Zinc in water and sediments of two finnish lakes

The distribution of zinc in Lake Vanajavesi and Lake Mallasvesi, South Finland, was determined on the basis of water and sediment studies. Lake Vanajavesi is one of the most polluted of large inland lakes, in Finland. The zinc load comes mainly from industrial sources. Lake Mallasvesi, situated near Vanajavesi, is in almost natural condition. The water samples were taken by a Ruttner sampler. In collecting sediment samples, a freezing technique was used. The results of zinc analyses indicate that, during several winters, zinc has spread with waste water to different parts of L. Vanaja against the main course of flow. A close correlation between sedimentation of zinc and waste discharge from a textile factory was found in the present study.     

Genetic analysis of X-linked mutagen-sensitive mutants of Drosophila melanogaster

Mutants at 2 new loci which control mutagen-sensitivity are described. Mutants at both loci are female-sterile and are hypersensitive to killing by MMS; neither increases the frequency of sex-linked recessive lethals. A screen of previously described female-sterile and meotic mutants has revealed that a number of these are also sensitive to mutagens. In addition, several new mutants have been identified on the basis of sensitivity to either HN2 or MMS. An anlysis of complementation data suggests that all of the X-linked genes controlling sensitivity to MMS may now have been identified. Among the new mei-41 alleles are mutants which show verly little meiotic nondisjunction or loss. Cytogenetic mapping of previously known mutants is also described. The mutants mus(1)104^D1 and mei-41^D5 are located in th eregion 14B13±?14D1,2 on the polytene chromosome map, and they map very close to each other genetically. Cytogenetically mus(1)101^D1 is between salivary chromosome bands 12A6,7 and 12D3, mus(1)103^D1 is between bands 12A1,2 and 12A6,7, and mus(1)-109^A1 is in section 8F3-9A2.     

The rotifer fauna of the River Loire (France), at the level of the nuclear power plants

In the heated affluents of nuclear power plants of the river Loire, rotifers are abundant. Cosmopolitan species are numerically dominant, but a tropical fauna is also present, among which the genus Brachionus, representing 20% of the total species, is best represented. From a comparison between water upstream and downstream of the power plants, it further appears that in downstream warmed-up waters, some species show an important development, but not in colder upstream waters.     

若尔盖沙化土地治理土壤微生物群落与功能基因比较研究

【目的】在高寒沙地中建立以赖草和沙生苔草等先锋植物为主的人工草方格,探究其土壤微生物群落动态变化以及养分循环过程。【方法】采用宏基因组测序和qPCR方法进行土壤微生物群落结构组成分析、功能基因注释和绝对丰度测定,并结合土壤理化因子数据进行冗余分析。【结果】人工建立草方格后,沙地土壤中全氮、速效磷以及有机碳含量分别提高了20%-68%、10%-247%、19%-56%;细菌和真菌的群落数量分别提高了17%-81%和2%-95%,与植物促生长相关的鞘氨醇单胞菌属(Sphingomonas)、慢生根瘤菌属(Bradyrhizobium)、硝化螺旋菌属(Nitrospira)、Solirubrobacter属和类诺卡氏菌属(Nocardioides)等细菌种类的相对丰度呈上升趋势;氮循环中与氨氧化和亚硝酸盐氧化相关的amoCAB基因簇和nxrAB基因簇显著富集,发现了完全氨氧化的基因标志。【结论】人工建立草方格有效提升了高寒沙地土壤养分和微生物群落数量,促进了养分循环。适度放牧可以增加沙地生态系统的氮汇扩散性,有助于本土先锋植物定植,为今后在同等高海拔地区采取沙地生态修复措施提供理论参考。     

Alleviation of Both Water and Nutrient Limitations is Necessary to Accelerate Ecological Restoration of Waste Rock Tips

Hard rock quarries are commonly located close to national parks and special areas of conservation and are generally regarded as visually intrusive. Consequently, restoration strategies that effectively accelerate natural plant regeneration processes are required. Slate waste tips present extreme conditions for plant establishment with multiple potential limiting factors (e.g., lack of organic matter, nutrients, and poor water retention). In this study, we investigated ecological strategies to accelerate natural regeneration at the largest slate quarry in Europe. A field experiment was conducted to assess ecosystem restoration using a contrasting set of native woody species. Treatments included amendments of waste tips with: polyacrylamide gel to increase water‐holding capacity; mineral fertilizer to increase nutrient supply; and two treatments that increased both (organic waste or boulder clay addition). Ecosystem recovery was evaluated through above‐ and below‐ground productivity (plant and microbial, respectively) and soil analyses. Neither increasing nutrient supply (with mineral fertilizer) nor water‐holding capacity (with polyacrylamide gel) was sufficient, alone, to improve plant establishment. However, both boulder clay and organic waste amendment significantly enhanced plant growth. There was a marked positive interaction in the effects on tree growth of the amendment with organic waste and boulder clay. Large interactions occurred between tree species and substrate amendments. The growth of N₂‐fixing species was strongly favored over non‐fixers where there was no addition of material increasing soil nitrogen supply, whereas the growth advantage of pioneer species over non‐pioneers was greatest with fertilizer, organic waste, or clay additions. Organic waste addition had the greatest positive impact on soil processes.     

Leaf traits of natural populations of <Emphasis Type="Italic">Adiantum reniforme</Emphasis> var. <Emphasis Type="Italic">sinensis</Emphasis>, endemic to the Three Gorges region in China

Leaf mass per unit area (LMA), carbon and nitrogen contents, leaf construction cost, and photosynthetic capacity (P _max) of Adiantum reniforme var. sinensis, an endangered fern endemic to the Three Gorges region in southwest China, were compared in five populations differing in habitat such as soil moisture and irradiance. The low soil moisture and high irradiance habitat population exhibited significantly higher LMA, area-based leaf construction (CC_A), and carbon content (C_A), but lower leaf nitrogen content per unit dry mass (N_M) than the other habitat populations. The high soil moisture and low irradiance habitat populations had the lowest CC_A, but their cost/benefic ratios of CCA/P _max were similar to the medium soil moisture and irradiance habitat population due to their lower leaf P _max. Hence A. reniforme var. sinensis prefers partially shaded, moist but well-drained, slope habitats. Due to human activities, however, its main habitats now are cliffs or steeply sloped bare rocks with poor and thin soil. The relatively high energy requirements and low photosynthetic capacity in these habitats could limit the capability of the species in extending population or interspecific competition and hence increase its endangerment.     

临泽绿洲边缘区棉花群体光合速率、蒸腾速率及水分利用效率

在甘肃河西走廊中部黑河中游绿洲边缘区,于6月下旬和8月上旬,利用Li-8100土壤碳通量测定系统与改进的同化箱联合对田间条件下早熟陆地棉(Gossypium hirsutum)品种新陆早8号的群体光合特性进行了研究.结果表明：试验地6月下旬的土壤呼吸速率和土壤蒸发速率显著高于8月上旬（P＜0.01）;棉花群体光合速率日变化均呈“单峰型”,6月下旬的群体光合速率显著高于8月上旬,其日平均值分别为（43.11±1.26）和（24.53±0.60）μmol CO₂·m^-2·s^-1, 差异极显著（P＜0.01）;群体蒸腾速率日变化也呈“单峰型”,6月下旬和8月上旬的日平均值分别为（3.10±0.34）和（1.60±0.26）mmol H₂O·m^-2·s^-1,两者存在极显著差异（P＜0.01）;6月下旬和8月上旬的群体水分利用效率日平均值分别为（15.67±1.77）和（23.08±5.54） mmol CO₂·mol^-1 H₂O,但差异不显著（P＞0.05）.两生育时期棉花群体光合速率与温度、光合有效辐射及土壤含水量均呈正相关关系.表明棉花群体光合速率在6月下旬和8月上旬均没有出现中午光合下调,8月由于土壤水分降低和植物叶片衰老,棉花群体光合速率和蒸腾速率显著降低,但水分利用效率并无显著下降.     

Evaluation of genotoxicity of combined soil pollution by cadmium and imidacloprid

Cadmium (Cd) is one of the important pollutants of soil and the genotoxicity of Cd-contaminated soil was studied in combination with imidacloprid. The single cell gel electrophoresis or comet assay was used to quantify DNA strand breaks as a measure of DNA damage induced by Cd and imidacloprid contamination in soil. The soil was artificially contaminated by Cd 2 h at 25℃ and were used in the comet assay. DNA damage was measured as the values of percentage of nuclei with tails, tail length, tail DNA, tail moment (TM), and Olive tail moment (OTM). DNA damages of root tips of Vicia faba increased after Cd treatment and there were dose-related increases in DNA damage measured as these parameters. However, the addition of imidacloprid further increased the DNA damage. These data confirmed the genotoxic effect of Cd to plants, and that the combined pollution with imidacloprid can enhance the genotoxicity of Cd.     

Sulfate is transported at significant rates through the symbiosome membrane and is crucial for nitrogenase biosynthesis

Legume–rhizobia symbioses play a major role in food production for an ever growing human population. In this symbiosis, dinitrogen is reduced (“fixed”) to ammonia by the rhizobial nitrogenase enzyme complex and is secreted to the plant host cells, whereas dicarboxylic acids derived from photosynthetically produced sucrose are transported into the symbiosomes and serve as respiratory substrates for the bacteroids. The symbiosome membrane contains high levels of SST1 protein, a sulfate transporter. Sulfate is an essential nutrient for all living organisms, but its importance for symbiotic nitrogen fixation and nodule metabolism has long been underestimated. Using chemical imaging, we demonstrate that the bacteroids take up 20‐fold more sulfate than the nodule host cells. Furthermore, we show that nitrogenase biosynthesis relies on high levels of imported sulfate, making sulfur as essential as carbon for the regulation and functioning of symbiotic nitrogen fixation. Our findings thus establish the importance of sulfate and its active transport for the plant–microbe interaction that is most relevant for agriculture and soil fertility.     

A Framework for Development and Communication of Absolute Environmental Sustainability Assessment Methods

An absolute environmental sustainability assessment (AESA) addresses whether a production or consumption activity can be considered environmentally sustainable in an absolute sense. This involves a comparison of its environmental pressure to its allocated environmental carrying capacity. AESA methods have been developed in multiple academic fields, each using their own set of concepts and terms with little communication across the fields. A recent growing interest in using AESA methods for decision support calls for a better common understanding of the constituents of an AESA method and how it can be communicated to scientific peers and to potential users. With this aim, we develop a framework for AESA methods, composed of a succession of four assessment steps and involving six methodological choices that must be made by the method developer or the user. We then use the framework to analyze and compare five selected AESA methods that focus on the release of phosphorus and nitrogen to the environment. In this manner, we show that the framework is able to systematically differentiate AESA methods that initially appear to be similar. Intended users of the framework include (1) method developers communicating new AESA methods to academic peers or potential method users and (2) researchers comparing a group of existing AESA methods and communicating their differences to their peers and to potential users looking for guidance on method selection.