有机肥施用下稻田田面水中消毒副产物前体物的赋存规律

稻田有机肥输入会使田面水含有含量的溶解性有机碳(DOC).溶解性有机物(DOM)是具有三致效应的消毒副产物(DBPs)的前体物,而DOC是用于表征DOM浓度的一个指标.本研究旨在评估水稻田田面水的三卤甲烷(THMs)前体物的生成反应性,解析猪粪有机肥对于THMs前体物从水稻田输出的潜在影响.于水稻种植季选取4个猪粪施用梯度(以C计,下同)(0对照],714.1低],1428.2中]与2142.3高]kg·hm-2),检测了稻田田面水中的DOC,UVA254与三卤甲烷生成潜能(THMFP).结果表明,3个指标两两之间呈线性相关性.田面水中以上3个指标都与有机肥施用量呈正相关性.在施肥后的7d内,DOC的输出潜能降低了32.9%至47.5%.有机肥施用与预期的降雨或灌溉之间的时间间隔相隔一周以上,将能在满足作物营养需求的条件下降低消毒副产物前体物输出的风险,使稻田土壤成为DOC的汇而非DOC输出至周边水体的源.

Occurrence of disinfection byproduct precursors in floodwater of paddy fields under swine manure amendments

Floodwater of paddy field under swine manure amendments contains high levels of dissolved organic carbon (DOC). Dissolved organic matter (DOM) is a precursor of carcinogenic and mutagenic disinfection byproducts (DBPs), and DOC is an indicator of DOM concentration. The major objectives of this paddy field experiment were to evaluate the reactivity of trihalomethanes (THMs) precursors in floodwater and to measure the potential effects of organic fertilization via swine manure on THMs precursors' export from organic rice production. Four swine manure organic amendment rates (0, 714.1, 1428.2, and 2142.3 kg·hm^-2) were applied over the rice growing seasons in 4- by 5-m plots constructed to facilitate the measurement of DOC, ultraviolet absorbance at 254 nm (UVA₂₅₄) and trihalomethanes formation potential (THMFP) in floodwater. There were linear correlations (p<0.001) between these measurements. The three indicators in floodwater increased with the increase of amendment rates. Within 7 days, exporting potential of DOC had decreased by 32.9% to 47.5% across the amendment rates. At least 1 week between swine manure amendment and a predicted rainfall event or irrigation event would be the best case scenario for managing organic matter to meet crop requirements and lowering risk of DBPs precursors' export, thus paddy soil behaved as sinks rather than sources of DOC exporting into surrounding waterways.