亚热带森林源头溪流细颗粒沉积物钾和钠在雨季的动态特征

Dynamic Features of Potassium and Sodium in Subtropical Forest Headwater Stream Fine Sediments During the Rainy Season

森林源头溪流不仅是下游水域的水源源头,其所含的钾(K)、钠(Na)等元素也是森林生态系统营养元素的重要组成部分,研究其动态特征有助于深入了解森林-水体连续体间的物质循环和能量流动,但目前仍缺乏关注。因此,以中亚热带森林源头溪流为研究对象,于2021年3—8月连续监测了源头溪流17条河段中细颗粒沉积物K、Na含量和储量的动态。结果表明:1)K、Na含量在整条溪流中相差较小,储量空间异质性较大。2)K含量与储量分别为39.65~47.18 g·kg^(-1)和1572.86~3861.29 g·m^(-2),均在5、6月份达到了较大值,而Na含量和储量分别为5.59~8.50 g·kg^(-1)、220.81~608.05 g·m^(-2),均在8月份达到了最大值。3)Na和K含量与储量在各河段具有显著性差异,其中,溪流两侧植被类型和不同径流对K、Na含量均有显著影响。4)K和Na含量与溪流水面宽度、溪流pH、溶解氧等密切相关,储量与水位、沉积物深度、溪流pH、降雨等呈显著正相关关系。综上所述,K、Na能在溪流中积累,且其动态变化在溪流生态系统中具有一定的稳定性。这些研究结果为深入研究森林-水体作为养分纽带所发挥的重要作用提供新思路。

Forest headwater streams are not only the source of downstream waters,but also the important constitutes of forest potassium(K),sodium(Na)and other nutrients.Exploring their dynamic features in fine sediments will be useful for a better understanding of the material cycling and energy flow between forest-water continuums,however little attention has been paid so far.The dynamics of K and Na concentration and storage in fine sediments at 17 sites of a headwater stream were investigated during March to August in 2021.Results showed that,1)the concentration of K and Na were stable in the whole stream,while those of storage in the stream were unstable.2)The K concentration and storage were 39.65~47.18 g·kg^(-1) and 220.81~608.05 g·m^(-2),respectively.They reached the comparatively large value in May and June.The Na concentration and storage were 5.59~8.50 g·kg^(-1) and 220.81~608.05 g·m^(-2),respectively,with the maximum values observed in August.3)The sampling sites had significantly affected the K and Na concentrations and storages,and vegetation type and streamflow had an effect on the sediment K and Na concentrations.4)The concentrations of K and Na were significantly correlated with stream active width,pH and DO were closely related,and the storage was significantly positively correlated with the water level,sediments,pH and precipitation.Overall,the findings of this research suggested that K and Na accumulated in stream sediments and their dynamic changes had certain stability in streams,which provided new insights for better understanding the important role played by forest-water bodies as nutrient bonds.