三权分置改革中新型农业经营主体的政策认知及其行为响应——以上海市青浦区为例

农村土地三权分置是现阶段我国农地产权制度的重大创新,其政策逻辑是通过农地产权的细化和明晰促进资源的优化配置,以推动农业转型发展。但是三权分置能否改善人们对土地产权的长期、安全、稳定的预期,改变经营主体的行为方式,依然有待实践的检验。以新型经营主体对政策的认知为切入点,以三权分置实践较早的上海市青浦区为典型案例,在问卷调查和实地访谈的基础上,基于“三权分置改革—主体认知—行为响应”的政策传导机制,应用结构方程模型,研究新型农业经营主体的政策认知程度对其规模经营行为、长期投入行为和向环境友好型农业转型等行为的影响。结果显示：新型农业经营主体对三权分置政策的认知对其三大类生产经营行为的转变均存在显著影响;并且认知程度越深,其实践农业生产方式转型的可能性越大。需要进一步完善配套制度建设、加强三权分置政策的宣传和解释力度,提升农业从业者人力资本水平,为农业转型升级提供内生动力。     

Forced ventilation effect by Air-Fin-Cooler on flammable gas cloud dispersion

This paper is the second installment of a paper published on Process Safety and Environment Protection in 2013, which evaluates the Air-Fin-Cooler (AFC) forced ventilation effect over natural ventilation inside congested LNG process train, i.e., modularized LNG, considering the Air Change per Hour (ACH) using Computational Fluid Dynamics (CFD) analysis. This second paper evaluates the effect of forced ventilation on gas cloud dispersion using CFD in order to evaluate possible design measures, such as safety distance in trains and whether to shut down the AFC in case of releases. The results of this evaluation show that gas cloud accumulation is reduced by AFC induced air flow in the case of shorter separation distances between modules. Based on the results, two design measures are proposed, i.e., keep AFC running during emergency and train orientation against prevailing wind direction.     

Assessing the inter-annual variability of separation distances around odour sources to protect the residents from odour annoyance

In recent years, there has been a growing concern about potential impacts on public health and wellbeing due to exposure to environmental odour. Separation distances between odour-emitting sources and residential areas can be calculated using dispersion models, as a means of protecting the neighbourhood from odour annoyance. This study investigates the suitability of using one single year of meteorological input data to calculate reliable direction-dependent separation distances. Accordingly, we assessed and quantified the inter-annual variability of separation distances at two sites with different meteorological conditions, one in Brazil and the other in Austria. A 5-year dataset of hourly meteorological observations was used for each site. Two odour impact criteria set in current regulations were selected to explore their effect on the separation distances. The coefficient of variation was used as a statistical measure to characterise the amount of annual variation. Overall,for all scenarios, the separation distances had a low degree of inter-annual variability(mean coefficient of variation values from 8% to 21%). Reasonable agreements from year to year were therefore observed at the two sites under investigation, showing that one year of meteorological data is a good compromise to achieve reliable accuracy. This finding can provide a more cost-effective solution to calculate separation distances in the vicinity of odour sources.     

一种封闭式选煤车间的设计

近年来,随着国家对煤炭行业控制环境污染的条件越来越严格,为了更有效的治理煤场环境污染,改善煤场周边地区环境质量,根据国内已建成的大型封闭厂房的设计经验,提出一种封闭式煤炭风选车间,车间采用轻型门式钢架结构设计,常规经济柱距6m,抗风柱柱距7．5m,室内净高10m。工程长度90m,跨度35m,屋盖系统采用钢桁架结构体系,单层压型彩色钢板封闭。封闭车间同时配套通风除尘系统,有效降低煤尘量。     

毛细管色谱柱分离氯苯类化合物的优化

介绍了不同极性毛细管色谱柱分离11种氯苯类化合物的方法,通过实验证明,随着色谱柱极性的增加,11种化合物的分离得到改善,采用DB-5和AC-20双柱定性可以避免各种氯代物的干扰,达到准确定性的目的。     

Removal of heavy metals and arsenic from a co-contaminated soil by sieving combined with washing process

Batch experiments were conducted with a heavy metals and arsenic co-contaminated soil from an abandoned mine to evaluate the feasibility of a remediation technology that combines sieving with soil washing.Leaching of the arsenic and heavy metals from the different particle size fractions was found to decrease in the order: 0.1,2–0.1,and 2 mm.With increased contact time,the concentration of heavy metals in the leachate was significantly decreased for small particles,probably because of adsorption by the clay soil component.For the different particle sizes,the removal efficiencies for Pb and Cd were75%–87%,and 61%–77% for Zn and Cu,although the extent of removal was decreased for As and Cr at 45%.The highest efficiency by washing for Pb,Cd,Zn,and As was from the soil particles 2 mm,although good metal removal efficiencies were also achieved in the small particle size fractions.Through SEM-EDS observations and correlation analysis,the leaching regularity of the heavy metals and arsenic was found to be closely related to Fe,Mn,and Ca contents of the soil fractions.The remediation of heavy metal-contaminated soil by sieving combined with soil washing was proven to be efficient,and practical remediation parameters were also recommended.     

Preparation and characterization of carbon-enriched coal fly ash

Carbon-enriched fractions have been obtained from two coal fly ash (FA) samples. The FA came from two pulverized-coal fired power stations (Lada and Escucha, Spain) and were collected from baghouse filters. Sieving was used to obtain carbon-enriched fractions, which were further subjected to two beneficiation processes: acid demineralization using HCl and HF, and oil agglomeration using soya oil-water. Yield in weight after sieving, unburned carbon content, and several physicochemical characteristics of the obtained fractions were used to compare the performance of the beneficiation methods. Low carbon concentration was obtained by sieving, particularly in the case of Escucha FA. However, after acid demineralization or oil agglomeration, fractions containing unburned carbon in a range of 63% to 68% were obtained. These fractions showed differences in mineral phase composition and distribution depending on the FA and on the beneficiation method used. The textural properties of the obtained fractions varied as a function of their carbon content and the beneficiation method used. However, no significant differences in morphology of the carbonaceous particles were found.     

膜法水处理技术的研究与应用现状

介绍了膜法水处理技术的发展历程,其应用和研究现状,对超滤、微滤、纳滤、反渗透、电渗析、渗透蒸发、液膜技术等在给水处理,废水处理方面的应用作了较全面的介绍。     

自然环境中微塑料样品的采集与分离方法

综述了自然环境中微塑料样品采集与分离方法的研究进展,介绍了水环境、土壤与沉积物、环境空气、生物体等不同介质中微塑料的采集方法、技术原理和使用条件,以及密度分离、筛选分离、滤膜过滤等分离提取和预处理方法,提出了建立统一的微塑料采样指南,开展空气中微塑料富集、采样、分离和检测标准方法研究等建议。     

Recovery of volatile fatty acids via membrane contactor using flat membranes: Experimental and theoretical analysis

Volatile fatty acid (VFA) separation from synthetic VFA solutions and leachate was investigated via the use of a membrane contactor. NaOH was used as a stripping solution to provide constant concentration gradient of VFAs in both sides of a membrane. Mass flux (12.23 g/m² h) and selectivity (1.599) observed for acetic acid were significantly higher than those reported in the literature and were observed at feed pH of 3.0, flow rate of 31.5 ± 0.9 mL/min, and stripping solution concentration of 1.0 N. This study revealed that the flow rate, stripping solution strength, and feed pH affect the mass transfer of VFAs through the PTFE membrane. Acetic and propionic acid separation performances observed in the present study provided a cost effective and environmental alternative due to elimination of the use of extractants.