江苏省农户秸秆还田的影响因素分析

农户秸秆还田不仅有利于土壤有机质的增加,实现耕地的可持续利用,而且在发挥我国农田土壤固碳潜力,积极应对气候变化方面具有重要意义.文章以江苏省农户调查数据为基础,建立Logistic模型,对影响农户秸秆还田的因素进行分析,以期为制定促进农户秸秆还田的政策提供科学依据.结果表明,不同地区农户对于秸秆还田的决策存在差异:在较为发达地区,秸秆还田与否,农户更多的是从秸秆处理的边际成本出发;而略欠发达地区,则主要是基于秸秆的利用效益.此外,技术因素也影响农户秸秆还田的行为决策.在制定促进秸秆还田技术应用的激励政策时,要充分考虑地区农业生产以及农户生产经营的基本特征及差异,因地制宜,有效地促进秸秆还田在各地区最大限度地被应用和推广.     

茂名小良桉树人工林生态经济效益分析与评价

利用模糊数学的方法,通过对小良的实地调杳和专家走访,挑选了30个对小良桉林生态经济影响较大的因子.建立了评价因子指标体系和五个评价等级,采用二个层次的综合评价模型对小良桉林生态经济效益首次进行了定量的综合评价.评价结果是:现在小良桉林生态经济效益为一般.总体态势是:16%为好,26%为较好,31%为一般.23%为较差,4%为差.综合评价得分为79.85分,介于一般和良好之间,这说明在小良桉树人工林的发展过程中存在许多显性的、潜在的问题,如果还不注意合理利用林地资源,就会使森林资源变为不可更新资源,不可持续利用.因此,科学客观地分析与评价小良桉林产业生态经济效益,为区域可持续发展提供科学依据和发展良策,实现生态和经济的综合调控具有现实意义.     

Simulating soil organic matter with CQESTR (v. 2.0): Model description and validation against long-term experiments across North America

Soil carbon (C) models are important tools for examining complex interactions between climate, crop and soil management practices, and to evaluate the long-term effects of management practices on C-storage potential in soils. CQESTR is a process-based carbon balance model that relates crop residue additions and crop and soil management to soil organic matter (SOM) accretion or loss. This model was developed for national use in U.S and calibrated initially in the Pacific Northwest. Our objectives were: (i) to revise the model, making it more applicable for wider geographic areas including potential international application, by modifying the thermal effect and incorporating soil texture and drainage effects, and (ii) to recalibrate and validate it for an extended range of soil properties and climate conditions. The current version of CQESTR (v. 2.0) is presented with the algorithms necessary to simulate SOM at field scale. Input data for SOM calculation include crop rotation, aboveground and belowground biomass additions, tillage, weather, and the nitrogen content of crop residues and any organic amendments. The model was validated with long-term data from across North America. Regression analysis of 306 pairs of predicted and measured SOM data under diverse climate, soil texture and drainage classes, and agronomic practices at 13 agricultural sites having a range of SOM (7.3–57.9 g SOM kg⁻¹), resulted in a linear relationship with an r² of 0.95 (P < 0.0001) and a 95% confidence interval of 4.3 g SOM kg⁻¹. Using the same data the version 1.0 of CQESTR had an r² of 0.71 with a 95% confidence interval of 5.5 g SOM kg⁻¹. The model can be used as a tool to predict and evaluate SOM changes from various management practices and offers the potential to estimate C accretion required for C credits.     

氨基酸对烷烃降解菌GS3C降解性能的影响

从广州石油化工总厂污水处理站旁的油泥混合物中分离筛选得到一株烷烃降解菌GS3C,从生理生化及16S rDNA基因扩增测序等方面进行了鉴定,并在振荡好氧培养条件下研究该菌的降解性能及酵母浸膏、碳源、氮源、维生素、水解酪蛋白等营养物对其降解的影响,同时考察不同氨基酸对降解的影响. 结果表明,该菌的16S rDNA基因扩增序列与Burkholderia cepacia的同源性为97%,初步断定该菌株属于洋葱伯克霍尔德氏菌(Burkholderia cepacia),酵母浸膏能促进其对正十六烷的降解,其主要因素为氨基酸对降解的促进作用. 谷氨酸、脯氨酸、赖氨酸、缬氨酸及亮氨酸的混合物对降解菌GS3C的代谢促进作用最好,其中赖氨酸与脯氨酸为关键的2种氨基酸.      

Use of thermal analysis techniques (TG-DSC) for the characterization of diverse organic municipal waste streams to predict biological stability prior to land application

The use of organic municipal wastes as soil amendments is an increasing practice that can divert significant amounts of waste from landfill, and provides a potential source of nutrients and organic matter to ameliorate degraded soils. Due to the high heterogeneity of organic municipal waste streams, it is difficult to rapidly and cost-effectively establish their suitability as soil amendments using a single method. Thermal analysis has been proposed as an evolving technique to assess the stability and composition of the organic matter present in these wastes. In this study, three different organic municipal waste streams (i.e., a municipal waste compost (MC), a composted sewage sludge (CS) and a thermally dried sewage sludge (TS)) were characterized using conventional and thermal methods. The conventional methods used to test organic matter stability included laboratory incubation with measurement of respired C, and spectroscopic methods to characterize chemical composition. Carbon mineralization was measured during a 90-day incubation, and samples before and after incubation were analyzed by chemical (elemental analysis) and spectroscopic (infrared and nuclear magnetic resonance) methods. Results were compared with those obtained by thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. Total amounts of CO₂ respired indicated that the organic matter in the TS was the least stable, while that in the CS was the most stable. This was confirmed by changes detected with the spectroscopic methods in the composition of the organic wastes due to C mineralization. Differences were especially pronounced for TS, which showed a remarkable loss of aliphatic and proteinaceous compounds during the incubation process. TG, and especially DSC analysis, clearly reflected these differences between the three organic wastes before and after the incubation. Furthermore, the calculated energy density, which represents the energy available per unit of organic matter, showed a strong correlation with cumulative respiration. Results obtained support the hypothesis of a potential link between the thermal and biological stability of the studied organic materials, and consequently the ability of thermal analysis to characterize the maturity of municipal organic wastes and composts.     

35kV并联电抗器工频电磁场分布特性研究

针对500kV变电站内产生较高工频磁场强度的电气设备——35kV并联电抗器,研究不同类型、不同排列方式下35kV并联电抗器周围工频电磁场分布规律。结果表明,35kV并联电抗器的电磁场强度随着离开电抗器中心距离的增加而降低,三角形排列的电抗器磁场强度大于水平排列的。     

冷轧乳化液废水处理试验研究

对武钢冷轧乳化液废水采用超滤和氧化破乳法进行对比试验,从试验运行效果、投资费用、运行成本等方面进行了比较分析,得出处理冷轧乳化液废水的最佳方法－超滤法。对冶金行业乳化液废水的处理具有一定的参考价值。     

Integrating Nonindigenous Aquatic Plant Control with Protection of Snail Kite Nests in Florida

The endangered snail kite (Rostrhamus sociabilis) feeds primarily on the freshwater apple snail (Pomacea paludosa) in Florida. The nonindigenous, floating water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) impede kites from finding snails. Effective control of these aquatic plants in the littoral zone of central and south Florida lakes benefits kites by maintaining open foraging habitat. However, incidental herbicide spraying of nesting substrates result in nest collapse when kites breed in nonwoody, emergent plants [cattail (Typha spp.) and giant bulrush (Scirpus validus)] in the outer littoral zone during lower lake levels. Many endangered species recovery plans and their implementation have experienced problems due to inaction and/or noncooperation by various governmental agencies and their personnel. Herein, we describe the development and implementation of a buffer zone strategy to prevent secondary impacts from an aquatic plant control program to snail kites nesting on lakes in central and south Florida. A strategy was jointly developed by personnel of five state and federal agencies to control herbicide application near kite nesting areas during the normal breeding season. Although requiring various modifications during its implementation, this cooperative effort successfully integrated aquatic plant control objectives with snail kite conservation on Lake Okeechobee during 1988. The program was expanded the following year to lakes Kissimmee and Tohopekaliga. Since the implementation of the snail kite impact preclusion program, no nest loss was attributed to incidental herbicide applications on lakes Okeechobee, Kissimmee, and Tohopekaliga.     

环境微塑料与有机污染物的相互作用及联合毒性效应研究进展

环境微塑料可吸附有机污染物,并与有机污染物进行相互作用从而改变其毒性效应,增加微塑料的治理难度.本文就全球范围内微塑料与有机污染物的相互作用及毒性效应的研究进展进行综述,分析不同介质中微塑料与有机污染物的共存水平、吸附机理、影响因素以及联合毒性效应等.研究表明,微塑料可作为多环芳烃(PAHs)、多氯联苯(PCBs)、六...     

Adsorption/Desorption of Polyvinyl Alcohol on Solid Substrates and Relevant Biodegradation

The rates and extents of absorption and desorption of polyvinyl alcohol (PVA) samples on different solid substrates comprising montmorillonite, quartz sand, and farm soil, as well as humic acid mixture are reported. The uptake of PVA by the substrates was analyzed as a function of PVA hydrolysis (72–98%), molecular weight, and molecular weight distribution. Higher adsorption was detected on montmorillonite followed by farm soil, whereas the quartz sand did not display any specific adsorption affinity for the PVA. An increase in the hydrolysis degree of PVA increased the adsorption rate and extent whereas this feature was reversed by an increase in PVA molecular weight. The desorption of PVA samples from the different substrates was performed both under various pH conditions and in the presence of concentrated HF that was used to dissolve the silicon derivatives present in the substrates. Biodegradation experiments carried out in liquid cultures of PVA adsorbed on montmorillonite showed that the mineralization of the adsorbed PVA was much lower than that detected for the nonadsorbed PVA. This investigation suggests that irreversible adsorption of PVA on the clay component occurs in soil, thus substantially inhibiting PVA biodegradation.