深圳湾及邻近水域总溶解磷的来源和时空分布

摘要

依据2000~2012年每月一次的调查资料,简要描述和讨论了深圳湾及邻近沿岸水域中总溶解磷(TDP)质量浓度的时空分布,并结合现场盐度和溶解无机磷(DIP)实测数据探讨TDP 的组成和来源以及DIP 和溶解有机磷(DOP)之间的转化.结果表明,深圳湾和珠江口东南部沿岸TDP质量浓度分别为(0.26±0.22)和(0.05±0.02)mg/L.研究期间,珠江口东南部沿岸TDP质量浓度的年内和年际变化不大,趋势平稳.在深圳湾,由于受到周边陆源排放的影响,TDP 质量浓度在丰水期较低,枯水期较高,且在2000~2004 年呈上升趋势,从0.24mg/L 上升至0.33mg/L,而在2005~2012 年则呈下降趋势,从0.33mg/L 下降至0.16mg/L.研究海区中的TDP 具有“保守性”,主要来自陆源排放.依二元混合质量平衡模式估算的珠江口东南部沿岸TDP的陆源质量分数约为53.9%,而深圳湾的均大于80%. TDP的赋存形态从河口的以DIP为主逐渐转变至近外海的以DOP为主,可能暗示磷从河口向海迁移期间,复杂的生物地球化学过程使DIP转化为DOP的速率大于DOP转化为DIP的速率.%Based on the data obtained from monthly cruises from 2000 to 2012, temporal and spatial distributions of the total dissolved phosphorus (TDP) concentration in the Shenzhen Bay and the coastal southeastern Pearl River Estuary were briefly presented and discussed. Composition and sources of the TDP and transformations between the dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) were also investigated by combining with measurements of the salinity and DIP. The results showed that the TDP concentration was (0.26±0.22) mg/L in the bay and (0.05±0.02) mg/Lin the estuary. The intra- and inter-annual variabilities of the TDP concentration did not change much and were keeping an even trend in the estuary during the study period. The TDP concentration was higher in the low water periods than the high water periods, while increased from 0.24 to 0.33mg/L in the period 2000~2004 and decreased from 0.33 to 0.16mg/L in the period 2005~2012 in the bay under influence of the seaward discharges from the peripheral areas. The TDP in the studied area was nearly conservative and mainly originated from the terrestrial sources. A two-component mixing mass balance model was used for estimating the TDP terrestrial fraction at about 53.9% in the estuary and more than 80% in the bay. The major existing form of TDP shifted gradually from the DIP in the river’s outlets to the DOP in the coastal waters near the open sea, which probably implied that the transformation rate from the DIP to DOP was bigger than the one from the DOP to DIP through the complex biogeochemical processes during the transport of phosphorus from the river’s outlets to the open sea.