Liu Wen, Xu Xianli, McGoff Nicola M, Eaton James M, Leahy Paul, Foley Nelius, Kiely Gerard
College of Resources and Environmental Sciences, Hunan Normal University, Changsha, 410081, China,
Environ Manage. 2014 May;53(5):959-67. doi: 10.1007/s00267-014-0259-1. Epub 2014 Mar 19.
Dissolved organic carbon (DOC) concentrations have increased in many sites in Europe and North America in recent decades. High DOC concentrations can damage the structure and functions of aquatic ecosystems by influencing water chemistry. This study investigated the spatial and seasonal variation of DOC concentrations in Irish streams across 55 sites at seven time occasions over 1 year (2006/2007). The DOC concentrations ranged from 0.9 to 25.9 mg/L with a mean value of 6.8 and a median value of 5.7 mg/L and varied significantly over the course of the year. The DOC concentrations from late winter (February: 5.2 ± 3.0 mg/L across 55 sites) and early spring (April: 4.5 ± 3.5 mg/L) had significantly lower DOC concentrations than autumn (October: mean 8.3 ± 5.6 mg/L) and early winter (December: 8.3 ± 5.1 mg/L). The DOC production sources (e.g., litterfall) or the accumulation of DOC over dry periods might be the driving factor of seasonal change in Irish stream DOC concentrations. Analysis of data using stepwise multiple linear regression techniques identified the topographic index (TI, an indication of saturation-excess runoff potential) and soil conditions (organic carbon content and soil drainage characteristics) as key factors in controlling DOC spatial variation in different seasons. The TI and soil carbon content (e.g., soil organic carbon; peat occurrence) are positively related to DOC concentrations, while well-drained soils are negatively related to DOC concentrations. The knowledge of spatial and seasonal variation of DOC concentrations in streams and their drivers are essential for optimum riverine water resources management.
近几十年来，欧洲和北美的许多地区溶解有机碳（DOC）浓度有所上升。高DOC浓度会通过影响水化学性质来破坏水生生态系统的结构和功能。本研究调查了爱尔兰溪流中DOC浓度在1年（2006/2007年）内7个时间点、55个地点的空间和季节变化。DOC浓度范围为0.9至25.9毫克/升，平均值为6.8毫克/升，中值为5.7毫克/升，且在一年中变化显著。冬末（2月：55个地点的平均值为5.2±3.0毫克/升）和早春（4月：4.5±3.5毫克/升）的DOC浓度明显低于秋季（10月：平均值为8.3±5.6毫克/升）和初冬（12月：8.3±5.1毫克/升）。DOC的产生源（如凋落物）或干旱期DOC的积累可能是爱尔兰溪流DOC浓度季节变化的驱动因素。使用逐步多元线性回归技术对数据进行分析，确定地形指数（TI，指示饱和超渗径流潜力）和土壤条件（有机碳含量和土壤排水特征）是控制不同季节DOC空间变化的关键因素。TI和土壤碳含量（如土壤有机碳；泥炭出现情况）与DOC浓度呈正相关，而排水良好的土壤与DOC浓度呈负相关。了解溪流中DOC浓度的空间和季节变化及其驱动因素对于优化河流水资源管理至关重要。
