Microcystin accumulation and biochemical responses in the edible clam Corbiculaleana P. exposed to cyanobacterial crude extract

We investigated the accumulation and effects of cyanobacterial crude extract(CCE)containing microcystins(MCs) on the edible clam Corbicula leana P. Toxic effects were evaluated through the activity of antioxidant and detoxification enzymes: catalase(CAT),superoxide dismutase(SOD), and glutathione-S-transferases(GSTs) from gills, foot, mantle and remaining soft tissues. Clams were exposed to CCE containing 400 μg MC-LReq/L for10 days and were then kept in toxin-free water for 5 days. Clam accumulated MCs(up to 3.41 ± 0.63 μg/g dry weight(DW) of unbound MC and 0.31 ± 0.013 μg/g DW of covalently bound MC). Detoxification and antioxidant enzymes in different organs responded differently to CCE during the experiment. The activity of SOD, CAT, and GST in the gills and mantle increased in MC-treated clams. In contrast, CAT and GST activity was significantly inhibited in the foot and mostly only slightly changed in the remaining tissues. The responses of biotransformation, antioxidant enzyme activity to CCE and the fast elimination of MCs during depuration help to explain how the clam can survive for long periods(over a week) during the decay of toxic cyanobacterial blooms in nature.     

Detection of free microcystins in the liver and muscle of freshwater fish by liquid chromatography-tandem mass spectrometry

MC analysis of biological tissue is considered to be very difficult due to the lack of validated methods. This is the primary limiting factor for monitoring potential risks in both the flesh of aquatic organisms and the aquatic ecosystem. In this study, an effective method to determine free MCs (MC-LR and MC-RR) in the muscle and liver tissues of freshwater cultured fish was developed using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC/MS-MS). The extraction solvent, time of extraction, eluent and purification of the extract were optimized. Various SPE cartridges were also investigated. In this optimized analytical procedure, an 85% methanol/water solution (v/v) was selected as the extraction solvent, after which the extracts were purified by removing fats and proteins; a HLB cartridge was chosen for MCs enrichment; and 90% methanol containing 0.02% formic acid/water solution (v/v) was used as the eluent. Under the optimized pretreatment conditions and instrument parameters, good recoveries of MC-LR and MC-RR were obtained at three concentrations (0.5, 1.0 and 2.0 µg g^?1 dry weight (DW)), with values ranging from 92.5 to 98.3% and 92.1 to 98.6%, respectively. The method detection limit (MDL) for muscle samples was 0.5 µg kg^?1 and 0.4 µg kg^?1 (DW) for MC-LR and MC-RR, respectively. The MDL for the liver samples was 0.8 µg kg^?1 (DW) for both MC-LR and MC-RR. The developed procedure was successfully applied to analyze MCs in the muscle and liver of fish samples collected from a Chinese freshwater aquaculture pond during bloom seasons. The MC-LR concentrations ranged from below the MDL to 4.17 µg kg^?1 and the MC-RR concentrations ranged from below the MDL to 2.64 µg kg^?1.     

Impacts of climate change on surface water quality in relation to drinking water production

Besides climate change impacts on water availability and hydrological risks, the consequences on water quality is just beginning to be studied. This review aims at proposing a synthesis of the most recent existing interdisciplinary literature on the topic. After a short presentation about the role of the main factors (warming and consequences of extreme events) explaining climate change effects on water quality, the focus will be on two main points. First, the impacts on water quality of resources (rivers and lakes) modifying parameters values (physico-chemical parameters, micropollutants and biological parameters) are considered. Then, the expected impacts on drinking water production and quality of supplied water are discussed. The main conclusion which can be drawn is that a degradation trend of drinking water quality in the context of climate change leads to an increase of at risk situations related to potential health impact.     

蓝藻毒素的毒性及其生物富集、暴露途径和危险度评估

概述了淡水蓝藻释放的毒素，在毒性、生物富集等方面的某些研究进展，并探讨了人其与人群健康相关的主要暴露途径及危险度评估。蓝藻毒素的暴露途径主要有“皮肤接触、呼吸道吸入、血液透析、消化道摄入等。未来的研究将集中于不同暴露途径下，蓝藻毒素对人群健康效应的现场评价，并提出合理的预防措施及对其进行现场考核。