Hong Yi, Li Dong, Xie Can, Zheng Xiaoxiao, Yin Jing, Li Zhidong, Zhang Kailu, Jiao Yangqiu, Wang Baijie, Hu Yueming, Zhu Zhiqiang
College of Tropical Crops, Hainan University, Haikou 570228, China.
College of Ecology and Environment, Hainan University, Haikou 570228, China.
Sci Total Environ. 2022 Dec 10;851(Pt 1):158033. doi: 10.1016/j.scitotenv.2022.158033. Epub 2022 Aug 13.
Soil amendments are used extensively to remediate soils contaminated with heavy metals. However, the effects of soil amendments on heavy metal bioavailability, plant yield, and bacterial community structure in tropical farmland soils remain largely unknown. In the present study, seaweed organic fertilizer (S), apatite (A), biochar (B), and seaweed organic fertilizer-apatite-biochar mixtures (SAB) were applied at different rates to assess their influence on cadmium (Cd), lead (Pb), and chromium (Cr) bioavailability in contaminated farmland soils, using different component ratios and doses in maize field plots, and maize yield. Effects on soil bacterial community structure were also evaluated based on high-throughput sequencing. Following addition of 2 % S + A + B combined amendment at a ratio of 1:0.5:1.5 (2%SAB), soil pH and electrical conductivity (EC) were elevated, and bioavailable Cd, Pb, and Cr concentrations were reduced in potted soils, leading to higher heavy metal immobilization. Under field conditions, soil pH, EC, organic matter, ammonium‑nitrogen, available phosphorus, available potassium, and crop productivity were all increased considerably, whereas soil Cd and Cr bioavailability were lower in the combined amendment treatments than in the control treatments. Particularly, application of a 2.49 t·ha combined amendment (0.83 t·ha S + 0.41 t·haA + 1.25 t·haB,1:0.5:1.5) decreased Cd, Pb, and Cr concentrations in maize grain by 68.9 %, 68.9 %, and 65.7 %, respectively. Species abundance and evenness in bacterial communities increased in field soils subjected to combined amendments, with shifts in community structure and function mostly driven by changes in soil pH, organic matter content, and nutrient availability. Overall, the results suggest that 1.5%SAB is the optimal treatment for remediating heavy metal co-contaminated soil, and thereby, improving maize yield and quality. Combined organic and inorganic amendments achieve high remediation efficiency, mainly by improving chemical properties, reducing heavy metal bioavailability, and altering bacterial community structure and function in heavy metal contaminated farmland soils.
土壤改良剂被广泛用于修复受重金属污染的土壤。然而，土壤改良剂对热带农田土壤中重金属生物有效性、植物产量和细菌群落结构的影响在很大程度上仍不清楚。在本研究中，以不同比例施用海藻有机肥（S）、磷灰石（A）、生物炭（B）以及海藻有机肥 - 磷灰石 - 生物炭混合物（SAB），通过在玉米田块中使用不同的组分比例和剂量，评估它们对受污染农田土壤中镉（Cd）、铅（Pb）和铬（Cr）生物有效性以及玉米产量的影响。还基于高通量测序评估了对土壤细菌群落结构的影响。在以1:0.5:1.5的比例添加2%的S + A + B复合改良剂（2%SAB）后，盆栽土壤的pH值和电导率（EC）升高，生物可利用的Cd、Pb和Cr浓度降低，导致更高的重金属固定率。在田间条件下，土壤pH值、EC、有机质、铵态氮、有效磷、速效钾和作物生产力均显著提高，而复合改良剂处理的土壤中Cd和Cr的生物有效性低于对照处理。特别是，施用2.49吨·公顷的复合改良剂（0.83吨·公顷S + 0.41吨·公顷A + 1.25吨·公顷B，1:0.5:1.5）使玉米籽粒中Cd、Pb和Cr的浓度分别降低了68.9%、68.9%和65.7%。复合改良剂处理的田间土壤中细菌群落的物种丰度和均匀度增加，群落结构和功能的变化主要由土壤pH值、有机质含量和养分有效性的变化驱动。总体而言，结果表明1.5%SAB是修复重金属复合污染土壤、从而提高玉米产量和品质的最佳处理。有机和无机改良剂联合使用可实现较高的修复效率，主要是通过改善化学性质、降低重金属生物有效性以及改变重金属污染农田土壤中的细菌群落结构和功能来实现的。
