Impact of global warming on agricultural product markets: stochastic world food model analysis

Climatic change through global warming and drought is a major issue for agricultural production. Most researchers who discuss the effects of such changes on agriculture report estimated yield changes based on crop process models. However, studies focusing on the impact of climatic change on agricultural product markets are very rare. This paper examines the relationship between climatic change and world food markets, i.e., the supply and demand of crops, by using a stochastic version of a world food model, the International Food and Agricultural Policy Simulation Model. The results suggest that variations in the production of maize and soybeans in some major producing countries will be large, and variations in the producer prices of all crops will increase. Countries that suffer higher price risk because of high sensitivity to temperature fluctuations may need to consider changes in cropping patterns.     

Effect of additives in the Neem formulations on deposition,volatilization and persistence of Azadirachtin in spruce foliage

Abstract

Foliar deposits, volatilization and persistence of azadirachtin‐A (AZ‐A) were investigated after application of four spray mixes prepared from a wettable powder (WP) and three emulsifiable concentrate (EC) formulations of neem. They were applied at the dosage rate of 50 g AI in 4 L/ha onto potted spruce seedlings in a laboratory spray chamber. Droplet‐size spectra and deposits were assessed using Kromekote^® card/glass plate collection units. Foliar residues [dislodgeable residues (DR), penetrated residues (PR) and total residues (TR)] of AZ‐A and their volatilization were measured by HPLC at different intervals of time up to 60 h after treatment. Differences in the droplet‐size spectra and deposit levels were observed among the four spray mixes due to the influence of additives present in them. Dissipation half‐lives (DT₅₀) of the DR, PR and TR in the foliage were low (range, 19.5 to 38.9 h) and varied according to the residue type and the spray mix used. The DT₅₀ values of the DR were consistently lower (range, 19.5 to 31.9 h) than those of the PR (range, 30.5 to 38.9 h) due to preferential loss of the surface residues. The low DT₅₀ values observed for the DR and TR in the foliage sprayed with the WP spray mix were attributed to the particulate nature of the deposit. AZ‐A volatilized appreciably from the DR rather than from the PR. The variations found in the amounts of AZ‐A volatilized (42 to 58%) and unaccountable (38 to 46%) from the initial TR values in spruce foliage, after 60 h, were attributed to the physical form of the deposits on the target surface and the influences of additives present in the different spray mixes.     

Hemoglobin (Hb) immobilized on amino-modified magnetic nanoparticles for the catalytic removal of bisphenol A

Catalytic removal of bisphenol A from aqueous solution with hemoglobin immobilized on amino-modified magnetic nanoparticles as an enzyme catalyst was reported. The amino-modified magnetite nanoparticles were firstly prepared by the coprecipitation of Fe²⁺ and Fe³⁺ with NH₃·H₂O and then modified by 3-aminopropyltriethoxysilane. The immobilization process was optimized by examining enzyme concentration, glutaraldehyde concentration, cross-link time, and immobilization time. The optimum conditions for the removal of bisphenol A with immobilized hemoglobin were also investigated. Under the optimality conditions, the removal efficiency of bisphenol A was about 80.3%. The immobilization had a beneficial effect on the stability of hemoglobin and conversions of bisphenol A. According to the proposed breakdown pathway and the intermediates, the enzyme-catalytic removal of bisphenol A by the immobilized hemoglobin is considered to be an effective method.     

Sorption of 17α-ethinyl estradiol, bisphenol A and phenanthrene to different size fractions of soil and sediment

The potential for negative effects caused by endocrine disrupting chemicals (EDCs) release into the environment is a prominent concern and numerous research projects have investigated possible environmental fate and toxicity. However, their sorption behavior by size fractions of soil and sediment has not been systematically represented. The sorption of bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and phenanthrene (Phen) by different size fractions of soil and sediment were investigated. Sorption isotherms of EE2, BPA, and Phen by size fractions of soil (SL) and sediment (ST) were well fitted to the Freundlich model. The positive correlation between EE2, BPA and Phen sorption capacity (log K_d) of size fractions and their organic carbon (OC) content suggests that OC of size fractions in SL and ST should regulate sorption, while the surface area (SA) of size fractions may not account for sorption of EE2, BPA and Phen. Each size fraction of ST had higher sorption capacity (K_d or K_OC) of EE2 and BPA than that of SL due to their difference in the polarity of organic matter (OM) between terrestrial and aquatic sources. Sorption capacity logK_d for size fractions of SL and ST did not follow the order: clay > silt > sand due to the difference in OM abundance and composition between the size fractions. Large particle fractions of ST contributed about 80% to the overall sorption for any EE2, BPA, and Phen. This study was significant to evaluate size fractions of soil and sediment as well as their associated OM affecting EE2 and BPA sorption processes.     

超声波／零价铁降解水中双酚A

研究了超声波／零价铁（US／Fe^0）工艺对水中双酚A（BPA）的降解效果及影响因素。结果表明，US／Fe^0工艺可以有效降解水中的BPA，具有协同作用，且降解过程符合一级动力学规律；Fe^0具有促进和抑制的双重作用；超声功率越大，越有利于BPA的降解；初始浓度较低时，BPA的降解效果较好；弱酸性条件有利于BPA的降解；加入一定量的自由基捕获剂（正丁醇）可以抑制BPA的降解；联合作用2h后，TOC的去除率较低，说明其矿化程度不完全。     

低C/N比老龄化垃圾渗滤液处理工程的提标改造

采用两级厌氧好氧活性污泥法(A/O)与活性污泥浸没式膜生物反应器(AS-SMBR)结合的生化处理系统和纳滤(NF)深度处理系统,处理BOD5/NH3-N比为0.13～0.22,BOD5/COD比仅0.11左右的老龄化垃圾渗滤液。在水力停留时间不变的条件下,采用同步培养驯化法,控制生化系统DO值在3～4 mg/L,回流比为400%～500%,pH≥7.2,考察了处理系统对垃圾渗滤液中主要污染物的去除情况和MLSS、pH和SV30等运行指标的变化情况,结果表明,生化系统出水的NH3-N去除率>99%,COD平均去除率>50%;NF系统出水的COD去除率≥91%,NH3-N浓度<8 mg/L,且回收率≥75%,出水完全达到GB16889-2008标准中表2的污染物浓度限值和提标改造的要求。     

沸石强化A/O生物脱氮工艺氨氮去除机理研究

沸石强化A/O生物脱氮实验研究表明,沸石对配水氨氮具有良好的吸附性能,其吸附特征可以通过Frend lich和Langmu ir吸附等温线表征,但对污水中氨氮的吸附较配水吸附要复杂。由于沸石能与微生物构成沸石-生物复合体,从而增加了系统的硝化细菌和反硝化细菌数量,改善了A段的反硝化作用和O段的硝化作用。吸附饱和的铵沸石在硝化细菌和电导率的协同作用下,经好氧曝气4.5 h,能再生69.8%。在A段,进水氨氮浓度较高,沸石吸附氨氮,提高污水碳氮比,促进生物反硝化;进入O段,在盐度和微生物的协同作用下,混合液氨氮浓度因为生物降解而逐渐降低,不断打破铵沸石的吸附-脱附平衡,铵沸石不断释放氨氮而得到充分的再生。     

分段进水A/O工艺流量分配方法与策略研究

分段进水缺氧/好氧(A/O)工艺是一种高效的污水生物脱氮工艺。但原水多点投配给该工艺带来诸多好处的同时, 也为其优化运行带来一定困难。其中,可行的流量分配方法的建立是分段进水工艺发挥其优势并高效运行的瓶颈问题。提出3种不同的流量分配方法并进行相应的理论分析: (1) 采用等负荷流量分配法,其遵循的原则是保证各段硝化菌负荷相同, 以利于硝化菌生长,优先满足系统硝化, 最大程度地降低出水氨氮浓度; (2)采用流量分配系数， 原则是各缺氧段进水有机物质恰好可以为上段好氧区产生的硝酸盐氮反硝化提供充足的电子供体。 利用该方法可以充分利用原水中碳源,发挥缺氧区反硝化潜力,并保证最后一段进水量最少, 降低出水硝酸盐氮含量; (3)末端集中进水，用于暴雨等产生洪峰流量时, 将进水点向系统末端移动, 并加大末端进水量, 以减小二沉池固体负荷, 避免污泥冲刷流失。3种流量分配方法的提出,可以应对水厂不同的进水水质和出水要求,增强分段进水A/O生物脱氮工艺的实际可操作性,提高处理效率,为目前采用分段进水A/O工艺的污水厂的优化运行管理提供可靠的理论借鉴。     

A股市场环保脱硫类上市公司经营情况分析

分析对比了国内A股市场环保脱硫类上市公司的经营情况,包括市场占有率、业务收入、实现利润、集团综合收入结构、业务成本结构等。