Zeng Yu, Fang Guodong, Fu Qinglong, Peng Fei, Wang Xinghao, Dionysiou Dionysios D, Guo Jianbo, Gao Juan, Zhou Dongmei, Wang Yujun
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
Environ Sci Technol. 2022 Apr 5;56(7):4221-4230. doi: 10.1021/acs.est.2c00145. Epub 2022 Mar 11.
The photochemical properties of paddy water might be affected by the commonly used amendments in rice fields owing to the associated changes in water chemistry; however, this important aspect has rarely been explored. We examined the effects of agricultural amendments on the photochemistry of paddy water during rice growth. The amendments significantly influenced the photogenerated reactive intermediates (RIs) in paddy water, such as triplet dissolved organic matter (DOM*), singlet oxygen, and hydroxyl radicals. Compared with control experiments without amendments, the application of straw and lime increased the RI concentrations by up to 16.8 and 11.1 times, respectively, while biochar addition had limited effects on RI generation from paddy water in in situ experiments under sunlight. Fluorescence emission-excitation matrix spectroscopy, Fourier transform ion cyclotron resonance mass spectrometry, and structural equation modeling revealed that upon the addition of straw and lime amendments, humified DOM substances contained lignins, proteins, and fulvic acids, which could produce more RIs under irradiation. Moreover, the amendments significantly accelerated the degradation rate of 2,4-dichlorophenol but led to the DOM*-mediated formation of more toxic and stable dimeric products. This study provides new insights into the effects of amendments on the photochemistry of paddy water and the pathways of abiotic degradation of organic contaminants in paddy fields.
由于水化学性质的相关变化，稻田水的光化学性质可能会受到稻田中常用改良剂的影响；然而，这一重要方面很少被研究。我们研究了农业改良剂对水稻生长期间稻田水光化学的影响。这些改良剂显著影响了稻田水中光生反应中间体（RIs），如三线态溶解有机物（DOM*）、单线态氧和羟基自由基。与未添加改良剂的对照实验相比，添加秸秆和石灰分别使RI浓度提高了16.8倍和11.1倍，而在阳光照射下的原位实验中，添加生物炭对稻田水中RI的生成影响有限。荧光发射-激发矩阵光谱、傅里叶变换离子回旋共振质谱和结构方程模型表明，添加秸秆和石灰改良剂后，腐殖化的DOM物质含有木质素、蛋白质和富里酸，在辐照下可产生更多的RI。此外，这些改良剂显著加快了2,4-二氯苯酚的降解速率，但导致了由DOM*介导形成更多有毒且稳定的二聚体产物。本研究为改良剂对稻田水光化学的影响以及稻田中有机污染物的非生物降解途径提供了新的见解。
