To expand the knowledge on the tempo-spatial patterns of zooplankton and the key modulated factors in urban aquatic ecosystem, we investigated zooplankton and water quality from April 2018 to January 2019 in the hinterland of the Three Gorges Reservoir area, Wanzhou City of China. The results indicated that water quality indicated by the trophic state index (TSI) reached a state of mesotrophication to light eutrophication in the Yangtze River, and a state of moderate- to hyper- eutrophication in its tributaries. Based on the biomass of zooplanktons, Asplanchna priodonta was the most common specie in April; Encentrum sp., Filinia cornuta and Epiphanes senta were the most noticeable species in summer; Cyclopoida Copepodid, Sinocalanus dorrii and Philodina erythrophthalma became the dominant species in winter. Generally, rotifers prevailed in April and August, and copepods became the most popular in January. According to canonical correspondence analysis, nitrate, temperature (T), ammonia, water level and permanganate index (CODMn) significantly influenced the community structure of zooplankton (p < 0.05). The dominant species shifts of zooplankton were partly associated with nutrient level (nitrate and ammonia) under periodic water level fluctuations. Rotifers and protozoans were characterized as high T adapted and CODMn-tolerant species comparing with cladocerans and copepods. The ratio of microzooplankton to mesozooplankton (Pmicro/meso) has presented a strongly positive relationship with T (p < 0.001), as well as Pmicro/meso and CODMn (p < 0.001). It implied that zooplankton tended to miniaturize individual size via species shift under high T and/or CODMn conditions induced by global warming and human activities. The information hints us that climate change and human activities are likely to produce fundamental changes in urban aquatic ecosystem by reorganizing biomass structure of the food web in future.
Batch test had been carried out to determine the potential and the effectiveness of the novel composite adsorbent in removal of fluoride, iron and manganese from aqueous solution. It was found that the composite adsorbent could effectively not only remove Fe (II) and Mn (II) also fluoride from water, the maximum adsorption capacities for F-, Fe (II) and Mn (II) were 4.09mg·g-1 4.00mg·g-1 and 3.50mg·g-1 respectively. Kinetics data obtained for the adsorption process fitted the Lagergren First-order equation. The Langmuir adsorption isotherm was found to fit the experimental data derived from F- (R2= 0.9992), Fe (II) (R2=0.9858) and Mn (II) (R2=0.9876) removal. Both Fe (II) and Mn (II) removal increased with increase in solution pH, but F- removal remained relatively stable in pH 4.0~9.0. The process of adsorption of F-, Fe (II) and Mn (II) from aqueous solutions by the composite adsorbent was an endothermic process. The above results indicated the composite adsorbent can be possibly applied in F-, Fe (II) and Mn (II) removal from drinking water.
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