Abstract：
Seawater physicochemical parameters and environmental capacity are important ecological indicators and typical features of the marine environment. It has great significance in the marine material cycle and ecological health. In September 2021 (wet season) and March 2022 (dry season), two voyage investigations were conducted at 12 stations (D1-D12) on Dapeng Bay (DPB), northern South China Sea. The distribution of nutrient, water-quality status, environmental capacity, and impact of ecological environment were discussed. Results showed that NH4-N was the main form of dissolved inorganic nitrogen (DIN) during the wet season, with concentrations ranging from 0.008 mg/L to 0.109 mg/L, accounting for ~53 % of DIN. Conversely, NO3-N was the main form of DIN during the dry season, with concentrations ranging from 0.005 mg/L to 0.117 mg/L, accounting for ~50 % of DIN. The DIP concentration ranged from 0.002 mg/L to 0.019 mg/L, accounting for ~51 % and 31 % of the total dissolved phosphorus in the wet and dry seasons, respectively. The distributions of NH4-N, NO3-N, NO2-N, and DIP were relatively similar, decreasing from the inner bay to the outer bay. The eutrophication indices of 12 stations <1, indicating a poor eutrophication state. Single-factor indices including chemical oxygen demand (COD), DIN, and dissolved inorganic phosphorus (DIP) were less than the class I seawater-quality standard. However, except for station D1, the overall water quality was good. Dissolved oxygen with DIP had a significantly negative correlation during the dry season, indicating that DIP was primarily dominated by marine biological activity and organic-matter decomposition. The remaining environmental capacities of COD, DIN, and DIP in DPB were calculated to be 13,742, 1418, and 141 tons, respectively. Based on the functional-zone division of the sea area, the remaining environmental capacities of COD, DIN, and DIP were exceeded 75 % of the total environmental capacity. This study provided a scientific basis for the protection of marine ecological environment and the sustainable development of DPB.
摘要：
海水理化参数和环境容量是海洋环境的重要生态指标和典型特征。它对海洋物质循环和生态健康具有重要意义。2021年9月（雨季）和2022年3月（旱季），在大鹏湾（DPB）的12个站点（D1-D12）进行了两次航行调查，南海北部。营养的分布，水质状况,环境容量,并对生态环境的影响进行了讨论。结果表明，NH4-N是湿季溶解无机氮（DIN）的主要形式，浓度范围从0.008mg/L到0.109mg/L，占DIN的~53%。相反，NO3-N是旱季DIN的主要形式，浓度范围从0.005mg/L到0.117mg/L，占DIN的50%左右。DIP浓度范围为0.002mg/L至0.019mg/L，占干湿季节总溶解磷的约51%和31%，分别。NH4-N的分布，NO3-N,NO2-N,和DIP相对相似，从内舱到外舱逐渐减少。12个站点的富营养化指数<1，表明富营养化状态较差。包括化学需氧量(COD)在内的单因素指标，DIN,溶解无机磷（DIP）低于I类海水质量标准。然而,除D1站外，总体水质良好。在旱季，溶解氧与DIP呈显著负相关，表明DIP主要由海洋生物活性和有机物分解主导。COD的剩余环境容量，DIN,DPB中的DIP计算为13,742、1418和141吨，分别。根据海域的功能区划分，COD的剩余环境容量，DIN,和DIP超过了总环境容量的75%。该研究为海洋生态环境的保护和DPB的可持续发展提供了科学依据。
