黄河三角洲典型潮汐湿地碳、氮、磷生物地球化学特征

Biogeochemical characteristics of soil C, N, P in the tidal wetlands of the Yellow River Delta

选择位于黄河三角洲的广饶潮汐湿地为研究对象,对比了在不同的植被覆盖和水文条件下潮汐湿地土壤碳、氮、磷元素的垂直分布及生态化学计量学特征。结果表明,在芦苇（Phragmites australis）覆盖下的 GRA2区域沉积物总有机碳（TOC）和总氮（TN）含量明显高于碱蓬（Suaeda salsa）覆盖下的GRA1区域。GRA1柱样TOC含量均值为1.798 mg/g,而GRA2柱样则为3.109 mg/g。GRA1柱样的TN含量范围在0.108~0.213 mg/g,均值为0.165 mg/g,而GRA2柱样TN含量范围则为0.307~0.473 mg/g,均值为0.353 mg/g。总体上,总磷（TP）含量的变化水平相对于TOC和TN来说较大,其垂直变异系数较高。而与TOC和TN相反的是, GRA2柱样中TP含量均值为0.298 mg/g,低于GRA1的0.388 mg/g,这可能跟 GRA2区域芦苇的生长比碱蓬需要吸收更多的 P 元素有一定关系。研究区域沉积物 C、N、P 元素生态化学计量学比值普遍较低。相对较高的C/N值,较低的C/P值和N/P则显示黄河三角洲潮汐湿地的生物地球化学过程可能更多地受营养元素N和P等的限制,而前者可能是主要限制因素。本研究可为滨海湿地对全球碳和氮的储存提供基础数据,为滨海湿地可持续发展的管理和保护提供科学依据。

This study analyzed the variations of soil organic carbon （TOC）, total nitrogen （TN） and total phosphorus （TP） in tidal wetland of the Yellow River Delta. While GRA2 surface was covered with Phragmites australis had much higher biomass and sufficiently stronger roots than GRA1 with Suaeda salsa. TOC and TN contents in GRA2 profile were higher than those in GRA1. The average TOC contents of GRA1 and GRA2 were 1.798 and 3.109 mg/g, respectively. It was obvious that GRA2 profile contained quite high TN content （a range of 0.307~0.473 mg/g） as compared to GRA1 profile（a range of 0.108~0.213 mg/g）, possibly due to the higher organic matter retention in GRA2. The average TP content in GRA1 profile was slightly higher than that in GRA2, with values of 0.388 mg/g and 0.298 mg/g, in GRA1 and GRA2 respectively. The growth of P.australis in GRA2 area that needed more phosphorus than S. salsa in GRA1 area may be the potential explanation. However, no clear trend was found on the vertical variations of TP. Additionally, C, N, and P ecological stoichiometry had high complexities within this tidal wetland. The C/N ratios were generally higher, while the C/P ratios and the N/P ratios were comparatively low, indicating the coastal wetland biogeochemical processes were more limited by N and P, with the former may being the primary factor. This study would be helpful for future research on the carbon burial, nutrients balance, and promoting sustainable management of the coastal plain.