Effects of dissolved organic matter from sewage sludge on sorption of tetrabromobisphenol A by soils

Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics ...     

Sorption of dissolved organic matter and its effects on the atrazine sorption on soils

IntroductionApplication of organic amendments, such as sewagesludge to agricultural soils, has been considered as aneffective way to improve the soil physico chemical propertiesand organic matter compositions. Dissolved organic matter(D…     

水溶性有机物对草萘胺在土壤中吸附与迁移的影响

采用批次吸附试验和土柱淋洗试验,研究了绿肥和污泥中水溶性有机物(DOM)对除草剂草萘胺在黄棕壤和石灰性潮土上吸附和迁移影响.结果表明,供试DOM均能明显降低草萘胺在2种土壤上的吸附,促进草萘胺的迁移,在黄棕壤上效果更明显.在所研究的草萘胺和DOM浓度范围内,绿肥DOM(GM)都比污泥DOM(SS)作用显著.草萘胺的吸附等温线可用Freundlich方程定量描述.绿肥DOM和污泥DOM可分别使黄棕壤中草萘胺吸附量比对照处理(不加DOM)减少22.9%和11.3%,使迁移出土体的草萘胺总量提高了73.42%和26.87%,而使潮土中草萘胺的吸附量减少了9.5%和6.5%,迁移出土体的草萘胺总量增加了43.54%和28.29%.因此,农业土壤中溶解性有机物对农药环境行为有一定影响.     

Biochar affects methylmercury production and bioaccumulation in paddy soils: Insights from soil-derived dissolved organic matter

Biochar has been used increasingly as a soil additive to control mercury (Hg) pollution in paddy rice fields. As the most active component of soil organic matter, soil dissolved organic matter (DOM) plays a vital role in the environmental fate of contaminants. However, there are very few studies to determine the impact of biochar on the Hg cycle in rice paddies using insights from DOM. This study used original and modified biochar to investigate their effect on DOM dynamics and their potential impact on methylmercury (MeHg) production and bioaccumulation in rice plants. Porewater DOM was collected to analyze the variations in soil-derived DOM in paddy soils. The results showed that the addition of biochar, whether in original or modified form, significantly reduced the bioaccumulation of MeHg in rice plants, especially in hulls and grains (p<0.05). However, MeHg production in soils was only inhibited by the modified biochar. Biochar addition induced a significant increase in DOM's aromaticity and molecular weight (p<0.05), which decreased Hg bioavailability. Furthermore, enhanced microbial activity was also observed in DOM (p<0.05), further increasing MeHg production in the soil. Thus, the effect of biochar on the fate of Hg cycle involves competition between the two different roles of DOM. This study identified a specific mechanism by which biochar affects Hg behavior in rice paddy soil and contributes to understanding the more general influence of biochar in agriculture and contaminant remediation.     

Biochar: A review of its impact on pesticide behavior in soil environments and its potential applications

Biochar is produced from the pyrolysis of carbon-rich plant- and animal-residues under low oxygen and high temperature conditions and has been increasingly used for its positive role in soil compartmentalization through activities such as carbon sequestration and improving soil quality. Biochar is also considered a unique adsorbent due to its high specific surface area and highly carbonaceous nature. Therefore, soil amendments with small amounts of biochar could result in higher adsorption and, consequently, decrease the bioavailability of contaminants to microbial communities, plants, earthworms, and other organisms in the soil. However, the mechanisms affecting the environmental fate and behavior of organic contaminants, especially pesticides in biochar-amended soil, are not well understood. The purpose of this work is to review the role of biochar in primary processes, such as adsorption–desorption and leaching of pesticides. Biochar has demonstrable effects on the fate and effects of pesticides and has been shown to affect the degradation and bioavailability of pesticides for living organisms. Moreover, some key aspects of agricultural and environmental applications of biochar are highlighted.     

有机质胶体对卡马西平在多孔介质中迁移影响模拟实验

有机质胶体与有机污染物的相互作用会影响污染物在多孔介质中迁移转化等环境行为.为研究有机质胶体对药物和个人护理品(PPCPs)在土壤环境中迁移的影响,本实验以卡马西平(CBZ)为目标污染物,用商用腐殖酸制备有机质胶体,分别选择石英砂、标准土和野外所取土样为研究介质,通过室内土柱模拟实验探究有机质胶体存在时污染物在多孔介质中的迁移行为.结果表明,描述一维溶质运移的两点化学非平衡模型能够较好模拟CBZ在各介质土中的运移过程,说明污染物运移过程中与介质间发生了化学非平衡吸附作用;石英砂柱中加入胶体后,对CBZ的吸附过程无明显影响,但在解吸时阻滞因子及滞留量变小,可见胶体与石英砂间作用微弱,解吸过程中胶体与污染物结合形成复合体后对污染物有增溶作用;胶体存在时,标准土和自然土对CBZ的吸附量和迁移阻滞强度均明显大于石英砂,其中有机质及黏土矿物的作用最为明显,有机质中的低能/高能吸附位点以及黏土矿物极性表面均能够固定污染物;由于有机质含量较高,自然土对CBZ在吸附-解吸过程中的阻滞截留强度大于标准土.针对本实验中CBZ的迁移情况,提出了疏水性有机污染物在含有机质胶体土壤中的迁移过程中各种作用的概念模型.     

Electrochemical and spectroscopic characteristics of dissolved organic matter in a forest soil profile

Dissolved organic matter （DOM） represents one of the most mobile and reactive organic compounds in ecosystem and plays an important role in the fate and transport of soil organic pollutants, nutrient cycling and more importantly global climate change. Electrochemical methods were first employed to evaluate DOM redox properties, and spectroscopic approaches were utilized to obtain information concerning its composition and structure. DOM was extracted from a forest soil profile with five horizons. Differential pulse voltammetry indicated that there were more redox-active moieties in the DOM from upper horizons than in that from lower horizons. Cyclic voltammetry further showed that these moieties were reversible in electron transfer. Chronoamperometry was employed to quantify the electron transfer capacity of DOM, including electron acceptor capacity and electron donor capacity, both of which decreased sharply with increasing depth. FT-IR, UV-Vis and fluorescence spectra results suggested that DOM from the upper horizons was enriched with aromatic and humic structures while that from the lower horizons was rich in aliphatic carbon, which supported the findings obtained by electrochemical approaches. Electrochemical approaches combined with spectroscopic methods were applied to evaluate the characteristics of DOM extracted along a forest soil profile. The electrochemical properties of DOM, which can be rapidly and simply obtained, provide insight into the migration and transformation of DOM along a soil profile and will aid in better understanding of the biogeochemical role of DOM in natural environments.     

水体中溶解有机物对多氯联苯在淮河水体沉积物上的吸附和生物富集作用的影响

利用淮河4个采样点同时采集的水、表层沉积物和鲤鱼体内多氯联苯不同同系物的浓度分析数据,讨论该类污染物在水体多介质体系中转移分配规律．研究结果表明,在现场条件下观察到的水,沉积物有机碳分配系数(KOC)的对数及生物富集因子(BCF)的对数与正辛醇,水分配系数(KOW)的对数之间没有相关性．但是当假定水中的多氯联苯同系物与溶解有机碳相互作用并改变了有机污染物在水中形态分布时,以游离态多氯联苯浓度重新计算得到的log KOC和log BCF正比于log KOW,因此,在评价多氯联苯污染生态效应时,溶解有机物的影响不可忽视．     

污灌条件下非离子表面活性剂对土壤中有机农药迁移的影响研究

采用振荡平衡法和淋洗法,研究了污灌条件下非离子表面活性剂Tween－80在表层土壤和深层土壤上的吸附行为及其对有机农药甲萘威迁移的影响。结果表明：在振荡平衡条件下,低Tween－80浓度的污水灌溉会促进甲萘威在表层土壤中的吸附,而高Tween－80浓度的污水灌溉会抑制甲萘威在深层土壤中的吸附;在淋洗条件下,Tween－80在深层土壤中表现出较强的吸附能力。     

重金属污染的长春水田黑土对菲的吸附作用

以菲为多环芳烃(PAHs)代表物,研究了Pb、Zn、Cu污染后黑土对PAHs的吸附作用.结果表明,分配作用是黑土吸附菲的主要机制,无论重金属污染与否,黑土对菲的等温吸附曲线均呈线性.实验条件下,重金属污染后黑土对菲的吸附作用明显增强,且随重金属含量提高,黑土对菲的吸附系数(Kd)和有机碳标化的吸附系数(Koc)增大.由于重金属的“键桥”作用,黑土吸附菲的平衡溶液中水溶性有机质(DOM)浓度降低,土壤固相有机质含量略有增加(不超过原有有机质含量的0.53%).计算了这部分增加的固相有机质对菲的吸附系数K_Ph/soc,并分析了溶液中DOM对土壤吸附菲的影响.结果显示,溶液中DOM浓度变化及其与菲的结合作用对重金属影响土壤吸附菲的贡献甚微;而K_Ph/soc值则比土壤原有有机质对菲的吸附系数K_d值大2～3个数量级,这是重金属污染导致土壤吸附作用增强的根本原因.     

源自腐殖土的溶解性有机质组分对棕壤和黑土吸附苯并三唑的影响

溶解性有机质(DOM)影响着有机污染物在土壤中的吸附行为.将从腐殖土中提取的DOM(DOMbulk)用XAD-8树脂和阴/阳离子交换树脂进行分级,用红外光谱、元素分析、紫外分光光度计和电位滴定的方法对DOM不同组分特征进行分析.用吸附批次实验方法研究了DOM不同组分对棕壤和黑土吸附苯并三唑(BTA)的影响.结果表明,DOMbulk中疏水酸性(HOA)、疏水中性(HON)、亲水酸性(HIA)、亲水碱性(HIB)和亲水中性(HIN)组分比例分别为61%、17%、6%、2%和14%.由于黑土有机碳(OC)含量高于棕壤,黑土对BTA和DOM组分的吸附能力均大于棕壤.相对于黑土,棕壤吸附DOM的标化分配系数Koc较高,其原因是棕壤中含有较多的对吸附DOM起重要作用的黏粒和粉砂.由于水分子占据DOM结合点位,DOM组分与BTA在溶液中结合较弱.DOMbulk中HIN在土壤上吸附最强.HIN的吸附增加了土壤吸附BTA的点位,增加点位的促进吸附作用大于HIN与BTA的竞争吸附作用,最终表现为促进吸附.疏水组分在土壤上的吸附较弱,产生的新吸附点位较少,主要通过竞争吸附作用抑制土壤对BTA的吸附.DOMbulk由78%的疏水组分构成,对土壤吸附BTA的影响与疏水组分相似.     

水溶性有机物在土壤剖面中的分馏及对Cu迁移的作用

通过室内土柱试验研究了DOM在土壤剖面中的“分馏”作用,DOM在纵向运移过程中的穿透行为及对污染的红壤和潮土中重金属Cu溶出效果的影响.结果表明,绿肥和猪粪DOM经过土柱后极性都有所降低,在潮土上的降低幅度较大,分别为11.4%和10.72%;DOM能够明显地增加污染土壤中Cu的溶出,且这种作用效果与DOM及土壤的性质有关,绿肥DOM的作用效果比猪粪DOM的强,整个淋洗过程中潮土上Cu的平均溶出量是红壤上的4.37倍(绿肥DOM)和3.03倍(猪粪DOM);由于微生物对DOM的分解作用,降低了DOM对土壤中Cu的溶出效果.     

Molecular behavior and interactions with microbes during anaerobic degradation of bio-derived DOM in waste leachate

It is the key to control bio-derived dissolved organic matters (DOM) in order to reduce the effluent concentration of wastewater treatment, especially for waste leachate with high organic contaminants. In the present study, the anaerobic degradation of aerobically stabilized DOM was investigated with DOM substrate isolated through electrodialysis. The degradation of bio-derived DOM was confirmed by reduction of 15% of total organic carbon in 100 days. We characterized the molecular behavior of bio-derived DOM by coupling molecular and biological information analysis. Venn based Sankey diagram of mass features showed the transformation of bio-derived DOM mass features. Occurrence frequency analysis divided mass features into six categories so as to distinguish the fates of intermediate metabolites and persistent compounds. Reactivity continuum model and machine learning technologies realized the semi-quantitative determination on the kinetics of DOM mass features in the form of pseudo-first order, and confirmed the reduction of inert mass features. Furthermore, network analysis statistically establish relationship between DOM mass features and microbes to identify the active microbes that are able to utilize bio-derived DOM. This work confirmed the biological technology is still effective in controlling recalcitrant bio-derived DOM during wastewater treatment.     

污染场地地下水中汞污染反应运移模拟

汞（Hg）是人们持续关注的全球环境污染物之一,其对地下水的污染严重威胁着与地下水相关的生态环境系统.汞在地下水系统中的物理与地球化学反应过程的准确刻画是研究汞迁移转化规律的重点和难点.基于某工业场地汞污染数据,首先采用PHREEQC研究地下水中无机二价汞的存在形态,然后利用PHT3D程序建立汞污染物反应性溶质运移二维剖面模型.该模型考虑了汞污染物在地下水系统中的对流、弥散过程及地球化学反应过程（包括水相络合作用、表面络合吸附作用及受动力学控制的氧化还原作用）.结果表明,无机二价汞的存在形态以HgCl₂和Hg（OH）Cl占主导地位,氧化还原作用是影响地下水中汞污染反应性运移的主要控制因素;另一方面,水合氧化铁HFO对汞迁移的阻滞影响较小,而溶解性有机质对汞较强的络合作用不能忽视.本文研究成果可为预测与评估特定污染场地地下水汞污染的变化趋势及制定相应的修复策略提供科学依据.     

水溶性有机物在土壤中的吸附及对Cu沉淀的抑制作用

通过室内序批试验研究了来自绿肥(GM)和猪粪(PM)的水溶性有机物(DOM)在潮土和红壤中的吸附行为以及来自绿肥和猪粪堆肥(PMC)的DOM对Cu在高pH下沉淀的影响.结果表明,当没有外源DOM加入时,潮土、红壤中存在DOM的净释放,分别为33.58mg·L^-1和17.17mg·L^-1.随外源DOM加入量的增加土壤净释放量减小,存在土壤对DOM的吸附作用.与绿肥DOM相比,土壤对猪粪DOM的吸附能力更强,m、K_d分别为0.424 1、2.946(红壤),0.284 6、1.58(潮土).比绿肥对应高出32.9%、57.1%(红壤),67%、93.7%(潮土).红壤由于Fe、Al、Mn等氧化物含量较高及低pH值,使其对DOM的亲和力比潮土强.试验结果还表明绿肥和猪粪堆肥DOM能够明显地抑制Cu的沉淀,在pH6～10范围内效果明显,其中Cu的沉淀率分别降低了43.6%(Cu+GM),22.6%(Cu+PMC).     

Interactions between engineered nanoparticles and dissolved organic matter: A review on mechanisms and environmental effects

Dissolved organic matter (DOM) is ubiquitous in the environment and has high reactivity. Once engineered nanoparticles (ENPs) are released into natural systems, interactions of DOM with ENPs may significantly affect the fate and transport of ENPs, as well as the bioavailability and toxicity of ENPs to organisms. However, because of the complexity of DOM and the shortage of useful characterization methods, large knowledge gaps exist in our understanding of the interactions between DOM and ENPs. In this article, we systematically reviewed the interactions between DOM and ENPs, discussed the effects of DOM on the environmental behavior of ENPs, and described the changes in bioavailability and toxicity of ENPs caused by DOM. Critical evaluations of published references suggest further need for assessing and predicting the influences of DOM on the transport, transformation, bioavailability, and toxicity of ENPs in the environment.     

Enhanced and irreversible sorption of pesticide pyrimethanil by soil amended with biochars

Biochar derived from partial combustion of vegetation is ubiquitous and potentially effective in sequestration of environmental contaminants.Biochars were prepared by burning of red gum(Eucalyptus spp.) woodchips at 450 and 850°C(labeled as BC450 and BC850).These two biochars were found to possess markedly different properties in terms of surface area and porosity.Short-term equilibration tests(24 hr) were conducted to assess the sorption-desorption behavior of pyrimethanil in the soil amended with various amounts of biochar of each type,with a special focus on the desorption behavior of the sorbed pesticide through four times successive desorption by dilution.Sorption coefficient and isotherm nonlinearity of the amended soils progressively increased with the content of biochar in the soil.Biochar BC850 with higher surface area and microporosity showed a stronger effect on the reversibility of sorption pesticide.The soils amended with 5% BC450 and 1% BC850 had nearly the same sorption capacity for pyrimethanil;however,their desorption processes were very different with 13.65% and 1.49% of the sorbed pesticide being released,respectively.This study suggested that biochar in soil could be an important factor for immobilization of a pesticide and thus affecting its environment fate in soil.     

农药在包气带中迁移过程的数值模拟

根据水动力学弥散理论建立农药在包气带中运移与转化过程的数学模型,评价农药使用对地下水环境的影响。选择应用范围广、用量大、毒性高的7种农药为目标污染物,以汉江流域的中下游地区的气象与土壤特征为条件进行模拟,结果表明,甲胺磷、乐果、甲草胺容易在土壤中淋溶,对地下水造成很大威胁。根据地下水埋深和设定的浓度限值,估算了农药对地下水的安全使用量。     

几种低分子量有机酸和氨基酸对黄棕壤吸附菲的影响

采用批量平衡试验方法,研究了根系分泌物中几种常见的低分子量有机酸(LMWOA)和氨基酸对黄棕壤吸附菲的影响.结果表明,在供试有机酸和氨基酸的影响下黄棕壤对菲的等温吸附曲线仍呈显著的线性关系,分配作用是黄棕壤吸附菲的主导机制,供试LMWOA和氨基酸对黄棕壤吸附菲有抑制作用,且加入量越大,抑制作用越强.与氨基酸相比,LMW...     

Effects of fulvic acid and humic acid from different sources on Hg methylation in soil and accumulation in rice

Humus is often used as an organic modifier to reduce the bioaccumulation of heavy metals in plants, but the effects of different humus components from different sources on the fate of mercury (Hg) in paddy fields are still unclear. Here, fulvic acid (FA) and humic acid (HA) extracted from composted straw (CS), composted cow dung (CCD), peat soil (PM) and lignite coal (LC) were used to understand their effects on the methylation and bioaccumulation of Hg in paddy soil by pot experiments. Amendments of both FA and HA largely increased the abundance of Hg-methylating microbes and low-molecular-weight organic matters (e.g, cysteine) in paddy soil. They were also found to change the aromaticity, molecular size and Chromophoric DOM concentration of DOM, and resulted in heterogeneous effects on migration and transformation of Hg. All the FA-amended treatments increased the mobility and methylation of Hg in soil and its absorption in roots. Nevertheless, FA from different sources have heterogeneous effects on transport of Hg between rice tissues. FA-CCD and FA-PM promoted the translocation of MeHg from roots to rice grains by 32.95% and 41.12%, while FA-CS and FA-LC significantly inhibited the translocation of inorganic Hg (IHg) by 52.65% and 66.06% and of MeHg by 46.65% and 36.23%, respectively. In contrast, all HA-amended treatments reduced the mobility of soil Hg, but promoted Hg methylation in soil. Among which, HA-CCD and HA-PM promoted the translocation of MeHg in rice tissues by 88.95% and 64.10%, while its accumulation in rice grains by 28.43% and 28.69%, respectively. In general, the application of some FA and HA as organic modifiers to reduce Hg bioaccumulation in rice is not feasible.