边缘海环境中陆源有机质的化学生物标志物研究进展

边缘海是陆地和大洋的连接带,是陆源物质向开阔海输送的主要途径,在全球碳循环过程发挥着重要的作用。示踪边缘海沉积有机碳的来源,可以为有机碳的分布、降解、迁移和转化等研究提供基础。本文从高等植物类脂化合物(如长链正构烷烃、正构烷醇、脂肪酸、甾醇等)、维管植物木质素和土壤有机质支链和类异戊二烯四醚(BIT)等几个方面,介绍了基于化学生物标志物示踪边缘海陆源有机质来源的研究进展。指出以包含木质素、BIT等指标在内的多重示踪方法和多端元模型是指示边缘海沉积有机质来源的良好方法,能够提供比单指标方法更为准确可靠的结果。     

Characteristics of the natural organic matter sorption affects of organic contaminants

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Gender influences decisions to change land use practices in the tropical forest margins of Jambi,Indonesia

This study explores the role of gender as a factor in decision making about alternative land use options and in responses to new investment opportunities, which has received little attention to date. An observational study to determine the different factors affecting male and female decisions to change land use at the individual level in a forest margin landscape in Jambi (Sumatra, Indonesia) was combined with a set of role playing games (RPGs) designed to assess participant responses in a simulated social setting of women-only and men-only groups. The RPG included simulated agents offering new opportunities to convert or conserve agroforest. In the study area, rubber (Hevea braziliensis) agroforests that support high biodiversity and carbon storage are giving way to monoculture rubber and oil palm (Elaeis guineensis) plantations. When women from both the upland and lowland villages played the RPGs, external investors proposing logging or oil palm conversion were approached very positively and the resulting land use change was more dynamic and extensive than in the equivalent men-only groups. Consequently, women outperformed men in achieving income targets. In lowland areas gender is strongly associated with land use change, while in the uplands the level of conservation awareness plays a more crucial role in the maintenance of rubber agroforests. Based on the data, and contrary to expectations and gender stereotypes, it is expected that the greater involvement of women in landscape level decision making will increase emissions from deforestation and forest degradation in the area, posing further challenges to efforts to reduce such emissions.     

Hybrid and enhanced electrokinetic system for soil remediation from heavy metals and organic matter

The electrokinetic(EK)process has been proposed for soil decontamination from heavy metals and organic matter.The advantages of the EK process include the low operating energy,suitability for fine-grained soil decontamination,and no need for excavation.Dur-ing the last three decades,enhanced and hybrid EK systems were developed and tested for improving the efficiency of contaminants removal from soils.Chemically enhanced-EK processes exhibited excellent efficiency in removing contaminants by controlling the soil pH or the chemical reaction of contaminants.EK hybrid systems were tested to overcome environmental hurdles or technical drawbacks of decontamination technologies.Hybridiza-tion of the EK process with phytoremediation,bioremediation,or reactive filter media(RFM)improved the remediation process performance by capturing contaminants or facilitating biological agents'movement in the soil.Also,EK process coupling with solar energy was proposed to treat off-grid contaminated soils or reduce the EK energy requirements.This study reviews recent advancements in the enhancement and hybrid EK systems for soil remediation and the type of contaminants targeted by the process.The study also cov-ered the impact of operating parameters,imperfect pollution separation,and differences in the physicochemical characteristics and microstructure of soil/sediment on the EK per-formance.Finally,a comparison between various remediation processes was presented to highlight the pros and cons of these technologies.     

Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming

Organic farming systems often comprise crops and livestock, recycle farmyard manure for fertilization, and preventive or biocontrol measures are used for plant protection. We determined indicators for soil quality changes in the DOK long-term comparison trial that was initiated in 1978. This replicated field trial comprises organic and integrated (conventional) farming systems that are typical for Swiss agriculture. Livestock based bio-organic (BIOORG), bio-dynamic (BIODYN) and integrated farming systems (CONFYM) were compared at reduced and normal fertilization intensity (0.7 and 1.4 livestock units, LU) in a 7 year crop rotation. A stockless integrated system is fertilized with mineral fertilizers exclusively (CONMIN) and one control treatment remained unfertilized (NOFERT). The CONFYM system is amended with stacked manure, supplemental mineral fertilizers, as well as chemical pesticides. Manure of the BIOORG system is slightly rotted and in BIODYN it is composted aerobically with some herbal additives. In the third crop rotation period at normal fertiliser intensity soil organic carbon (C_org, w/w) in the plough layer (0–20 cm) of the BIODYN system remained constant and decreased by 7% in CONFYM and 9% in BIOORG as compared to the starting values. With no manure application C_org-loss was severest in NOFERT (22%), followed by CONMIN together with the systems at reduced fertiliser intensity (14–16%). Soil pH tended to increase in the organic systems, whereas the integrated systems had the lowest pH values. At the end of the third crop rotation period in 1998 biological soil quality indicators were determined. Compared to soil microbial biomass in the BIODYN systems the CONFYM soils showed 25% lower values and the systems without manure application were lower by 34%. Relative to the BIODYN soils at the same fertilization intensity dehydrogenase activity was 39–42% lower in CONFYM soils and even 62% lower in soils of CONMIN. Soil basal respiration did not differ between farming systems at the same intensity, but when related to microbial biomass (qCO₂) it was 20% higher in CONFYM soils and 52% higher in CONMIN as compared to BIODYN, suggesting a higher maintenance requirement of microbial biomass in soils of the integrated systems. The manure based farming systems of the DOK trial are likely to favour an active and fertile soil. Both, C_org and biological soil quality indicators were clearly depending on the quantity and quality of the applied manure types, but soil microbial biomass and activities were much more affected than C_org.     

The migration and transformation of dissolved organic matter during the freezing processes of water

This study investigated the partitioning behavior of dissolved organic matter(DOM) in liquid and ice phases, as well as the changes in the optical properties and chlorine reactivity of DOM during the freezing processes of water. DOM was rejected from the ice phase and accumulated in the remaining liquid phase during water freezing. Moreover, the decrease in freezing temperature, as well as the increase in dissolved organic carbon(DOC)concentration of feed water, caused an increase in DOM captured in the ice phase. The ultraviolet-absorbing compounds, trihalomethane precursors, as well as fulvic acid- and humic acid-like fluorescent materials, were more liable to be to be rejected from the ice phase and were more easily retained in the unfrozen liquid phase during water freezing, as compared with organics(on average) that comprise DOC. In addition, it was also found a higher accumulation of these organics in the unfrozen liquid phase during water freezing at higher temperature. The freeze/thaw processes altered the quantity, optical properties, and chlorine reactivity of DOM. The decrease in ultraviolet light at 254 nm as well as the production of aromatic protein- and soluble microbial byproduct-like fluorescent materials in DOM due to freeze/thaw were consistently observed. On the other hand, the changes in DOC, trihalomethane formation potential, and fulvic acid- and humic acid-like fluorescence caused by freeze/thaw varied significantly between samples.     

Impact of dissolved organic matter on the photolysis of the ionizable antibiotic norfloxacin

Norfloxacin(NOR), an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ubiquity.Therefore, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter(DOM), which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance(EPR) were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical(U OH) and singlet oxygen(1O2) based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of U OH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and1O2. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored.     

废水生化处理中有机物的分析和转化

有机物的种类、含量、物化特性、分子量等性质直接影响废水处理工艺的处理效果。本文综述了近年来废水生化处理中有机物的分析方法及废水生化处理过程中有机物的转化规律。     

Interactive effect of dissolved organic matter and phenanthrene on soil enzymatic activities

The investigation of dissolved organic matter (DOM) on urease, catalase and polyphenol oxidase activity in a phenanthrene (Phe)-contaminated soil was conducted under laboratory incubation conditions. Values of soil enzymatic activity depended mainly on incubation time. In the initial 16 days, urease activity increased, and was followed by a decrease. In the initial 8 days, catalase activity decreased and then increased. Variation of polyphenol oxidase activity was just the reverse of catalase activity. After 30 days of incubation, no pronounced difference among treatments with Phe, Phe and DOM, and control were detected in urease, catalase and polyphenol oxidase activity. Phe might inhibit urease and catalase, and stimulate polyphenol oxidase. DOM could improve inhibition of Phe in soil urease and catalase activity during the initial period of applying DOM. Nevertheless, DOM had no significant effect on polyphenol oxidase activity in the Phe contaminated soil. There was a negative correlation between catalase and polyphenol oxidase (r = -0.761~(***)), and catalase and urease (r = -0.554~(**)). Additionally, a positive correlation between polyphenol oxidase and urease was also detected (r = 0.701~(***)). It is implied that the formed DOM after application of organic wastes into soils may counteract the inhibition of polycyclic aromatic hydrocarbons in soil enzyme activities.     

河流与海洋溶解有机物荧光激发-发射矩阵光谱的测定

通过对河流与海洋现场样品、微藻培养液和牛血清蛋白溶液的实验,确定了HITACHI F-4500型荧光分光光度计的测定河流和海洋溶解有机物荧光激发-发射矩阵光谱的激发和发射通带分别为5 nm和10 nm,波长扫描速度为12 000 nm/min,标准偏差在0.6%~8%。     

水环境中溶解性有机物溯源分析及分子结构表征概述

溶解性有机物(DOM)是地球上最大的碳基化合物反应性储层之一,涉及各种生物地化反应并且在污染物溶解度、毒性、生物利用度、流变性和分布中发挥重要作用。本文介绍了当前用于表征水环境中DOM的策略和工具,探讨了当前研究在技术限制(预处理过程复杂、仪器分辨率低、数据处理困)、结构复杂性、结构多变性等方面存在的诸多局限性。分析认为:已有研究主要侧重于溯源分析和分子结构特征解析,未来研究应该在不同的结构层面和角度开展,加强多学科融合、数据库创建、对照实验和协同工作。     

珠江口及近海沉积有机质来源判断

用二元混合模型对有机地球化学指标之间的关系进行模拟,结果表明珠江口和近海沉积物样品OC/N与δ15N在早期成岩过程中均发生了较大改变,OC/N可用作判断有机质来源的辅助证据,而δ15N不宜用作沉积有机质来源的指示.δ15Corg 则可以较可靠地用来评价来源的贡献.稳定C同位素二元混合模拟结果表明从珠江河流出海口往近海方向,陆源有机质所占比例呈下降趋势,在珠江口内,陆源有机C的比例略大于水生有机C,而近海有机质以当地水生藻类为主要来源.     

The role of soil organic matter in maintaining the productivity and yield stability of cereals in China

The role of soil organic matter (SOM) in agricultural systems has been widely studied in conjunction with the potential for greenhouse gas mitigation. However, the link between SOM accumulation in croplands, crop productivity and yield stability has not yet been clearly established. In this paper, we collected data on provincial yearly crop productivity (yields, total cropland area) during 1949–1998 and the average SOM contents in croplands sampled and determined from the National Soil Survey in 1979–1982 of mainland China. The cereal productivity was assessed both with an overall mean of 1949–1998 and with the mean values for different time periods within this overall time, respectively. The yield variability within a single stabilizing stage, and between the fluctuating years, was calculated as a negative measure of yield stability. The correlation between SOM and cereal productivity was very significant for most provinces, but the relationship has become less significant as we approach the present. Moreover, the average yield variability was very significantly and negatively correlated with the cropland SOM level. The findings support our previous hypothesis from case studies, that C sequestration in China's croplands may provide win–win benefits, by enhancing crop productivity and stabilizing yield. This offers a sound basis as a greenhouse gas mitigation strategy by promoting C sequestration in croplands, and enhancing food security in China's agriculture.     

Atomic force microscopy study on the microtopography of natural organic matter and newly formed hydrous MnO2

To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process, the microtopography of its reductive products, the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide, was investigated. The morphology of natural organic matter (NOM) adsorbed by the newly formed hydrous manganese dioxide was also compared with that of NOM alone. By using the tapping mode atomic force microscopy (AFM), the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet (with a thickness of 0–1.75 nm) as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time, which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity. When 1 mmol/L newly formed hydrous manganese dioxide was added, the microtopography of NOM molecules shifted from a loosely dispersed pancake shape (with adsorption height of 5–8.5 nm) to a densely dispersed and uniform spherical structure. These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation. Translated from Environmental Science, 2006, 27(5): 945–949 [译自: 环境科学]     

Development of biodiversity in field margins recently taken out of production and adjacent ditch banks in arable areas

Taking field margins out of intensive cultivation is a common form of agri-environmental scheme and on-farm nature management. Typically, no nutrients or pesticides are applied in these margins, which may be sown either with a crop or with grasses and native flowering plants. In some cases the margins are mown, while in others they are left alone. Newly established grass margins are less species-rich than field boundaries or road verges with a long history, justifying the expectation that field margins, if properly managed and given time and appropriate seed sources, could develop into relatively species-rich vegetation. We studied the biodiversity of both margins taken out of production and adjacent ditch banks in the years following initial establishment of the margins. To this end we combined the data of three different projects in order to increase the sensitivity of the statistical analyses. The results showed that the plant species richness of the field margins increased in the years following establishment over a period of four years. In addition, shifts in species composition indicated a decrease in soil nitrate concentrations. The species richness of both butterflies and dragonflies may increase. The most striking result was the marked increase in the plant species richness of the adjacent ditch banks in the five years following creation of the margins. Here, too, changes in species composition indicated a decrease in soil nitrate. In the years following establishment of the field margins there was no increase in the cover of agriculturally harmful weeds in these margins. However, the number of harmful nematodes increased. Our results show the short term effect of establishing field margins. Long term effects are still in need for further research.     

Composition regulates dissolved organic matter adsorption onto iron(oxy)hydroxides and its competition with phosphate:Implications for organic carbon and phosphorus immobilization in lakes

Dissolved organic matter(DOM)is a heterogeneous pool of compounds and exhibits diverse adsorption characteristics with or without phosphorous(P)competition.The impacts of these factors on the burial and mobilization of organic carbon and P in aquatic ecosystems remain uncertain.In this study,an algae-derived DOM(ADOM)and a commercially available humic acid(HA)with distinct compositions were assessed for their adsorption behaviors onto iron(oxy)hydroxides(FeOx),both in the absence and presence of phosphate.ADOM contained less aromatics but more protein-like and highly unsaturated structures with oxygen compounds(HUSO)than HA.The adsorption capacity of FeOx was significantly greater for ADOM than for HA.Protein-like and HUSO compounds in ADOM and humic-like compounds and macromolecular aromatics in HA were preferentially adsorbed by FeOx.Moreover,ADOM demonstrated a stronger inhibitory effect on phosphate adsorption than HA.This observation suggests that the substantial release of autochthonous ADOM by algae could elevate internal P loading and pose challenges for the restoration of restore eutrophic lakes.The presence of phosphate suppressed the adsorption of protein-like compounds in ADOM onto FeOx,resulting in an increase in the relative abundance of protein-like compounds and a decrease in the relative abundance of humic-like compounds in post-adsorption ADOM.In contrast,phosphate exhibited no discernible impact on the compositional fractionation of HA.Collectively,our results show the source-composition characters of DOM influence the immobilization of both DOM and P in aquatic ecosystems through adsorption processes.The preferential adsorption of proteinaceous compounds within ADOM and aromatics within HA highlights the potential for the attachment with FeOx to diminish the original source-specific signatures of DOM,thereby contributing to the shared DOM characteristics observed across diverse aquatic environments.     

大鹏澳网箱养殖海域底质有机物污染特征

大鹏澳网箱养殖海域表层底质有机物含量为1.65%~3.50%,平均为2.57%,明显高于我国浅海的一般水平和一类评价标准,超标率82.5%,超标0.04~0.75倍。有机物含量以春季和夏季较高,冬季次之,秋季明显较低,在网箱区内外的平均值分别为2.66%、2.42%。不同测站底质中有机物含量与硫化物含量正相关(r=0.704,p<0.05),其中以夏季的相关最显著(r=0.818,p<0.02)。网箱海域底质有机物单因子质量指数为1.28,老化风险为3级,说明沉积环境受到有机物的明显污染,面临中等程度的老化风险。     

Effects of a dynamic membrane formed with polyethylene glycol on the ultrafiltration of natural organic matter

The formation of a dynamic membrane (DM) was investigated using polyethylene glycol (PEG) (molecular weight of 35000 g/mol, concentration of 1 g/L). Two natural organic matters (NOM), Dongbok Lake NOM (DLNOM) and Suwannee River NOM (SRNOM) were used in the ultrafiltration experiments along with PEG. To evaluate the effects of the DM with PEG on ultrafiltration, various transport experiments were conducted, and the analyses of the NOM in the membrane feed and permeate were performed using high performance size exclusion chromatography, and the effective pore size distribution (effective PSD) and effective molecular weight cut off (effective MWCO) were determined. The advantages of DM formed with PEG can be summarized as follows: (1) PEG interferes with NOM transmission through the ultrafiltration membrane pores by increasing the retention coefficient of NOM in UF membranes, and (2) low removal of NOM by the DM is affected by external factors, such as pressure increases during UF membrane filtration, which decreases the effective PSD and effective MWCO of UF membranes. However, a disadvantage of the DM with PEG was severe flux decline; thus, one must be mindful of both the positive and negative influences of the DM when optimizing the UF performance of the membrane.