Electrosynthesis of κ-Carrageenan Complexes with Gelatin

Electrosynthesis at pH 9, 12, and 11 of -carrageenan–gelatin complexes from electrolytes containing the components at proportions varying from 1:5 to 5:1 provided complexes in the composition varying in a range from 1:10 to 1:1.8. Components were bound mainly electrostatically, although partial insolubility of complexes in 7 M aqueous urea pointed to a part of the complexes bound covalently. None of the performed tests except solubility could confirm formation of covalent complexes. The complexation of -carrageenan to gelatin significantly increased the thermal stability of carrageenan, whereas the thermal stability of gelatin increased rather insignificantly.     

中小型水泥厂大气污染防治初探

根据机械化立窑水泥生产工艺和设备的特声、，分析中小型水泥厂大气污染的因素和污染防治措施，供环境影响评价和环保工程设计参考．     

重庆的国家重点保护植物研究

基于《中国植物红皮书》第一、二册名录，重庆有国家重点保护植物７７种，隶属于４７科，７１属。根据第一批公布的国家重点保护植物，重庆有５２种４９属３２科；其中一级５种，二级２４种，三级２３种，濒危６种，稀有２１种，渐危２５种。水平分布有三个中心，即大巴山南缘地区、武陵山区、大娄山北缘地区。论文最后提出了珍稀濒危植物的保护措施。     

清河电厂河滩灰场植被重建技术的研究

阐述了电厂灰场植被覆盖技术的原理、实施方案和主要效益     

NTA和DTPA对小麦幼苗对金属吸收的诱导效应

通过盆栽试验和化学提取实验研究了有机配体NTA和DTPA对小麦对沙土中外源重金属Cd,Cu,Pb和Zn的吸收的影响.研究表明,在所试验的土壤金属浓度下,有机配体NTA和DTPA的添加均明显导致小麦幼苗中金属Cu,Zn,Cd和Pb富集量的增加,且DTPA的作用效果高于NTA.10mmol·kg-1DTPA作用效果高于5mmol·kg-1DTPA,但提高程度有限.NTA处理组各金属14 d茎叶富集系数高于7 d茎叶富集系数.对于不同金属,DTPA的作用导致小麦幼苗茎叶富集系数随时间变化的规律不同.5mmol·kg-1NTA,5mmol·kg-1DTPA和10mmol·kg-1DTPA的添加明显导致土壤中4种外源金属的0.01 mol·L-1CaCl2提取态含量的增加.小麦茎叶重金属富集量与0.01mol·L-1CaCl2提取态金属含量具有较好的相关性,说明配体NTA和DTPA的添加导致小麦幼苗对4种金属的富集量的增加是与其导致0.01 mol·L-1CaCl2提取态含量的增加是密切相关的.     

植被对恢复卫生填埋场环境的作用

卫生填埋是目前我国城市生活垃圾处置的主要手段，以城市生活垃圾主要成份的卫生填埋汤，由于来源广，成份复杂，含有大量的易腐有机物和带病原菌的污染物，不可避免地给填埋场周边环境带来一定影响，有些甚至是较严重的影响。     

Environmental variability and allocation trade-offs maintain species diversity in a process-based model of succulent plant communities

Ecological theory suggests that environmental variability can promote coexistence, provided that species occupy differential niches. In this study, we focus on two questions: (1) Do allocation trade-offs provide a sufficient basis for niche differentiation in succulent plant communities? (2) What is the relative importance of different forms of environmental variability on species diversity and community composition? We approach these questions with a generic, individual-based simulation model. In our model, plants compete for water in a spatially explicit environment. Species differ in their size at maturity and in the allocation of carbon to roots, leaves and storage tissue. The model was fully specified with independent literature data. Model output was compared to characteristics of a species-rich community in the semi-arid Richtersveld (South Africa). The model reproduced the coexistence of plants with different sizes at maturity, the dominance of succulent shrubs, and the level of vegetation cover. We analyzed the effects of three forms of environmental variability: (a) temporal fluctuations in precipitation (rain and fog), (b) spatial heterogeneity of water supply due to run-on and run-off processes and (c) ‘rock pockets’ that limit root competition in space. The three types of variability had differential effects on diversity: diversity exhibited a strong hump-shaped response to temporal variation. Spatial variability increased diversity, with the strongest increase occurring at intermediate levels of temporal variability. Finally, rock pockets had the weakest effect, but contributed to diversity by providing refuges for small species, particularly at low temporal variability. The model thus shows that spatio-temporal variation of resource supply can maintain diversity over long time scales even in small systems, as is the case in the Richtersveld succulent communities. Trade-offs in allocation provide the basis for necessary niche differentiation. By describing resource competition between individual plants, our model provides a mechanistic basis for the link from species traits to community composition at given environmental conditions. It thereby contributes to an understanding of the forces shaping plant communities. Such an understanding is critical to reduce the threats environmental change poses to biodiversity and ecosystem services.     

Using native plants as problem-solvers

The Federal Highway Administration encourages state highway agencies to use native plants in erosion control, revegetation, and landscaping solutions. This paper explains both policy reasons and technical reasons for the use of native plants. How native species can be used is shown through a roadside case study. Other applications of native plant use will be explained through a plant community approach.     

REGIONAL SEWERING AND GROUNDWATER QUALITY IN THE SOUTHERN SAN JOAQUIN VALLEY1

ABSTRACT: Sewage effluent is commonly disposed of on land in arid regions, and the majority usually recharges the groundwater. Few evaluations have been made of the effect of effluent disposal on groundwater quality in the west. Groundwater hydrologists are rarely involved with treatment plant design and operation or effluent disposal in the San Joaquin Valley, California. The author's purpose is to evaluate the effect of regional sewering programs on groundwater quality in this valley. Research was conducted on past studies of sewage effluent disposal. An extensive water sampling program was undertaken near the Fresno Sewage Treatment Plant. Chloride contents were used to trace recharged effluent. The extent of recharged effluent was delineated and traced for about ten miles. Sampling between the plant and the urban Fresno area indicated a high probability of large-scale leakage of raw sewage into the groundwater.     

Sources of variability in plant toxicity testing

Published literature is investigated regarding the response of plants to various substances to determine the sensitivity of agricultural plants versus other species, the similarity of effects seen at different taxonomic levels, sensitivity of plants growing outdoors versus in a greenhouse, and the sensitivity of different measurement endpoints. We find that agricultural species are not consistently more or less sensitive to the herbicides tested than non-crop species. Genus and family taxonomic groupings may show similar responses among species, but this similarity quickly decreases as the comparison progress between orders and classes. Results from field and greenhouse studies are less in agreement between studies than data from the other topics. Shoot length will be affected at concentrations lower than for other vegetative endpoints for most species tested for inorganic substances, but for organic substances root and shoot mass were more sensitive. Overall, there is no one species or endpoint that is consistently the most sensitive for all species or all chemicals in all soils, and differences in bioavailability among compounds may confound comparison of test results. Therefore, species sensitivity distributions, adjusted for bioavailability when possible, should be considered in order to better evaluate effects to non-target terrestrial plants.