组配改良剂对稻田镉砷复合污染的调控效果及机制研究

发布时间：2017-12-28 01:26

  本文关键词：组配改良剂对稻田镉砷复合污染的调控效果及机制研究　出处：《中南林业科技大学》2017年博士论文　论文类型：学位论文

  更多相关文章： 镉 砷 组配改良剂 水稻 生物有效性

【摘要】：伴随我国工农业的快速发展,我国耕地受Cd和As等重金属污染的问题日益严重。湖南省是有色金属之乡和鱼米之乡,规模化矿业开采与冶炼对矿区生态环境及农业生产带来了严重破坏,严重地制约着湖南省广大地区水稻生产安全和稻米食用安全。如何治理Cd和As复合污染农田,如何控制Cd和As向水稻中转移是一个亟待解决的环境问题。本研究围绕稻田土壤Cd和As复合污染的修复,以郴州柿竹园矿区(A矿区)及湘西州保靖县复兴村矿区(B矿区)不同Cd和As污染程度的稻田土壤为研究对象,通过改良剂筛选实验、水溶液吸附实验、水稻盆栽实验以及大田实验等研究,研发了一种组配改良剂QFJ,系统阐述了应用QFJ降低土壤Cd、As生物有效性和糙米Cd、As含量的机制,提出了一套控制稻田Cd和As生物有效性和迁移转运的有效技术。研究结果如下:(1)研制出以羟基磷灰石、沸石和改性秸秆炭3种物质为主要成分,按一定质量比例组配的改良剂QFJ,确定其作用机制:3种物质具有较大的比表面积,可与溶液中Cd2+和As5+发生表面吸附和孔道吸附,QFJ含有的-OH、-COOH、-Si-O-Si以及C032-基团与溶液中Cd2+、As5+离子发生了交换吸附、共价结合,生成了羧酸盐类、硅酸盐类和碳酸盐类物质,从而将土壤溶液中游离的Cd2+、As3+和As5+原位钝化。(2)施用组配改良剂QFJ改良Cd和As复合污染稻田土壤,水稻盆栽实验显示:根际土壤pH值、CEC和OM含量呈现上升趋势。QFJ的施用使得水稻黄华占和T优272根际土壤中Cd的交换态含量呈现下降趋势,可分别下降12.6%～39.8%和20.6%～70.6%;QFJ施用量在0.5～2.0 g·kg-1之间对As的交换态含量有降低作用,分别降低12.2%～55.1%和7.0%～39.5%,但施用量增加后使得交换态As含量急剧增大。随着QFJ施用量的增加,土壤中Cd的毒性浸出量逐渐下降,As的毒性浸出量先下降后上升。土壤pH值、CEC与土壤中Cd的交换态含量、毒性浸出量及酸提取态含量具有正的线性关系;土壤pH值与土壤中As的交换态含量、毒性浸出量具有负的线性关系。(3)盆栽实验中,施用QFJ改变了 Cd和As的赋存形态,降低了 Cd酸提取态含量,使难溶的有机结合态Cd分别增加6.8%～49.5%和2.5%～56.5%;同时,降低了As交换态含量,使难溶的钙结合态As含量分别增加34.1%～93.4%和2.8%～53.3%;但QFJ施用量超过4.0 g·kg-1时,土壤中交换态As含量增大。(4)盆栽实验中,QFJ施用使得水稻各部位Cd含量均低于对照组CK,糙米中Cd含量可从0.49 mg·kg-1下降到0.11 mg·kg-1;水稻植株各部位Cd的含量大小依次是根茎叶糙米谷壳。QFJ施用量控制在0.5～2.0g·kg-1水平,显著降低水稻地上各部位As含量,且在2.0 g·g-1施用量,2种水稻糙米中As含量从0.27 mg·kg-1、0.28mg·kg-1下降到最低值0.11mg·kg-1、0.16mg·kg-1,但随着施用量的增加,水稻各部位中As含量呈现上升趋势;水稻植株各部位As含量大小依次是根茎叶谷壳糙米。(5)盆栽实验显示,水稻根系对Cd和As的富集系数BAF分别为0.65～1.26和0.024-0.061,根系富集Cd的能力较As强;水稻各部位对Cd的转运系数TF依次是TFCd-hbTFCd-shTFCd-rs,对 As 的是 TFAs-rsTFAs-hbTFAs-sh,水稻谷壳对 Cd 的转运能力最强,而根对As的转运能力最强;QFJ的施用降低了水稻植株对Cd和As转运量的系数,有效降低了水稻植株地上部位Cd和As的累积总量。(6)田间实验显示,随着QFJ施用量的增加,2矿区水稻各生育期根际土壤pH值、CEC和OM含量有增大趋势;QFJ的施用在各生育期均可显著降低2矿区土壤中交换态Cd含量,且在水稻分蘖期时,降低土壤交换态Cd含量的幅度最大;而针对土壤交换态As含量2个矿区呈现相反的结果,A矿区有增大风险而B矿区呈现降低风险的趋势。QFJ的施用也可显著降低水稻各生育期2矿区土壤中Cd的毒性浸出量,对B矿区土壤As的毒性浸出量也有降低的作用,但对土壤A矿区中As的毒性浸出量,在4.0 g·kg-1施用量时则有提高的风险。(7)田间实验显示,灌浆期是水稻植株大量累积Cd和As的时期。QFJ的施用可有效降低A矿区(土壤Cd总量3.58 mg·kg-1,As总量124.79 mg kg-1)各生育期水稻各部位中Cd含量,也可降低成熟期水稻各部位中As含量。QFJ施用量在4.0g·kg-1水平时,使成熟期糙米Cd含量从0.46mg·kg-1下降到0.18mg·kg-1,无机As含量从0.22 mg·kg-1降低到0.18 mg·kg-1,糙米中Cd和无机As含量同时低于0.2 mg·kg-1,达到水稻安全生产要求。
[Abstract]:With the rapid development of industry and agriculture in China, the problems of heavy metal pollution such as Cd and As are becoming more and more serious in our country. Hunan province is the home of non-ferrous metals and Yumizhixiang, scale mining and smelting has brought serious damage to the ecological environment and agricultural production, which seriously restricts the safety of rice production and rice area of Hunan province food safety. How to control the Cd and As compound polluted farmland and how to control the transfer of Cd and As into rice is an urgent environmental problem. The repair of Cd and As in paddy soil around the composite pollution in Chenzhou mining area, Shizhuyuan (A mine) and Xiangxi County of Baojing Fuxing Village area (B area) of different soil Cd and As pollution in paddy field as the research object, through improved agent selection research, water adsorption experiment, pot experiment and field experiment of rice so, developing a group with a modifier QFJ, application of QFJ and As decreased soil Cd bioavailability and rice Cd, As content mechanism, put forward a set of effective technical control of paddy field Cd and As bioavailability and transfer. The results are as follows: (1) developed with hydroxyapatite, zeolite and modified straw charcoal 3 kinds of materials as the main ingredient, modifier QFJ according to a certain weight proportion group, determine the mechanism: 3 material has larger specific surface area, surface adsorption can occur and pore adsorption with Cd2+ and As5+ solution in QFJ, -OH, -COOH, containing -Si-O-Si and C032- groups and Cd2+ in solution, As5+ ion exchange adsorption, covalent binding, formation of carboxylic acid salts, silicate and carbonate species, which will be free in the soil solution Cd2+, As3+ and As5+ in situ passivation. (2) the experiment of rice pot experiments showed that the content of pH, CEC and OM in rhizosphere soil showed an upward trend with the use of the combination of QFJ and As to improve the soil soil of Cd and As. The application of QFJ makes the rice Huang Huazhan and T 272 in the rhizosphere soil exchangeable Cd content showed a downward trend, can be reduced by 12.6% ~ 39.8% and 20.6% ~ 70.6% respectively; QFJ fertilizer with exchangeable content of As between 0.5 ~ 2 g / kg-1 decreased, decreased by 12.2% ~ 55.1% and 7% ~ 39.5% respectively., but increased the concentration of exchangeable As increased sharply. With the increase of the amount of QFJ, the toxic leaching of Cd in the soil decreased gradually, and the toxic leaching amount of As decreased first and then increased. There was a positive linear relationship between soil pH and CEC and the content of exchangeable Cd in soil, the amount of toxic leaching and the content of acid extract. The pH value of soil had negative linear relationship with the exchange state content of As and the amount of toxic leaching. (3) pot experiment, the application of QFJ has changed the chemical speciation of Cd and As, decreased Cd acid extractable content, the organic combination of insoluble Cd increased 6.8% ~ 49.5% and 2.5% ~ 56.5%; at the same time, reduce the content of exchangeable As, the insoluble calcium bound As was increased by 34.1% ~ 93.4% and 2.8% ~ 53.3% respectively; but the QFJ dosage is more than 4 g - kg-1, increase the content of the exchangeable As in soil. (4) pot experiment, QFJ application makes the Cd content in different parts of rice were lower than the control group CK, Cd content in brown rice decreased from 0.49 mg to 0.11 mg - kg-1 - kg-1; the size of each part of Cd content in rice plant in rhizome and leaf of rice husk. Control QFJ application amount in the range of 0.5 ~ 2.0g and kg-1 levels decreased significantly on As content in different parts of rice, and in 2 G - g-1 fertilizer, 2 kinds of As content in brown rice from 0.27 Mg - kg-1, 0.28mg - kg-1 dropped to the lowest value of 0.11mg - kg-1, 0.16mg - kg-1, but with the increasing of the amount the As content in different parts of rice in rice plants showed an upward trend; As contents in different parts of the size of the order is the rhizome and leaf of brown rice husk. (5) pot experiment showed that the enrichment coefficient of BAF rice root of Cd and As were 0.65 ~ 1.26 and 0.024-0.061, the ability of root enrichment of Cd is stronger than As; transfer coefficient TF on Cd in different parts of rice followed by TFCd-hbTFCd-shTFCd-rs, As TFAs-rsTFAs-hbTFAs-sh, transport capacity of the strongest rice shell on the Cd Valley, and the root of the As transport capacity of the strongest; QFJ application decreased the coefficient of Cd and As translocation amount of rice plants, effectively reducing the rice plants on site Cd and As cumulative total. (6) field experiments show that with the increase of QFJ dosage, 2 in different growth stages of rice rhizosphere soil pH, CEC and OM content increased; the administration of QFJ decreased significantly in each growth period can be exchangeable Cd content of 2 Soil in mining area, and at the tillering stage, decrease soil exchange state Cd content is the biggest; while the contents of soil exchangeable As 2 mining areas showed the opposite results, A and B have an increased risk of mining area showed a decreasing trend in risk. The application of QFJ can also significantly reduce the toxic leaching amount of Cd in the 2 mining area soil at different growth stages, and decrease the toxic leaching amount of As in B mining area. However, the toxic leaching amount of As in soil A mining area is increased at 4 g / kg-1 dose. (7) field experiments showed that the grain filling period was a period of accumulation of Cd and As in rice plants. The application of QFJ can effectively reduce the A mining area (total Cd content of soil 3.58 mg kg-1, As total 124.79 mg kg-1). The Cd content in different parts of rice at different growth stages can also reduce the As content in different parts of mature rice. When QFJ dosage was 4.0g / kg-1, the content of Cd in brown rice decreased from 0.46mg to kg-1, 0.18mg to kg-1, and the content of inorganic As decreased from 0.22 mg to 0.18, and the content of inorganic and inorganic compounds in brown rice was lower than 0.2.
【学位授予单位】：中南林业科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S511;X53
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本文编号：1344023