Panda K K, Lenka M, Panda B B
Genetic Toxicology Laboratory, Department of Botany, Berhampur University, Berhampus 760 007, Orissa, India.
Environ Pollut. 1992;76(1):33-42. doi: 10.1016/0269-7491(92)90114-p.
Barley (Hordeum vulgare L.) was used to assess plant-availability, tissue-concentration and genotoxicity of mercury from the solid waste deposits of a chloralkali plant. Seeds of H. vulgare, presoaked in distilled water, were allowed to germinate and grow on agricultural soil mixed with solid waste containing 2550+/-339 mg Hg kg(-1) at different proportions (0.75, 1.5, 2.5 and 5%). Plants raised from germinating seeds on uncontaminated agricultural soil served as controls. On day 7, germination counts and seedling heights were recorded. The concentration of mercury in soil, and plant tissue (dry weight) were determined at different stages of plant growth from day 7 till maturity and harvest. The availability of mercury from the soil was assessed by extracting mercury at a range of pH values (2-6) and by chemical methods. The embryonic shoots excised at 36 h of germination were subjected to cytological analysis to determine mitotic index and frequency of mitoses with chromosomal aberrations. The pollen mother cells from anthers of young M1-spikes were analysed to score meiotic aberrations. Subsequently, the pollen fertility and seed set were determined. Furthermore, M2-seedlings were analysed for chlorophyll-deficient mutations. The cytogenetic analysis revealed the effects of mercury on the mitotic and meiotic chromosomes which were significantly correlated with soil-mercury. The bioconcentration of mercury in aerial tissues decreased with the age of the plant. Roots, in particular, were found to concentrate most of the mercury taken up by the plant. At the time of harvest, the bioconcentration of mercury in straw was at a minimum. The accumulation of mercury in grain, which was significant, did not increase with the increase in concentration of mercury in soil but maintained a plateau, indicating a restriction of transport of mercury through the phloem. The unique advantage with the use of Hordeum assay is that, besides assessing the germline toxicity, the assay takes into account the possible contamination of the agricultural food-chain.
利用大麦（Hordeum vulgare L.）评估氯碱厂固体废物沉积物中汞的植物有效性、组织浓度和遗传毒性。将预先浸泡在蒸馏水中的大麦种子，置于与含有2550±339毫克汞/千克（-1）的固体废物以不同比例（0.75%、1.5%、2.5%和5%）混合的农业土壤上发芽生长。在未受污染的农业土壤上由发芽种子培育的植物作为对照。在第7天，记录发芽数和幼苗高度。在植物生长的不同阶段，从第7天到成熟和收获，测定土壤和植物组织（干重）中的汞浓度。通过在一系列pH值（2 - 6）下提取汞并采用化学方法，评估土壤中汞的有效性。在发芽36小时时切下的胚轴进行细胞学分析，以确定有丝分裂指数和有染色体畸变的有丝分裂频率。对年轻M1穗花药中的花粉母细胞进行分析，以评估减数分裂畸变。随后，测定花粉育性和结实率。此外，对M2幼苗进行叶绿素缺乏突变分析。细胞遗传学分析揭示了汞对有丝分裂和减数分裂染色体的影响，这些影响与土壤汞含量显著相关。汞在地上组织中的生物富集随植物年龄增长而降低。特别是根部，发现其集中了植物吸收的大部分汞。收获时，秸秆中汞的生物富集量最低。谷物中汞的积累显著，但不随土壤汞浓度的增加而增加，而是保持稳定，这表明汞通过韧皮部的运输受到限制。使用大麦试验的独特优势在于，除了评估生殖系毒性外，该试验还考虑了农业食物链可能受到的污染。
