盐城滨海湿地表层沉积物有机碳特征

对比研究盐城滨海湿地表层沉积物总有机碳(TOC)含量及其时空分布,揭示不同季节,不同植被覆盖对滨海湿地TOC分布的影响。结果表明,盐城滨海湿地表层沉积物TOC含量为0.69~10.34 g/kg,平均值4.55 g/kg。TOC含量的季节变化表现为:光滩呈单峰型分布,最高值出现在秋季(0.86±0.11 g/kg),除光滩外,TOC含量峰值均出现在冬季,即植被非生长季。TOC含量的空间变化表现为:互花米草滩(10.34±2.42 g/kg)>芦苇滩(3.90±1.11 g/kg)>盐蒿滩(3.28±1.86 g/kg)>光滩(0.69±0.16 g/kg);不同生态带内TOC 含量差异显著,光滩空间变异性最小(0.06),芦苇滩最大(0.14)。此外,湿地表层沉积物中TOC含量与总氮(TN, g/kg)、含水量(WFPS,%)、平均粒径(Φ)、分选系数以及C/N均呈显著正相关。通过研究发现,互花米草相对于其他植被类型由于其对有机碳很好的富集能力,可以有效增强滨海湿地生态系统土壤的固碳潜力。

The Characteristics of Surficial Sediments Organic Carbon in Yancheng Coastal Wetland

In this paper, Total Organic Carbon (TOC) content of surficial sediments and its temporal and spatial distribution in Yancheng coastal wetland were comparatively investigated, which was aimed to explore the effects of different seasons, vegetation coverage and soil characteristics on the TOC in coastal wetland. The result indicated that TOC ranged from 0.69 to 10.34 g/kg, with an average of 4.55 g/kg. The seasonal characteristics of TOC showed that the peak of TOC in the entire flats appeared in winter, that is the non-growing season of vegetation, except for the mud flat, the highest TOC turned out to be in autumn (0.86±0.11 g/kg), the seasonal variations of TOC differed significantly in Artemisia schrenkiana flat (0.565) which was influenced by the presence and growth stages of vegetations. For the spatial changes of TOC, it exhibited a tendency that Spartina alterniflora flat (10.34 ± 2.42 g/kg) >Phragmites australis flat (3.90±1.11 g/kg) >Artemisia schrenkiana flat (3.28±1.86 g/kg) > mud flat (0.69±0.16 g/kg). TOC showed significant spatial heterogeneity, with the minimum value appeared in mud flat (0.06) and maximum was observed in Phragmites australis flat (0.14). What's more, surficial sedments TOC content has significant correlation with total nitrogen (TN), water- filled pore space (WFPS), mean grain size, sorting coefficient and C/N ratio. This study shows that the invasion of exotic species, such as Spartina alterniflora might effectively enhance soil carbon sequestration potential of the coastal wetlands ecosystem due to its higher enrichment capability of organic carbon and greater biomass compared to thoses of other vegetation types. The main reason of high correlation between TOC and TN is that they have the same way of source and consumption, while, WPFS, mean grain size and C/N play an important role in determining TOC content through affecting microorganism activity.