黄河三角洲潮间带盐地碱蓬湿地土壤磷含量和储量的季节动态变化特征

以黄河三角洲潮间带盐地碱蓬湿地为研究对象,通过在春季、夏季和秋季分别采集0～10 cm和10～20 cm土层的土壤样品,分析了盐地碱蓬湿地土壤磷素的时空动态变化特征。研究结果表明:盐地碱蓬湿地土壤总磷(TP)、有效磷(AP)和AP/TP比值的变化趋势相似,且具有高度的时间异质性,都呈现秋季低、夏季和次年春季高的"V"形分布特征;湿地土壤TP水平较高,已超过生态毒性的最低阈值(600 mg·kg~(-1)),但该区土壤AP/TP比值低于磷的生物利用度的阈值(2%);湿地土壤TP储量随夏季、秋季、次年春季呈依次减少的变化趋势,AP储量也呈现秋季低、夏春季高的"V"形分布特征;湿地土壤TP、AP含量和储量在两个土层之间不存在显著性差异(P0.05)。湿地土壤TP和土壤含水量(P0.05)、Al和Mg(P0.01)均存在显著正相关关系,和土壤盐度呈显著负相关关系(P0.05);AP和土壤含水量及容重显著正相关(P0.05);土壤磷素与土壤有机质、土壤pH的相关性均未达到显著性水平(P0.05)。总体上,黄河三角洲盐地碱蓬湿地土壤磷的垂直变异性不大,但具有明显的季节变异性,其含量与土壤铝镁化合物以及土壤盐度和含水量具有显著的相关性。

Seasonal dynamics of soil phosphorus contents and stocks in Suaeda salsa wetlands in the intertidal zone of the Yellow River Delta, China

Soil samples at both 0~10 cm and 10~20 cm soil layers were collected in summer, autumn, and spring to investigate temporal and spatial dynamics of soil phosphorus in Suaeda salsa wetlands in the intertidal zone of the Yellow River Delta. Our results showed that variations in soil total phosphorus (TP), available phosphorus (AP) and AP/TP ratios were similar, showing high temporal heterogeneity, with a V-shaped temporal distribution, where their values were low in autumn and high in summer and spring. Total phosphorus levels in wetland soils were higher than the lowest threshold of ecotoxicity (600 mg·kg^-1), but the AP/TP ratios were lower than the threshold of bioavailability of phosphorus (2%). Total phosphorus stocks in wetland soils decreased seasonally following the order summer, autumn, and spring, and the available phosphorus stocks also exhibited a V-shaped distribution. No significant differences in contents and stocks of soil total phosphorus and available phosphorus were observed between 0~10 cm and 10~20 cm soil layers. Soil total phosphorus had significant positive correlations with soil water content (P<0.05), and Al and Mg contents (P<0.01). There was a significant negative correlation between total phosphorus and soil salinity (P<0.05). Available phosphorus was significantly correlated with soil water content and bulk density (P<0.05). However, no significant correlations were observed between soil phosphorus and soil organic matter and soil pH (P>0.05). Generally, there was no large vertical variability of soil phosphorus in the Yellow River Delta, but an obvious seasonal variability was observed, and soil phosphorus contents were clearly related to soil aluminum-magnesium compounds, soil salinity, and water content.