贵州红枫湖近10年来(2009—2018年)水质变化及影响因素

Water quality change and influencing factors in Lake Hongfeng(Guizhou Province),2009-2018

为更好地研究贵州红枫湖的水质变化情况,本文利用贵阳市两湖一库环境保护监测站2009 2018年对红枫湖7个代表性监测点的营养盐、叶绿素a(Chl.a)浓度和水温、气温、透明度、降雨量等水文气象条件逐月监测数据,分析红枫湖10年间水体营养盐和Chl.a浓度以及部分水文气象条件的变化趋势.运用综合营养状态指数(TLI)对红枫湖营养状态进行评价,采用Pearson相关系数法统计分析10年内Chl.a浓度与总磷(TP)、总氮(TN)等水化学组成及水位、气温等水文气象条件的相关性.结果表明,2009—2018年红枫湖水体逐月TN浓度有较大波动(0.56~2.80 mg/L),春、夏季高于秋、冬季;水体逐月TP浓度为0.016~0.103 mg/L,夏季略高于冬季;逐月氨氮(NH3-N)浓度为0.007~0.71 mg/L,春季>冬季>秋季>夏季;水体逐月Chl.a浓度呈季节性波动(0.8~38.9 mg/m3),夏季>春季>秋季>冬季,年内先上升后下降.TP、NH3-N、Chl.a浓度整体呈下降趋势,10年间水质有很大改善.经计算红枫湖在这10年间处于中营养状态至轻度富营养状态,且营养状态指数呈逐年下降趋势,夏季TLI明显高于其他季节.统计分析表明,红枫湖水体Chl.a浓度与高锰酸盐指数、NH_3-N、TP浓度均呈显著正相关,与氮磷比呈显著负相关,与水温、pH、降雨量、气温、日照时数呈显著正相关,与透明度、气压呈显著负相关,与水位、湿度、风速无显著相关关系.表明这10年来红枫湖水体Chl.a浓度不仅受营养盐浓度控制,很大程度上还受控于气象和水文条件.

In order to better study the variation of water quality in Lake Hongfeng,the changing trend of nutrient and chlorophyll a concentration was analyzed,and the water nutritional status was evaluated by water trophic level index(TLI)method based on monthly sampling monitoring data of 7 representative monitoring sites of Lake Hongfeng from 2009 to 2018 by environmental protection monitoring station of two lakes and one reservoir in Guiyang Province.Besides,the correlation between TLI and water chemical composition(total phosphorus,total nitrogen,etc.)and hydrometeorological conditions(water level,temperature,etc.)was statistically analyzed by Pearson.The results showed that the monthly concentration of total nitrogen in the water body fluctuated sig nificantly(ranging from 0.56 mg/L to 2.80 mg/L),and the concentration in spring and summer was higher than that in autumn and winter.The monthly concentration of total phosphorus(from 0.016 mg/L to 0.103 mg/L)in summer was slightly higher than that in winter,and monthly ammonia nitrogen(from 0.007 mg/L to 0.710 mg/L)was spring>winter>autumn>summer,The monthly concentration of chlorophyll a fluctuated seasonally from 0.8 mg/m3 to 38.9 mg/m3,summer>spring>autumn>winter,and the inter annual trend was first increased and then decreased.The concentration of total phosphorus,ammonia nitrogen and chlorophyll a decreased on the whole,which suggests the water quality is improving greatly during the past ten years.Lake Hong feng was in the state of medium nutrition to the mild eutrophication state in the past ten years,and the TLI showed a trend of de cline year by year.TLI in summer was significantly higher than that in other seasons.Statistical analysis showed that the chloro phyll a concentration in Lake Hongfeng was significantly positively correlated with ammonia nitrogen,total phosphorus and potassi um permanganate index,while negatively correlated with the nitrogen phosphorus ratio.The chlorophyll a concentration was also significantly positively correlated with water temperature,pH,rainfall,air temperature,and sunshine,and negatively correlated with transparency and air pressure,it was not significant correlation with water level,humidity,and wind speed.The results suggest that chlorophylla concentration in the reservoir ecosystem is not only controlled by nutrient concentration,but also controlled by meteorological and hydrological conditions.