九龙江口湿地表层沉积物微观形貌特征与成因分析

基于沉积物N2吸附脱附曲线,通过不同植被沉积物采样、扰动模拟和化学清洗实验,分析河口滨海湿地表层沉积物的微观形貌特征与形成原因.研究表明,光滩(A)的沉积物比表面积最低(17.07m2/g),表面分形维数也是最低(2.5177);互花米草(E)沉积物的比表面积和表面分形维数次之,分别为20.82m2/g、2.5354;而湿地中间的红树(D)、互花米草(B)及其二者混交(C)的3种沉积物的比表面积和表面分形维数较高.其原因可能是光滩(A)和互花米草(E)由于靠近河边,受到河流与潮水影响较大,较其他长有植被且离河流较远的沉积物,更易受到扰动与污染,空间填充能力弱化所致.相关关系分析表明,沉积物比表面积与表面分形分数同沉积物无机氮磷形态显著正相关,这表明沉积物比表面积和表面分形维数较低的沉积物,其表面吸附能力和空间填充能力较弱,而使得吸附的无机氮磷形态污染物减少.另外,受扰动的沉积物具有较低的比表面积和表面分形维数,污染程度较轻的沉积物具有较高的比表面积和表面分形维数.可见,受潮汐、河流扰动和污染程度的不同是九龙江口湿地表层沉积物微观形貌差异形成的主要原因.

Microscopic morphology of surface sediments and its related causes in Jiulongjiang estuary wetland

To explore the microscopic morphology of surface sediments and its related causes in Jiulongjiang estuary wetland,the surface area(SA) and surface fractal dimension(SFD) of different sediments,from the different vegetation,water disturbance and chemical clean,were determined based on the adsoption-desorption curves of nitrogen.For all sediments,SA of sediments from bare flat(A sample site) was the lowest with 17.07 m2/g,and the SFD(2.5177) was also the lowest.The following was spartina sediment(E sample site),which was 20.82 m2/g for the SA and 2.5354 for SFD.While SA and SFD of the sediments from the mangrove(D),spartina(B) and the mix of spartina with mangrove(C) were much greater than that of the sediments from A and E sites.The reasons were possible that the space fill capacity of the sediment from A and E sites was weakened,resulting in the decreases of SA and SFD,due to the sediments were near to the river,subsequently much more influenced by the disturbance and pollution from the tides and rivers.The Pearson correlation showed that sediment SD and SFD were positively correlated to inorganic nitrogen and phosphorus,indicated that the sediment with the lower SD and SFD could not have high adsorption capacity for nitrogen and phosphorus due to the subsequent decreases of the space fill capacity of the sediments.Additionally,the disturbed sediments by the tides and rivers showed lower SA and SFD,while the less contaminated sediment showed greater SA and SFD.Therefore,the changes in the microscopic morphology of the different sediments would suffer from the disturbance and contamination from tides and rivers.