洱海农田生产/生活景观区交替分布及昼夜节律对丰水期沟渠水质影响

Alternating distribution of farmland and inhabited landscapes in Erhai Lake and the influence of circadian rhythm on the water quality of a ditch during flood

为揭示洱海农田生产与农村生活交替分布及昼夜节律对农灌沟渠水质影响,选定丰水期典型沟渠设置多个断面并进行昼夜连续取样监测。结果表明:沿水流方向沟渠断面水质TN、NO_3^--N、TP、DP浓度先增加后相对稳定;NH_4^+-N和COD浓度在出田后削减2.08%~55.56%和23.65%~38.19%,出村后浓度增加;在不同生产生活单元N和COD是水体中的主要污染因子,其中NO_3^--N为氮素主要形态,占TN浓度52.73%~79.33%。沟渠水质TN和NO_3^--N浓度受村民作息周期和生活节律影响较大,磷素昼夜变化幅度总体较小。在洱海农田生产和生活交替区域提高水样取样频率有助于准确了解水质浓度变化特征,从削减污染负荷角度建议增加生态沟渠并加强污水管网管理。

To elucidate the influence of farmland production, rural life, and circadian rhythm on the water quality of agricultural irrigation ditches, several sections of a typical ditch was selected for continuous sampling and monitoring at day and night during the wet season. The results showed that the concentration of TN, NO3-N, TP, and DP in the ditches along the direction of water flow was relatively stable and the concentration of NH＋4-N and COD in the water reduced by 2.08%～55.56% and 23.65%～38.19% after exiting the field. Whereas, the concentration of NH＋4-N and COD in the water increased after exiting the village. Nitrogen and COD were the major water pollutants in different production and inhabited units. NO3-N was the main form of N, accounting for 52.73%～79.33% of TN concentration. The concentration of TN and NO-3-N in ditches is greatly affected by the work cycle and life rhythm of villagers. The diurnal variation in phosphorus con-centration is generally small. Increasing the frequency of water sampling in alternate farmland and inhabited areas of Erhai Lake will help accurately understand the characteristics of water quality changes. Increasing the number of ecological ditches and strengthening the management of sewage pipelines are necessary to reduce pollution load.