School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China; Funiu Mountain Forest Ecosystem Observation and Research Station, Zhengzhou University, Zhengzhou, 450001, China.
College of Resources and Environment, Southwest University, Chongqing, 400715, China.
Environ Pollut. 2022 Dec 1;314:120341. doi: 10.1016/j.envpol.2022.120341. Epub 2022 Oct 3.
Both inorganic and organic fertilizers are widely used to increase rice yield. However, these fertilizers are also found to aggravate mercury methylation and methylmercury (MeHg) accumulation in paddy fields. The aim of this study was to reveal the mechanisms of inorganic and organic fertilizers on MeHg accumulation in rice grains, which are not yet well understood. Potting cultures were conducted in which different fertilizers were applied to a paddy soil. The results showed that both inorganic and organic fertilizers increased MeHg concentrations rather than biological accumulation factors (BAFs) of MeHg in mature rice grains. Inorganic fertilizers, especially nitrogen fertilizer, enhanced the bioavailability of mercury and the relative amount Hg-methylating microbes and therefore intensified mercury methylation in paddy soil and MeHg accumulation in rice grains. Unlike inorganic fertilizers, organic matter (OM) in organic fertilizers was the main reason for the increase of MeHg concentrations in rice grains, and it also could immobilize Hg in soil when it was deeply degraded. The enhancement of MeHg concentrations in rice grains induced by inorganic fertilizers (5.18-41.69%) was significantly (p < 0.05) lower than that induced by organic fertilizers (80.49-106.86%). Inorganic fertilizers led to a larger increase (50.39-99.28%) in thousand-kernel weight than MeHg concentrations (5.18-41.69%), resulting in a dilution of MeHg concentrations in mature rice grains. Given the improvement of soil properties by organic fertilizer, increasing the proportion of inorganic fertilizer application may be a better option to alleviate MeHg accumulation in rice grains and guarantee the rice yield in the agricultural production.
无机肥和有机肥被广泛用于提高水稻产量。然而，这些肥料也被发现会加剧稻田中汞的甲基化和甲基汞（MeHg）的积累。本研究旨在揭示无机肥和有机肥对水稻籽粒中 MeHg 积累的机制，这些机制尚未得到很好的理解。采用盆栽培养的方法，在稻田土壤中施加不同的肥料。结果表明，无机肥和有机肥都增加了成熟水稻籽粒中 MeHg 的浓度，而不是生物积累因子（BAFs）。无机肥，特别是氮肥，增加了汞的生物可利用性和相对数量的汞甲基化微生物，从而加剧了稻田中汞的甲基化和 MeHg 在水稻籽粒中的积累。与无机肥不同的是，有机肥中的有机质是导致水稻籽粒中 MeHg 浓度增加的主要原因，而且当有机质深度降解时，它也可以固定土壤中的汞。无机肥引起的水稻籽粒中 MeHg 浓度的增加（5.18-41.69%）明显低于有机肥引起的增加（80.49-106.86%）。无机肥导致千粒重增加（50.39-99.28%）大于 MeHg 浓度增加（5.18-41.69%），从而稀释了成熟水稻籽粒中的 MeHg 浓度。鉴于有机肥可以改善土壤性质，增加无机肥的施用量可能是减轻水稻籽粒中 MeHg 积累并保证农业生产中水稻产量的更好选择。
