Weight and salinity effects on zinc uptake and accumulation for the American oyster (Crassostrea virginica Gmelin)

The power relationships of short-term net uptake and of in-situ body burden with body weight were examined. The accumulation of soft tissue zinc in the American oyster (Crassostrea virginica) was related to time integration of uptake. Short term uptake of (65)Zn was measured in the laboratory. It was (i) a function of the (dry soft-tissue) weight of the oyster, (ii) inversely related to the salinity of the ambient water, and (iii) increased linearly with ambient concentrations. When in-situ soft-tissue zinc body burdens of oysters from the James River and the Rappahannock River were fit to power functions of body weights (y = aWb), the values of b for all sites were larger by 1 than the powers for (65)Zn uptake when b was adjusted for the oyster-bed salinities. The soft-tissue zinc concentration (y/W) of an oyster increased continuously, but the rate of the increase was reduced as the oyster grows larger. Both short-term uptake and in-situ body burden varied with salinity. The soft-tissue zinc concentrations of hooked mussels (Ischadium recurvum) from the Rappahannock River oyster beds, contrary to the oysters, appeared to be in equilibrium with ambient concentrations.     

温度对湖泊沉积物中沉水植物残体厌氧分解的影响

淡水湖泊水生植物残体的腐烂分解过程为沉积物中的异养微生物提供了重要的碳源,但是目前关于温度对沉水植物残体有机质分解的影响研究还不够深入.本研究通过室内微宇宙模拟实验,研究了4℃和25℃时马来眼子菜残体在沉积物中厌氧分解特征及其主要的微生物代谢途径.结果表明,温度对马来眼子菜残体的分解影响显著,25℃实验组沉积物中总有机碳（TOC）和纤维素去除率显著高于4℃实验组.25℃实验组沉积物初始腐殖质占TOC比例为18.23%±1.47%,90 d后达到约46%,这说明微生物对马来眼子菜残体的分解促进了沉积物腐质化.此外,温度升高促进了纤维素降解细菌（如拟杆菌门,Bacteroidetes）的生长繁殖,且硫酸盐还原细菌（如GOUTA19、脱硫球菌属（Desulfocuccus）、LCP-6、HB118）和铁还原细菌（如地杆菌属,Geobacter）是沉积物中主要的优势菌种.在25℃条件下,微生物硫酸盐还原、铁还原和产甲烷作用占马来眼子菜残体厌氧代谢的比例分别达到37.3%、27.8%和10.3%.综上所述,本研究表明温度升高促进了沉积物中马来眼子菜残体的厌氧分解,且微生物硫酸盐还原、铁还原和产甲烷过程在其厌氧分解过程中发挥了重要作用.     

Characterization of precipitation in the background of atmospheric pollutants reduction in Guilin: Temporal variation and source apportionment

Rainfall samples were collected from three observation sites in Guilin from 2013 to 2017, and the chemical composition characteristics of precipitation and the contribution made by different ion sources were analyzed when atmospheric pollutants levels were reduced. The results showed that acid gas emissions and atmospheric pollutant concentrations continued to decline during the study period. However, the change in the volume-weighted mean pH at the three sites suggested that acid rain pollution was not alleviated and began to deteriorate after 2015. The continuing downward trend for alkaline neutralizing ions (Ca²⁺, NH₄⁺) in precipitation indicated that the reduction in alkaline neutralizing substances in the atmosphere was an important factor that led to the deterioration in acid rain across Guilin. The principal component analysis and spearman correlation analysis indicated five sources of ions in precipitation. Quantitative assessment of these five sources indicated that fossil fuel combustion contributed the most ions concentration in precipitation at the three sites, followed by agriculture, terrestrial (crustal) sources, marine sources, and biomass burning. Long-distance airflow might affect the acidity, the electrical conductivity (EC), and ion concentrations in precipitation across Guilin. The airflow trajectory from the west and southeast directions corresponded to higher acidity and ion concentrations. According to the current air pollution control strategy planned by Guilin, reducing atmospheric coarse particles and NH₃ at the same time may potentially lead to further deteriorations in acid rain contents. Therefore, Guilin needs to develop more reasonable pollution prevention measures that synergistically control atmospheric pollutants and acid rain pollution.     

Physiological and biochemical responses of Microcystis aeruginosa to phosphine (PH3) under elevated CO2

Phosphine (PH₃) is an important factor driving the outbreak of cyanobacterial blooms that produce toxic microcystin threating human health. To clarify the physiological and biochemical responses of cyanobacteria to PH₃ under elevated CO₂ concentration, Microcystis aeruginosa was used in the coupling treatment of 1000 ppmv CO₂ and PH₃ at different concentrations respectively. The chlorophyll a (Chl-a), carotenoid, net photosynthetic rate and total protein of M. aeruginosa exhibited evidently increasing tendency under the coupling treatment of 1000 ppmv CO₂ and PH₃ at different concentrations (7.51 × 10^?3, 2.48 × 10^?2, 7.51 × 10^?2 mg/L). The coupling treatments resulted in the higher concentrations of Chl-a and carotenoid of M. aeruginosa, compared to those in the control and the treatment with CO₂ alone, and their enhancement increased with the increase in PH₃ concentrations. The total antioxidant capacity (T-AOC) in the coupling treatment with CO₂ and PH₃ of 2.48 × 10^?2 mg/L and 7.51 × 10^?3 mg/L showed increasing tendency, compared to the treatment with PH₃ alone. Additionally, the coupling treatment with 1000 ppmv CO₂ and PH₃ also altered the pH and DO level in the culture medium. In this regard, the coupling treatment with CO₂ and PH₃ at an appropriate concentration can enhance the resistance of M. aeruginosa to PH₃ toxicity and is beneficial to the reproduction of M. aeruginosa, presumably resulting in potential for the outbreak of cyanobacteria bloom. Given the concern about global warming and the increase in atmospheric CO₂ level, our research laid a foundation for the scientific understanding of the correlation between PH₃ and cyanobacteria blooms.     

电子废弃物资源化技术现状

随着电子废弃物数量的日益增加和对电子废弃物资源化利用要求的提高,电子废弃物经历了由堆存到资源化利用的发展过程.目前电子废弃物资源化技术主要包括物理处理法、化学处理法和热处理法等方法,实现电子废弃物的资源化.     

我国环境管理中经济手段的应用现状和发展对策

市场经济条件下,在环境管理中采用经济手段的重要作用日显突出,分析目前环境管理经济手段在我国的应用现状以及存在的问题,提出我国实施环境经济手段应具备的条件和应用发展对策。     

褐菖鲉肝HSC70基因的环介导等温扩增技术的建立及对石油污染的剂量效应研究

从褐菖鲉肝脏中克隆了热休克蛋白HSC70基因,利用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)建立HSC70基因的定量检测方法。为检测该方法的可行性,将褐菖鲉分别暴露于石油水溶性成分(water-soluble fraction,WSF) 20、60、180 μg·L^-1 1 d后,利用real-time PCR及LAMP技术同时测定褐菖鲉肝HSC70 mRNA表达量,两种方法测定结果基本一致,证实LAMP技术可用于褐菖鲉肝HSC70基因的定量。为更细致了解石油WSF影响褐菖鲉肝脏HSC70基因表达的剂量－效应关系,将褐菖鲉分别暴露于25、50、75、100、125、150、175 μg·L^-1 WSF中,5天后采样,用LAMP技术定量检测HSC70 mRNA。结果表明,HSC70 mRNA表达量在50 μg·L^-1浓度组即被显著诱导,在75 μg·L^-1浓度下达到最大值,这说明褐菖鲉肝HSC70基因对石油污染较敏感,有潜力作为海洋石油污染的生物标志物。     

Characteristics and risk assessment of organochlorine pesticide residues in surface sediments collected at the Qingshitan Reservoir

ABSTRACT

An ultrasonic extraction – gas chromatography – electron capture detector analytical method was used to measure the concentration and types of organochlorine (OC) pesticides in sediment to obtain a better understanding of the characteristics and hidden ecological risks associated with OC pesticide exposure in surface sediment of the Qingshitan Reservoir. Fifteen types of OC pesticides were detected in the sediment, and the sum concentration of these chemicals was in the 149.32–490.19 ng/g range (mean value: 319.39 ng/g). The concentrations of detected OC pesticides occurred in the following order: hexachlorohexanes (HCHs) (mean value: 200.17 ng/g) > DDTs (mean value: 36.92 ng/g) > heptachlors (mean value: 32.74 ng/g) > methoxychlor (mean value: 24.13 ng/g). There was a 100% detection rate for HCH isomers, and their concentrations occurred in the following order: β-HCH > δ-HCH > γ-HCH > α-HCH. β-HCH was the main component of HCHs. Ratios between α-HCH/γ-HCH and β-/(α+γ)-HCH were used to investigate the sources of pollution. Most of the surveyed areas were polluted by lindane, which originated from past pesticide residue usage, and no new inputs of HCHs were found. DDT was the major component of the DDTs, and accounted for 52%–87% of the DDTs. The ratios of (DDE+DDD)/DDT at all sample collection points were less than 1, indicating that degradation rate of DDTs in sediment was low and there was a new input of DDTs in these surveyed areas. The ratio of DDD/DDE was less than 1 at most of the sample collection points, indicating that the degradation of DDT in the sediments primarily took place under aerobic conditions. Comparison of OC pesticide residual levels in the underwater sediment collected at the Qingshitan Reservoir to other states and countries showed the pollution level of these chemicals of the Qingshitan Reservoir was relatively high. The ecological risk was assessed based on guideline values of effects range-low (ERL) and effects range-medium (ERM). The results showed that DDD, DDE, DDTs and endrin residues in the sediment posed a moderate ecological risk, but DDT and γ-HCH showed high ecological risk. These OC pesticides might adversely affect biological systems, and need to be addressed.     

4种唑类杀菌剂对蛋白核小球藻的急性毒性及其致毒机理

唑类杀菌剂因其广谱性和稳定性会残留在水环境中,从而危害人类及其他生物的健康.目前对唑类杀菌剂的毒性研究大多集中在急性毒性,对其致毒机理知之甚少.本研究将三唑醇、三唑酮、克霉唑和氯咪巴唑4种常见的唑类杀菌剂作为目标污染物,以蛋白核小球藻作为指示生物,研究4种唑类杀菌剂暴露96 h后对蛋白核小球藻生长和生理变化的抑制作用.结果表明,4种目标污染物浓度越高对蛋白核小球藻的生长抑制程度越强,在50％效应下,96 h时毒性大小为:氯咪巴唑>克霉唑>三唑醇>三唑酮.其毒性机制可能与活性氧(ROS)的持续积累有关,随着污染物浓度升高,ROS含量不断增加,其中刺激作用最明显的是克霉唑,ROS的增加促进丙二醛(MDA)的大量产生,从而使绿藻产生氧化损伤,激发了不同水平的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性;同时,它们对叶绿素和蛋白质的合成也存在明显的抑制,破坏了绿藻的光合机制,最终造成藻细胞凋亡.研究结果为评估唑类杀菌剂对水生生物的毒性提供重要的理论支持.