Rhizosphere dissolved organic matter and iron plaque modified by organic amendments and its relations to cadmium bioavailability and accumulation in rice.
Rhizosphere dissolved organic matter and iron plaque modified by organic amendments and its relations to cadmium bioavailability and accumulation in rice.
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有机改良剂修饰的根际溶解有机物和铁斑及其与水稻镉生物利用度和积累的关系。
DOI：
10.1016/j.scitotenv.2021.148216
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发表时间：
2021-06
影响因子：
9.8
通讯作者：
Shiqiang Wei
中科院分区：
文献类型：
--
作者：
Na Liu;Xuge Lou;Xiong Li;Zuping Shuai;Hanyi Liu;Zhenmao Jiang;Shiqiang Wei
有机添加剂可以改变水稻根际溶解性有机质（DOM）的性质和铁膜数量，从而影响水稻对镉的吸收和生物有效性。采用盆栽试验，研究了生物炭（BC）和蚯蚓粪（VC）不同施用量（0、1%和5%）对高、低Cd积累水稻品种（HAC和LAC）根际DOM特征和铁膜数量的影响，以及对Cd生物有效性和积累的影响。利用紫外-可见光谱（UV-Vis）和荧光激发发射矩阵（EEM）光谱对土壤DOM进行了表征。采用水培试验研究了BC或VC源DOM与Fe膜复合对水稻Cd吸收的影响。结果表明，有机添加量的增加使根际和非根际土壤中DOM含量增加，而Cd有效性和水稻组织中Cd含量降低。添加有机改良剂后，LAC籽粒中Cd的去除率（31.9%~ 72.7%）高于HAC籽粒中Cd的去除率（6.3%~ 25.4%）。有机改良剂对土壤DOM的性质进行了改良，使其具有更高的芳香度、分子量和稳定性。VC导致根际DOM中类腐殖酸组分的增加幅度更大，但类蛋白质的比例比BC降低。根际类腐殖酸组分与有效态Cd呈负相关。VC（特别是5%VC）促进了Fe膜的形成，限制了Cd向根际的转运，而BC组则相反。水培试验结果证实，BC和VC来源的DOM和Fe-菌膜分别通过与Cd络合和螯合Cd进一步抑制水稻对Cd的吸收。因此，施用VC与低镉水稻相结合是镉污染土壤安全利用的有效策略。
Organic amendments can modify rhizosphere dissolved organic matter (DOM) properties and Fe–plaque quantity, thereby affecting cadmium (Cd) bioavailability and uptake by rice. Pot experiments were conducted to investigate effects of biochar (BC) and vermicompost (VC) at different rates (0, 1%, and 5%) on rhizosphere DOM characteristics and Fe–plaque quantity, and their impacts on Cd bioavailability and accumulation in high and low Cd–accumulation rice cultivars (HAC and LAC). Soil DOM was characterized by ultraviolet–visible (UV–Vis) and fluorescence excitation–emission matrix (EEM) spectrum analyses. Hydroponic experiments were conducted to investigate effects of BC– or VC–derived DOM combined Fe–plaque on Cd uptake by rice. Results showed that increasing rates of organic amendments increased DOM concentration while decreased Cd availability in rhizosphere and bulk soils and Cd contents in rice tissues. The Cd reduction in LAC grains (31.9%–72.7%) was better than that in HAC grains (6.3%–25.4%) after organic amendment addition. Soil DOM properties were modified by organic amendments towards higher aromaticity, molecular weight, and stability. VC resulted in a greater increase of humic–like fractions but reduced protein–like proportions in rhizosphere DOM over BC. Negative correlations were observed between humic–like fractions and available Cd in the rhizosphere. Likewise, VC (especially 5%VC) promoted the formation of Fe–plaque and limited Cd soil-to-root transport, while BC groups showed a reverse trend. The results of hydroponic experiments confirmed BC– and VC–derived DOM and Fe–plaque further inhibited Cd uptake by rice via the complexation with Cd and the sequestration of Cd, respectively. Hence, VC application combined with low Cd–accumulation rice could be an effective strategy for the safe utilization of Cd–contamination soils.