Fluctuation of Cadmium Load on a Tide‐Influenced Waterfront Lake in the Middle‐Lower Reaches of the Yangtze River

Abstract

The Inner Lake, a typical waterfront lake located in the middle-lower reaches of the Yangtze River, is selected as the research area in this paper. Through field measurements and laboratory experiments, spatial distribution characteristics of the heavy metal cadmium (Cd) contents were revealed, and the release rate-flow disturbance curve in sediment of the Inner Lake was formed. The mathematical models of the migration and transformation of Cd were built and calibrated. With the models, the fluctuation characteristics of Cd pollution load were quantitatively assessed in different time scales, as in typical years (1998, 2001, and 2004) and in typical tidal cycles of dry seasons and flood seasons. The results showed that: there was a positive correlation between the release rate of Cd and flow disturbance intensity. Influenced by the hydrologic regime of the Yangtze River, the Cd pollution load was higher in high-water years than that in common-water years and low-water years, and was higher in flood seasons than that in dry seasons. Influenced by the tide of the Yangtze River, the Cd pollution load increased during ebb tide and reduced during the rising tide.

Research on the Relationship between Water Diversion and Water Quality of Xuanwu Lake, China

“…Through related research, the minimum flow of water transferred from Xuanwu Lake to urban rivers is 2 m 3 /s, which means that the minimum amount of water supply to Xuanwu Lake is 172,800 m 3 /day. We set the maximum water diversion (3,500,000 m 3 /day), daily water diversion (2,800,000 m 3 /day), and optimal water diversion (1,800,000 m 3 /day) as the calculation plan, taking into account no wind and prevailing winds (southeast wind and northwest wind) [47,48,49]. According to the field survey, the pollutant ratio of the ③ drainage ditch was significant, so the ③ drainage ditch will be blocked during the optimal water diversion [50,51,52], as shown in Table 2.…”

Research on Water Environment Regulation of Artificial Playground Lake Interconnected Yangtze River

“…Chl-a concentration was regarded as the evaluation index. According to the principle of mass conservation, the basic equation of eutrophication variables is [36,37,38,39,40,41]: $\frac{\partial C_{c\mathrm{hl}-\mathrm{normala}}}{\partial t}+U\frac{\partial C_{\mathrm{chl}-\mathrm{normala}}}{\partial x}+V\frac{\partial C_{\mathrm{chl}-\mathrm{normala}}}{\partial y}=\frac{\partial }{\partial x}\left(E_x\frac{\partial C_{\mathrm{chl}-\mathrm{normala}}}{\partial x}\right)+\frac{\partial }{\partial y}\left(E_y\frac{\partial C_{\mathrm{chl}-\mathrm{normala}}}{\partial y}\right)+S_{\mathrm{chl}-\mathrm{normala}}$ where:$S_{chl-a}=G_{PI}\left(t\right)-D_{PI}\left(t\right)-\frac{V_s}{D}$ $G_{PI}={\mathrm{K}}_1·Phtsy·F\left(N,P\right)$ $D_{PI}=\mu ·F\left(N,P\right)$…”

“…Due to the current planning state and no excavation operations on the playground, the model calculation results were checked according to Wang [35,36,37,38], in situ data and routine monitoring data of Neijiang Lake and diversion channel, in order to meet more the strong relation between the real status of the park and the model to estimate the effect of changes. The model water quality and eutrophication parameters are listed in Table 2.…”

“…In the early stages of lake eutrophication, phosphorus is the limiting factor for the algae growth, and its increased concentration leads to the massive growth of algae. With the rapid growth of urban population and the rapid development of industrial and agricultural production in China, the eutrophication of urban water bodies has become increasingly serious and has become a serious ecological problem of urban environment [35,36,37]. The concentration of dissolved oxygen in water decreases, which can cause the death of aquatic animal, especially fish [38,39,40,41].…”

Research into the Eutrophication of an Artificial Playground Lake near the Yangtze River

“…Due to the current under-planning state and no excavation operations at Playground Lake, the results of the model calculation were checked to ensure that they meet stronger relations between the real status of the park and the model to estimate the effect of changes, according to Wang Hua's in situ data and routine monitoring data of Neijiang Lake and diversion channel [22][23][24][25]. The main water quality and eutrophication parameters in the model are shown in Table 1.…”