二噁英的理化性质及在乳及乳制品中污染的研究进展

本文主要分析了二噁英的理化性质,重点介绍了乳及乳制品中二噁英的污染情况,并提出有效措施给予预防和解决,以有效降低二噁英在乳及乳制品中的危害性,确保乳及乳制品行业的健康发展。通过对二噁英的理化性质进行研究,为乳及乳制品的安全生产提供可靠保障,以实现经济与社会效益的最大化。     

Optimal forecast evaluation: fertilizer prices

High fertilizer price volatility makes production planning and inventory management difficult, so accurate fertilizer price forecasts would be beneficial. This article evaluates commercial forecasts for urea and diammonium phosphate (DAP) prices based on forecast accuracy and optimal forecast properties. Most forecasts pass the tests, but forecasts for the US New Orleans urea and the US Gulf DAP markets, in particular, do not and thus show potential to be improved.     

稻鳅共生种养模式试验研究

[目的]稻鳅共生是典型的稻田综合利用模式,符合生态农业发展方向。通过对稻鳅共生生态系统的生理生态学机制开展试验研究,为进一步推广稻鳅共生种养模式提供科学依据。[方法]采用田间试验方法,以水稻单作为对照,研究了不同泥鳅养殖密度下的稻鳅共生对水稻农艺性状、土壤理化性质、水稻产量构成的影响,并对稻鳅共生种养模式进行了经济效益分析。[结果]与对照处理相比,水稻长势在株高、有效分蘖率、根长等方面有一定提高。养殖田水稻株高增高了3%,有效分蘖率提高了8%~11%,根长提高了8.8%~31.3%。在土壤理化性质方面,与对照相比,土壤容重降低了7.1%~21.2%,孔隙度增加了4.1%~14.7%。实验前后养殖田内土壤有机质增加了3.5%~26.5%,对照田降低了2.5%~5.8%。土壤肥力(氮、磷、钾)减少,但减少幅度小于对照处理。稻鳅共生种养模式下水稻产量提高了5%~25%,同时稻田增收泥鳅1 725~3 375kg/hm2,净收入为1.836 0万~2.307 0万元/hm2,经济效益提高了3.65~4.84倍。稻鳅共生种养模式中泥鳅的养殖密度为30万尾/hm2时稻田的生态效益和经济效益最佳。[结论]稻鳅共生有效改善了土壤理化性质,促进了水稻的生长,提高了稻田产量和产值。     

农户减少化肥用量和采用有机肥的意愿研究——基于洱海流域上游面源污染防控的视角

[目的]过量施用化肥导致水体富营养化是造成洱海流域上游面源污染的主要原因之一,调查分析农户减少化肥用量和采用有机肥的意愿有助于了解其调整施肥结构的行为。当前研究忽视了农户减少化肥施用强度和采用有机肥的意愿间的替代性,未能开展联立研究。[方法]基于洱海流域上游397个水稻种植户的问卷调查数据,通过Bivariate-Probit模型对农户减少化肥用量和采用有机肥两种意愿进行分析。[结果]年龄负向影响农户减少化肥量的意愿,农户对有机肥好处的认知正向影响其减少化肥量的意愿,农户参加农业社会化服务对其减少化肥用量和采用有机肥的意愿均产生正向影响,相比之下,对农户采用有机肥意愿的促进作用更大。[结论]引导农户参加农业社会化服务以及加强宣传和培训,提高农户对有机肥作用的认知可能是加强其减少化肥用量和增加有机肥施用量意愿的有效途径。     

The Impact of Sustainability Aspects in the Meat Sector: A Cluster Analysis Based on Consumer Attitudes and Store Format Choice

Several consumer studies have shown considerable market potential for sustainable meat products, however, their markets shares are still marginal. In Germany, the sustainable aspects “organic,” “local origin,” and “animal welfare” are of special interest. To obtain a precise overview of potential target groups for these meat categories and their choice of store format, 620 German consumers were surveyed on their attitudes toward sustainable meat production and their shopping behavior. First, target groups based on consumers’ attitudes were identified by cluster analysis, taking into account possible overlaps. Consumers were also clustered by their store format choice and their preferred type of meat packaging. A cross tabulation of the results then provided insights into which store format and type of meat packaging is preferred by the target groups for sustainable meat products. Due to overlaps found in the target groups, the existence of important subgroups was shown. Amongst the target groups, only a slight preference for unpackaged meat products was found. Basically, the offer of sustainable meat products appears of interest for all store formats, with particular emphasis on supermarkets. The results of this study can support producers and retailers developing new and tailored marketing strategies for sustainable meat products.     

农户生物菌肥购买意愿及行为的影响因素研究*——基于山东省设施菜农的调研数据

[目的]生物菌肥对于土壤改良、环境改善、食品安全具有重要意义,但目前生物菌肥在整个肥料产业中所占份额较小,迫切需要探讨如何从农户角度提高生物菌肥的施用比例。[方法]基于设施蔬菜农户的数据,构建Bivariate Probit模型,对农户生物菌肥的购买意愿和行为的影响因素进行比较研究。[结果]农户的生物菌肥购买意愿和行为总体上呈现一致性,愿意购买的农户中有97. 77%的农户具有实际的购买行为;但两者的影响因素有所差异,从差异因素来看,质量安全检测对购买意愿具有显著的正向影响,但对购买行为的影响并不显著;农户文化程度、种植年限、对无公害、绿色、有机蔬菜的了解程度,经销商推荐,施肥指导对购买行为具有显著的正向影响。从共同因素来看,生态环境认知变量对购买意愿和购买行为影响不显著。[结论]要推广生物菌肥,需要进一步加强质量安全检测体系对农业行为的约束性,提升经销商的规范经营意识,采用集中招标等灵活的价格政策,提升农户的生态技能,并在保护生态环境方面出台更完善的农业绿色发展政策。     

"利剑斩污"行动下石家庄市挥发性有机物的污染特性变化研究

为研究石家庄市在"利剑斩污"行动管控期和非管控期挥发性有机物(VOCs)的污染特性变化,在2个时间段内对石家庄市3个国控点进行采样分析。通过苏玛罐(SUMMA罐)进行样品采集,利用气相色谱/质谱联用(GC/MS)仪对石家庄市区3个国控点的VOCs进行定性定量检测分析。结果表明,监测期间主要的特征污染物是二氯甲烷、二氯丙烷、苯和甲苯。与非管控期间相比,管控期间各污染物的质量浓度均有所降低,总VOCs平均质量浓度降低45.107μg/m~3,二氯甲烷质量浓度降低8.796μg/m~3,二氯丙烷质量浓度降低3.750μg/m~3,苯质量浓度降低18.285μg/m~3,甲苯质量浓度降低16.895μg/m~3。大气环境调控策略的实施,有效降低了VOCs浓度,减少了空气污染程度,空气质量改善效果显著。"利剑斩污"行动期间采取的相关举措,对于制定常态化下VOCs的防治对策具有一定的参考价值。     

Are international environmental policies effective? The case of the Rotterdam and the Stockholm Conventions

This is the first paper to show that participation in an international environmental agreement has some effectiveness. Our identification strategy consists of applying difference-in-differences techniques in a panel data framework to various levels of data aggregation. We find that ratification of the Rotterdam Convention (RC) and the Stockholm Convention (SC) leads to a reduction in trade of hazardous substances from OECD to non-OECD countries. In particular, we find that when the exporter ratifies the RC, there is a reduction in the import of hazardous chemicals of about 7 percent. In the case of the SC, the results show significant reductions of around 16 percent in trade shipments of persistent organic pollutants. This reduction is more than double the effect found for the RC, which was expected due to a more restricted obligation imposed by the SC convention.     

Factors Influencing Organic and Fair Trade Coffee Growers Level of Engagement with Cooperatives: The Case of Coffee Farmers in Mexico

We study the factors influencing the percentage of organic and fair trade certified coffee sold through a cooperative by growers of five cooperatives in Mexico. The percentage of coffee sold through the cooperative was used as a proxy of growers’ engagement with a cooperative. Using factor analysis and a fractional probit regression, we evaluated the proposition that the level of engagement can be explained by transaction cost economics, social norms and connections, and farmer and farm business characteristics. We found that farm size, uncertainty regarding cooperative time of payment to the members and cooperative commitment on price to be paid negatively influence the level of engagement. In contrast, asset specificity, relational commitment, and price have a positive impact on engagement. Our results may help cooperatives and policy makers to build strategies aiming to increase this level of engagement. This is relevant because lower grower engagement has been found to be positively correlated with weak performing cooperatives.     

破解“化工围江”难题的“湖北样本”和“江苏样本”

长江经济带化工产业在全国化工发展格局中占据重要地位。在长江经济带沿线11省份中，湖北省、江苏省化工产业规模位居前列，在化工产业快速发展的同时，“化工围江”难题日益凸显。湖北省、江苏省先后颁布实施一系列规划与政策，引导化工产业转型升级发展，成为破解“化工围江”难题的典型样本。通过对比分析“湖北样本”和“江苏样本”，得到破解“化工围江”难题的启示：科学理念引导化工产业绿色发展；规划先行推动化工产业创新发展；政策支持保障化工产业健康发展。