Impacts of the Rising Opportunity Cost of Farm Labor on Agricultural Land Use Structure: Theory and Empirical Evidences

Abstract

Nowadays the rising of opportunity cost of farm labor comes to the forefront of attention in China. In order to understand its impact on agricultural land-use structure, a theoretical framework of household economics is formulated drawn on Low’s model. Under the theoretical framework, the impact of the rising opportunity cost of on-farm on cropping structure is deduced in theory. And then, using statistic and survey data, taking mountain area of southern Ningxia as an example, the theoretical assumes are verified. The results show that the rise of opportunity cost of farm labor leads to less diversified cropping structure.     

湖北九宫山甜槠群落结构与优势种的空间分布格局研究

通过对湖北九宫山国家级自然保护区甜槠群落建立的1ha固定森林样地进行植物群落调查,分析了样地内木本植物物种组成、区系成分、种群径级结构和空间分布格局,结果表明:(1)样地内木本植物(DBH≥1 cm)共有132种,隶属于42科78属,其中,杜鹃花科、壳斗科、樟科、蔷薇科、冬青科等是优势科,短柄袍、鹿角杜鹃、青冈、长叶石栎、甜槠等是优势种.(2)样地内植物科、属的分布类型均以泛热带分布类型为主,分别为30.95％和20.51％.(3)样地内所有木本植物个体的径级结构均呈倒"J"型,幼龄个体数量大,森林群落更新状况良好.(4)样地内木本植物个体的空间分布格局以聚集分布为主,部分优势物种在小尺度上呈聚集分布,而在较大尺度上则为随机分布.     

神农架大九湖亚高山泥炭湿地甲烷通量变化特征及其与产甲烷菌群落组成的关系

2018年12月～2019年11月,采用涡度相关法和高通量测序技术,以湖北省神农架大九湖亚高山泥炭湿地为研究对象,对甲烷(CH4)通量以及产甲烷菌群落组成进行相关研究.结果 及分析表明:大九湖泥炭湿地研究期间表现为CH4的源,CH4总排放量为9333.26 mg· m-2,CH4日平均排放通量为18.50 nmol·m-2·s-1,冬、春、夏、秋四季的CH4平均排放通量分别为6.46、4.62、36.81、25.92 nmol·m-2·s-1,存在明显的季节变化;研究区产甲烷菌优势菌群为Methanoregula(66.73％)和Methanocella(21.99％);对样本中产甲烷菌的Shannon指数进行双因素方差分析发现,同一季节不同深度的样本中产甲烷菌多样性存在显著差异,随着深度的增加,产甲烷菌的多样性指数呈下降趋势;同一深度不同季节的样本中产甲烷菌多样性存在显著差异;夏季产甲烷菌群落组成与CH4排放通量为强正相关关系,春季产甲烷菌群落组成与CH4排放通量为强负相关关系,Methanothermus与CH4排放通量为显著正相关关系,Methanolinea与CH4排放通量为显著负相关关系.     

基于BMPs的鄱阳湖区小流域农村面源污染控制

鄱阳湖小流域农村面源污染严重,环境问题不断加剧。通过背景值调查与污染源解析,显示农村生活和种植业是鄱阳湖小流域农村面源污染的主要来源。采取集成式BMPs模式,将源头控制与末端治理相结合,充分利用当地优势,合理搭配植物缓冲带、沟渠湿地、人工湿地,兼性塘等,实现氮、磷流失的有效拦截,达到有效控制示范区小流域农村面源污染目的,从而为鄱阳湖农村面源污染控制提供借鉴。结果表明： BMPs系统污染物去除能力高,运行成本低。系统单位面积削减总量分别为CODcr 71017 kg、SS 11491 kg、TP 408 kg、TN 3593 kg、NO-3 N 474 kg、NH+4 N 1918 kg,而运行成本不到01元/t。整个系统中尤以表面流人工湿地减污效果最好,耐负荷冲击能力最强。沟渠湿地整体去污能力不低,但耐冲击负荷能力弱,易受外界因素的影响。为加强减污效果,可通过完善生态系统尤其是挺水性植物加以改进     

长三角地区城市居民出行交通碳排放特征与影响机理

随着能源问题及全球变化关注,城市居民出行交通碳排放研究已成为多学科关注焦点。选择南京、宁波和常州作为长三角典型城市,基于典型居住小区问卷调查获取第一手的城市居民出行基础数据,估算与分析城市居民出行碳排放特征及影响机理。结果表明：长三角2010年城市居民人均出行交通碳排放约1 1219 kg CO2/人,日常通勤和远距离出行碳排放量之比为75[DK]∶25;城市居民日常通勤交通碳排放的主要影响因子为交通方式、出行距离、家庭年收入、年龄和性别;远距离出行交通碳排放的主要影响因子为出行距离、交通方式和家庭年收入。建议采用差别化的行政干预和经济杠杆有效调控家庭小汽车保有量增长速度,鼓励小排量汽车和清洁能源汽车消费,兼顾汽车产业发展、家庭小汽车刚性需求与节能减排需求之间的博弈平衡;优化城市功能格局,大力发展公共交通网络;加强节能减排与低碳意识宣传,鼓励与引导公共交通出行     

Influence of different inoculation densities of black soldier fly larvae (Hermetia illucens) on heavy metal immobilization in swine manure

The disposal of organic waste by the biocomposting of black soldier fly larvae (BSFL) has drawn broad attention. However, the discrepancies in heavy metal immobilization between BSFL biocomposting with different inoculation densities and aerobic composting need to be further researched. In this study, BSFL with inoculation densities of 0.08%, 0.24% and 0.40% was added to swine manure to investigate its influence on heavy metal bioaccumulation and bioavailability. The physicochemical properties, BSFL growth performance and amino acid contents were measured. The results showed that the germination index, total prepupal yield and bioavailable fraction removal rate (%) of Cr and Pb at an inoculation density of 0.40% of BSFL were the highest among all of the BSFL biocomposting groups. Although the bioaccumulation factor and heavy metal (Cd, Cr, Cu and Zn) concentrations of the BSFL body from swine manure with inoculation densities of 0.24% and 0.40% of BSFL were similar, the BSFL inoculation density of 0.40% had the best absorption effect on these heavy metals in terms of total prepupal yield. Therefore, this study provides a basis for exploring the optimal inoculation density of BSFL biocomposting to reduce the harmful effects of heavy metals in swine manure.

     

What are the disease burden and its sensitivity analysis of workers exposing to Staphylococcus aureus bioaerosol during warm and cold periods in a wastewater treatment plant?

Environmental Science and Pollution Research - Biological treatment in wastewater treatment plants releases high amounts of pathogenic bioaerosols. Quantitative microbial risk assessment is a...     

Comprehensive evaluation of land reclamation schemes in mining areas based on linguistic intuitionistic fuzzy group decision-making

Schemes to protect the geological environment and reclaim land are core requirements for an application for mining rights and complying with mining regulations. Mining enterprises must be supervised to ensure they fulfill their obligations. To guide oversight of such schemes and to provide references for their compilation and review, this study evaluates land reclamation schemes in mining areas using a multi-attribute group decision-making method. First, linguistic intuitionistic fuzzy numbers are used to describe the evaluation information. Considering the authority and preferences of experts, methods for determining expert weights in four cases are established. Max–min deviation then determines the attribute weights, and a method for linguistic intuitionistic fuzzy group decision-making is proposed. Finally, the practicability of this method is verified through a comparative analysis of land reclamation schemes for four mining areas in Sichuan Province, China. The results show the proposed method to give simple and effective evaluation, making it reasonably applicable to the compilation and review of land reclamation schemes.

     

高锰酸钾修复PAHs污染土壤过程中Mn迁移转化规律

为探究高锰酸钾氧化修复技术应用过程中Mn元素迁移转化规律及其潜在的环境风险,通过室内模拟实验,采用某焦化厂PAHs污染土壤作为研究材料,探究了高锰酸钾修复技术中不同药剂投加量对PAHs去除、高锰酸钾消耗量、土壤中Mn质量分数、Mn赋存形态分布及有效态Mn质量分数等的影响。结果表明,高锰酸钾氧化处理可有效去除土壤中PAHs;当高锰酸钾投加量为0.20 mmol·g⁻¹、反应时间为1 d时,PAHs去除率最高,可达89.61%。氧化处理过程中,高锰酸钾消耗量和土壤Mn质量分数均与高锰酸钾的投加量有关,随投加量增加而升高。其中,土壤Mn的质量分数与高锰酸钾消耗量呈显著正相关关系。高锰酸钾氧化处理后土壤中Mn主要以铁锰氧化物结合态存在,所占比例为77.04%~92.17%。土壤经0.05 mmol·g⁻¹高锰酸钾氧化处理后,土壤有效态Mn的质量分数比对照组增加了0.94倍;而在高锰酸钾投加量为0.10~0.40 mmol·g⁻¹的处理条件下,土壤有效态Mn的质量分数下降了77.65%~99.09%。药剂投加量是影响高锰酸钾氧化修复PAHs污染土壤过程中Mn环境行为的关键因子。本研究结果可为高锰酸钾氧化修复技术应用工艺优化提供参考。     

磁絮凝-吸附技术对黑臭水体中浊度、氨氮和总磷的去除效果及机理

采用磁絮凝-吸附技术开展了同步去除黑臭水体浊度、氨氮和总磷(TP)实验。在磁絮凝阶段,通过聚合硫酸铁(PFS)、磁粉(MPs)和聚丙烯酰胺(PAM)复配使用,利用电荷中和作用去除浊度和TP;同时,利用化学吸附沉淀去除TP;在此阶段中,当PFS、MPs、PAM的投加量分别为16.00、100.00、2.20 mg·L⁻¹且以PFS+MPs在快速阶段先投加,PAM在慢速阶段后投加的顺序投配时,絮凝效果达到最佳。在吸附阶段,吸附剂质化壳聚糖-沸石(PCZ)主要通过离子交换作用去除氨氮以及通过静电吸附作用去除TP;当PCZ的投加量为1.25 g·L⁻¹时吸附效果达到最佳。利用所研究的磁絮凝-吸附技术对实际黑臭水体进行处理,其出水浊度能达到城镇污水处理厂污染物排放一级标准(≤10.00 NTU),TP和氨氮也分别能满足地表水环境质量Ⅲ类标准(≤0.20 mg·L⁻¹)和Ⅴ类标准(≤2.00 mg·L⁻¹)要求。