Biohydrogen production through fermentation using liquid swine manure as substrate

In this paper, continuous production of hydrogen through fermentation with liquid swine manure as substrate was researched using a semi-continuously fed fermenter (8 L in total volume and 4 L in working volume). The pH and temperature for the fermenter were controlled at 5.3 +/- 0.1 and 35 +/- 1 degrees C, respectively, throughout the experiment. Three hydraulic retention times (16, 20, and 24 h) were investigated for their impact on the efficiency and performance of the fermenter in terms of hydrogen yields. The results indicate that hydraulic retention time (HRT) has a strong influence on the fermenter performance. An increasing HRT would increase the variation in hydrogen concentration in the offgas. To produce hydrogen with a fairly consistent concentration, the HRT of the fermenter should not exceed 16 h, which, however, did not appear to be short enough to control methanogenesis because the offgas still contained about 5% methane. When methane content in the offgas exceeded 2%, an inverse linear relationship between hydrogen and methane was observed with a correlation coefficient of 0.9699. To increase hydrogen content in the offgas, methane production has to be limited to below 2%. Also, keeping oxygen content in the fermenter below 1.5% would increase the hydrogen concentration to over 15%. The product to substrate ratio was found to be around 50% for the fermenter system studied, evidenced by the observation that for every 6 liters of manure fermented, 3 liters of pure hydrogen were produced, which was significant and encouraging.     

Seasonal temperatures have more influence than nitrogen fertilizer rates on cucumber yield and nitrogen uptake in a double cropping system

Two-year greenhouse cucumber experiments were conducted to investigate seasonal effects on fruit yield, dry matter allocation, and N uptake in a double-cropping system with different fertilizer management. Seasonal effects were much greater than fertilizer effects, and winter-spring (WS) cucumber attained higher fruit yields and N uptake than autumn-winter (AW) cucumber due to lower cumulative air temperatures during fruit maturation in the AW season. Fertilizer N application and apparent N loss under recommended N management (Nmr) decreased by 40-78% and 33-48% without yield loss compared to conventional N management (Nmt) over four growing seasons. However, there were no seasonal differences in N recommendations, taking into consideration seasonal differences in crop N demand, critical nutrient supply in the root zone and N mineralization rate.     

淡水鱼类种质资源信息系统的研制

采用人工智能和多媒体技术、建成了淡水鱼类种质资源信息系统。本系统完整、准确地保存了鲢、鳙、草鱼、团头鲂、方正银鲫、兴国红鲤、散鳞镜锂、尼罗罗非鱼、奥利亚罗非鱼等十种淡水鱼类种质标准参数及其性状图形、图像集、,包括鱼类可量和可数性状;鱼类年龄与生长特征;鱼类性成熟和怀卵量特征;鱼类耗氧量、耗氧率和窒息点指标;鱼类肌肉成份;鱼类染色体核型图像;鱼类同工酶酶谱组成指标,为进行种质鉴别和保存探索了一条新路     

社会资本对农村贫困代际传递影响机制研究

社会资本在反贫困领域的重要作用已被理论和实践所证实。在新时代脱贫攻坚的决胜阶段,有效发挥社会资本的周急济贫功能,缓解乃至阻断贫困代际传递,已成为当前反贫困战略推进中亟待探讨的问题。研究整合了四期中国家庭追踪调查(CFPS 2010、2012、2014、2016)个体家庭和村庄的嵌套数据,建立了“认知型”和“结构型”两种类型以及“个体家庭”和“村庄”两个层级的社会资本框架,并基于探索性因子分析构建了社会网络、社会信任、社会声望、社会参与、集体参与以及公共服务6个社会资本变量。研究利用HLM软件构建了多层广义线性模型(HGLM),通过四阶段的空模型、截距模型、随机效应模型以及完整模型分析了绝对贫困背景下社会资本对农村贫困代际传递的影响机制。研究结果表明:①个体社会资本总量与贫困代际传递呈显著负相关。②在个体家庭层面,社会网络、社会声望、社会参与对贫困代际传递有显著负向影响,但社会信任和地方信任对贫困代际传递的影响并不显著。③在村庄层面,公共服务对贫困代际传递具有显著负向影响,集体参与对贫困代际传递具有显著正向影响,且公共服务水平对社会网络和贫困代际传递具有正向调节作用。研究提出要大力培植贫困群体和乡村两个层级的社会资本以缓解农村贫困代际传递趋势:①要通过协调“乡政”与“村治”以形成良性的乡村治理格局。②要促进精准扶贫与乡村振兴战略紧密衔接,在保障个体脱贫的同时完善农村公共服务及基础设施建设,推进城乡基本公共服务均等化;③须提振贫困群体脱贫信心,增强村级自治与集体参与的水平和能力。     

长江流域经济发展的省际差异与变化趋势

长江流域上中下游各省经济发展存在巨大差距，这是历史长期发展不平衡的产物，也与近几十年发展速度不同有关。分析当前各省社会固定资产总投资量，投资构成，投资效益和产业结构的差异，可以预见，流域内发达省份与欠发达省份的发展差距将进一步扩大。     

重庆境内江河水域渔业环境特点及对船体网箱养鱼的影响

重庆境内河流属长江水系，以长江，嘉陵江，涪江等河流为骨干和主体，水域面积８．２５万ｈａ，占水域总面积的７６．４％，船体网箱养鱼是近年来在该地区兴起并迅速发展的鱼类集约化养殖方式。本文根据船体网箱养鲤试验结果和有关资料，分析了重庆境内江河水温，含氧量，流速，含沙量，浮渣，工业污染特点及对船体网箱养鱼的影响，拟合了养殖舱内，外流速关系及含沙量与透明度关系，并就船体网箱养鱼的进一步发展提出了措施。     

浙江省农业自然资源合理利用战略研究

针对浙江省自然资源利用程度高,资源环境压力大,资源浪费和污染等严重问题,根据浙江省资源构成特点,从资源,环境与经济协调发展的观点提出减少非农建设占用耕地,完善基本农田保护工作,绝不以牺牲现有耕地为调整农业产业结构。与此同时,积极开发后备土地资源,补充现有耕地面积;对于水资源必须依法治,管并重,节约与开源相结合,合理利用水资源,着重开发山,海资源和改善农业生态环境等战略措施。     

空气微生物对铜陵市环境质量的指示作用

所测铜陵市区空气的平均细菌含量约４１８１．５ＣＦＵ．ｍ－３，总菌含量约４４９５．９ＣＦＵ．ｍ－３。与许多中国的大中城市比，污染不重，结果指示铜陵空气尚处于正常状态之中。     

长江流域土地资源情势及其发展战略对策

土地资源对国民经济和社会发展十分重要,在一些地区已成为制约因素。本文着重对长江流域土地资源情势进行分析,指出该流域的特点是:土地资源绝对量大,人均占有量少;土地资源态势优劣并存;土地资源形势喜忧相伴。同时提出如下几个战略对策:1.实行开源与节流并重的方针,走节约型农业发展道路;2.增加农业投资,改土治水,集约经营;3.统一规划,优势互补,联合协作,共同发展;4.完善土地法制建设,健全土地资源预测预报工作。     

关于长江产业带建设总体布局的初步思考

重点开发长江是90年代中国经济重大战略布署。将长江产业带建设成具有强大经济实力的国家一级经济轴线,宜采用分层次推进与中心辐射相结合的发展战略,以浦东开发和三峡建设为契机,加强基础产业,发展新兴产业和第三产业,优化产业结构,以能源和交通建设先行,改善基础设施。同时,要协调产业带建设与浦东开发、三峡工程建设的关系。