香溪河流域不同介质中碳、氮、磷的分布特征及相关性研究

为了解香溪河流域碳、氮、磷的分布情况及水、陆生态系统中这些生源要素间的相互关系,对流域内河岸带土壤、河流水体及沉积物中总有机碳(TOC)、总氮(TN)、总磷(TP)含量进行调查,分析它们在流域内的分布特点,探讨各要素在3种介质间的相关性及随河流级别的变化规律。研究发现,超过60%的样点土壤中TOC、TN含量处于"较丰富"或"丰富"等级,耕地附近样点的TOC、TN和磷矿区附近样点的TP普遍偏高。河流水体及沉积物中各要素的含量都与土壤中的含量紧密相关,但水、陆介质间TP的相关性较TOC、TN强。低级别河流样点土壤中TOC、TN、C/P、N/P值和沉积物中C/P及N/P值整体较高级别河流样点高。结果表明:以磷矿开发和农业施肥为代表的人类活动,对香溪河流域内生源要素的含量及分布产生了显著影响;水体中P元素含量与陆源关系最强,在水体污染控制中应予以重视。

SPATIAL DISTRIBUTIONS OF CARBON,NITROGEN AND PHOSPHORUS IN VARIOUS MEDIUMS OF THE XIANGXI RIVER WATERSHED AND THEIR CORRELATIONS

Studying the correlations of biogenic elements between terrestrial and aquatic systems is essential for understanding the source and migration processes of these elements in the whole watershed. To comprehend the spatial distributions and correlations of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the aquatic and terrestrial components of the Xiangxi River watershed, we investigated concentrations of these three biogenic elements in riparian soil, stream water and stream sediments from 76 sites. The results showed that more than 60% sampling sites belonged to "abundant" or "relative abundant" condition for TOC and TN in riparian soil, and the concentrations of TOC, TN, and TP in the river sediments were markedly higher than those of many other rivers. The concentrations of TP in stream water that adjoin phosphorus-mining area were dramatically higher than those of other reaches. From the perspective of stream orders, the concentrations of TOC in the riparian soil were significantly higher in the first-order sites than those of the fourth-order sites. TN, C/P ratio and N/P ratio of the riparian soil and N/P ratio of the sediments were notably higher in the first-and second-order sites than that of the fourth-order sites, but the C/P ratio of the sediments was considerably higher in the first-order than the third-and fourth-order sites. Considering stream water, there was no significant difference among stream orders for neither the concentrations of the elements nor their ratios. Our findings imply that fertilizer utilization and phosphorus exploitation had significant impacts on spatial distributions and correlations between terrestrial and aquatic systems of these three biogenic elements in the watershed.