Northwest Land and Resources Research Center, Shaanxi Normal University, Xi'an, 710119, People's Republic of China.
College of Natural Resources and Environment, Northwest A & F University, Yangling, 712100, People's Republic of China; Key Laboratory of Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, Sichuan Normal University, Chengdu, 610066, People's Republic of China.
Chemosphere. 2020 Jun;249:126207. doi: 10.1016/j.chemosphere.2020.126207. Epub 2020 Feb 13.
The problem of sulfate pollution is becoming increasingly serious in freshwater and wetlands. Since paddy fields are the largest constructed wetland in Earth's surface, the increased sulfate input may have great effect on dissolved organic matter (DOM) in paddy soils. To understand these effects, a 24-day anaerobic incubation experiment was conducted with four Chinese paddy soils amended with high concentrations (0, 10, 25, 50, and 100 mmol L) of NaSO. Dissolved organic carbon (DOC) and chlorophyll a (Chl a) concentrations were determined after incubation. Parallel factor analysis (PARAFAC) of the excitation-emission matrix (EEM) spectra was used to analyze the DOM composition. In all four soils, DOC concentrations generally increased with increasing sulfate concentration, while the Chl a concentrations decreased. The EEM spectra of DOM were resolved into four components by PARAFAC. With increasing sulfate concentration, the proportion of the ultraviolet C humic acid-like compound decreased and the tyrosine-like compound increased in two algae-rich soils (Sichuan and Tianjin). No obvious variation was observed in the humification index (HIX) or the ratio of peak β to peak α (β:α) in any soils with added sulfate. Specific ultra-violet absorbance at 254 nm (SUVA) decreased with increasing sulfate concentration in Jilin, Tianjin, and Ningxia soils, and the fluorescence index (FI) decreased in two algae-rich soils. In conclusion, although sulfate addition increased the DOC concentration, the DOM composition depended more strongly on soil type and physicochemical properties than sulfate. Sulfate addition only affected soil DOM origin and composition by inhibiting algal growth in algae-rich paddy soils.
硫酸盐污染问题在淡水和湿地中日益严重。由于稻田是地球表面最大的人工湿地，因此硫酸盐的大量输入可能会对稻田土壤中的溶解有机物质（DOM）产生重大影响。为了了解这些影响，我们进行了一项为期 24 天的厌氧培养实验，用四种中国稻田土壤进行培养，分别添加高浓度（0、10、25、50 和 100mmol/L）的 NaSO。培养后测定溶解有机碳（DOC）和叶绿素 a（Chl a）浓度。采用平行因子分析（PARAFAC）对激发-发射矩阵（EEM）光谱进行分析，以分析 DOM 组成。在所有四种土壤中，DOC 浓度通常随硫酸盐浓度的增加而增加，而 Chl a 浓度则降低。通过 PARAFAC 将 DOM 的 EEM 光谱解析为四个组分。随着硫酸盐浓度的增加，两个富藻土壤（四川和天津）中紫外 C 腐殖酸类化合物的比例下降，酪氨酸类化合物增加。在添加硫酸盐的任何土壤中，腐殖化指数（HIX）或峰β与峰α的比值（β:α）均无明显变化。在吉林、天津和宁夏土壤中，随着硫酸盐浓度的增加，254nm 处的特定紫外吸光度（SUVA）降低，而在两个富藻土壤中，荧光指数（FI）降低。总之，尽管硫酸盐的添加增加了 DOC 浓度，但 DOM 的组成更多地取决于土壤类型和理化性质，而不是硫酸盐。在富藻稻田土壤中，硫酸盐的添加仅通过抑制藻类生长来影响土壤 DOM 的来源和组成。
