Abstract：
Long-term variation of nitrate in the East Sea was monitored in order to investigate impact of Three Gorges Dam (TGD) in the Changjiang River\'s upstream, China and Nakdong River\'s estuary dam, Korea. Tracing source of nitrate was another objective in this study. For this study, nutrient data were collected for 20 years from 1999 to 2018 in the East Sea, and divided into 4 sections, and evaluated whether a significant difference exists among the averages of nitrate concentrations. The concentrations of nitrate were affected by the major rivers (the Nakdong and the Taehwa Rivers) and Tsushima Warm Current (TWC) which diverged from the Kuroshio Current passing through East China Sea (ECS). Our results also indicated that long-term nitrate concentrations decreased and its reasons. First, the construction of TGD in the upstream of the Changjiang River may have resulted in the decrease of the nitrate supply in the river and ECS which is carried by TWC, toward the East Sea. Second, decrease in the nitrate flux of the Nakdong River\'s estuary due to the construction of the estuary dam and sewer treatment plant could also be a factor for the nitrate decrease in the East Sea. Therefore, anthropogenic activities from the Nakdong River and Changjiang River had a long-term effect on the East Sea\'s nitrate concentrations. The amount of nitrate runoff reduced by the anthropogenic activities influenced the nitrate levels over a long period by the flow of currents in the East Sea.
摘要：
为了研究三峡大坝对长江上游的影响，对东海硝酸盐的长期变化进行了监测，中国和Nakdong河河口大坝，韩国。追踪硝酸盐的来源是本研究的另一个目标。对于这项研究，从1999年到2018年，在东海收集了20年的营养数据，分为四个部分，并评估硝酸盐浓度平均值之间是否存在显着差异。硝酸盐的浓度受到主要河流（Nakdong和大河）和对马暖流（TWC）的影响，这些河流与穿过东海（ECS）的黑潮流不同。我们的结果还表明硝酸盐浓度长期下降及其原因。首先,长江上游的TGD建设可能导致TWC携带的河流和ECS中硝酸盐的供应减少，朝向东海。第二,由于河口大坝和下水道处理厂的建设，Nakdong河河口的硝酸盐通量下降也可能是东海硝酸盐下降的一个因素。因此,Nakdong河和长江的人为活动对东海的硝酸盐浓度有长期影响。人为活动减少的硝酸盐径流量在很长一段时间内都受到东海水流的影响。
