浮游植物群落及粒径结构对光吸收特性的影响

浮游植物吸收及比吸收等光学特性表征浮游植物对光的吸收能力,很大程度上决定了其光合作用效率和碳固定量,是浮游植物生态学、水体光学和水色遥感领域研究热点和前沿问题.本研究基于2013年天目湖7个固定采样点逐月观测数据,分析了浮游植物生物量、群落结构、吸收以及比吸收系数等生物-光学参数的季节变化特征,构建了浮游植物生物量、群...     

Physicochemical characteristics of carbonaceous adsorbent for dioxin-like polychlorinated biphenyl adsorption

It has been known that dioxin-like polychlorinated biphenyls (DL-PCBs) are present in almost all types of environments worldwide. Activated carbon treatment has been expected for the removal of DL-PCBs because it is a simple and low-cost removal technology. In the present study, the physicochemical properties of activated carbon were investigated to identify the characteristics of 16 different types of activated carbon on adsorption properties for DL-PCBs. To accomplish this, micropore volume, and pore diameter were calculated by t-plot analysis and the mesopore volume was analyzed by the Barrett-Joyner-Halenda (BJH) method. In addition, the Brunauer-Emmett-Teller (BET) surface area, pH, metal elements, and surface acid functional groups were analyzed. Then, adsorption experiments using DL-PCB in hexane solution were conducted, and the relationship between adsorption and physicochemical properties of activated carbon was investigated. The results showed that activated carbons having a surface area of 700-1200 m² g⁻¹ and micropores with diameters of about 0.7-0.8 nm exhibited high activity for the adsorption of PCBs. The results also clearly showed that the mesopore volume of activated carbon influenced the adsorption rate and the equilibrium adsorption.     

汶川地震后四川省安县黄洞子沟泥石流特征

2008年5月12日汶川地震诱发了黄洞子沟流域规模巨大的大光包滑坡,部分滑体前冲堆积于沟道内,直接为后期泥石流的形成提供了丰富的松散固体物质,改变了黄洞子沟泥石流形成条件,使黄洞子沟从一条非泥石流沟演变成了一条高频泥石流沟。震后黄洞子沟几乎每年雨季都会暴发不同规模的泥石流,其中以2013年"7·09"泥石流灾害规模和危害最大。本文着重分析了黄洞子沟泥石流形成特征,并从地形、降水和地质三个方面将黄洞子沟和文家沟进行对比,得出了物源堆积体颗粒粒径与泥石流形成的关系。     

鼓泡式反应器高径比对氨法烟气脱碳性能的影响

以N2和CO2混合气模拟燃烧烟气,研究了鼓泡反应器的高径比以及反应条件对氨法烟气脱碳性能的影响。实验结果表明:在相同高径比的条件下,CO2吸收率随氨水质量分数的增加、反应温度的升高而逐渐增大,随进气CO2体积分数和模拟烟气流量的增加而逐渐减小;CO2吸收率随高径比的增加而增大,在高径比为3.98、氨水质量分数为28%、进气CO2体积分数为10%、模拟烟气流量为1.0L/min、反应温度为40℃的条件下,CO2吸收率最高可达100%。     

Tree and stand growth of mature Norway spruce and European beech under long-term ozone fumigation

In a 50- to 70-year-old mixed stand of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) in Germany, tree cohorts have been exposed to double ambient ozone (2×O₃) from 2000 through 2007 and can be compared with trees in the same stand under the ambient ozone regime (1×O₃). Annual diameter growth, allocation pattern, stem form, and stem volume were quantified at the individual tree and stand level. Ozone fumigation induced a shift in the resource allocation into height growth at the expense of diameter growth. This change in allometry leads to rather cone-shaped stem forms and reduced stem stability in the case of spruce, and even neiloidal stem shapes in the case of beech. Neglect of such ozone-induced changes in stem shape may lead to a flawed estimation of volume growth. On the stand level, 2×O₃ caused, on average, a decrease of 10.2 m³ ha⁻¹ yr⁻¹ in European beech.     

数学模拟好氧颗粒污泥的形成及水力剪切强度对颗粒粒径的影响

以生物膜数学模型和活性污泥数学模型为基础,建立好氧颗粒污泥一维数学模型,并模拟营养物质的去除、颗粒粒径变化、反应器周期表现以及好氧颗粒污泥内DO和菌群分布.模拟有机物SS浓度和出水NH4+-N浓度逐渐降低,在大约50 d左右达到稳定,50 d后模拟出水浓度分别<25 mg.L-1和<1.5 mg.L-1.模拟出水NO3--N浓度随着粒径的增加呈现降低趋势.当颗粒粒径由模拟30 d时的1.1 mm增加到100 d时的2.5 mm,颗粒污泥缺氧区面积相应增加,总氮(TN)的去除率由不到10%增加到91%左右,最终模拟出水NO3--N浓度降低到<3 mg.L-1.在好氧颗粒污泥系统内,由于氧气传质阻力,模拟颗粒污泥外层DO浓度高而内层浓度低,颗粒内可以发生同时硝化反硝化,且好氧颗粒污泥内DO特征随时间而发生变化.在好氧初期,好氧颗粒污泥代谢活性高,模拟DO传质深度大约为100～200μm;而在好氧末期,模拟DO传质深度为800μm.模拟自养菌主要分布在DO浓度高的颗粒外层,异养菌分布在整个颗粒.当水力剪切系数kde由0.25(m.d)-1逐渐增加到5(m.d)-1时,模拟颗粒平衡粒径依次由3.5 mm左右减小到大约1.8 mm.在不同水力剪切强度下模拟颗粒污泥生长特征相似,其平衡状态下粒径随曝气强度的增加而减小,可以通过控制曝气强度来控制好氧颗粒污泥的平衡粒径.     

活性污泥颗粒化过程中理化性状及脱氮性能的研究

在SBR反应器中对活性污泥进行颗粒化培养,研究了活性污泥在颗粒化过程中的理化性状及脱氮性能.结果表明,活性污泥颗粒化过程可以分为颗粒形成、颗粒生长和颗粒成熟3个阶段.第1阶段SVI值迅速降低,在30 d内由接种时的110mL/g降低到23 mL/g;第2阶段颗粒粒径迅速增加,在15 d内由0.25 mm增加到0.82 ...     

颗粒粒径与数量对硝化与反硝化过程的影响

以实验为基础,建立了一个基于多底物的多种微生物生长、维持和衰减过程的好氧硝化颗粒SBR反应器一维动力学模型,分析了颗粒粒径及数量对硝化、反硝化等过程的影响.研究发现,在相同生物量条件下,氨氮的消耗随颗粒的数量增加而增加,表明氨氮的消耗主要与NH4+-N和颗粒接触表面有关.同时,系统中所产生的NO2--N及NO3--N与颗粒数量和粒径有密切关系,而在NH4+-N不足时才只与数量有关,表明DO对颗粒的渗透决定NO2--N及NO3--N的产生.就反硝化过程而言,当粒径>1 000μm时反硝化会随粒径的增加而加强,而小于该值时,虽然反硝化也会发生但与颗粒粒径关系不大,表明颗粒粒径>1 000μm时粒径对DO的扩散限制才会明显从而加强反硝化过程.     

国Ⅴ公交车燃用生物柴油的颗粒物碳质组分排放特性

以一辆国Ⅴ柴油公交车为研究对象,在重型底盘测功机上运行中国典型城市公交循环,研究了纯柴油（D100）,体积混合比例分别为5%,10%和20%餐厨废弃油脂制生物柴油-柴油混合燃料（即B5,B10,B20）的颗粒物（PM）碳质组分排放特性.结果表明：国Ⅴ柴油公交车尾气颗粒物碳质组分包括有机碳（OC）和元素碳（EC）,OC占73%~82%,OC的主要组分是OC2和OC3,生物柴油对车辆尾气颗粒物OC组成比例没有影响;随着生物柴油混合比例的增加,公交车尾气颗粒物OC和OC+EC排放呈降低的趋势,EC排放增加,且B10的OC排放较高;PM_0.05~0.1,PM_0.1~0.5,PM_0.5~2.5,PM_2.5~18 4个粒径段颗粒物中,PM_0.1~0.5的OC和EC排放最高,PM_2.5~18的EC排放几乎为零,生物柴油可改善公交车尾气超细颗粒（PM_0.05~0.1）的OC排放,对公交尾气颗粒物EC排放基本没有影响;公交使用生物柴油混合燃料尾气颗粒物OC/EC减小,且PM_0.05~0.1和PM_0.5~2.5OC/EC降低幅度明显,对大气二次气溶胶的影响减弱.