骆马湖夏季水质空间分布特征及评价

    Trophic Assessment and Water-Quality Spatial Distribution of Luoma Lake During Summertime

    • 摘要: 开展人类活动影响下骆马湖水质状况调查,明确水体理化指标分布特征,有助于城郊过水性湖泊的有效保护和开发利用。2017年夏季(6-8月)对骆马湖水体理化指标开展调查,分析水质现状和水体营养状态变化特征,并结合Piper三角图和等值线图法分析骆马湖理化指标空间分布规律。结果表明,夏季骆马湖透明度、ρ(DO)和pH值较1991-2014年平均水平无明显变化,但N、P和有机污染物浓度以及主要离子组成变化显著。骆马湖ρ(TN)、ρ(TP)及CODMn达Ⅴ类水标准,大部分湖区处于中度富营养化状态,小部分湖区处于重度富营养化状态,湖区东北部主要离子组成由Ca2++HCO3-转变为Na+(K+)+HCO3-,其余湖区则转变为Na+(K+)+Cl-。水体中HCO3-、Ca2+、Mg2+和PO43+浓度以及pH、总碱度和总硬度等具有显著空间差异性(P < 0.05)。骆马湖水质指标空间分布复杂,Ca2+和Mg2+浓度以及总碱度、总硬度呈现东北部高、西南部低的特点,而TN、TP和叶绿素a浓度以及CODMn总体呈现北部高、东部低的特点。不同理化指标空间分布主要与入湖径流中污染物、湖泊内生产活动和湖泊净化能力有关,人类活动对骆马湖水质的干扰已不容忽视。

       

      Abstract: Luoma Lake is a suburban lake with the characteristics of water carrying in the northern Jiangsu Province, China. The information of physicochemical parameters in Luoma Lake will help to assess the trophic state and well understand the application values of suburban lakes, and further provide scientific basis for protecting and exploiting the water resources. In this study, the current water-quality characterization and trophic state at 20 uniform distributed sites in Luoma Lake were investigated monthly from June to August, 2017. The spatial distributions of the physicochemical parameters were assessed by the piper plot and isoline map. Results show that total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (CODMn) were significantly increased and the dominant ions were transformed from Ca2++HCO3- to Na+(K+)+Cl-, while the secchi depth, dissolved oxygen and pH were not changed compared to the years from 1991 to 2014. The concentrations of ρ(TN), ρ(TP) and CODMn varied in the range of 2.540-3.246, 0.173-0.531 and 9.90-14.29 mg·L-1, respectively. According to the Environmental Quality Standards for Surface Water, Luoma Lake fell into the categories of Ⅴ in water quality. The comprehensive trophic level index indicate that most sites of the Lake were reached the state of mesotrophication, some sites even reached the state of hypertrophication. The spatial distributions of pH, HCO3-, Ca2+, Mg2+, total alkalinity and total hardness were significant different among sampling sites (P < 0.05). The spatial distributions of water-quality parameters were complicated, Ca2+, Mg2+, total alkalinity and total hardness were higher in the northeast region than that in the southwest region, while ρ(TN), ρ(TP), CODMn and ρ(chlorophyll a) were higher in the north region than in the east region in Luoma Lake. The differences of spatial distribution among these physicochemical parameters were attributed to the contaminants contained in the inflowing rivers, the human activities and the self-purification functions in the Luoma Lake, which indicate that the disturbances in suburban lakes caused by human activity should not be ignored.

       

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