中国大豆压榨企业空间格局及其演变机制

随着中国居民生活水平的不断提高,国内肉蛋奶的消费需求逐年增长,致使作为主要饲料蛋白原料的豆粕需求也不断增加。而豆粕是大豆压榨行业的主要产品,因此,大豆生产、大豆压榨、饲料生产和畜禽养殖组成了一个密切关联的产业系统,大豆原料生产与供给区分布、饲料生产和畜禽养殖业布局又会对大豆压榨行业空间格局的形成产生重要影响。以大豆压榨企业为研究对象,通过产业链视角,运用平均最近邻分析、核密度分析方法,研究了1996-2016年间中国大豆压榨企业的空间格局演变规律与集聚特征,然后构建了条件Logit模型探讨影响中国大豆压榨企业区位选择的主要因素。结果表明：中国大豆压榨企业空间集聚程度较高,自1996年以来,经历了从大豆主产区向沿海港口城市集聚再沿长江、哈大铁路、陇海铁路等交通运输线路扩散的演化特点。各地原料资源禀赋、运费成本、市场规模与潜力、集聚经济以及政府政策都会不同程度地影响中国大豆压榨企业的空间格局,并且不同时期影响大豆压榨企业空间格局的因素显著性及强度都会有所变化。2000-2005年原料资源禀赋、运输成本、豆粕市场规模以及集聚经济发挥着较大作用;2006-2010年间集聚经济和政府政策共同主导了大豆压榨企业的区位决策;2010年以后市场潜力与集聚不经济则表现出更强的作用。     

浅析鼓风机房在污水处理中的节能潜质

在城市污水处理厂能耗结构中,鼓风机房权重约50%,并且由于技术和管理水平的限制,鼓风机房存在严重的电能浪费问题。以采用A2/O工艺的污水处理厂工程为例,通过鼓风机房单位水量电耗与生物系统单位水量需氧量的比较,对2009年12个月鼓风机房的节能潜质进行分析。结果表明,鼓风机房单位水量电耗和好氧池需氧量随月份的变化趋势不一致,其年均节能潜力为62%;仅通过鼓风机房的节能,污水处理厂的年均节能潜力就能达到27.2%,污水处理单耗就能由0.219kW·h/m3降到0.159kW·h/m3,可节约运行费用110.8858万元/a。     

三峡库区消落带4种典型植物根际土壤养分与氮素赋存形态

三峡水库消落带土壤N循环受到植被覆盖和季节性淹水的影响,对三峡水库水质具有潜在的不利影响,进行消落带植被恢复和提高土壤N保持能力成为保护库区水环境的重要措施.选择三峡库区一级支流澎溪河消落带为研究对象,分别在冲积潮土、紫色土和水稻土分布区采集狗牙根、香附子、苍耳以及玉米这4种典型植物根际、非根际土壤,分析了根际与非根际土壤理化性质与N赋存形态特征,并比较了不同植物类型根际富集效果,初步探究不同植物根际效应对消落带土壤N循环的影响.结果表明,所有植物根际土壤p H均低于非根际,有机质、全氮、全磷、速效氮均高于非根际,且根际富集率表现为香附子狗牙根玉米苍耳;不同植物根际对土壤全钾、有效磷、速效钾影响作用不一致;植物根际土壤中可转化态氮TF-N及其不同赋存形态离子交换态氮(IEF-N)、碳酸盐结合态氮(CF-N)、铁锰氧化态氮(IMOF-N)和有机态和硫化物结合态氮(OSF-N)均高于非根际土壤,植物根际效应能够改变土壤N赋存形态及其对N循环的贡献率,但狗牙根和香附子根际土壤中TF-N占TN的比率低于非根际,而玉米和苍耳相反,表明消落带玉米和苍耳覆盖加快了N素向TF-N转化,不利于土壤N素保持;消落带土壤有机质、总磷和有效磷含量与可转化态N形态显著相关,是土壤N形态转化的主要因素.研究表明,消落带狗牙根和香附子覆盖对土壤N素的保持优于玉米和苍耳,植物根际效应对消落带土壤N循环的影响为消落带植被恢复中植物选择提供了参考.     

3种水生植物腐解过程中磷营养物质迁移、转化过程研究

室内模拟沉水植物狐尾藻(Myriophyllum verticillatum L)、浮水植物菱角(Trapa bispinosa Roxb)、挺水植物荷花(Lotus flower)在5.7 g·L~(-1)初始生物量密度下的腐解过程,并探究该过程中磷营养物质迁移、转化规律.结果发现,3种植物腐解速率在第2 d上升至最大值(分别为1.075、1.455、1.16 g·d~(-1))后出现下降-上升-下降的变化规律,并且在整个腐解周期内种间差异性显著(p0.01),造成整个腐解周期内狐尾藻、菱角、荷花3种植物平均磷释放速率分别为0.456、0.670、0.537 mg·g~(-1),且以无机磷酸盐为主;水中释放的磷在底泥吸附及其自身沉降等作用下,明显向底泥迁移转化,水中磷含量下降,最终在试验结束时恢复至初始水平(0.5 mg·L~(-1));该研究可为湖泊水生植被系统的修复或重建提供科学参考.     

蓝藻水华聚集对水葫芦生理生态的影响

蓝藻水华聚集后常会引起水体溶氧(DO)下降、水体环境恶化,从而对水生植物的生长产生影响.采用模拟实验,研究了在不超过25℃、5种不同浓度蓝藻聚集后,对水葫芦生长的影响及其生理响应变化,以期为减轻蓝藻聚集对植物不良影响和提高水体净化效果提供理论依据.结果表明,蓝藻聚集浓度低于60 g·L-1的处理中,随着蓝藻浓度的增加,水体的DO、p H下降,ORP值降低到100 m V左右,TN降低了58%~78%、TP降低了43%~68%、COD降低了59%~73%,植物叶片可溶性蛋白、可溶性糖、MDA含量增加;并且蓝藻浓度越高,MDA含量越高.在不同蓝藻浓度处理中,在低于60 g·L-1的蓝藻聚集下,水葫芦仍可以生长;超过60 g·L-1的处理中,DO、ORP大幅度降低,水体出现缺氧乃至厌氧状态,植物叶片中可溶性糖的含量随着实验的进行表现为先增加、后减小的变化趋势,表明随着蓝藻浓度的增加,水葫芦对水体中氮磷的吸收能力降低,蓝藻聚集将对其产生不可逆的胁迫.各处理中植物的根长、总长、鲜重与实验刚开始相比,都呈现增加的趋势,根长增加0.29~2.44倍,总长增加0.41~0.76倍,鲜重增加0.9~1.43倍,并且随蓝藻浓度的增加,根长、总长增加的幅度减小.因此在利用漂浮植物水体净化中,将避免蓝藻的严重聚集,从而更好地发挥其水体净化功能.     

五种红树植物根区原位溶解性有机物(DOM)浓度及其荧光构成分析

红树植物对根际微生物群落产生影响,应与其根区微域中的溶解性有机物(dissolved organic matter,简称DOM)密切相关.采用总有机碳(TOC)分析仪和三维荧光分析法对5种主要红树植物建群种的DOM浓度和组分进行原位采样与测定.根际土和非根际土孔隙水DOC的总平均值分别为207.87 mg·L-1、144.51 mg·L-1.从三维荧光光谱图及荧光特征值r和荧光指数FI判断,根际土中有机物浓度及成分均大于非根际土中,根际土孔隙水DOM的内源性较非根际土中强,外源输入的腐殖酸量大于富里酸量.     

辽宁省外来入侵植物现状与防治对策

通过对野外调查资料和相关文献资料的分析,确定辽宁省外来入侵植物有70种,隶属于21科,其中,菊科、茄科、禾本科、苋科、十字花科和豆科6个科的入侵植物占了入侵植物总种数的68.6%。探讨了辽宁省外来入侵植物的种类和性状组成、分布特点、危害以及防治对策。     

Laboratory models to evaluate phytotoxicity of sulphadimethoxine on terrestrial plants

Antimicrobial drugs soil contamination is a possible side effect of spreading animal wastes from intensive farming on arable land: waste often contain persistent drugs (like sulphonamides) that pollute soil. In laboratory tests different crop plants and weeds demonstrated, on both synthetic medium and soil, toxicity and sulphadimethoxine bioaccumulation. These data suggest potential adverse implications for organisms higher up the food net, including humans. The increasingly used technique of'soil top dressing will impose the monitoring of antimicrobial contamination in arable lands and their crops, to protect natural ecosystems and consumer. A possible tool for this monitoring is the use of weeds that can constitute a “mesh” where antimicrobial contamination can be detected.     

Synthesized magnetic nanoparticles coated zeolite for the adsorption of pharmaceutical compounds from aqueous solution using batch and column studies

The contamination of fresh water with pharmaceutical and personal care products (PPCPs) has risen during the last few years. The adsorption of some PPCPs namely, Diclofenac-Na, Naproxen, Gemfibrozil and Ibuprofen from aqueous solution has been studied, magnetic nanoparticles coated zeolite (MNCZ) has been used as the adsorbent. Batch adsorption experiment was conducted to study the influences of different adsorption parameters such as contact time, solution pH and PPCPs concentrations in order to optimize the reaction conditions. The removal was favored at low pH values. Thus, as pH turns from acidic to basic conditions these compounds were less efficiently removed. The initial concentration does not appear to exert a noticeable effect on the removal efficiency of the studied PPCPs at low concentrations, but it showed less removal efficiency during high concentration of PPCPs especially for Ibuprofen. The removal of Diclofenac-Na was independent on time, while the contact time was of significant effect on the adsorption of Naproxen, Gemfibrozil and Ibuprofen even though these compounds were removed up to 95% during 10 min using MNCZ. From the isotherm adsorption study, the adsorption of PPCPs studied on MNCZ was best fitted with Freundlich isotherm equation. Pseudo-second order model providing the best fit model with the experimental data. Column adsorption study was conducted to compare the removal efficiency of MNCZ with other processes used at drinking water treatment plants (DWTPs), MNCZ showed high removal efficiency (>99%) than other used processes at DWTPs.     

Effects of salinity on the uptake of lead and cadmium by two mangrove species Rhizophora apiculata Bl. and Avicennia alba Bl.

The uptake of lead (Pb) and cadmium (Cd) by Rhizophora apiculata and Avicennia alba under various salinity levels was examined using hydroponic cultivations. After 3 months of exposure at four levels of Pb (0, 0.03, 0.3 and 3 mg·L^?1) and four levels of Cd (0, 0.005; 0.05 and 0.5 mg·L^?1) at different salinities (0, 15 and 30), uptake of the metals was shown to be differently affected by salinity. For uptake of Pb by R. apiculata, the salinity effect was not significant for the leaves and was most significant in the stem, whereas for A. alba, the effect of salinity was significant only in the stem. Uptake of Pb in the roots and stems of both species was similar, but a higher concentration was recorded in the leaves of A. alba. Salinity was shown to affect the uptake of Cd by all tissues of R. apiculata, but most significantly roots. For A. alba, salinity significantly affects the total uptake of Cd, but this is most significant in the roots. The two mangrove species demonstrated different mechanisms of metal distribution into their organs which may be related to different adaptation mechanisms to saline conditions.