镉胁迫论文答辩
镉胁迫论文答辩
与镉相比,外源性钙与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫与镉相比,外源性钙优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫优先被植物吸收。这与使用植物从土壤中去除镉的目标不相悖吗?为何要研究钙缓解镉胁迫
梁永超的代表论文
1. Li P, Song AL, Li ZJ, Fan FL, Liang YC. 2011. Silicon ameliorates manganese toxicity by regulating manganese transport and antioxidant reactions in rice (Oryza sativa L.). Plant and Soil. (Accepted)(通讯作者)(影响因子:2.773)2. Fan FL, Yang QB, Li ZJ, Wei D, Cui XA, Liang YC. 2011. Impacts of organic and inorganic fertilizers on nitrification in a cold climate soil are linked to the bacterial ammonia oxidizer community. Microbial Ecology. 62:982-990(通讯作者)(影响因子:3.251)3. Zhang B, Chu GX, Wei CZ, Ye J, Li ZQ, Liang YC. 2011. The growth and antioxidant defense responses of wheat seedlings to omethoate stress. Pesticide Biochemistry and Physiology. 100: 273-279 (通讯作者)(影响因子:1.719)4. Su YH, Liang YC. 2011. Transport via xylem of atrazine, 2,4-dinitrotoluene, and 1,2,3-trichlorobenzene in tomato and wheat seedlings. Pesticide Biochemistry and Physiology. 100: 284-288(影响因子:1.719)5. Song AL, Li P, Li ZJ, Fan FL, Nikolic M, Liang YC. 2011. The alleviation of zinc toxicity by silicon is related to zinc transport and antioxidative reactions in rice. Plant and Soil. 344: 319-333. (通讯作者)(影响因子:2.773)6. Li ZJ, Xie XY, Zhang SQ, Liang YC. 2011. Wheat growth and photosynthesis as affected by oxytetracycline as a soil contaminant. Pedosphere. 21(2): 244–250(通讯作者)7. Sun WC, Zhang J, Fan QH, Xue GF, Li ZJ, Liang YC 2010. Silicon-enhanced resistance to rice blast is attributed to silicon-mediated defence resistance and its role as physical barrier. European Journal of Plant Pathology. 128:39-49 (通讯作者)(影响因子:1.931)8. Ge GF, Li ZJ, Fan FL, Chu GX, Hou ZA, Liang YC. 2010. Soil biological activity and their seasonal variations in response to long-term application of organic and inorganic fertilizers. Plant and Soil. 326:31–44(通讯作者)(影响因子:2.773)9. Liang YC, Zhu Y-G, Smith FA, Lambers H. 2010. Soil-plant interactions and sustainability of eco-agriculture in arid region: a crucially important topic to address. Plant and Soil. 326:1–2(通讯作者)(影响因子:2.773)10. Wakelin SA, Chu GX, Lardner R, Liang YC, McLaughlin MJ. 2009. A single application of Cu to field soil has long-term effects on bacterial community structure, diversity, and soil processes. Pedobiologia 53:149-158 (影响因子:2.414)11. Wakelin SA, Chu GX, Broos K, Clarke KR, Liang YC, McLaughlin MJ. 2010. Structural and functional response of soil microbiota across a Cu gradient are moderated by addition of plant substrate. Biology and Fertility of Soils 46:333-342 (影响因子:1.757)12. Song AL, Li ZJ, Zhang J, Xue GF, Fan FL, Liang YC. 2009. Silicon-enhanced resistance to cadmium toxicity in Brassica chinensis L. is attributed to Si-suppressed cadmium uptake and transport and Si-enhanced antioxidant defense capacity. Journal of Hazardous Materials. 172:74-83 (通讯作者)(影响因子:4.144)13. Zhang J, Sun WC, Li ZJ, Liang YC, Song AL. 2009. Cadmium fate and tolerance in rice cultivars. Agronomy for Sustainable Development. 29: 483-490 (通讯作者)(影响因子:1.65)14. Chen WP, Hou ZA, Wu LS, Liang YC, Wei CZ. 2009. Effects of salinity and nitrogen on cotton growth in arid environment. Plant and Soil. 326:61–73(通讯作者)(影响因子:2.773)15. Guo B, Liang YC, Li ZJ and Han FX, 2009. Phosphorus adsorption and bio-availability in a paddy soil amended with pig manure compost and decaying rice straw. Communications in Soil Science & Plant Analysis. 40: 2185-2199(通讯作者)(影响因子:0.357)16. Ma YB, Li JM, Li XY, Tang X, Liang YC, Huang SM, Wang BR, Liu H, Yang XY. 2009. Phosphorus accumulation and depletion in soils in wheat-maize cropping systems: modeling and validation. Field Crops Research. 110:207-212 (影响因子:2.336)17. Guo B, Liang YC, Zhu YG. 2009. Does salicylic acid regulate antioxidant defense system, cell death and cadmium uptake and partitioning to acquire cadmium tolerance in rice subjected to cadmium stress? Journal of Plant Physiology, 166: 20-31 (通讯作者)(影响因子:2.5)18. Su YH, Zhu YG and Liang YC. 2009. Interactions of mixed organic contaminants in uptake by rice seedlings, Chemosphere, 74: 890-895(通讯作者)(影响因子:3.253)19. Ge GF, Li ZJ, Zhang J, Wang LG, Xu MG, Zhang JB, Xie XL, Wang JK, Liang YC. 2009. Geographical and climatic differences in long-term effect of organic and inorganic amendments on soil enzymatic activities and respiration in field experimental stations of China. Ecological Complexity. 6: 421-431(通讯作者)(影响因子:2.03)20. Zhang J, Li ZJ, Ge GF, Liang YC, Wu LS. 2009. Impacts of soil organic matter, pH and exogenous copper on sorption behavior of norfloxacin in three soils. Journal of Environmental Sciences. 21: 632–640(通讯作者)(影响因子:1.414)21. Wang LG, Liang YC, Jiang X. 2008. Analysis of eight organophosphorus pesticide residues in fresh vegetables retailed in agricultural product markets of Nanjing, China. Bulletin of Environmental Contamination and Toxicology, 81(4):377-382(影响因子:0.609)22. Liang YC, Zhu J, Li ZJ, Chu GX, Ding YF, Zhang J, Sun WC. 2008. Role of silicon in enhancing resistance to freezing stress in two contrasting winter wheat cultivars. Environmental and Experimental Botany,64(3): 286-294 (通讯作者)(影响因子:3.164)23. Sun YH, Li ZJ, Guo B, Chu GX, Wei CZ, Liang YC. 2008. Arsenic mitigates cadmium toxicity in rice seedlings. Environmental and Experimental Botany, 64(3): 264-270(通讯作者)(影响因子:3.164)24. Liang YC. 2008. Silicon uptake and transport in higher plants. In: Plant membrane and vacuolar transporters. Jaiwal P.K., Singh R.P., and Dhankher O.P. (eds). CAB International, Wallingford, Oxfordshire, OX10 8DE, United Kingdom. pp. 205-212.25. Nikolic M, Nikolic N, Liang YC, Kirkby EA, Römheld V. 2007. Germanium-68 as an adequate tracer for silicon transport in plants: Characterization of silicon uptake in different crop species. Plant Physiology, 143 (1): 495-503(前三位作者同等贡献)(影响因子:6.235)26. Liang YC, Sun WC, Zhu YG, and Christie P. 2007. Mechanisms of silicon- mediated alleviation of abiotic stresses in higher plants: A review. Environmental Pollution, 147: 422-428(影响因子:3.135)(通讯作者)27. Guo B, Liang YC, Zhu YG and Zhao FJ. 2007. Role of salicylic acid in alleviating oxidative damage in rice roots (Oryza sativa) subjected to cadmium stress. Environmental Pollution, 147(3): 743-749(通讯作者)(影响因子:3.135)28. Guo B, Liang YC, Li ZJ, and Guo W. 2007. Role of salicylic acid in alleviating cadmium toxicity in rice roots. Journal of Plant Nutrition, 30(3): 427 - 439(通讯作者)(影响因子:0.593)29. Kong WD, Zhu YG, Liang YC, Zhang J, Smith FA and Yang M. 2007. Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.). Environmental Pollution, 147:187-193 (影响因子:3.135)30. Guo W, Zhu YG, Liu WJ, Liang YC, Geng CN, Wang SG. 2007. Is the effect of silicon on rice uptake of arsenate (AsV) related to internal silicon concentrations, iron plaque and phosphate nutrition? Environmental Pollution, 148: 251-257 (影响因子:3.135)31. Liang YC, Hua H. Zhu Y-G, Zhang J, Cheng C and Römheld V. 2006. Importance of plant species and external silicon concentration to active silicon uptake and transport. New Phytologist, 172(1):63-72 (影响因子:6.033)32. Liang YC, Zhang WH, Chen Q, Liu YL and Ding RX. 2006. Effect of exogenous silicon (Si) on H+-ATPase activity, phospholipids and fluidity of plasma membrane in leaves of salt-stressed barley (Hordeum vulgare L.). Environmental and Experimental Botany, 57(3): 212-219 (影响因子:3.164)33. Liang YC, Zhu YG , Xia Y, Li ZJ and Ma YB. 2006, Iron plaque enhances phosphorus uptake by rice (Oryza sativa) growing under varying phosphorus and iron concentrations. Annals of Applied Biology, 149(3):305-312(影响因子:1.868)(通讯作者)34. Liang YC, Si J, and Römheld V. 2005. Silicon uptake and transport is an active process in Cucumis sativus L. New Phytologist, 167(3):797-804(影响因子:6.033)35. Liang YC, Sun WC, Si J and Römheld V. 2005. Effect of foliar- and root-applied silicon on the enhancement of induced resistance in Cucumis sativus to powdery mildew. Plant Pathology, 54:678-685(影响因子:2.368)36. Liang YC, Si J, Nikolic M, Peng Y, Chen W and Jiang Y. 2005. Organic manure stimulates biological activity and barley growth in soil subject to secondary salinization. Soil Biology and Biochemistry, 37: 1185-1195.(影响因子:2.978)37. Liang YC, Wong JWC, and Wei L. 2005. Silicon-mediated enhancement of cadmium tolerance in maize (Zea mays L.) grown in cadmium contaminated soil. Chemosphere, 58(4): 475-483. (影响因子:3.253)38. Liang YC, Zhang WH, Chen Q and Ding RX. 2005. Effects of silicon on tonoplast H+-ATPase and H+-PPase activity, fatty acid composition and fluidity in roots of salt-stressed barley (Hordeum vulgare L.). Environmental and Experimental Botany, 53(1): 29-37.(影响因子:3.164)39. 姚建华,牛德奎,李兆君,梁永超,张树清,2010. 抗生素土霉素对小麦根际土壤酶活性和微生物生物量的影响, 中国农业科学,4340. 薛高峰,梁永超,孙万春,宋阿琳,李兆君,范分良,2010. 硅对水稻生长、白叶枯病抗性及病程相关蛋白活性的影响, 中国农业科学,43 (通讯作者)41. 薛高峰, 宋阿琳, 孙万春, 李兆君, 范分良, 梁永超, 2010.硅对水稻叶片抗氧化酶活性的影响及其与白叶枯病抗性的关系. 植物营养与肥料学报,16(通讯作者)42. 杨佳佳, 李兆君, 梁永超, 张林静, 李万峰, 2009. 温度和水分对不同施肥条件下黑土磷形态转化的影响及机制 , 植物营养与肥料学报,15 (6): 1295-130243. 范琼花, 孙万春, 李兆君, 梁永超, 2009, 硅对短期低温胁迫小麦叶片光合作用及其主要相关酶的影响,植物营养与肥料学报,15:544-550(通讯作者)44. 孙万春,薛高峰,张杰,范琼花,葛高飞,李兆君,梁永超,2009,硅对水稻病程相关蛋白活性和酚类物质含量的影响及其与诱导抗性的关系,植物营养与肥料学报,15:756-762(通讯作者)45. 孙万春,薛高峰,张杰,宋阿琳,葛高飞,李兆君,梁永超,2009,硅对水稻防御性关键酶活性的影响及其与抗稻瘟病的关系,植物营养与肥料学报,15:1023-1028(通讯作者)46. 姚志鹏,李兆君,梁永超,张永清,姚建华,解晓瑜,2009,土壤酶活性对土壤中土霉素的动态响应,植物营养与肥料学报,15:695-700(通讯作者)47. 李兆君,徐建明,梁永超,汪海珍,马国瑞,2008,甲磺隆结合残留对土壤酶活性的影响,生态毒理学报,3:499-50648. 李兆君,姚志鹏,张杰,梁永超,2008,兽用抗生素在土壤环境中的行为及其生态毒理效应研究进展,生态毒理学报,3:15-20(通讯作者)49. 纪雄辉,梁永超,鲁艳红,廖育林,聂军,郑圣先,李兆君,2007,污染稻田水分管理对水稻吸收积累镉的影响及其作用机理,生态学报,27(9): 3930-3939(通讯作者)50. 万小羽,梁永超,李忠佩,宋阿琳,娄运生,2007.种植转Bt基因抗虫棉对土壤生物学活性的影响, 生态学报,27(12): 5414-542051. 朱佳, 梁永超*,丁燕芳,李兆君,2006,硅对低温胁迫下冬小麦幼苗光合作用及相关生理特性的影响,中国农业科学,39(9):1780-1788(通讯作者)52. 丁燕芳,梁永超*,朱佳,李兆君,2007,硅对干旱胁迫下小麦幼苗生长及光合参数的影响,植物营养与肥料学报,13:471-478(通讯作者)53. 李平远,娄运生,梁永超*,李兆君,2006,CO2体积分数升高对污染土壤中Cu、Cd形态分布及其生物活性的影响,环境科学学报,26(12)2018-2025(通讯作者)54. 张杰,梁永超,娄运生,华海霞,2005, 镉胁迫对两个水稻品种幼苗光合参数、可溶性糖和植株生长的影响 植物营养与肥料学报 11(6) : 774-780. (通讯作者)55. 华海霞,梁永超*, 娄运生, 张杰, 2005, 水稻硅吸收动力学参数固定方法的研究,植物营养与肥料学报,12:358-36256. 杨超光,豆虎,梁永超,娄运生,2005,硅对土壤外源镉活性和玉米吸收镉的影响,中国农业科学,38(1):122-127.(通讯作者)57. 张敏,王校常,严蔚东,梁永超,施卫明,2005,盐胁迫下转Bt 基因棉的K+ 、Na + 转运及SOD 活性的变化,土壤学报,42(3): 460-467.58. 朱晓军,梁永超,杨劲松,娄运生,2005, 钙对盐胁迫下水稻幼苗抗氧化酶活性和膜脂过氧化作用的影响,土壤学报,42(3): 453-459(通讯作者)59. 朱晓军,杨劲松,梁永超,娄运生,杨晓英,2004, 盐胁迫下钙对水稻幼苗光合作用及相关生理特性的影响,中国农业科学,37(10):1497-150360. Lou YS Li ZP Zhang TL and Liang YC. 2004. CO2 emissions from subtropical arable soils of China. Soil Biology and Biochemistry, 36(11): 1835-1842.(影响因子:2.926)61. Liang YC, Hu F, Yang MC and Yu JH. 2003. Antioxidative defenses and water deficit-induced oxidative damage in rice (Oryza sativa L.) growing on non-flooded paddy soils with ground mulching. Plant and Soil, 257(2): 407-416. (影响因子:1.998)62. Liang YC, Chen Q, Liu Q, Zhang WH and Ding RX. 2003. Exogenous silicon (Si) increases antioxidant enzyme activity and reduces lipid peroxidation in roots of salt-stressed barley (Hordeum vulgare L.). Journal of Plant Physiology, 160: 1157-1164. (影响因子:2.437)63. Liang YC, Yang YF, Yang CG, Shen QR, Zhou JM, and Yang LZ. 2003. Soil enzymatic activity and growth of rice and barley as influenced by organic manure in an anthropogenic soil. Geoderma, 115:149-160. (影响因子:2.068)64. Lou YS, Liang YC and Yang YA. 2003. Effects of fertilization on plant growth and nutrient uptake in oilseed rape under varying boron supply. Commun. Soil Sci. Plant Anal. 34(7&8): 1059-1075(影响因子:0.357)65. 杨艳芳,梁永超,娄运生,2003,硅对小麦过氧化物酶、超氧化物歧化酶和木质素的影响及其与抗白粉病的关系,中国农业科学,36(7):813-817. (通讯作者)66. 梁永超,丁瑞兴,2002, 硅对大麦根系中离子的微域分布的影响及其与大麦耐盐性的关系. 中国科学(C缉),32(2): 113-121. (影响因子:0.45)67. 梁永超,孙万春,2002,硅和诱导接种对黄瓜炭疽病的抗性研究,中国农业科学,35(3): 267-271.68. 孙万春,梁永超, 2002,硅和接种炭疽菌对黄瓜过氧化物酶活性的影响及其与抗病性的关系,中国农业科学, 35(6): 1560-1564. (通讯作者)69. 夏瑶,娄运生,杨超光,梁永超, 2002, 几种水稻土对磷的吸附与解吸特性研究, 中国农业科学35(5):1369-1374. (通讯作者)70. Liang YC, Yang CG and Shi HH. 2001. Effects of silicon on growth and mineral composition of barley grown under toxic levels of aluminium. Journal of Plant Nutrition, 24(2): 229-243. (影响因子:0.569)71. Wu LH, Zhu ZR, Liang YC and Zhang FS. 2001, Plastic film mulching cultivation: a new technology for resource saving water N fertiliser and reduced environmental pollution. In: Host W J et al. (eds.), Plant nutrition—Food security and sustainability of agro-ecosystems. Dordrecht: Kluwer Academic Publishers. pp.1024~1025.72. 梁永超,胡锋,沈其荣,吴良欢,吕世华,张福锁,2000,水稻覆膜旱作研究现状与展望,见《植物营养研究---进展与展望》,冯锋、张福锁、杨新泉主编,中国农业大学出版社,pp.114-127.73. Liang YC, 1999. Effects of silicon on enzyme activity, and sodium, potassium and calcium concentration in barley under salt stress. Plant and Soil, 209(2): 217-224.(影响因子:1.998)74. 梁永超,胡锋,杨茂成,朱遐亮,王广平,王永乐,1999,水稻覆膜旱作高产节水机理研究,中国农业科学,32(1): 26-32.75. 梁永超,丁瑞兴,刘谦,1999,硅对大麦耐盐性的影响及其机制,中国农业科学,32(6): 75-83.76. 梁永超,沈其荣,张爱国,沈振国,1999,钙、硅对酸雨胁迫下小麦生长和养分吸收的影响,应用生态学报,10(5):589-59277. Wang HL, Li CH, and Liang YC. 1999, Chapter 21, Agricultural utilization of silicon in China, In: Datnoff et al., (eds.), Studies in Plant Science, 8. Silicon In Agriculture, Elsevier, pp. 343-35278. Liang YC, Zhang YC, Yin SX and Yang MC. 1998. Feasibility of using trichloroacetic acid soluble silicon as a diagnostic index for silicon deficiency in rice. Pedosphere, 8(1): 21-2679. Liang YC, 1998, Effects of silicon on leaf ultrastructure, chlorophyll content and photosynthetic activity of barley under salt stress. Pedosphere, 8 (4): 289-296.80. Liang YC, Shen QR and Shen ZG.1996. Effects of silicon on salinity tolerance of two barley cultivars. Journal of Plant Nutrition, 19(1): 173-183. (影响因子:0.569)81. Liang YC, and Shen ZG. 1994. Interaction of silicon and boron in oilseed rape plants. Journal of Plant Nutrition, 17(2&3): 415-425. (影响因子:0.569)82. Liang YC, Ma TS, Li FJ and Feng YJ. 1994. Silicon availability and response of rice and wheat to silicon in calcareous soils. Commun. Soil Sci. Plant Anal. 25(13&14): 2285-2297. (影响因子:0.357)83. Shen ZG. Shen QR, Liang YC and Liu YL. 1994. Effect of nitrogen on the growth and photosynthetic activity of salt-stressed barley. Journal of Plant Nutrition, 17(5): 787-799. (影响因子:0.569)84. Shen ZG. Liang YC and Shen K. 1993. Effect of boron on the nitrate reductase activity in oilseed rape plants. Journal of Plant Nutrition, 16(7): 1229-1239(影响因子:0.569)
赵秀兰的近五年代表性论文
1. X. L. Zhao, Z. J. Mu, C. M. Cao & D. Y. Wang: Growth and Heavy-Metal Uptake by Lettuce Grown in Soils Applied with Sewage Sludge Compost. Communications in Soil. Science and Plant Analysis, 2012,43:11, 1532-1541. 2. Zhao Xiulan, Wang Dingyong. Mercury in some chemical fertilizers and the effect of calcium superphosphate on mercury uptake by corn seedlings(Zea mays L.). Joural of Environmental Sciences 2010,22(8):1184-1188. 3. Zhao Xiulan, Masahiko Sagusa. Amelioration of Cadmium Polluted Paddy Soils by Porous Hydrated Calcium Silicate. Water, Soil and Air pollution, 2007,183(1-4): 309-315. 4. Zhao Xiulan, Masahiko Sagusa. Fractionation and solubility of cadmium in soils amended with porous hydrated calcium l of Environmental Science, 2007, 19:343–347. 5. Zhu Hualan, Zhao Xiulan. Effects of lime stabilized sewage sludge compost on soil physicochemical properties and heavy metal uptake by ryegrass. Advanced Materials Research, Trans Tech Publications(Ei Compendex). 6.李映廷,刘双营,赵秀兰,陈宏,王定勇.秸秆-膨润土-聚丙烯酰胺对砂质土壤吸附氮素的影响.农业工程学报,2012,27(1):326-331. 7.包娇,韦惠琴,赵秀兰.低分子量有机酸强化烟草修复镉污染土壤的适用性研究.水土保持学报,2012,26(2):265-270. 8.王树芹,罗松涛,李国忠,赵秀兰.阴离子型聚丙烯酰胺分子量和水解度对污泥脱水性能影响的研究.环境科学学报,2011,31(8):1706-1713. 9.唐淦海,谷春豪,刘郡英,赵秀兰.作物秸秆与城市污泥高温好氧堆肥产物对土壤氮矿化的影响.农业工程学报,2011,27(1):326-331. 10.龚咏梅,木晓丽,赵秀兰.餐厨垃圾与污泥联合两步厌氧发酵产酸阶段条件优化试验.环境化学, 2011,30(4):156-161. 11.李萍,郭喜丰,徐莉莉,王玉林,赵秀兰.细胞分裂素类物质对玉米幼苗镉吸收和转运的影响.水土保持学报, 2011,25(1):119-121. 12.徐莉莉,李萍,王玉林,郭喜丰,赵秀兰.细胞分裂素类物质对镉胁迫下玉米幼苗生长和抗氧化酶活性及脯氨酸含量的影响.环境科学学报,2010,30(11):2256-2263. 13.林玉海,王楠,赵秀兰,何丙辉.三峡库区澎溪河流域消落区土壤氮磷释放研究.水土保持学报,2010,24(5):131-134. 14.方云,赵秀兰,魏源送,杨宇,沈颖,郑嘉熹.春冬季节对堆肥修复多环芳烃(PAHs)污染土壤的影响.环境科学,2010,31(6):1688-1697. 15.赵秀兰,刘晓.不同品种烟草生长和镉及营养元素吸收对镉胁迫响应的差异,水土保持学报,2009,23(1),117-122. 16.赵秀兰,陈萍莉,卢吉文,王德辉.重庆市城市污泥中的重金属及其农用环境容量,农业工程学报,2008,24(11):188-192.
土壤镉污染及其相关问题研究
Cd是土壤重金属污染的重要来源之一,它有高毒性,化学性质接近于锌,在土壤中具有稳定、积累和不易消除性,并通过食物链富集,构成对人类生存环境多个层面上的不良胁迫,给人类的健康和动植物健康以及周围生态环境带来严重危害。国际癌症研究局(IARC)将镉及其化合物划为第Ⅰ类“对人体致癌”物质。
土壤中镉的来源
当农业土壤中Cd的含量超过了1.0 mg/kg时,我们就认为其受到了污染。土壤镉污染来源很多,可分为自然源和人为源。自然源主要指成土的母质,如硫镉矿、方硫镉矿等。人为来源主要包括采矿、冶炼、化肥施用、污水灌溉、大气沉降、城市垃圾等。采矿冶炼是镉排放的主要工业源,并以“三废”的形式影响周围环境,工业废气中的镉伴随着粉尘扩散,以降雨和自然沉降的形式进入土壤,工业废水中的镉通过污水灌溉农田或城市居民用水处理不达标等形式进入土壤,长期使用磷肥和高量有机肥会增加土壤镉的含量,含镉肥料主要是磷肥和一些含镉生活垃圾。此外,机动车尾气排放能引起公路两侧土壤的重金属污染。
土壤镉的迁移富集机理
1、镉的存在状态。Cd在土壤中有水溶态和难溶态两种存在状态。不同形态的污染物有不同的环境行为和生物效应。水溶性镉主要以离子态或络合态存在,易为作物所吸收;难溶性镉可以是交换态(粘土交换及腐殖质交换)、化学沉淀态及难溶性螯合态存在于土壤颗粒中,不易被植物所吸收。土壤中水溶性镉和非水溶镉在一定的条件下可相互转化,其主要影响因素为土壤的酸碱度、氧化-还原条件和碳酸盐的含量。
2、镉的迁移转化。由于土壤的强吸附作用,镉很少发生向下的再迁移而累积于土壤表层。在降水的影响下,土壤表层的镉的可溶态部分随水流动就可能发生水平迁移,进入界面土壤和附近的河流或湖泊而造成次生污染。
3、土壤镉活性的影响因素。影响镉在土壤中转化的因素很多,例如pH值、土壤氧化还原条件等。pH值增大,镉溶解度降低。土壤的氧化还原条件与镉的活性关系密切,旱地通风良好,镉多呈可溶性,易被吸收,作物与土壤镉含量呈正相关;水田还原条件下, S2 -与Cd2+结合生成难溶CdS抑制Cd2+的迁移和作物对Cd2+的吸收,抑制土壤中镉的活性。此外,土壤粘土成分、有机质含量和PO43 -含量都能影响镉的迁移能力。其中pH值是影响Cd2+溶解度的主要因素,是引起植物吸收Cd2+的主要原因。如果不考虑其他反应,可写成下列平衡反应式:
上式表明,Cd2+的理论浓度随着土壤pH值的上升而下降。
土壤镉污染的修复
土壤镉污染治理的原则为“预防为主,防治结合”具体手段有如下几种:
1、物理修复。物理修复方法包括改土法、土壤淋洗法、热力学修复法、电动力学修复法等,目前应用最广泛的是改土法,改土法包括客土、换土、去表土和深耕翻土等。土壤淋洗法是利用淋洗液将土壤固相中的镉转移至液相中,再把富含镉的废水进一步回收处理,目前土壤淋洗液包括有机或无机酸、碱、盐和螯合剂等。热力学修复法是利用高压变频电压产生电磁波,产生热能对土壤加热,使污染物从土壤颗粒内解析出来。而电动力学修复法则是指在污染土壤中插入电极对,并通以低强度的直流电,使土壤的镉离子在电场作用下定向移动,在电极附近富集,从而达到清除镉的目的。
2、化学修复。即在土壤中施用化学修复剂,与镉污染物发生一定的化学反应,以降低土壤镉污染物的水溶性、扩散性和生物有效性的修复技术。化学修复法发展较早,也相对成熟有效,主要包括:化学淋洗技术、化学氧化修复技术、土壤性能改良技术等等。目前,广泛应用的方法是施用改良剂,如磷酸盐、硅酸盐、沸石、膨润土,通过改变土壤pH、沉淀、吸附、离子交换和络合等化学反应等,显著降低镉在土壤中的生物有效性。有研究发现,施用磷酸二氢铵对矿区镉污染土壤进行修复,镉的有效浓度下降达94.6%。
3、植物修复。植物修复费用低、耗费人力少、处理效率高、不会产生二次污染并且可以易回收利用金属。植物修复是指利用植物及其根际圈微生物体系的吸收、挥发和转化、降解作用,清除土壤中污染物质,主要包括两个方面:一是利用一些超积累植物对污染物进行吸收、固定、转化和积累。温室栽培试验结果表明,印度芥菜根和叶中的最高镉含量可达300 mg/kg、160 mg/kg。 此外,对镉耐性和富集能力较强的植物还有小犬蕨、向日葵等。二是为微生物修复提供有利于修复进行的条件,促进生物降解和无害化。 严理等研究发现,镉污染土壤种植苎麻后, 土壤微生物活菌量明显增加,土壤细菌活菌量增加幅度最大的为1.33倍, 土壤真菌增加幅度最大的达2.42倍;镉污染土壤种植苎麻可提高土壤有机质含量,明显减少土壤中镉含量,起到修复土壤镉污染的作用。
4、生物修复。生物修复包括微生物修复和动物修复。微生物修复机理包括细胞代谢、吸收、沉淀和氧化还原反应等。刘红娟等发现,其所研究的蜡状芽孢杆菌RC可以在镉浓度为200 mg/L的固体培养基平板上生长良好,表明菌株具有强抗镉的能力。动物修复是指利用土壤中某些低等动物的代谢活动来降低污染土壤中重金属比例的方法。例如,Ramseier等研究发现蚯蚓具有强烈的镉富集能力,当土壤镉浓度为3mg/kg时,蚯蚓的镉富集量可以达到120mg/kg。但由于低等动物生长受环境等因素的严重制约,该项技术在实际应用中受到了一定限制。
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