外源氮输入对生长季黄河口碱蓬湿地土壤无机硫形态变化特征的影响

选择黄河口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮输入模拟试验,探讨了不同氮输入梯度下(对照处理(N0)、低氮处理(N1)、中氮处理(N2)、高氮处理(N3))湿地土壤无机硫赋存形态在生长季的变化差异。结果表明:不同氮处理下各形态无机硫含量均表现为水溶性硫(H2O-S)吸附性硫(Adsorbed-S)盐酸溶解性硫(HCl-Soluble-S)盐酸挥发性硫(HCl-Volatile-S),且总无机硫(TIS)占全硫(TS)的比例介于34.52%~39.58%。外源氮输入不同程度地改变了湿地土壤的H2O-S、Adsorbed-S、HCl-Soluble-S和HCl-Volatile-S含量,且这种影响在生长季的某些时期达到了显著水平(P0.05)。相对于N0,N1和N2处理下H2O-S含量分别增加了6.12%和7.07%,而在N3处理下降低了0.98%;Adsorbed-S含量在N1处理下增加了11.73%,但在N2和N3处理下分别降低了23.53%和13.77%;HCl-Soluble-S和HCl-Volatile-S在N1、N2和N3处理下均呈降低趋势,降幅分别为5.21%,19.63%,59.59%和0.28%,16.10%,6.44%。尽管不同氮输入处理下土壤养分条件、水盐及酸碱状况均是影响无机硫赋存的关键因素,但pH和EC对其动态变化的影响尤为明显。研究发现,外源氮输入可能通过改变植物生长节律和土壤酸碱状况来影响植物对不同形态无机硫的吸收与利用,进而间接改变了土壤中不同形态无机硫含量及TIS赋存量。

Effects of Exogenous Nitrogen Enrichment on Variations of Inorganic Sulfur Fractions in Soils of Suaeda salsa Marsh in the Yellow River Estuary During the Growing Season

The Suaeda salsa marsh in high tidal flat of the northern Yellow River estuary were selected as study object, and the variations of inorganic sulfur fractions during the growing season were investigated by conducting an in situ experiment of nitrogen (N) import which included four treatments (N0, no N input; N1, low N input; N2, middle N input; and N3, high N input). Results showed that the inorganic sulfur contents in soils under different treatments generally followed the order of H₂O-S > Adsorbed-S > HCl-Soluble-S > HCl-Volatile-S, and the total inorganic sulfur (TIS) contents accounted for 34.52%~39.58% of the total sulfur (TS) in the four treatments. The contents of H₂O-S, Adsorbed-S, HCl-Soluble-S and HCl-Volatile-S in wetland soil was changed by exogenous N enrichment in varying degrees, and the effects reached significant levels in some periods of the growing season (P<0.05). Compared with N0, the contents of H₂O-S increased by 6.12% and 7.07% under N1 and N2 treatments, respectively, and decreased by 0.98% under N3 treatment. The content of Adsorbed-S increased by 11.73% under N1 treatment, but decreased by 23.53% and 13.77% respectively under N2 and N3 treatments. The contents of HCl-Soluble-S and HCl-Volatile-S showed a decreasing trend under N1, N2 and N3 treatments, and the decline were 5.21%, 19.63%, 59.59% and 0.28%, 16.10%, 6.44% respectively. Soil nutrient condition, water salinity, and acid-alkali conditions under different N enrichment treatments were the key factors that affected the amount of TIS, but the effects of pH and EC on the dynamics of different inorganic sulfur fractions were especially obvious. This study found that the exogenous N enrichment could affect the absorption and utilization of inorganic sulfur fractions by altering the growth rhythm of plants and the acid-base status of soils, which consequently changed the contents of inorganic sulfur fractions and the stock of TIS in marsh soils.