The decomposition of Microcystis can dramatically change the physicochemical properties of freshwater ecosystems. Bacteria play an important role in decomposing organic matters and accelerating the cycling of materials within freshwater lakes. However, actions of the bacterial community are greatly influenced by temperature and the amount of organic matter available to decompose during a bloom. Therefore, it is vital to understand how different temperatures and biomass levels affect the bacterial community during the decomposition of Microcystis. Microcystis addition reduced the diversity of bacterial community. The composition of bacterial community differed markedly between samples with different biomass of Microcystis (no addition, low biomass addition: 0.17 g/L, and high biomass addition: 0.33 g/L). In contrast, temperature factor did not contribute much to the different bacterial community composition. Total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), ammonia nitrogen (NH4+-N) and oxidation-reduction potential (ORP) were the key measured environmental variables shaping the composition of bacterial community. Decomposition of Microcystis changed the physicochemical characteristics of the water and controlled the diversity and composition of the bacterial community. Microcystis biomass rather than temperature was the dominant factor affecting the diversity and composition of the bacterial community.

Phragmites australis has been used to treat acid mine drainage (AMD)-contaminated soil. However, the mechanism about metal translocation in reeds was not widely reported. This study investigated metal (Fe, Al, and Mn) storage location in reeds grown in five different sampling sites of an AMD field. As expected, the more metals in soil, the more metals entered the belowground organs of plants. Reeds grown in soils with the highest levels of metals accumulated 0.16 ± 0.04 mg/g Mn, 16.29 ± 4.15 mg/g Fe, and 1.31 ± 0.22 mg/g Al in roots. Most of the iron was sequestered in the roots, while Al was transferred to the shoots. Histological staining found that most of the iron was sequestered in the exodermis, while Al extended the endodermis of roots. Al even entered the stele of roots grown in soil with higher Al levels. The epidermis, cortex, and central cylinder of rhizomes were the main tissues for Fe and Al storage. The more metals in rhizomes, the stronger intensity of the staining was observed around the vascular systems of rhizomes. No structural difference was observed among reeds collected from different sites. Further studies may be needed to enhance the transfer of metals in reeds and increase the phytoremediation efficiency.

Potentially toxic metals contaminate the environment and threaten human health. This study investigated the effect of chelator citric acid (CA) on enhancing metals (Cu, Ni and/or Pb) accumulation in duckweed (Lemna minor). Lemna minor were cultured in solutions with single or mixed metals (Ni 50 ppm, Cu 50 ppm and/or Pb 10 ppm) added with different levels of CA (0 ppm, 10 ppm, 50 ppm or 100 ppm CA) for 4 weeks, then harvested, dried and digested. For single-metal solutions, duckweed treated with higher levels of CA (50 ppm or 100 ppm CA) accumulated more Ni or Cu; 100 ppm CA increased Cu and Ni accumulation in plants by 96% and 120%. Meanwhile, 10 ppm CA, 50 ppm or 100 pm CA had similar effects on improving Pb accumulation in duckweed, which enhanced Pb accumulation in duckweed by 100%. For duckweed cultured in mixed-metals solutions, 50 ppm and 100 ppm CA still significantly increased the amounts of Cu and Ni in duckweed by 50% and 100%, while Pb sequestration was not enhanced. The role of CA in increasing metal accumulation in duckweed depended on the levels of CA, the concentrations and types of metals. Future studies are needed to further investigate the potential of CA to assist phytoremediation of different metals contaminated environment.

Wetland plants such as Phragmites australis has been used to treat acid mine drainage (AMD) contaminated soil which is a serious environmental issue worldwide. This project investigated metal plaque content(s) and metal uptake in reeds grown in an AMD field in winter and spring. The results indicated that the level of Fe plaque was much higher than Mn and Al plaque as the soil contained more Fe than Al and Mn. The amounts of Mn and Al plaque formed on reeds in spring were not significantly different from that in winter (p > .05). However, more Fe plaque was formed on reeds collected in spring. The concentrations of metals in underground organs were positively related to the metal levels in soils. More Mn and Al transferred to the aboveground tissues of reeds during the spring while the Fe levels in reeds did not significantly vary with seasons. Roots and rhizomes were the main organs for Fe sequestration (16.3 ± 4.15 mg/g in roots in spring) while most Al was sequestered in the shoots of reeds (2.05 ± 0.09 mg/g in shoots in spring). Further research may be needed to enhance the translocation of metals in reeds and increase the phytoremediation efficiency.