Page 99 - 《渔业研究》2025年第3期

356 渔 业 研 究 第 47 卷

Numerical simulation study on the effect of aquaculture wastewater discharge
on nutrient salt distribution in Zhao’an Bay, Fujian Province

ZHU Yuchen，LIN Jianwei *
(Key Laboratory of Cultivation and High-value Utilization of Marine Organisms in Fujian Province,
Fisheries Research Institute of Fujian, Xiamen 361013, China)

Abstract: [Background] Reasonable utilization of the bay will strongly contribute to the prosperous develop-
ment of China’s marine economy. [Objective] The study aims to understand the impact of the discharge of
culture wastewater on the distribution of nutrient salts in Zhao’an Bay. [Methods] The hydrological observa-
tion data of Zhao’an Bay in September 2022 was selected, combined with the survey data of the culture dis-
charge outlets around the bay in April 2022, to simulate the migration of major nutrient salts after discharge
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from the discharge outlets in the bay. [Results] The results showed that: 1) The variation of NH -N during high
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and low tides: during high tide, NH -N accumulates in the bay, with concentrations stabilizing between 0.03 and
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0.30 mg/L. During low tide, the NH -N concentration on the east and west sides of the bay increases signific-
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antly, generally ranging from 0.10 to 0.30 mg/L; 2) Changes in TN at high and low tides: at high tide, the con-
centration of TN was as high as 0.30~1.00 mg/L in the north-central part of the bay and the area west of the Ba-
chi Gate; as the tide level increased, the concentration of TN generally decreased, but the northwestern side of
the bay still remained at a high level. At low tide, TN concentration increased, mainly concentrated in the shal-
low water area on the northwest side of the bay; 3) Changes in TP at high and low tides: at high tide, TP reached
0.15~0.30 mg/L in the north-central part of the Bay and the area west of Bachi Gate. At low tide, the concentra-
tion increased, concentrated in the shallow water area on the northwest side of the bay, and the concentration
was higher in general, especially in the nearshore waters on the east and west sides of the bay, which was in line
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with the situation of TN. [Conclusion] The migration and diffusion of NH -N, TN and TP are controlled by
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tidal currents, and the tidal currents determine the distribution and concentration of the three nutrient salts in the
bay. The high concentration of the three nutrient salts are mainly found in the near-shore waters with small wa-
ter depths on the east and west sides of the bay.
Key words: aquaculture water; Zhao’an Bay; model simulation; high and low tide