三峡库区古夫河水质时空分异特征

以湖北省神农架林区和兴山县境内长江三峡库区香溪河支流古夫河为研究对象,于2010年8月-2011年7月在整条河流中选取20个采样点,进行样本采集,并测定溶解氧、碱度、硬度、电导率、总磷、总氮、化学需氧量、二氧化硅、总有机碳共9项水质指标,运用多元统计方法,分析水质的时空分异特征.依据研究区土地利用类型差异,将20个采样点分成4组,即森林(A组)、耕地(B组)、水库(C组)和村镇(D组)；根据该区域的水文节律,将5-10月归为湿季,其余月份为干季.判别分析和方差分析结果表明,古夫河水质具有时空显著性差异:总磷、二氧化硅、电导率、化学需氧量、总硬度和总碱度等指标具有空间显著性差异；总氮、化学需氧量、溶解氧、二氧化硅和总有机碳与季节存在显著相关性,所测9项水质指标在不同空间类别上呈现出显著的季节变化.主成分分析表明,不同空间类别上的干湿季节引起水质变化的主导因子是不同的:A组中,湿季主要体现为二氧化硅和总有机碳,干季主要体现为总磷、二氧化硅、总有机碳和化学需氧量,该组水质主要受地表径流、地质成因和风化作用等自然因素的影响；B组中,湿季主要体现为硬度和总有机碳,干季主要体现为总磷、化学需氧量、总碱度和总硬度,该组除了受自然因素的影响,还受如农业径流、未处理的生活污水排放等人为因素影响；C组中,湿季主要体现为二氧化硅、总氮和总磷,干季主要体现为总氮、总有机碳和二氧化硅,该组主要受农业径流、地表径流以及未经处理的生活污水等的影响；D组中湿季主要体现为二氧化硅、总氮和总磷,干季主要体现为碱度、硬度、总氮和总有机碳,该组主要受村镇生活污水和农业径流等的影响.结果表明,古夫河水质受自然和人为因素影响而发生变化,其中受人为因素影响更大.因此,加强水资源的管理和保护,改善水质,做好水源地的长期水质监测显得尤为重要.

Spatial-temporal differentiation of water quality in Gufu River of Three Gorges Reservoir

In order to provide scientific supports for rivers ecological management of the Three Gorges Reservoir, we conducted a study to determine the spatial and temporal differentiation of water quality in the Gufu River. Gufu River, a tributary of Xiangxi River flowing into Three Gorges Reservoir, passes Shennongjia Forest District and Xingshan County, Hubei Province, Central China. We arranged 20 sampling sites along the Gufu River and measured 9 water quality parameters once a month from August 2010 to July 2011 at these sites. According to landscape difference, the sampling sites were divided into 4 groups: forest area (Group A), cultivated land area (Group B), reservoir area (Group C), village/small town area (Group D). According to hydrological rhythm, May to August were classed as wet season, and the other months were classed as dry season. The 9 water quality parameters were: total nitrogen (TN), dissolved oxygen (DO), total organic carbon (TOC), total phosphorus (TP), silicon dioxide (SiO₂), electrical conductivity (EC), chemical oxygen demand (COD), total hardness(T-Hard)and total alkalinity (T-Alk). Using the Discriminant Analysis (DA) and Analysis of Variance (ANOVA), we found the water quality showed spatial and temporal differentiation pattern: TP, SiO₂, EC, COD, T-Hard and T-Alk are significantly different among the different spatial group; TN, COD, DO, SiO₂ and TOC are different among the seasons; all water quality parameters presented significant seasonal changes at different spatial types. Using the Principal Component Analysis (PCA), we found the factor determining the water quality at different part of the river in different seasons. At the forest area (Group A), SiO₂ and TOC were the main factors which affect the water quality in the wet seasons, but in the dry seasons TP, SiO₂, TOC and COD were the mainly factors, which indicated that in forest area water quality was influenced by the natural factor such as surface runoff, vegetation and weathering. At the cultivated land area (Group B), in the wet season, T-Hard and TOC were the main factors affecting water quality while in the dry season TP, COD, T-Hard and T-Alk were the main factors affecting water quality. In cultivated land area, the variation of water quality was not only caused by the influence of natural factors, but also by factors of human activities such as agricultural runoff and domestic sewage without treatment. At reservoir area(Group C), SiO₂, TN and TP were the main factors affecting water quality in the wet season, while TN, TOC and SiO₂ were the main factors in the dry seasons. The water quality of the stream beside the villages/small towns was influenced by nitrogen and phosphorus particle entering into reservoir with farmland runoff, surface runoff and untreated domestic sewage. At village/small town area (Group D), SiO₂, TN and TP were the main factors affecting water quality in the wet season, while T-Alk, T-Hard, TN and TOC were the main factors in the dry seasons. The water quality at the village/small town area was influenced by municipal sewage, agricultural runoff. Our study indicated that the water quality of Gufu River is affected by natural and anthropogenic factors and the later one are greater. Therefore, the strengthening of the management and protection of water resources and good long-term water quality monitoring is particularly important for the improvement of water quality.