Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China.
Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China.
Ecotoxicol Environ Saf. 2020 Feb;189:109928. doi: 10.1016/j.ecoenv.2019.109928. Epub 2019 Nov 22.
Human exposure to arsenic (As) through rice consumption is a global food safety issue, especially in Southeast Asia. To investigate the impacts of biochar amendment (rice husk and smooth cordgrass-derived biochar) and/or silicate fertilizer on As mobility/phytoavailability in soil and on As accumulation in rice, pot and microcosm experiments were conducted. The results showed that both single application of low doses of biochar (0.5%, w/w) and coapplication of biochar with silicate fertilizer decreased As levels in grain (brown rice) by 14-16%, but not in straw and roots. The biodilution of As in grain resulting from increased grain biomass (by 6-21%) could be mainly a response to the decline in grain As levels with biochar and/or silicate fertilizer amendment. However, both applications exerted limited effects to decrease the overall As uptake by rice grain and straw, potentially due to the small changes in As mobility/phytoavailability in amended soil relative to the control, although plant-available silicon (Si) from amendment could potentially inhibit As uptake. Furthermore, microcosm-based anaerobic incubation experiments demonstrated that As levels in soil solution increased (up to 11-14-fold) with increasing doses of biochar amendment (up to 5%, w/w), possibly due to biochar enhancing the reductive dissolution of iron (oxyhydr) oxides via an increase in the total number of iron-reducing bacteria (up to 1.6-3.2-fold). Our findings suggested that a low application rate of biochar may not be a very effective approach for mitigating As accumulation in rice, while a high application rate could enhance the health risk of As in As-contaminated flooded soil.
人类通过食用大米摄入砷（As）是一个全球性的食品安全问题，尤其在东南亚地区更为严重。为了研究生物炭改良（稻壳和光滑蔺草衍生生物炭）和/或硅肥对土壤中砷迁移/植物可利用性以及水稻中砷积累的影响，进行了盆栽和微宇宙实验。结果表明，低剂量生物炭（0.5%，w/w）的单一应用以及生物炭与硅肥的共同应用均使稻谷（糙米）中的砷含量降低了 14-16%，但对稻草和根系中的砷含量没有影响。生物炭和/或硅肥改良导致稻谷生物量增加（6-21%），从而使砷在稻谷中的生物稀释作用可能主要是由于稻谷中砷含量下降的反应。然而，这两种应用都对减少水稻稻谷和稻草对砷的整体吸收作用有限，这可能是由于与对照相比，改良土壤中砷的迁移/植物可利用性变化较小，尽管改良土壤中的有效硅（Si）可能会抑制砷的吸收。此外，基于微宇宙的厌氧培养实验表明，随着生物炭施用量的增加（最高可达 5%，w/w），土壤溶液中的砷含量增加了（最高可达 11-14 倍），这可能是由于生物炭通过增加铁还原菌的总数（最高可达 1.6-3.2 倍）来促进铁（氢）氧化物的还原溶解。我们的研究结果表明，低生物炭施用量可能不是减轻水稻砷积累的一种非常有效的方法，而高生物炭施用量可能会增加砷污染淹水土壤中砷的健康风险。
