深圳湾及邻近水域中的溶解有机氮——其时空分布、来源和生物利用率

依据2000～2014年每月的监测资料，分析了深圳湾及邻近沿岸水域中溶解有机氮（DON）质量浓度的时空分布，并结合盐度、5d生物需氧量和颗粒有机物实测数据探讨DON的来源和生物利用率.结果表明，深圳湾中DON质量浓度为（0.45±0.45）mg/L，夏、冬季较高，春、秋季较低，在2000～2004年呈上升趋势，而在2005～2014年呈下降趋势；珠江口东南沿岸中DON质量浓度为（0.16±0.08）mg/L，季节变化小，研究期间总体上略呈上升趋势.深圳湾和珠江口东南沿岸中DON均呈现出保守并具有同源性.依二元混合质量平衡模式估算的深圳湾中DON陆源质量分数约为80%，而珠江口东南沿岸中约为38%，显示深圳湾DON主要来自陆源，而珠江口东南沿岸主要来自海源.依实测数据和回归分析结果估算的深圳湾中平均DON生物利用率为14.8%，而珠江口东南沿岸中为15.5%，与珠江口下段高盐区中实测溶解有机碳生物利用率相近.

Dissolved organic nitrogen in the Shenzhen Bay and adjacent coastal waters: Its temporal and spatial distributions,sources and bioavailability

Based on the data obtained monthly from 2000 to 2014, temporal and spatial distributions of dissolved organic nitrogen (DON) concentration in the Shenzhen Bay and coastal southeastern Pearl River Estuary were analyzed. Also sources and bioavailability of the DON were investigated in combination with the salinity, 5-d biochemical oxygen demand and particulate organic matter measurements. The results showed that the DON concentration was 0.45±0.45mg/L with an increase trend from 2000 to 2004 and a decrease one from 2005 to 2014 and higher in summer and winter than spring and autumn in the bay, and 0.16±0.08mg/L with small seasonal changes and an increase trend in the whole period studied in the estuary. The DON appeared conservative and was from simultaneous sources in both of the bay and estuary. A two-component mixing mass balance model was used for estimating the DON terrestrial fraction at about 80% in the bay and 38% in the estuary, suggesting that the DON was mainly from the terrestrial sources in the bay but from the marine sources in the estuary. According to the measurements and regression results, the DON bioavailability was found to be about 14.8% and 15.5% in the bay and estuary respectively, nearly equal to the dissolved organic carbon bioavailability observed in the lower Pearl River Estuary.