Release and sedimentation behaviors of biochar colloids in soil solutions

The release of biochar colloids considerably affects the stability of biochar in environment. Currently, information on the release behavior and suspension stability of biochar colloids in real soil solutions is scarce. In this study, 20 soils were collected from different districts in China and the release behavior of biochar colloids and their suspension stability in soil solutions were systematically examined. The results showed that both pyrolysis temperature and biomass source had important effects on the formation of biochar colloids in soil solutions. The formation amount of biochar colloids from low pyrolysis temperatures (400 °C) (average amount of 9.33–16.41 mg/g) were significantly higher than those from high pyrolysis temperatures (700 °C) (average amount of less than 2 mg/g). The formation amount of wheat straw-derived biochar colloids were higher than those of rice straw-derived biochar colloids probably due to the higher O/C ratio in wheat-straw biochar. Further, biochar colloidal formation amount was negatively correlated with comprehensive effect of dissolved organic carbon, Fe and Al in soil solutions. The sedimentation curve of biochar colloids in soil solutions is well described by an exponential model and demonstrated high suspension stability. Around 40% of the biochar colloids were maintained in the suspension at the final sedimentation equilibrium. The settling efficiency of biochar colloids was positively correlated with comprehensive effect of the ionic strength and K, Ca, Na, and Mg contents in soil solutions. Our findings help promote a deeper understanding of biochar loss and stability in the soil-water environment.     

Interactions of extracellular DNA with aromatized biochar and protection against degradation by DNase I

With increasing environmental application, biochar (BC) will inevitably interact with and impact environmental behaviors of widely distributed extracellular DNA (eDNA), which however still remains to be studied. Herein, the adsorption/desorption and the degradation by nucleases of eDNA on three aromatized BCs pyrolyzed at 700 °C were firstly investigated. The results show that the eDNA was irreversibly adsorbed by aromatized BCs and the pseudo-second-order and Freundlich models accurately described the adsorption process. Increasing solution ionic strength or decreasing pH below 5.0 significantly increased the eDNA adsorption on BCs. However, increasing pH from 5.0 to 10.0 faintly decreased eDNA adsorption. Electrostatic interaction, Ca ion bridge interaction, and π-π interaction between eDNA and BC could dominate the eDNA adsorption, while ligand exchange and hydrophobic interactions were minor contributors. The presence of BCs provided a certain protection to eDNA against degradation by DNase I. BC-bound eDNA could be partly degraded by nuclease, while BC-bound nuclease completely lost its degradability. These findings are of fundamental significance for the potential application of biochar in eDNA dissemination management and evaluating the environmental fate of eDNA.     

Phytotoxicity of nanoparticles: inhibition of seed germination and root growth

Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC50) of nano-Zn and nano-ZnO were estimated to be near 50mg/L for radish, and about 20mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles.     

过硫酸盐对电动-铁/碳复合材料联合修复多氯联苯污染土壤的强化作用

研究了3种浓度过硫酸盐溶液(2、20和200 g·L^-1,以下分别表示为0.2%、2%、20%)作为电解液对电动-铁/碳复合材料（EK-Fe/C）联合修复多氯联苯（PCBs）污染土壤的强化作用,并探究了EK-Fe/C-PS修复技术对土壤理化性质的影响.结果表明,EK-Fe/C-PS修复7 d后,土壤温度和可溶性有机质含量增加,p H显著降低,电导率下降.PS对EK-Fe/C联合修复PCB28污染土壤具有显著的强化作用,修复效果整体随PS浓度增加而增加.在PS浓度为20%时,PCB28的7 d平均去除效率最高（60.9%）,是EK-Fe/C处理组（20.5%）的3倍,EK-20%PS处理组（32.0%）的近2倍.阳极侧土壤PCB28去除效率显著高于阴极侧,达到92.7%±7.7%.在两个电极中间区域,PS浓度增加对修复效果的影响不显著.为降低修复成本和对土壤的影响,污染土壤修复实践中可先使用高浓度PS快速修复阳极和阴极侧土壤,再使用低浓度PS强化修复中间区域土壤.     

环境与经济协调发展理论研究进展

简述了协调发展的内涵及其定量化研究概况，综述了协调发展相关理论－可持续发展，环境承载力，生态经济规划等的研究进展，并指出了协调发展理论的研究趋势。     

天然有机质与重金属相互作用的分析方法进展

由于NOM(natural organic matter,天然有机质)种类及来源的多样性及其结构和性质的复杂性,导致NOM与重金属之间的相互作用存在一定的不确定性. 针对NOM与重金属之间相互作用的一系列分析方法,重点阐述了谱学分析有关分析方法、等温滴定微量热法、溶出伏安法、zeta电位变化分析以及高效体积排阻色谱法等,这些方法从NOM的谱学特征、zeta电位、分子量、热力学参数及电化学性质等方面对二者之间的相互作用进行深入研究,取得了一定进展,但也存在不足. 针对各分析方法的特点及其局限性,建议今后联合使用多种方法分析NOM与重金属之间的相互作用机制;通过确定不同影响因素对二者结合作用的大小和权重,建立多因素影响下二者相互作用的模型,以定性、定量分析天然水体中NOM与重金属的相互作用.      

Co-transport of biochar colloids with organic contaminants in soil column

Environmental Science and Pollution Research - Co-transport of biochar (BC) colloids with coexisting organic contaminants (OCs) in soil involves complex interactions among BC colloids, OCs, and...     

Different stabilities of multiwalled carbon nanotubes in fresh surface water samples

The stability of multiwalled carbon nanotubes (MWNTs) in particulate aggregates and surfactant-facilitated suspensions after being mixed into eight types of fresh surface water samples was investigated. MWNTs in particulate aggregates could not be stabilized in any of the water samples except for the one having relatively high content of dissolved organic matter with the aid of sonication. Sodium dodecyl benzenesulfonate (SDBS), polyethylene glycol octylphenyl ether (TX100) and cetyltrimethyl ammonium bromide (CTAB) were used to prepare MWNT suspensions. SDBS- and TX100-stabilized MWNTs could partly remain suspending after being mixed into the water samples, whereas CTAB-stabilized MWNTs readily sedimentated due to the surface charge neutralization by the surface water contained negatively-charged anions and colloids. This is a first systematic study examining the stability of carbon nanotubes in natural surface waters, the results from which will be useful for understanding the transport, fate and ecological effect of carbon nanotubes in the aqueous environment.     

工业生态学的演化与原理

在总结当前工业生态学（IE）主要研究成果的基础上，分析了IE的演化进程，阐述了IE的原理，并展望了研究方向。指出：IE是一门以提高工业过程中原料使用效率、降低废物排放弃为目的，研究工业系统及其与环境之间相互关系的应用生态学；其化过程经历了孕育、萌芽的提出第三个阶段；其主要研究对象是工业生态系统，而工业生态系统的主体是工业生产部门；工业生态系统的功能主要表现在工业生产过程中的物流、能流和信息流三个方面。