摘要:基于开放培养系统，在25℃的淹水和非淹水条件下研究了黄河口碱蓬湿地野外原位氮输入试验（N0：对照处理；N1：低氮处理；N2：中氮处理；N3：高氮处理）末期获取的相应氮梯度下表层土壤（记为NS0、NS1、NS2和NS3）的硫矿化特征。结果表明，不同氮处理土壤的硫矿化量在非淹水条件下整体表现为NS3 > NS1 > NS2 > NS0，在淹水条件下其硫矿化量较为接近，且均在培养的第3天取得最大值。不同水分条件下，不同氮处理土壤的硫矿化特征可能与培养过程中pH和EC的变化有关。连续培养119 d后，NS0、NS1、NS2和NS3的硫累积矿化量在非淹水条件下分别为233.03、419.99、401.16 mg/kg和526.51 mg/kg，在非淹水条件下分别为263.52、313.58、251.53 mg/kg和322.05 mg/kg。不同氮处理土壤硫累积矿化量主要来自0-14 d的矿化贡献，其值在非淹水条件和淹水条件下分别为41.01%-54.53%和79.49%-86.82%。除NS0外，其他3种土壤硫累积矿化量均表现为非淹水条件大于淹水条件，说明外源氮输入影响下非淹水土壤具有更大的供硫潜势。不同氮处理土壤硫累积矿化量及矿化势（S₀）在非淹水条件下表现为NS3>NS1≈NS2>NS0，在淹水条件下则表现为NS3≈NS1 > NS0 > NS2，说明高氮处理下湿地土壤具有最高的供硫潜势。研究发现，未来黄河口氮负荷增强条件下，土壤氮基质状况的改变将会促进土壤硫的矿化，而这可在一定程度上提高土壤的潜在供硫能力；但当受到强降水、大潮或风暴潮影响使得土壤处于短期滞水状态时，湿地土壤的潜在供硫能力将明显降低，特别是中氮输入条件下土壤供硫潜势的降幅最为明显。



Abstract:The topsoil with different nitrogen (N) treatments (NS0, NS1, NS2 and NS3) were sampled at the end of the growing season from the corresponding N import plots (N0, no N import treatment; N1, low N import treatment; N2, middle N import treatment; and N3, high N import treatment) in Suaeda salsa marsh in high tidal flat of the northern Yellow River estuary and their sulfur (S) mineralization were investigated by means of an open-incubation system at 25 ℃ at un-flooded and flooded conditions. The results showed that, the mineralized S in soils with different N enrichments at un-flooded condition showed NS3 > NS1 > NS2 > NS0, while those at flooded condition demonstrated a similar tendency, and for each treatment, the value of sulfur mineralization reached the maximum all at the third day of incubation. And in different incubation conditions, the variations of sulfur mineralized in soils with different N enrichments might be related to the variations of pH and EC during incubation. During 119 d incubation, the cumulative amounts of mineralized S in NS0, NS1, NS2 and NS3 were 233.03 mg/kg, 419.99 mg/kg, 401.16 mg/kg, and 526.51 mg/kg at un-flooded condition and 263.52 mg/kg, 313.58 mg/kg, 251.53 mg/kg and 322.05 mg/kg at flooded condition. The cumulative amounts of mineralized S in soils with different N treatments were mainly dependent on the mineralization contributions of initial stage (0-14 d), and the values at un-flooded and flooded conditions were 41.01%-54.53% and 79.49%-86.82%, respectively. Except for NS0, the higher cumulative amounts of mineralized S were observed in NS1, NS2 and NS3 at un-flooded condition compared to those at flooded condition, indicating that higher potential of mineralized S generally occurred at un-flooded condition. Both the cumulative amounts of mineralized S and the potentially mineralizable S (S₀) in soils at un-flooded condition showed NS3>NS1≈NS2>NS0, whereas those at the flooded condition showed NS3≈NS1 > NS0 > NS2, indicating that the highest potential of mineralized S in soils occurred in high N enrichment (N3). The study found that, in future, increasing of N loading in the Yellow River estuary would promote the mineralization of S in soils by altering their substrate qualities, which, to some extent, enhance the potentially supply capacity for S. However, as the marsh soil was flooded at short-term period due to the influence of severe precipitation, spring tide or storm surge, the potentially mineralizable S in marsh soil would decline significantly and, particularly, the decrease amplitude was evident in middle N enrichment (N2).





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