Diatom Thalassiosira weissflogii in oligotrophic versus eutrophic culture: models and ultrastructure

Populations of marine diatom Thalassiosira weissflogii were grown in continuous cultures enriched with f/2 medium. One of the two contrasting cultures (‘eutrophic’) received 5.6 times more nutrients than the other (‘oligotrophic’). Two mathematical models are analyzed to estimate eutrophication differences. The second model based on the Michaelis–Menten uptake and Droop growth shows that cells in the eutrophic culture should have about 56% higher content of silica which is the limiting nutrient. Diatom samples were prepared for the transmission electron microscopy after cells have been kept in chemostats for 37 days. The structure of diatom cells was investigated and a comparison is made between cells grown in oligotrophic and eutrophic conditions. In eutrophic culture, dividing cells were encountered more frequently while cell concentration was approximately equal in both chemostats. The central vacuole of cells in eutrophic culture accumulated dispersed and compact material from amorphous to spherical shape. In some cells the large central vacuole had fibrilar and peppered dense materials in addition to translucent granules, vesicules and multivesicular bodies. In the cytoplasm we found increased number of multivesicular bodies, dense and lucent granules some of which enclose membrane particles and lucent vesicules. Dense material depositions observed in the vacuole are also seen in the cytoplasm associated with organelles, mitochondria and plasmalemma. Cells have well-developed, active and slightly increased number of dictyosomes (5–6). Some dictyosomes with dense secretory material in the cistern are apparently engaged in a granule formation process. Functional significance of dense material in the central vacuole, which has not been observed in cells grown in oligotrophic condition, is discussed.     

我国现阶段应采取的节水措施

文中提及我国现阶段节水工作要从提高新水资源利用率入手，在进行节水宣传教育的同时，建立能动的节水机制，充分利用宝贵的降水资源，发挥可利用新水资源最大的效率，为我国未来经济社会的发展创造有利的条件。     

Food chain transfer of cadmium and lead to cattle in a lead–zinc smelter in Guizhou, China

Cadmium (Cd) and Lead (Pb) are environmental pollutants. Environmental samples and bovine tissues were collected from the areas around a lead–zinc smelter in Guizhou, China for Cd, Pb, zinc (Zn) and copper (Cu) analysis. Cd in soil (10 mg/kg) and feed (6.6 mg/kg) from the polluted areas was 10 times higher than the Chinese Standards, resulting in higher Cd in bovine kidney (38 mg/kg) and liver (2.5 mg/kg). Pb in feed (132 mg/kg) from the polluted area was much higher than unpolluted areas, causing higher Pb levels in bovine tissues. Environmental Zn was elevated, but bovine tissue Zn was normal. Cu in bovine liver decreased with increased Cd and Pb. Metals in drinking water and in bovine muscle were within the Standard range. Thus, in the areas of this lead–zinc smelter, the environment has been contaminated with Cd and Pb, which has been transferred to cattle through the food chain.     

Carbofuran-induced effects on acetylcholinesterase (AChE) in erythrocytes and liver of Cyprinus carpio

A study was conducted to determine the effects of long-term exposure to carbofuran on erythrocyte and liver acetylcholinesterase (AChE) activity in Cyprinus carpio, and assess which tissue was more sensitive to pesticide exposure examining this enzyme. Fish were allowed to accilimatize in toxicant-free water for 24 days after 60-day exposure. AChE activity was determined with a spectrophotometer using acetylthiocholine iodide as a substrate in erythrocytes and liver. Enzymic activity of erythrocytes and liver decreased over time. A higher degree of enzyme inhibition was observed in erythrocyte compared to liver. The degree of enzyme inhibition was positively correlated with exposure time. When exposed fish were transferred to clean water, recovery was greater in erythrocytes than liver. Erythrocyte AChE activity recovered after 18 days, while it required 21 days in liver. The findings of this study indicate that erythrocyte AChE is more sensitive to carbofuran than liver. The greater sensitivity of erythrocyte AChE suggests that it may be more useful as a biomarker for monitoring status of pollution in freshwater bodies.     

类二噁英多氯联苯生殖毒性的研究进展

类二噁英多氯联苯(DlPCBs)作为典型的环境内分泌干扰物,会干扰接触个体或其后代的内分泌功能,破坏机体的神经系统、免疫系统,尤其对生殖系统的影响最为明显,比如对生殖器官的形态与功能、生殖内分泌、原始生殖细胞及其受精和早期胚胎发育等产生严重影响,最终导致各种生殖系统疾病的发生。DlPCBs的蓄积性及半挥发性使其在环境中分布广泛,半衰期长的特点使其将对动物及人类的生存和健康造成难以想象的影响。本文综述了DlPCBs的分类与构成、一般性质、生殖毒性以及其可能的致病机理,并对DlPCBs生殖毒性机理研究的重点方向进行了展望。     

Coalition of injustice? Bodies,business, and the biosphere in struggles against unwanted land uses

Scholars of environmental injustice have pushed to see beyond the spatial distribution of environmental harms in studies of unwanted land uses. Building upon this work, this article examines how the complex geographies of environmental injustice play out in a coalition to prevent the construction of a coal-fired power plant in Surry County, Virginia. While spatially dispersed coalitions of negatively affected actors can strengthen efforts to prevent the construction of an unwanted land use, they can also perpetuate the environmental injustices surrounding it. To make this argument, particular attention is paid to the diverse reasons and ways differentially situated actors oppose an unwanted land use. It is demonstrated how the disparate concerns and differential tactics deployed by actors in coalitions against unwanted land uses are often embedded in and potentially contribute to longer histories of social injustice.     

常州市典型臭氧污染天气过程及成因分析研究

臭氧是一种存在于地球臭氧层和近地面的气体,它对人类和环境是否有益取决于大气中存在的位置。高空臭氧层使人类免受紫外线伤害,而近地面臭氧是光化学烟雾产生的主要污染物,损害农作物、树木和其他植物生长,危害人体健康诱发儿童哮喘等疾病。本文结合2013年8月12日常州市出现的臭氧污染天气,利用气象和空气自动监测数据,对污染过程、变化特征和成因进行了分析。结果表明,在连续高温、太阳辐射强度大、风速低、大气扩散条件差等气象因素和臭氧前体物（NMHC）较高等不利条件下,易形成臭氧污染天气,导致空气质量下降。     

The adaptive response of lichens to mercury exposure involves changes in the photosynthetic machinery

Lichens are an excellent model to study the bioaccumulation of heavy metals but limited information is available on the molecular mechanisms occurring during bioaccumulation. We investigated the changes of the lichen proteome during exposure to constant concentrations of mercury. We found that most of changes involves proteins of the photosynthetic pathway, such as the chloroplastic photosystem I reaction center subunit II, the oxygen-evolving protein and the chloroplastic ATP synthase β-subunit. This suggests that photosynthesis is a target of the toxic effects of mercury. These findings are also supported by changes in the content of photosynthetic pigments (chlorophyll a and b, and β-carotene). Alterations to the photosynthetic machinery also reflect on the structure of thylakoid membranes of algal cells. Response of lichens to mercury also involves stress-related proteins (such as Hsp70) but not cytoskeletal proteins. Results suggest that lichens adapt to mercury exposure by changing the metabolic production of energy.