Rising temperature contributed to the outbreak of a macrozooplankton Creseis acicula by enhancing its feeding and assimilation for algal food nearby the coastal Daya Bay Nuclear Power Plant

The impact of thermal pollution caused by cooling water discharge of power plant on the surrounding marine ecology has been a hot issue in oceanographic research. To reveal the distribution pattern of cooling water discharge of Daya Bay Nuclear Power Plant in summer and the impact on the surrounding marine environment, this research established a high-resolution three-dimensional (3D) numerical model based on ECOMSED in the Daya Bay. The model results are consistent with the observations on the distribution of tide level and temperature. The simulated horizontal distribution of temperature rise is consistent with the distribution trend of remote sensing images. The study showed that the stratification of the Daya Bay water is stronger in summer. The cooling water mainly spreads in the surface layer, and the temperature rise in the bottom layer is not apparent. Quantitative analysis showed that around 18.8-21.6 km2 of the area has 1°C surface temperature rises. The area of temperature rises that exceeds 2 °C is between 6.2 and 8.1 km2. The area of temperature rises that exceeds 4 °C is between no more than 1.2 km2. The area with a bottom temperature rises of 1 °C does not exceed 2.2 km2, and there is no area that has a bottom temperature rise over 1 °C. The tidal dynamics process influences on the dispersion of cooling water discharge from Daya Bay Nuclear Power Plant, where the influence is more significant in the spring tide period than in the neap tide period. Our findings are consistent with previous researches.

Section: Introductionmentioning

confidence: 99%

Three-dimensional numerical study of cooling water discharge of Daya Bay Nuclear Power Plant in southern coast of China during summer

Geng

Lu²,

Cao

et al. 2023

“…The primary cause of NPP blocking events is the formation of aquatic organism aggregations. The rate of growth and aggregation of aquatic organisms is closely bound up with their surrounding environment, and this relationship has been a focus for many researchers (e.g., Li et al, 2011;Zeng et al, 2021;Liu et al, 2022). However, physical ocean processes, such as the tide, ocean circulation, and waves, can also cause blocking events by transporting organisms into the inlets of NPPs, and research into these processes is scarce.…”

Section: Introductionmentioning

confidence: 99%

The strategies preventing particle transportation into the inlets of nuclear power plants: Mechanisms of physical oceanography

Xu²,

Lin³

et al. 2023

The formation of aquatic organism aggregations near the inlets of nuclear power plants (NPPs) has become an important global concern, as the aggregated organisms can block the cooling systems of NPPs, and, therefore, threaten their operational safety. In this study we focus on the trajectory of aquatic organisms, that is., how these organisms can be transported to the inlets of NPPs by physical ocean processes related to currents and waves. The Changjiang NPP, located on the west side of Hainan Island in China, is occasionally subject to serious gulfweed blocking events in spring. To study the physical mechanism, with the use of a three-dimensional numerical current–wave-coupled model, the current and wave conditions near the NPP were simulated. Based on the model, several particle-tracking simulations were run to evaluate the extent of the blocking that occurred in the inlet of the NPP’s cooling system with different forcings introduced. The results showed that the windage effect and the surface Stokes drift induced by waves were the main causes of blocking events in the Changjiang NPP, with the former transporting surface particles from upstream and the latter transporting surrounding particles onshore, into the NPP’s inlet. Further simulations revealed that bending of the inlet and changing the offshore mouth to downstream mouth could limit the blocking greatly, as particles were seldom transported into the mouth by cross-shore transport processes such as the Stokes drift. We suggest that such findings may provide a valuable reference for the development of strategies to prevent aquatic organism aggregation events in other NPPs.

“…In the drainage area of the nuclear power plants, the analysis of continuous observation data for nearly 20 years showed that the average temperature of the surface layer in summer rose from 27.8°C in 1982 to 34.8°C in 2005, and the phytoplankton community structure showed a trend of transformation from diatom dominance to dinoflagellate dominance (Li et al, 2011), resulting in a trend of miniaturization (Hao and Tang, 2010). Furthermore, the frequency of harmful algal blooms is significantly positively correlated with the rise in water temperature (Yu et al, 2007;Tian et al, 2021), and the outbreaks of other organisms that could influence the nuclear power plant operation also increased (Liu et al, 2022). Most of the recent studies on the effect of thermal discharge on phytoplankton have focused on the changes in community structure; however, the physiological response of phytoplankton under thermal stress in the outlet regions is rarely reported.…”

Section: Introductionmentioning

confidence: 99%

Short-term responses of phytoplankton size-fractionated structure and photosynthetic physiology to thermal effluent in a subtropical coastal bay

Zhang

Liu

et al. 2023

Self Cite

Elevated water temperature caused by the thermal discharge from power plants can exert multiple ecological impacts on the phytoplankton community in coastal ecosystems. Most recent studies have focused on the reshaping effects on the community structure; however, the short-term response of phytoplankton physiology to thermal discharge remains unclear. This study conducted research on the scope of thermal discharge from the nuclear power plant and the size-fractionated phytoplankton structure combined with photosynthetic physiology in Daya Bay, China. The thermal discharge significantly affected the surface temperature in the outlet regions, and the thermal plume mainly diffused along the northeast coast of the outfall site, resulting in a significant difference in the surface temperature between the inlet and outlet transects (p<0.05). Elevated surface temperatures decreased the total chlorophyll a concentrations by 33.19% at the outlet regions, with pico-phytoplankton decreasing the most. Chlorophyll a concentrations were higher at sites further away from the outlets, indicating that elevated water temperature might stimulate the rapid growth of phytoplankton, especially nano-phytoplankton which replaced pico-phytoplankton as the dominant group at stations away from the outlets. Significant negative correlations were observed between the photochemical quantum yield (Fv/Fm) and temperature (p<0.05), and the relative electron transport rate (rETR) and temperature (p<0.05). Phytoplankton showed a normal photosynthetic physiological state at most sites with a surface temperature<33°C but was severely affected at the outlet site with a 5°C rise, decreasing from ~0.5 on the inlet transect to 0.07. During the diurnal survey, the high temperatures near the outlet at midday had a compensatory effect on phytoplankton’s light suppression. The results indicated that the physiological state of phytoplankton was clearly influenced by the thermal discharge with diurnal variation, and different size-fractionated phytoplankton groups exhibited heterogeneous responses. The findings may provide further insights into the ecological impacts of thermal discharges as well as global warming in subtropical regions.