless of AM fungal isolates and As levels. Stimulative effects of Aphelenchoides sp. on the development of mycorrhiza, slightly different between two AM fungi, were found particularly at the lowest As level. Irrespective of mycorrhizal inoculi, increasing soil As level decreased plant growth, but increased plant As uptake. Co-inoculation of AM fungi and Aphelenchoides sp. led plants to achieving further growth and greater As accumulation at the lowest As level. Results showed that the interactions between AM fungi and fungivorous nematodes were important in plant As tolerance and phytoextraction at low level As-polluted soil.     

高砷硫铁矿周边农田土壤砷分布及真菌群落结构特征研究

本研究主要以高砷硫铁矿区周边农田中的真菌群落为研究对象,研究利用Miseq高通量测序技术系统分析矿区周边不同区域土壤中真菌的群落特征,通过本研究以明确矿区土壤真菌群落结构特征及其适应机制。结果表明:(1)砷、铁复合污染土壤可促使土壤真菌丰富度降低,而对土壤真菌多样的影响则表现为先促进后抑制;(2)砷、铁复合污染抑制土壤中Ascomycota(子囊菌门)代谢,促进Basidiomycota(担子菌门)代谢,而对Zygomycota(接合菌门)则表现为低浓度促进,高浓度抑制,对Fusarium(镰刀菌属)、Pseudallescheria(假霉样真菌属)、Cryptococcus(隐球菌属)也呈现"低浓度促进、高浓度抑制"作用;(3)砷、铁的复合物污染使土壤中真菌群落结构产生了明显差异,环境因子对土壤环境真菌群落结构差异影响大小依次为总砷、总铁。因此,在高砷硫铁矿的开采过程中对土壤中的真菌群落结构造成一定的影响,需对矿物及矿渣的堆放进行严格的管理以免对土壤中各种生物的生境造成严重破坏。     

微波消解一氢化物原子荧光光谱法测定粤东地区海产品中砷的研究

[目的]建立一种测定海产品中微量砷的有效方法。[方法]采用微波消解一氢化物原子荧光光谱法测定了粤东地区海产品中砷的含量。[结果]砷在1．0-50．0μg/L范围内线性关系良好，相关系数为0．995，方法的检出限为0．02107μg/L，相对标准偏差为0．932％。部分海产品的含砷量超过国家标准，其超标原因可能与沿海地区的工业污染有关。[结论]该方法试剂用量少、污染小、简便、快速、准确，适于各类海产品中砷含量的检测。     

Use of water-treatment residue containing polysilicate-iron to stabilize arsenic in flooded soils and attenuate arsenic uptake by rice (Oryza sativa L.) plants

A pot experiment was conducted to examine how soil amendment with water-treatment residue (WTR) containing polysilicate-iron affected dissolved arsenic (As) in flooded soils and As uptake by rice plants (Oryza sativa L.). The WTR was applied at a rate of 0 (control), 5, 10 or 20 t ha^?1. Simple linear regression analyses showed significant negative relationships between the concentrations of dissolved As in soil solution and WTR application rates at all sampling times, probably due to adsorption of As onto ferrihydrite in the WTR. Compared to As concentrations in rice plants grown on control soil, the concentrations in plants grown on WTR-treated soils decreased by 20.1–41.6% in straw (stems and leaves), 19.8–31.7% in husk and 18.6–21.0% in grain. The regression analyses demonstrated that the concentration and content of As in rice are negatively correlated with WTR application rate. Total As content was 16.5–32.0% lower in rice shoots grown on WTR-treated soils than on control soil. The percentage of each As species in grain decreased in the following order: As(III) » dimethylarsinic acid » As(V). The application of WTR did not change the As speciation in grain. Silicon contents in shoot significantly increased with application of WTR, indicating the potency of WTR as a silicate fertilizer. Taken together, our results indicate that WTR containing polysilicate-iron promises to be a practical amendment for stabilizing As and attenuating As uptake by rice plants.     

原子荧光光谱法同时测定环境水样中砷和汞

对原子荧光光谱法同时测定环境水中砷和汞进行了研究。优化了仪器条件、盐酸浓度、硼氢化钾浓度和预还原剂浓度等因素,确定了最佳的测定条件,并对方法检出限,线性范围,精密度和准确度进行了测定。结果显示,在最优的测定条件下,该方法的检出限为：砷,0.10μg/L;汞,0.05μg/L。精密度好,准确度高,适合于环境水样中砷和汞的同时测定。     

砷盐的检测方法及研究进展

详述了砷盐含量检测的方法与原理、研究进展,对常见检测方法的简便性、成本、特异性等方面进行了比较,并对砷盐检测方法的发展方向和应用进行了展望.     

砷对烤烟氮代谢的影响

采用盆栽试验，系统研究了砷对烤烟全生育期氮代谢的影响。结果表明，砷毒害对烤烟的氮代谢有显著影响。砷降低了整个生育期的硝酸还原酶(NR)活性，抑制了烤烟对硝态氮(NO₃^--N)的同化；提高了全生育期的谷氨酰胺合成酶(GS)活性，增强了烤烟对铵态氮(NH₄⁺-N)的同化。砷提高了全生育期的谷氨酸—丙酮酸转氨酶(GPT)活性和天冬酰胺酶(Asparaginase, ASG)活性，以及现蕾以后的游离氨基酸含量，使烤烟的氮转化代谢旺盛。与此同时，砷降低了烤烟生育前期的蛋白质含量，随着生育进程的推进，又引起中、后期的蛋白质含量增加，最终导致烤烟蛋白质的积累，但使整个生育期的烟碱含量降低。     

Mechanisms of cadmium accumulation in rice grains and molecular breeding for its reduction

ABSTRACT

Cadmium (Cd) has an important impact on agriculture, as the excessive consumption of this element from contaminated food crops leads to toxicity in humans. Rice is the greatest source of dietary Cd intake in populations consuming rice as a staple food. Therefore, reducing the Cd concentration of rice grains for diminishing the potential risk of Cd for human health is a major challenge. This review summarizes the main achievements on Cd accumulation in rice by our research group. Using a positron-emitting tracer imaging system, we succeeded to visualize differences in real-time Cd dynamics from roots to panicles in rice varieties with different Cd accumulation abilities. Several loci or genes responsible for Cd accumulation in rice were found through quantitative trait loci (QTLs) analysis. Using the QTL qCdp7 responsible for efficiently extracting Cd from paddy soils, practical rice varieties for Cd-phytoextraction were developed by DNA marker-assisted breeding. A rice variety named ‘Koshihikari Kan No.1? carrying a mutant allele of OsNramp5 for reducing Cd concentration in rice grains was produced by mutant breeding with ion-beams, and breeding programs have been implemented to transfer this allele into many Japanese rice varieties by DNA marker-assisted breeding. Growing low-Cd varieties aerobically would be a feasible way to simultaneously reduce inorganic arsenic and Cd concentrations in rice grains. These results provide basis for reducing Cd concentration in rice through breeding new varieties.     

Mechanisms of arsenite elimination by Thiomonas sp. isolated from Carnoulès acid mine drainage

Weathering of the arsenopyrite-rich tailings of the Carnoulès abandoned mining site (Gard, France) results in the formation of acid mine waters heavily loaded with arsenic. Dissolved arsenic present in the seepage waters is precipitated within a few meters from the bottom of the tailing dam by microorganisms. From these effluents, we have isolated and characterized a Gram negative bacterium involved in this bioremediation process. This bacterium, which belongs to the Thiomonas genus, is very efficient in removing arsenite from contaminated acidic waters by oxidizing it to arsenate, which precipitates.