考虑轮换更新的应急物资政企协同预置储备优化研究

为解决具有轮换更新环节的应急物资政企协同预置储备优化问题,探讨轮换更新环节中的操作过程及成本构成,构建轮换更新费用的应急物资政企协同预置储备优化模型,并以美国东南部墨西哥湾飓风灾害为背景设计3组数值算例,采用Python语言编码模型并调用Gurobi求解器的方式进行算例优化求解。研究结果表明：合同期内,应急物资的轮换更新次数无论多少,需要支出的差价(折旧)补贴普遍较高;轮换更新频次不会影响库存维持成本,但会影响储备库与企业的协同关系。     

城郊稻田生态系统高效生产模式的研究与评价

根据天津市宝坻区的自然条件、区位优势和现有的农业种植结构,提出了稻藕轮作与稻鱼蟹混养相结合的高效生产模式并分析其生态优势。借助Ecopath软件,从系统可持续性和净产值角度,比较分析了稻鱼蟹混养与稻藕轮作相结合生产模式与稻田养鱼、稻田养蟹、稻鱼蟹混养、单一种稻4种稻田生产模式的优劣。结果表明:5种稻田生产模式F inn′s指数值从大到小依次为稻鱼蟹混养与稻藕轮作相结合、稻田养鱼、稻田养蟹、稻鱼蟹混养和单一种稻;稻鱼蟹混养与稻藕轮作相结合生产模式的可持续性指标优于其他3种生态种植模式,其净生产力、生物量/输出量、输出量/输入量和稳定性指标分别是单一种稻模式的2.63、4.25、2.03和3.56倍;与其他4种稻田生产模式相比,稻鱼蟹混养与稻藕轮作相结合模式的净产值很高,是适合于在北方推广的最优生态种植模式。     

华北平原冬小麦-夏玉米轮作体系氮肥的氨挥发

 利用可多点原位测定氨挥发的风洞系统,监测了华北平原2002～2004年冬小麦-夏玉米轮作体系传统和优化氮肥管理下的氨挥发损失.结果表明,氨挥发主要发生在施肥后2～3周内,以施肥后连续采样15d的氨挥发累积量作为总排放量,相同施氮量下生长季夏玉米的氨挥发大于冬小麦.优化处理的氨挥发平均损失率(35.9%)显著高于传统处理(20.9%),但从氨挥发绝对量上看,传统处理为125.1kgN/hm²,优化处理为42.3kgN/hm²,降幅达66.2%.施肥和灌水方式显著影响氨挥发,撒施碳铵后翻耕的氨挥发损失为10.1%,追肥撒施的氨挥发损失平均为24.6%;撒施尿素后立即灌水,氨挥发损失为19.7%,5h后灌水氨挥发损失为34.0%,增加了72.6%.     

秸秆还田配施化肥对稻-油轮作土壤酶活性及微生物群落结构的影响

秸秆还田是农业生态系统提高土壤肥力和维持作物生产力的有效管理措施.为了研究秸秆还田配施化肥对巢湖地区稻-油轮作农田土壤养分含量、酶活性和微生物群落的影响,开展连续4 a （2016~2020年）的田间定位试验,设置无秸秆+无施肥（CK）、常规施肥（F）、秸秆还田+常规施肥（SF）和秸秆还田+常规施肥减20%（SDF）这4个处理,探究不同处理下影响土壤酶活性与细菌、真菌群落发生变化的关键环境因子.结果表明,秸秆还田配施化肥较常规施肥处理能够提高土壤养分含量,SF处理的土壤养分含量最高.与F相比,SF处理的水稻季土壤有机质（OM）和全磷（TP）含量显著提高了7.94%和24.07%（P<0.05）,油菜季碱解氮（AN）含量显著提高了13.62%（P<0.05）.SF较F处理的土壤磷酸酶和脲酶在水稻季显著提高了28.54%和24.13%,在油菜季显著提高了38.97%和30.70%,而SDF处理的4种土壤酶中仅脲酶活性较F处理显著提高,水稻季和油菜季分别提高了20.31%和24.33%（P<0.05）.秸秆还田对水稻季土壤细菌的Chao1和Shannon指数有所增加,油菜季则有所减少,而对真菌群落的Chao1和Shannon指数均增加.对于微生物群落结构而言,SF和SDF较F处理的变形菌门相对丰度在水稻季分别增加了8.22%和7.88%,油菜季分别增加了18.53%和5.68%.与F相比,SF和SDF处理的绿弯菌门相对丰度在水稻季分别增加了12.00%和11.25%,油菜季分别增加了15.02%和8.43%.水稻季SF和SDF处理的担子菌门较F相比相对丰度显著提高了70%和43.42%（P<0.05）,油菜季SF和SDF处理的子囊菌门与F相比显著提高了69.79%和43.72%（P<0.05）.综上,秸秆还田配施化肥可提高土壤养分含量,土壤脲酶和磷酸酶对秸秆还田的响应更为敏感,稻-油轮作农田土壤的细菌群落构成发生改变主要受土壤TP和速效磷（AP）影响,而土壤OM、AN和pH则是引起真菌群落构成变化的主要环境因子,因而秸秆还田有利于提高农田土壤肥力和维护生态系统健康.     

不同时相急性毒性值的相关性及其应用

本文测试了硫氰酸钠、二甲基甲酰胺、乙腈和丙烯腈等四种石油化工废水中常见污染物对１５种水生生物的急性毒性,以考察不同时刻ＬＣ５０之间的相关性。试验结果表明,２４、４８和７２小时的ＬＣ５０（或ＥＣ５０）与９６小时的ＬＣ５０（或ＥＣ５０）之间存在十分密切的相关关系,在特定情况下可以用２４、４８或７２小时的急性毒性试验结果代替９６小时毒性试验结果,比较污染物的毒性大小,进行污染物结构活性分析,完成短期生物监测。     

Forest loss,monetary compensation,and delayed re-planting: The effects of unpredictable land tenure in China

Over the past 65 years, forest tenure in China has oscillated unpredictably between private and village property regimes. This policy-induced uncertainty has distorted the harvesting decisions of individuals granted rights to grow trees and has lowered the value of China׳s forest output. We provide an analytical framework for assessing these effects quantitatively. Understanding the consequences of this policy-induced uncertainty is particularly important since China is currently engaged in an ambitious plan to increase its domestic supply of timber. To conduct this analysis, we extend the literature on forestry economics when there is a risk of loss due to forest fire or pests. We (1) take account of the possibility that replanting can only resume after an interval of uncertain length (with immediate replanting as a special Case); (2) investigate the effects of compensation for such losses based only on the net value of the stand of trees at the time of the loss; and (3) compare it to compensation that would leave the wealth and rotation decisions of the farmer unaffected by the presence of uncertainty.     

稻-麦轮作模式下不同钝化材料对镉污染农田土壤的原位钝化效应

为明确大田条件下施用钝化材料对镉(Cd)污染农田土壤的原位钝化效应及其持续性,以秸秆生物炭、 YH粉、粉煤灰、海泡石和页岩粉(粒径均<0.2 mm,施用量均为2.25kg·m^-2)这5种钝化材料为研究对象,连续监测3 a稻-麦轮作模式下原位钝化处理对土壤养分、土壤酸碱度、土壤Cd污染状况和种植作物籽粒Cd含量的影响,探讨其钝化效应及持续性,为有效控制农田土壤Cd污染、保证作物安全生产提供理论依据和数据支撑.结果表明：(1)稻-麦轮作模式下,施用5种钝化材料对土壤养分含量影响较小,但均可提高土壤pH,促使土壤Cd由酸提取态向残渣态转化,降低土壤Cd有效性,其中秸秆生物炭与YH粉处理下当季土壤有效Cd含量的降幅最大(20.42%～22.53%),是其它钝化处理的1.07～1.84倍.(2)稻-麦轮作模式下,首年施用5种钝化材料后均显著降低了水稻和小麦籽粒Cd含量,降幅分别达19.88%～48.77%和5.06%～24.00%.施用秸秆生物炭、粉煤灰和YH粉后作物籽粒Cd含量显著低于对照和其它钝化材料,该处理条件下的水稻籽粒ω(Cd)(0.195、0.197和0....     

油-稻轮作模式下修复材料对土壤铜修复的持续性影响

通过3 a持续的油菜-水稻轮作小区实验,其中前2a连续施用修复材料,后1a不施用修复材料,探究羟基磷灰石、生石灰、生物炭、生物有机肥和纳米材料对铜污染土壤的修复效果,及其对铜在油菜和水稻不同部位的富集情况.结果表明,羟基磷灰石、生石灰和纳米材料均能显著提高土壤pH值;不同修复材料均可有效地抑制土壤铜的移动,以生石灰修复土壤处理的有效铜降幅最大,连续施用修复材料的四季分别为38.9%、34.9%、27.88%和29.04%,且生石灰钝化有效铜的后续效果也较其他修复材料理想.修复材料的施用,促使油菜和水稻可食用部分中铜含量显著降低,修复材料施用的四季中,不同作物可食用部分铜含量最大值分别降低46.03%、22.2%、29.44%和31.71%,由于修复材料的施用效果,不施修复材料两季节作物可食用部分中铜含量均未超过国家食品安全限值.不同修复材料的使用,油菜和水稻产量均有所提高.本文可为铜污染地区土壤改良提供一定的理论依据和技术支撑.     

Air quality and climate change: Designing new win-win policies for Europe

Anthropogenic activities are responsible for the emission of gaseous and particulate pollutants that modify atmospheric composition. Such changes are, in turn, responsible for the degradation of air quality at the regional/local scale as well as for changes of climate. Air pollution and climate change are two intimately connected environmental issues. However, these two environmental challenges are still viewed as separate issues, which are dealt with by different science communities and within different policy frameworks. Indeed, many mitigation options offer the possibility to both improve air quality and mitigate climate change but, at the same time, mitigation options that may provide benefits to one aspect, are worsening the situation in the other. Therefore, coordinated actions taking into account the air quality-climate linkages are required. These actions need to be based on strong scientific grounds, as recognised by the European Commission that in the past few years has promoted consultation processes among the science community, the policy makers and the relevant stakeholders. Here, the main fields in which such coordinated actions are needed are examined from a policy perspective.     

Short‐chain fatty acids affect cell‐association and invasion of HEp‐2 cells by Salmonella typhimurium

Abstract

This study demonstrates that the growth of S. typhimurium in Luria Bertani broth supplemented with acetate, propionate, butyrate, or a mixture of the three SCFA, affected cell‐association and the ability to invade cultured HEp‐2 cells. Cell‐association and invasion was determined after growth for 4 h of growth in the presence of the SCFA at pH 6 and 7. The results suggest that the growth rate of the culture may have affected cell‐association and invasion since accompanying the significant decrease in growth rate in the presence of SCFA at pH 6 was a decrease in cell‐association and invasion. However, the results also suggest that the individual SCFA may play a role in modulating cell‐association and the invasion phenotype and the regulation of cell‐association and invasion by the SCFA was dependent on the concentration and the pH of the medium. Although the growth rates were similar for S. typhimurium in the SCFA mixture, butyrate (100 mM) and propionate (50 mM) at pH 6, differences in cell‐association and invasion were observed among these cultures. Also, at pH 7, differences were observed among the SCFA treatments even though the growth rates were similar.