1-アミノシクロプロパン-1-カルボン酸処理が,種々の発育段階のカキ果実のエチレン生成に及ぼす影響

Health and environmental effects of heavy metals

Comprehensive assessment and source apportionment of heavy metals in Shanghai agricultural soils with different fertility levels

Assessment of heavy metal pollution, distribution and quantitative source apportionment in surface sediments along a partially mixed estuary (Modaomen, China).

Bioaccumulation and health risk assessment of heavy metals to bivalve species in Daya Bay (South China Sea): Consumption advisory.

The Yangzi River has been seriously affected by intensive anthropogenic activities in recent years. In this study, the levels and distribution, risk assessment, and source apportionment of heavy metals in sediments were investigated in the Yangtze River (Anqing section). The heavy metal concentration and chemical characteristics (Cu/Pb/Zn/Cd/Cr/As/Hg) of 16 samples over four sections were measured using Atomic Fluorescence Spectrometry and Graphite Furnace Atomic Absorption Spectrometry. The metal concentration in the study area showed variance in different sampling sites. The mean heavy metal content was also higher than the background value. Vertical analysis of metal concentration showed the decreasing order from surface sediment. The analysis of Hakanson’s potential risk assessment indicated that the total potential ecological risk of these elements amounted to a considerable pollution level in the study area. The result of geo-accumulation index indicated that the risk of the studied metals had the following decreasing order: Cd > Hg > Pb > Cu > Zn > As > Cr. Based on the result of enrichment factor and principal component analysis, Cr, As, Hg, and partly Zn, Cu, and Cd mostly originated from natural sources. Pb and partly Cu and Zn mostly originated from gas companies, industries, and traffic sources, whereas Cd and partly Zn represented agricultural activities, such as fertilizer and pesticide consumption.

Comprehensive risk assessment and source apportionment of heavy metal contamination in the surface sediment of the Yangtze River Anqing section, China

The quest for new, promising and indigenous plant growth-promoting rhizobacteria and a deeper understanding of their relationship with plants are important considerations in the improvement of phytoremediation. This study focuses on the screening of plant beneficial Cu/Zn-resistant strains and assessment of their bioremediation potential (metal solubilization/tolerance/biosorption and effects on growth of Brassica napus seedlings) to identify suitable rhizobacteria and examine their roles in microbes-assisted phytoremediation. Sixty Cu/Zn-resistant rhizobacteria were initially isolated from Sonchus oleraceus grown at a multi-metal-polluted site in Shanghai, China. From these strains, 19 isolates that were all resistant to 300 mg·L-1 Cu as well as 300 mg·L-1 Zn, and could simultaneously grow on Dworkin-Foster salt minimal medium containing 1-aminocyclopropane-1-carboxylic acid were preliminarily selected. Of those 19 isolates, 10 isolates with superior plant growth-promoting properties (indole-3-acetic acid production, siderophore production and insoluble phosphate solubilization) were secondly chosen and further evaluated to identify those with the highest bioremediation potential and capacity for bioaugmentation. Strain S44, identified as Acinetobacter sp. FQ-44 based on 16S rDNA sequencing, was specifically chosen as the most favorable strain owing to its strong capabilities to (1) promote the growth of rape seedlings (significantly increased root length, shoot length and fresh weight by 92.60%, 31.00% and 41.96%, respectively) under gnotobiotic conditions; (2) tolerate up to 1000 mg·L-1 Cu and 800 mg·L-1 Zn; (3) mobilize the highest concentrations of water-soluble Cu, Zn, Pb and Fe (16.99, 0.98, 0.08 and 3.03 mg·L-1, respectively); and (4) adsorb the greatest quantities of Cu and Zn (7.53 and 6.61 mg·g-1 dry cell, respectively). Our findings suggest that Acinetobacter sp. FQ-44 could be exploited for bacteria-assisted phytoextraction. Moreover, the present study provides a comprehensive method for the screening of rhizobacteria for phytoremediation of multi-metal-polluted soils, especially those sewage sludge-amended soils contaminated with Cu/Zn.

/pdf/screening-and-evaluation-of-the-bioremediation-potential-of-19xgp417cu.pdf

Screening and Evaluation of the Bioremediation Potential of Cu/Zn-Resistant, Autochthonous Acinetobacter sp. FQ-44 from Sonchus oleraceus L

Microcystin-LR (MCLR) is the most common cyanotoxin in contaminated aquatic systems. MCLR inhibits protein phosphatases 1 and 2A, leading to liver damage and tumor formation. MCLR is relatively stable owing to its cyclic structures. The combined UV/H2O2 technology can degrade MCLR efficiently. The second-order rate constant of the reaction between MCLR and hydroxyl radical (·OH) is 2.79(±0.23)×1010 M−1 s−1 based on the competition kinetics model using nitrobenzene as reference compound. The probable degradation pathway was analyzed through liquid chromatography mass spectrometry. Results suggested that the major destruction pathways of MCLR were initiated by ·OH attack on the benzene ring and diene of the Adda side chain. The corresponding aldehyde or ketone peptide residues were formed through further oxidation. Another minor destruction pathway involved ·OH attack on the methoxy group of the Adda side chain, followed by complete removal of the methoxy group. The combined UV/H2O2 system is a promising technology for MCLR removal in contaminated aquatic systems.

/pdf/mechanism-and-reaction-pathways-for-microcystin-lr-1wbn6an6g9.pdf

Yafeng Liu

Papers

Bioaccumulation and health risk assessment of heavy metals to bivalve species in Daya Bay (South China Sea): Consumption advisory.

Comprehensive risk assessment and source apportionment of heavy metal contamination in the surface sediment of the Yangtze River Anqing section, China

Screening and Evaluation of the Bioremediation Potential of Cu/Zn-Resistant, Autochthonous Acinetobacter sp. FQ-44 from Sonchus oleraceus L

Mechanism and Reaction Pathways for Microcystin-LR Degradation through UV/H2O2 Treatment.