基于遥感的黄河三角洲湿地时空变化特征及驱动因素研究

为适应黄河三角洲湿地快速频繁变化的特点并提高数据解释力度,为黄河三角洲科学规划和管理保护提供必要参考,基于Landsat影像密集观测1986—2021年15个时期的黄河三角洲湿地,研究湿地时空变化,定量分析驱动因素。结果表明:(1)黄河三角洲湿地存在波动变化和阶段性特征,自然湿地减少1 579.07 km²,滩涂和草甸灌丛损失率均超过60%;人工湿地面积增加了1 210.67 km²。(2)农田、建设用地和人工湿地扩张与自然湿地萎缩显著相关,相关系数分别为-0.682、-0.963、-0.976;2009年后因退耕还湿,开垦的影响减弱。(3)输沙量与自然湿地面积相关系数为0.614,在水文因素中起主导作用;1993年以前河口泥沙淤积效应强于海洋侵蚀作用,随后反转。(4)气温升高和干旱事件加剧了湿地损失。     

Assessing the impacts of light synthetic crude oil on microbial communities within Laurentian Great Lakes’ sediment habitats

The ability of microbial communities to respond to and degrade crude oil in marine environments is well understood, yet fewer studies have examined freshwater environments. The Laurentian Great Lakes are one of the world’s largest surface freshwater sources. A pipeline that transports light synthetic crude oil crosses between two of the Great Lakes (the Straits of Mackinac, connecting Lakes Michigan and Huron, U.S.A.), and there is uncertainty on how the various habitats within this region would respond to accidental crude oil exposure. In this study, sediment microbial communities from three distinct habitats (coastal beach, freshwater coastal wetland, and Lake Michigan deep sediments) were used in microcosm experiments to document their community response (16S rRNA gene sequencing) to light synthetic crude oil (headspace gas chromatography). Microbial community structure (beta diversity) was impacted after exposure to crude oil in each of the habitats examined, with each habitat showing a different level of resistance to crude oil. Additionally, within each habitat, beta diversity distinguished sub-communities that increased in abundance in experimental treatments. Specifically, an increase in total abundance of Alphaproteobacteria, Betaproteobacteria, or Gammaproteobacteria was observed in microcosms exposed to crude oil regardless of habitat type. Methane, a potential hydrocarbon degradation byproduct, was observed in the headspace of the microcosms after exposure to crude oil, which may indicate methanogenic hydrocarbon degradation. These data suggest Great Lakes freshwater microbial communities will respond differently to crude oil exposure but may have shared community members involved in resisting and degrading light synthetic crude oil.     

Performance evaluation of different macrophytes in small-scale vertical flow constructed wetlands for greywater treatment using principal component analysis

The scarcity of water is perceived as a systematic global risk due to increasing water demand. Vertical flow constructed wetland (VFCW) is proposed as an energetically efficient and economical process to treat greywater (GW) for non-potable purposes. Macrophyte contributes a significant amount to the treatment process, and it depends on species, and their ecology. In this study, four single-stage VFCW systems were planted with locally available plant species named Hymenocallis littoralis as Plant 1, Phragmites australis as Plant 2, Canna indica Plant as 3, and Colocasia as Plant 4, which were used for the treatment of GW. The mean removal efficiencies associated with Plant 1, Plant 2, Plant 3, and Plant 4 are 55.13%, 48.11%, 52.53%, and 56.39% for chemical oxygen demand (COD); 45.35%, 35.36%, 64.10%, and 56.39% for ammonia; and 32.97%, 20.85%, 71.57%, and 33.40% for phosphate, respectively. All systems show significant removal efficiency (more than 40%) of all pollutants, except TDS and pH. Among all the observed plants, C. indica achieved the highest removal efficiency for COD, ammonia, and phosphate. The obtained results were analyzed for the dependency of correlations with effluent, influent, and macrophytes used in the treatment system. The principal component analysis (PCA) identified two principal components from 13 variables and explained 50.25%, 47.47%, and 45.62% variance of normalized datasets in VFCW. The PCA also shows significant correlations of plant species with different targeted effluent parameters.