积石峡航道建设对水体水质的影响分析

通过实验室污染物释放模拟实验和同类工程比照法相结合,根据积石峡航道建设规模,定量分析了航道建设对水体水质的污染.分析结果表明：航道建设对水体水质的污染主要来自疏挖、运营期间的船舶扰动及丁坝坝田.疏挖的影响范围为挖槽起点以下3 350m内,可导致水体悬浮物浓度增加12.9mg/L,影响区水体处于轻度污染状态,主要污染指标是总氮（TN）和总磷（TP）.在丰水期、平水期和枯水期,船舶通航引起的航道水质污染均较轻,符合地表水环境质量Ⅱ类标准.由于丁坝坝田间水流接近静态,泥沙淤积量约为5cm,淤积泥沙污染物的释放可导致约20hm2的坝田水体发生污染,水质由原来的Ⅱ类标准降低至Ⅳ类标准.

Influence analysis of Jishi Gorge construction to water quality

Based on the waterway construction scale of Jishi Gorge,the water pollution of waterway induced by construction was quantitatively analyzed by using lab-scale simulation and comparison.The results show that the main pollution was resulted from dredging,ship disturbance during operation period and groin field of spur dike.The influence range of dredging was 3 350 m behind the starting point of dredged channel,and the suspended sediment concentration was enhanced to 12.9 mg/L,which resulted in slight pollution of water quality,TN and TP were the main pollution index.During high,mean and dry water seasons,the water pollution was slightly induced by ship disturbance and the water quality meets the Ⅱ standard of 《Surface Water Environment Quality Standard》(GB3838-2002).Since the velocity of water flow in groin field is very low,the amount of silting will reach 5 cm,and the pollutants’ release will result in water pollution about 20 hm2 in groin field,which makes the surface water environment quality decreased from Ⅱstandard to Ⅳstandard.