NaCl胁迫对高粱成熟叶质外体和共质体中Na~ 、Ca~(2 )浓度的影响

在c（NaCl）＝200mmol／L，t＝14d胁迫条件下，盐敏感品种糖高粱（T）成熟叶生长抑制、含水量的下降和质膜透性均明显大于耐盐品种独角虎（D）；盐胁迫下，质外体和共质体中Na＋浓度明显增加，增加的幅度是质外体大于共质体，T大于D．相反，盐胁迫下质外体和共质体Ca2＋浓度均明显下降，研究结果表明：质外体Na＋浓度剧增并没有改变细胞膨压，而可能通过取代质膜上Ca2＋而破坏质膜选择透性，从而引发盐害     

湘南水田施含SO_4~(2-)和Cl~-肥料对作物生长和养分吸收的效应

1990年4—11月,在湖南祁阳中国农科院红壤实验站布置田间试验,比较含SO_4~(2-)和Cl~ -类肥料对作物生长的效应。结果表明,SO_4~(2-)促进早稻和晚稻营养生长,但水稻收获时的稻谷产量以Cl~-肥料处理区较高。两种阴离子对水稻养分吸收无显著差异,但SO_4~(2-)对早稻体内的磷素转化不利,可能是稻谷产量较低的原因之一。     

北京城近郊区园林绿地多目标规划

北京市城近郊区人口密集,经济活动频繁,作为改善城市空气质量的重要环境资源之一,园林绿地提供了不可或缺的生态服务功能。针对研究区降尘大、SO_2浓度高以及生产生活耗氧量大等主要环境问题,以满足城市居民环境质量基本要求为目标,通过一系列决策变量与约束条件的设定,建立起北京城近郊区园林绿地多目标线性规划模型。应用Lingo 8．0软件对规划模型求解,结果表明,规划期(2020年)不同种类园林绿地面积分配较基期(2000年)更为合理,强调通过乔灌草相结合提高园林绿地整体生态服务功能,为北京建设生态城市提供了规划依据。     

渤海海水淡化反渗透法的预处理工艺

采用“消毒-混凝-澄清一砂滤”、“消毒-混凝-澄清-砂滤-超滤”以及“消毒-砂滤-超滤”三套海水淡化预处理工艺进行了试验对比。试验的目的在于获取可行的反渗透预处理工艺。表明,采用“消毒-混凝-澄清-砂滤-超滤”工艺或“消毒-砂滤-超滤”工艺是技术可行的反渗透预处理工艺,其中次氯酸钠为可选消毒剂,三氯化铁为较好的混凝剂,而超滤是不可或缺的单元处理工艺。     

应用灰色系统理论预测土壤酸化趋势

本文以各组分组成的土壤酸中和容量动态变化作为指标,用灰色系统控制理论对酸雨引起南方土壤的酸化趋势进行定量的预测分析。     

印钞擦版废液的处理技术

综述了印钞擦版废液的主要处理技术 ,包括中和法、絮凝法、生物法和超滤法 ;并阐述各种方法处理印钞擦版废液过程中存在的主要问题。     

好氧颗粒污泥处理高浓度氨氮废水的研究

在不同接种源污泥颗粒化过程中污泥理化性状对比研究的基础上,采用成熟好氧颗粒污泥处理高浓度氨氮废水,对其脱氮行为以及不同C/N条件下好氧颗粒污泥微生物的比耗氧速率、好氧颗粒污泥对氨氮的比降解速率随时间的变化等进行了研究.实验结果表明,在进水氨氮质量浓度较高(480 mg/L)、温度30℃左右的条件下,稳定运行15 d,氨氮的去除率维持在85%左右;进水氨氮的浓度越高,随着微生物对环境的逐渐适应,硝化菌的活性也逐步增加;随着进水氨氮浓度的提高,好氧颗粒污泥对氨氮的比降解速率也逐渐上升.     

Axi-symmetric simulation of soil vapor extraction influenced by soil fracturing

Fracturing, either pneumatic or hydraulic, is a method to improve the performance of soil vapor extraction (SVE) in relatively low permeability soils (< 10(-5) cm/s). A two-dimensional model is presented to simulate trichloroethylene (TCE) soil vapor extraction modified by fracturing. Flow and transport is modeled using mobile macropore and micropore networks, which also have been identified in the literature as dual porosity, dual permeability, or heterogeneous flow models. In this model, fluids can flow in both the macropore and micropore networks. This represents a more general model compared to immobile micropore, mobile macropore models presented thus far in the literature for vapor flow and transport in two dimensions. The model considers pressure- and concentration-driven exchange between the macropore and micropore networks, concentration-driven exchange between the gas and sorbed phases within each network, and equilibrium exchange between the gas and water and a sorbed phase within each network. The parameters employed in an example simulation are based on field measurements made at a fractured site. Considered in the simulations were the influence of the volume percentage of fractures, the length of fractures, the relative location of the water table, and the influence of pulsed pumping. For these simulations, internetwork concentration-driven exchange most significantly affected mass removal. The volume percentage of fractures more significantly influence flow and mass removal than the length of fractures. The depth of the water table below the contamination plume only significantly influenced flow and mass removal when the water table was within 60 cm of the bottom of the contaminated soil in the vadose zone for the parameters considered in this study. Pulsed pumping was not found to increase the amount of mass removed in this study.     

Preparation and investigation of poly(methylmethacrylate) nano-capsules containing haloxyfop-R-methyl and their release behavior

Abstract

In this study, the preparation and characterization of haloxyfop-R-methyl herbicide loaded in poly(methylmethacrylate) (PMMA) nano-capsules by emulsion polymerization and its release behavior were investigated. The chemical characterizations of PMMA/haloxyfop-R-methyl nano-capsules were confirmed by FT-IR spectroscopy method, and the surface morphology was studied by field emission scanning electron microscopy and transmission electron microscopy. Also, the herbicide loading and encapsulation efficiency were analyzed for the herbicide-loaded nano-capsules. The release rate of PMMA/haloxyfop-R-methyl nano-capsules was determined by UV-visible spectroscopy. The thermal properties and thermal stability of nano-capsules were explored by the thermal gravimetric analysis method. The diameter of the nano-capsules was in the range of 100–300?nm. Increasing the amount of herbicide in nano-formulations significantly affected the surface of the nano-capsules and reduced their surface smoothness. Triton-X100 was identified as the best surfactant for the preparation of nano-capsules, and the sample containing the lowest herbicide content showed the best performance in terms of encapsulation and loading efficiency. This sample showed a steady-state release rate during the six days.     

Dendroremediation of trinitrotoluene (TNT) Part 2: Fate of radio-labelled TNT in trees

BACKGROUND, AIM AND SCOPE: Problems of long-term existence of the environmental contaminant 2,4,6-trinitrotoluene (TNT) and necessities for the use of trees ('dendroremediation') in sustainable phytoremediation strategies for TNT are described in the first part of this paper. Aims of the second part are estimation of [14C]-TNT uptake, localisation of TNT-derived radioactivity in mature tree tissues, and the determination of the degree of TNT-degradation during dendroremediation processes. METHODS: Four-year-old trees of hybrid willow (Salix spec., clone EW-20) and of Norway spruce (Picea abies) were cultivated in sand or ammunition plant soil (AP-soil) in wick supplied growth vessels. Trees were exposed to a single pulse application with water solved [U-14C]-TNT reaching a calculated initial concentration of 5.2 mg TNT per kg dry soil. Two months after application overall radioactivity and extractability of 14C were determined in sand/soil, roots, stem-wood, stem-bark, branches, leaves, needles, and Picea May sprouts. Root extracts were analysed by radio TLC. RESULTS: 60 days after [14C]-TNT application, recovered 14C is accumulated in roots (70% for sand variants, 34% for AP-soil variant). 15-28% of 14C remained in sand and 61% in AP-soil. 3.3 to 14.4% of 14C were located in aboveground tree portions. Above-ground distribution of 14C differed considerably between the angiosperm Salix and the gymnosperm Picea. In Salix, nearly half of above-ground-14C was detected in bark-free wood, whereas in Picea older needles contained most of the above-ground-14C (54-69%). TNT was readily transformed in tree tissue. Approximately 80% of 14C was non-extractably bound in roots, stems, wood, and leaves or needles. Only quantitatively less important stem-bark of Salix and Picea and May shoots of Picea showed higher extraction yields (up to 56%). DISCUSSION: Pulse application of [14C]-TNT provided evidence for the first time that after TNT-exposure, in tree root extracts, no TNT and none of the known metabolites, mono-amino-dinitrotoluenes (ADNT), diaminonitrotoluenes (DANT), trinitrobenzene (TNB) and no dinitrotoluenes (DNTs) were present. Extractable portions of 14C were small and contained at least three unknown metabolites (or groups) for Salix. In Picea, four extractable metabolites (or groups) were detected, where only one metabolite (or group) seemed to be identical for Salix and Picea. All unknown extractables were of a very polar nature. CONCLUSIONS: Results of complete TNT-transformation in trees explain some of our previous findings with 'cold analytics', where no TNT and no ADNT-metabolites could be found in tissues of TNT-exposed Salix and Populus clones. It is concluded that 'cold' tissue analysis of tree organs is not suited for quantitative success control of phytoremediation in situ. RECOMMENDATIONS AND OUTLOOK: Both short rotation Salicaceae trees and conifer forests possess a dendroremediation potential for TNT polluted soils. The degradation capacity and the large biomass of adult forest trees with their woody compartments of roots and stems may be utilized for detoxification of soil xenobiotics.