Guo Hongyan

Adsorption isotherms of lanthanum to soil constituents and effects of pH, EDTA and fulvic acid on adsorption of lanthanum onto goethite and humic acid

Abstract La3+ adsorption isotherms to five soil constituents (quartz, feldspar, kaolinite, goethite and humic acid) are studied. EDTA, fulvic acid and pH effects are also investigated on the adsorption of lanthanum by goethite and humic acid because of their relative importance in affecting metal environmental behavior. Adsorption isotherms of La3+ to five constituents show differences in adsorption capacity and in shape in the studied range of La3+. These constituents can be classified according to their adsorption capacity: humic acid > goethite ≈ kaolinite > feldspar ≈ quartz. pH increase could promote humic acid and goethite adsorption of La3+ while EDTA could reduce the adsorption by these two adsorbents. Fulvic acid can reduce humic acid adsorption but has less effect on adsorption by goethite.

Plant-promoted dissipation of four submerged macrophytes to phenanthrene.

In order to investigate the function of submerged aquatic plants for recovery of water polluted by typical organic pollutants, and select potential plants for phytoremediation of polycyclic aromatic hydrocarbons contaminated water, removal efficiencies of four submerged macrophytes to phenanthrene were investigated, following 40-day exposure to phenanthrene solutions in an outdoor-simulated experiment. During the exposure period, phenanthrene concentration in water, sediments and the roots of submerged macrophytes were observed. Results showed that Elodeacanadensi exhibited the highest concentrations in roots, while Ceratophyllum demersum contained the lowest among these four submerged macrophytes. The disparity of phenanthrene in roots would come from plant properties including the shape and surface area of both shoots and roots. These plants enhanced the remediation of phenanthrene in solution through plant-promoted sedimentation and biodegradation. Potamogetoncrispu and Elodeacanadensi showed the higher performance to remove phenanthrene due to plant-promoted biodegradation.

Study of environmental risks incurred by leakage of lithium cells to the food chain in a freshwater ecosystem.

Water flea (Daphnia magna) and fish (Carassius auratus) at trophic level were used for comprehensive evaluation of environmental risks incurred by manufactured nanomaterial (nNi(OH)2) as leaked from lithium cells to the food chain in freshwater ecosystem. The 48, 72 and 96 h acute toxicities of water suspensions of nNi(OH)2 to the flea and the fish were tested, using the immobilization and the mortality as toxicological endpoints. The results showed that the water flea was more highly sensitive to nNi(OH)2 than the fish. Then, the fish were exposed to 1.0 mg/L nNi(OH)2 for 6, 12, 24, 36, 48, 60, 72 and 96 h, and the relationship between the concentrations in the water and the fish were described by a bioconcentration factor (BCF). After calculation, lgBCF is 1.61. Reactive oxygen species (ROS) generation was studied after fish were exposed to 1.0 mg/L water suspensions of nNi(OH)2 for 24 h. As proved by electron paramagnetic resonance, nNi(OH)2 may induce the generation of hydroxyl radical in the fish, and nNi(OH)2 as concentrated in the fish may incur redox reaction and produce redox metabolic intermediates. As one of the important toxic mechanisms of nNi(OH)2 to the fish, the oxidative stress mechanism requires further study.

Free radical generation and stress effect on Scenedesmus obliquus exposed to phenanthrene

通过静态模拟实验,研究不同浓度（0.005、0.01、0.025、0.05和0.1 mg/L）菲暴露96 h后,对斜生栅藻的生长、自由基含量、抗氧化系统以及脂质过氧化产物（MDA）的影响.结果表明,0.01 mg/L菲开始对藻细胞生长产生显著抑制作用,在此浓度下电子自旋共振检测到的自由基信号（g=2.0033,幅宽10.15 mT）显著增强;在浓度设置范围内,超氧化物酶歧化酶、过氧化物酶、谷胱甘肽-S-转移酶活性均被显著诱导,显示出抗氧化系统的应激机制.谷胱甘肽和MDA含量均在0.025 mg/L时被显著诱导.这说明斜生栅藻对菲暴露比较敏感,0.01 mg/L即已显示胁迫效应,自由基的诱导是斜生栅藻产生损伤的重要原因,藻细胞的生长量是比较敏感的损伤指标.