摇蚊幼虫扰动下沉积物微环境和微界面对物理扰动强度的响应

以太湖梅梁湾沉积物为研究对象,借助Rhizon间隙水采样技术、Unisense微电极技术,解析了物理扰动和摇蚊幼虫组合扰动下,沉积物微环境及微界面特征对物理扰动强度的响应规律.结果表明,高强度物理扰动下(240 r·min-1),溶解氧渗透深度(OPD)达到12.1 mm,远高于低强度(60 r·min-1)的3.8 mm.沉积物总氧气交换速率(TOE)、TOE与DOE差值、ORP、溶解氧渗透深度(OPD)、DO空间分布的差异性等均显示了与物理扰动强度正相关趋势.沉积物中p H增加的区域和幅度及Fe2+减小的区域和幅度也显示了相同响应规律;在沉积物表层0~6 cm范围内,相同深度沉积物的含水率、孔隙度、总微生物活性均随物理扰动强度增加呈递增趋势,并对物理扰动强度的响应程度随沉积物深度递增逐渐减弱.这暗示了物理扰动胁迫摇蚊幼虫构造更深和更多的廊道,进而从垂向的角度改造了沉积物微界面和微环境.

Response of Sediment Micro Environment and Micro Interface to Physical Disturbance Intensity Under the Disturbance of Chironomus plumosus

The response of sediment micro environment and micro interface to physical disturbance intensity under the physical and Chironomus plumosus disturbance was investigated by means of sediment Rhizon samplers and Unisense micro sensor system. The sediment and overlying water were taken from Meiliang bay of Taihu Lake. The results showed that the OPD reached up to 12.1 mm under the high intensity (240 r ·min^-1), while it was higher than 3.8 mm under low intensity (60 r ·min^-1). The TOE, the difference of TOE and DOE, OPD, ORP and the difference of DO spatial distribution were all positively correlated with the physical disturbance intensity. The increasing magnitude and range of pH as well as the decreasing magnitude and range of ferrous followed the same response tendency. Within the 0-6 cm sediment, the water content and porosity as well as the microbial activity at the same depth increased with the increase of physical disturbance intensity. In addition, the degree of response of the above parameters to the physical disturbance intensity was weakened with the increase of sediment depth. It was suggested that Chironomus plumosus dug more and deeper galleries under high intensity physical disturbance. Therefore, the sediment micro environment and micro interface were transformed in the vertical direction of the sediment.