闽江口水质对边界条件的响应关系模拟研究

为探究闽江河口水质变化趋势及超标原因，根据入海排污口详查成果，构建闽江下游至河口二维非稳态水动力水质模型，以主要污染物COD_Mn、无机氮和活性磷酸盐为指标，预测不同水文与外源污染负荷对闽江口水质的影响，阐明水质对水文和外源污染物的时空响应关系。结果表明：闽江口水质对不同水文的响应存在显著的时空差异性。闽江口COD_Mn和无机氮水质受上游影响较大，而活性磷酸盐所受影响相对较小；受潮汐潮流的影响，闽江口涨潮期水质大潮好于小潮，涨潮好于落潮；设置水口水库下泄水体水质为年内最好和下游污染物削减30%两种条件下，均不能有效保障河口无机氮和活性磷酸盐水质稳定达标，建议对水口水库下泄水总氮和总磷提出更严格的控制要求。

Simulation of water quality response to boundary conditions in the Minjiang Estuary

In order to study the change trend of water quality of the Minjiang Estuary and the reasons for it exceeding the seawater quality standard limit, a two-dimensional non-stationary hydrodynamic water quality model was constructed of the Minjiang River covering the downstream to the estuary based on the results of the detailed survey of the sewage outfalls. The main pollutants of COD_Mn, inorganic nitrogen and reactive phosphate were used as indicators to predict the effects of different hydrological and exogenous pollution loads on the water quality of the Minjiang Estuary, so as to elucidate the spatial and temporal response of water quality to the pollutants. The results show that the response of water quality of the Minjiang Estuary to different hydrology showed significant spatiotemporal variations. COD_Mn and inorganic nitrogen of the Minjiang Estuary were greatly affected by the upstream water quality, whereas the effect of reactive phosphate was relatively small; under the influence of the tidal currents, the water quality in the high tide period was better than that in the neap tide period, and that in tide rising was better than tide ebbing; when the discharge water quality of the Shuikou Reservoir was set as best in the year or 30% reduction of downstream pollutants, both conditions could not guarantee that the inorganic nitrogen and reactive phosphate concentrations of the estuary would meet the standards. Therefore, it is recommended that more stringent control requirements for total nitrogen and total phosphorus should be enforced on the discharge of the Shuikou Reservoir.