CSIR-National Institute of Oceanography, 176 Lawsons Bay Colony, Visakhapatnam, India.
Academy of Scientific and Innovative Research, Ghaziabad, India.
Environ Sci Pollut Res Int. 2024 May;31(22):31787-31805. doi: 10.1007/s11356-024-33354-2. Epub 2024 Apr 19.
The coastal ocean receives nutrient pollutants from various sources, such as aerosols, municipal sewage, industrial effluents and groundwater discharge, with variable concentrations and stoichiometric ratios. The objective of this study is to examine the response of phytoplankton to these pollutants in the coastal water under silicate-rich and silicate-poor coastal waters. In order to achieve this, a microcosm experiment was conducted by adding the pollutants from various sources to the coastal waters during November and January, when the water column physicochemical characteristics are different. Low salinity and high silicate concentration were observed during November due to the influence of river discharge contrasting to that observed during January. Among the various sources of pollutants used, aerosols and industrial effluents did not contribute silicate whereas groundwater and municipal sewage contained high concentrations of silicate along with nitrate and phosphate during both the study periods. During November, an increase in phytoplankton biomass was noticed in all pollutant-added samples, except municipal sewage, due to the limitation of growth by nitrate. On the other hand, an increase in biomass and abundance of phytoplankton was observed in all pollutant-added samples, except for aerosol, during January. Increase in phytoplankton abundance associated with decrease in biomass was observed in aerosol-added sample due to co-limitation of silicate and phosphate during January. A significant response of Thalassiothrix sp. was observed for industrial effluent-added sample during November, whereas Chaetoceros sp. and Skeletonema sp. increased significantly during January. Higher increase in phytoplankton biomass was observed during November associated with higher availability of silicate in the coastal waters in January. Interestingly, an increase in the contribution of dinoflagellates was observed during January associated with low silicate in the coastal waters, suggesting that the concentration of silicate in the coastal waters determines the response of the phytoplankton group to pollutant inputs. This study suggested that silicate concentration in the coastal waters must be considered, in addition to the coastal currents, while computing dilution factors for the release of pollutants to the coastal ocean to avoid occurrence of unwanted phytoplankton blooms.
沿海海域从各种来源接收营养污染物，例如气溶胶、城市污水、工业废水和地下水排放，其浓度和化学计量比各不相同。本研究的目的是研究在富含硅酸盐和贫硅酸盐的沿海水域中，沿海水域中浮游植物对这些污染物的响应。为了实现这一目标，在 11 月和 1 月进行了一项微宇宙实验，在这两个时期，水柱理化特性不同，通过向沿海海域添加来自各种来源的污染物来实现。由于河川径流的影响，11 月的海水盐度较低，硅酸盐浓度较高，而 1 月则相反。在所使用的各种污染物来源中，气溶胶和工业废水不含硅酸盐，而地下水和城市污水在两个研究期间都含有高浓度的硅酸盐以及硝酸盐和磷酸盐。11 月，除城市污水外，所有添加污染物的样品中浮游植物生物量都有所增加，这是由于硝酸盐限制了生长。另一方面，1 月，除气溶胶外，所有添加污染物的样品中浮游植物的生物量和丰度都有所增加。1 月，由于硅酸盐和磷酸盐的共同限制，在添加气溶胶的样品中观察到浮游植物丰度增加而生物量减少。11 月，工业废水添加样品中观察到 Thalassiothrix sp. 的显著响应，而 Chaetoceros sp. 和 Skeletonema sp. 在 1 月显著增加。1 月沿海海域硅酸盐可用性较高，浮游植物生物量增加较多。有趣的是，1 月沿海海域硅酸盐浓度较低，导致甲藻门的贡献增加，表明沿海海域硅酸盐浓度决定了浮游植物群对污染物输入的响应。本研究表明，在计算污染物向沿海海域释放的稀释因子时，除了沿海海流外，还必须考虑沿海海域的硅酸盐浓度，以避免出现不必要的浮游植物大量繁殖。
