Effect of low molecular weight organic acids on adsorption and desorption of fluoride on variable charge soils

The effect of four low molecular weight organic acids on F⁻ adsorption by two variable charge soils was investigated using a batch method. The organic acids reduced F⁻ adsorption through competition by the acids with F⁻ for sorption sites. Oxalic and malonic acids, both of which have simpler chemical structures, were more effective than citric or malic acid. The effect of organic acids on F⁻ adsorption was more prominent at higher pH values and with larger amounts of the organic acids. The desorption study showed that the organic acids enhanced the desorption of F⁻ adsorbed by the soils. In the control and malic acid systems, desorption increased sharply with decreasing pH, while in the oxalic acid system, desorption rose slightly with decreasing pH. Desorption also increased with increasing amount of organic acid added. There are two possible mechanisms for the effect of the organic acids on F⁻ adsorption and desorption: (1)␣competition of the organic acids with F⁻ for adsorption sites and (2) dissolution of the adsorbents, especially dissolution of soil Al.     

添加小分子有机物对污泥重金属生物沥滤的抑制作用

采用向城市污泥添加小分子有机物后进行生物沥滤,探讨了不同小分子有机物(甲酸、乙酸、丙酸、丁酸、乙醇、水杨酸、草酸、苯甲酸)对生物沥滤过程污泥中pH值、Eh、Cu含量和Zn含量的影响。结果表明,对于污泥中的pH和Eh,不同有机物对其影响程度在整个沥滤过程中大体上相似,即pH值都呈先升后降的趋势,Eh呈先降后升趋势。对不同类型的重金属来说,不同有机物对其影响程度Cu大于Zn,其中Cu的沥出效果从强到弱依次为:对照>苯甲酸>乙醇>草酸>水杨酸>丙酸>甲酸>丁酸>乙酸,而对Zn的沥出效果在整个沥滤过程中相似。总之,整体规律为:醇类化合物和二羧基酸对污泥中的硫细菌的生物沥滤影响不大,而对于结构相似的单羧基有机酸来说,碳链越短,对生物沥滤的影响越大,分子量较高的芳香族有机酸对于重金属的去除也有明显的抑制作用,影响程度随着羧基数目的增加而加剧,但其抑制作用不及小分子有机酸显著。此外,污泥中营养物质TN、TP和TK的释放也受到一定影响。     

Stimulation and inhibition of phytoplankton growth by low molecular weight hydrocarbons

Experiments on 4 phylogenetically different phytoplankton exposed in culture to a range of concentrations of benzene, toluene and xylene showed a variety of growth responses for marine microalgae. The degree of influence of these aromatic hydrocarbons, all components of fuel oils and crude oils, varied with concentration, compound and species. Stimulation of growth in Dunaliella tertiolecta resulted from low μg/l concentrations of all three compounds, Skeletonema costatum showed no growth enhancement, while Cricosphaera carterae and Amphidinium carterae were intermediate in their reactions. Closed culture vessels were found to be necessary to retain these volatile hydrocarbons. Many of the previous laboratory studies on oil using standard methods — cotton plugs, screw caps or beakers — have overlooked the important influence of the volatile fraction. The species-specific stimulation of low concentrations was further shown in experiments with mixtures of No. 2 fuel oil. The volatile fraction was most biologically reactive, being the source of growth enhancement at low levels and a major growth inhibitor at high concentrations. Thus, a significant environmental effect of oil on marine primary production could be the growth stimulation of particular species by low molecular weight aromatic compounds resulting in an alteration of the natural phytoplankton community structure and its trophic relationships.     

菲对黑麦草根系几种低分子量分泌物的影响

有机污染的植物修复过程与植物根系分泌密切相关,近年来,对于持久性有机污染多环芳烃的植物修复研究得到了很大发展,但对于多环芳烃污染下植物根系分泌物的研究很少.该实验以多年生黑麦草(Lolium perenne L.)为供试材料,以营养液栽培方式研究了在多环芳烃菲处理下,黑麦草根系对几种低分子量有机物的分泌情况.研究结果显示,黑麦草根系分泌有机酸、总糖以及氨基酸的量都随菲质量浓度的上升而变化.黑麦草根系分泌的低分子有机酸主要为草酸,在菲处理下,低分子有机酸的组成无明显变化,但含量随菲质量浓度上升而提高(由对照时的2.33 mg·g-1 FW升高至8 mg·L-1时的4.75 mg·g-1 FW);总糖和氨基酸含量均随菲质量浓度上升出现先升高后下降的趋势,但是最高值出现的菲质量浓度不同,从含量上来看,有机酸是黑麦草根系低分子量分泌物的主要部分.结合其它研究结果分析,植物分泌的有机酸可能在加速多环芳烃清除中发挥了重要作用.     

Evidence for Ph Insensitivity in Some Insects Inhabiting Peat Pools in the Loch Fleet Catchment

The impact of liming on the insects associated with peat pools was studied in the Loch Fleet catchment in 1991 and 1992. Fifty-six taxa were identified from 121 timed samples. Despite the raised pH associated with liming in 1986, the population densities of Odonata, Hemiptera and Coleoptera appeared to be unaffected when compared with those of untreated peat pools in the same area. the study demonstrated the existence of two main types of community, that of the steep-sided edges of pools, dominated by odonate nymphs and large species of beetles, and that of the shallower pools, dominated by Hydroporus species (Col., Dytiscidae).     

Evidence for Ph Insensitivity in Some Insects Inhabiting Peat Pools in the Loch Fleet Catchment

The impact of liming on the insects associated with peat pools was studied in the Loch Fleet catchment in 1991 and 1992. Fifty-six taxa were identified from 121 timed samples. Despite the raised pH associated with liming in 1986, the population densities of Odonata, Hemiptera and Coleoptera appeared to be unaffected when compared with those of untreated peat pools in the same area. the study demonstrated the existence of two main types of community, that of the steep-sided edges of pools, dominated by odonate nymphs and large species of beetles, and that of the shallower pools, dominated by Hydroporus species (Col., Dytiscidae).     

洱海沉积物不同分子量溶解性有机氮空间分布及光谱特征

利用超滤技术对洱海沉积物溶解性有机氮(DON)进行分子量分级,探究了DON各组分空间分布特征,并运用紫外-可见吸收光谱和三维荧光光谱对其结构进行了表征.结果表明,洱海沉积物总DON含量ω(DON)为23.46—61.40 mg·kg-1,平均值为37.19 mg·kg-1,空间分布总体呈现南部>北部>中部的趋势;分子量大于1K Da的大分子组分ω(>1KDa)占ω(DON)的比例为79.1%—93.0%,即洱海沉积物DON是以大分子为主.沉积物DON各组分的芳香性及腐殖化程度较高,芳香环取代基中活性官能团种类较多,且南部芳香性及腐殖化程度最高,北部芳香环取代基种类最多;大分子组分DON含有类富里酸荧光物质,其来源于陆源输入和微生物降解共同作用.由此可见,洱海沉积物DON主要由大分子物质组成,其腐殖化程度较高且含类富里酸荧光物质,而此类DON对藻类的生物有效性较低,这可能是洱海沉积物氮含量较高而上覆水氮浓度较低的原因之一,即沉积物DON分子组成及其结构特征可在一定程度上作为湖泊营养水平的衡量指标.     

High molecular weight algal substances in the sea

Phytoplankton exudates into culture media and extracts from littoral algae are shown to contain significant quantities of extracellular materials having molecular weights in excess of 50,000. A recent development in experimental fluid mechanics (the reduction of turbulent friction coefficients of flowing solutions by dissolved macromolecules) has been utilized as a specific test for high molecular weight compounds. Phytoplankton species in all major algal groups could be found which exude high molecular weight compounds into their culture media; the red alga Porphyridium cruentum typically produced friction reductions as high as 60%. Seaweed samples in the Chlorophyta, Phaeophyta, and Rhodophyta showed major changes in turbulent friction coefficient; in some cases the friction was less than 1/2 that of pure seawater. All samples of the genus Porphyra and Gigartina produced substantial friction changes. From these experiments it is concluded that algal exudates can be a prominent source of high molecular weight compounds in the sea.     

城市污染河道沉积物有机质的氧化稳定性

为了研究城市河道沉积物有机质的氧化稳定性,以氧化稳定系数(Kos)和腐殖化程度(HA/FA)作为评价指标,在用H2O2处理沉积物的基础上,探讨城市污染河道有机质含量、有机质组成等对氧化稳定性的影响.结果显示,污染河道沉积物有机质含量明显高于自然水生态系统沉积物有机质含量;富里酸(FA)、胡敏酸(HA)、胡敏素(HM)是污染河道沉积物有机质主要赋存形式,其中胡敏素是主体,占全部有机质的65%以上;易氧化有机质(OMr)和难氧化有机质(OMd)与总有机质含量均显著正相关(P0.05);OMd的含量可以更直观地反映河道污染程度;重污染河道沉积物有机质去除量较高;随着有机质的去除,沉积物Kos在总体上有上升的趋势;不同形态有机组分其Kos差异性明显(P0.05),以HM为主的紧结态腐殖质的Kos值最高;用HA/FA和OMr可从大体上表征沉积物的氧化稳定性;HA、FA是影响城市河道沉积物氧化稳定性的主要因素.     

滇池沉积物有机磷形态分级特征

考察沉积物磷对湖泊富营养化贡献时,大量研究涉足无机磷,对有机磷的研究十分薄弱.针对滇池的33个沉积物样品,采用有机磷分级提取方法,将沉积物有机磷分为活性磷、中等活性磷、非活性磷等三种具有不同稳定性的有机磷.结果表明:排除滇池西北部外源污染严重的样品后,沉积物有机磷与总磷有自北向南逐渐降低的变化趋势,有机质与总磷、活性有机磷、中等活性有机磷以及非活性有机磷都表现出了显著相关关系.沉积物活性有机磷和中等活性有机磷与NaHCO3提取无机磷均显著相关,说明二者具有潜在的生物有效性.     

Modelling the diagenetic fate of persistent organic pollutants in organically enriched sediments

The fate of persistent organic pollutants (POPs) in aquatic ecosystems is intimately linked to the cycling of organic matter. In this paper, we present a model of the effect of organic matter decomposition on the distribution of persistent organic pollutants in sediments. The model predicts a diagenetic (sediment-ageing) magnification of chemical concentrations in sediments enriched with labile organic matter. We predict two- to four-fold diagenetic magnification across a wide range of realistic parameter values, and higher levels (up to 20-fold) for labile organic matter in systems with low burial rates (i.e., residence times on the order of years). As an illustration, we apply our model to understand the fate of waste organic matter and associated PCBs discharged by marine fish farms. The available data support both the spatial pattern (as a function of burial rate) and the range of sediment PCB concentrations predicted by our model. This model explains why equilibrium models fail to predict the very high sediment-water partitioning coefficients often observed in the field. Effectively, diagenetic processes impose an additional biomagnification step at the bottom of the detritus-based food web, increasing the exposure to POPs of organisms at higher trophic levels.     

The addition of FeOOH binds phosphate in organic matter-rich sediments

Due to climate change and anthropogenic nutrients’ runoff into freshwater or shallow lakes, eutrophication caused by phosphorus (P) can be seen in the frequent occurrence of cyanobacterial blooms and excessive growth of macrophytes. Subsequently, decomposition of cyanobacterial bloom biomass (CBB) and macrophytes leads to massive autochthonous organic matter (OM) and creates hypoxia in bodies of water. In this study, we investigated the effects of OM and iron on phosphorus release from lake sediments under anaerobic conditions. As with CBB, the addition of cellulose also enhanced P release from sediments during microcosm experiments, while total phosphorus (TP) concentration in the overlying water displayed an inverse relationship to cellulose amendment, with high TP concentration (0.41?±?0.07?mg?L^?1) observed in the treatment of less cellulose amendment (1?g of cellulose). In addition, P release from OM-rich sediments was effectively inhibited when amorphous FeOOH was added to the microcosms. P release was inhibited by 66–92% when the weight ratio between total Fe and total P in sediments varied from 18 to 60. Thus, iron treatment was useful to inhibit P release from OM-rich sediments, and could alleviate eutrophication problems.     

Mesoscale variability of organic matter composition in nw adriatic sediments

We investigated the spatial variability of sediment organic matter content and composition in three areas (A, B and C) of the Northwestern Adriatic Sea, subjected to a putative gradient of trophic state ( i.e. , increasing distance from the Po river outflow) in order to determine the appropriate sample size and replication. The analysis of the mesoscale variability was carried out comparing variability on the scale of meters ( i.e. among different deployments) with the variability observed on a scale of several kilometres ( i.e. among different sampling areas). Sediment samples, collected on April 1999, October 1999, April and October 2000, were analysed for chloropigment content (chlorophyll-a and phaeopygments) and protein, carbohydrate and lipid concentrations. Chloropigment, protein, carbohydrate and lipid concentrations were high, indicating that this system shares trophic conditions typical of highly productive environments. All organic matter components displayed a distribution independent from the increasing distance from the Po river outflow and a clear spatial variability, characterised by significant differences among different areas, but not among deployments. Carbohydrates were the biochemical compound displaying the highest spatial variability among the three areas. Chloropigment, protein, carbohydrate and lipid concentrations displayed also significant temporal changes. When spatial and temporal variability were compared, chlorophyll-a, phaeopigment and protein concentrations displayed a higher temporal than spatial variability. Conversely, for carbohydrates and lipids spatial and temporal variability was of the same order of magnitude. Organic matter composition displayed limited changes among areas, but a strong temporal variability. The results from the Adriatic sea suggest that analyses from sediments collected from a single deployment are sufficient for assessing organic matter concentration and composition over areas of several hundreds of square meters. However, for estimating organic matter composition over larger spatial scales ( i.e. miles) the identification of different sampling areas is needed.     

Influence of low molecular weight anionic ligands on the sorption of heavy metals by soil constituents: a review

Environmental Chemistry Letters - The sorption of heavy metals by soil constituents reduces the absorption of these pollutants by crops and vegetables, and thus limit food contamination. Low...     

厦门近海沉积物中高分子有机质的来源初探

采用多步连续-湿法-化学方法,分离提纯了于2010年7月和12月在厦门近海采集的沉积物样品,获得3类高分子有机质,即腐殖酸（HA）、干酪根和碳黑（KB）和碳黑（BC）。以扫描电镜（SEM）作为有效的辅助手段,观察沉积物原样及高分子有机质的形貌特征,结合稳定碳同位素（δ13C）的分析,初步探讨了厦门近海沉积物中高分子有机质的来源。扫描电镜观察发现,在原样沉积物中存在多种海源物质（如钙质硅藻和圆筛藻/冠盘藻）;而在KB样品中同时发现类似于陆地植物的木质碎片以及来自海洋的藻胶鞘,暗示了其来源是海源与陆源共同作用的结果。稳定碳同位素研究表明厦门湾近海海域沉积物中有机质以陆源影响占优势,其比例在58.32%至84.45%之间;δ13C值整体上显示为夏季的贫于冬季的,这与研究区域的生态系统中陆源C3植被和海源水生植物的繁殖生长有关,同时还有排海污水及化石燃料煤燃烧后或者运煤船只洒落的碎屑的贡献。     

A link between biologically imported particulate organic nutrients and the detritus food web in reef communities

Previous work with planktivorous fishes has shown that they import particulate organic and inorganic material to reefs in the form of fecal pellets, which, in part, are deposited in crevices on the reef where these fishes shelter during their inactive period. Since these feces do not accumulate in fish shelters, we predicted that some of the feces could be rapidly consumed by reef detritivores. We examined the attractiveness of fish feces to potential reef detritivores by placing traps baited with planktivorous fish feces, along with unbaited control traps, in crevices on rocky reefs at Santa Catalina Island, California, USA, between June 1982 and November 1983, and on coral reefs at St. Croix, U.S. Virgin Islands, during June 1983. Significantly more animals (the majority being crustaceans) were trapped in the baited traps compared to the unbaited controls on both reefs. There was also a significant association between the presence of trapped animals and fish feces at Santa Catalina Island (p = 0.009); this association was not quite as strong in St. Croix (p = 0.069). The consumption by shrimp of feces marked with carmine particles and, in turn, the predation on these shrimp by a reef fish demonstrates the links between this type of imported particulate organic and inorganic material and the food web of the reef community.Please address all correspondence and requests for reprints to Dr. Miller at California State University, Long Beach     

Road-deposited sediments mediating the transfer of anthropogenic organic matter to stormwater runoff

Environmental Geochemistry and Health - It has been regarded that road-deposited sediment (RDS) is one of the important sinks of anthropogenic pollutants as well as the major source of pollutants...     

Detection and quantitation of trace levels of low molecular weight halocarbons (LMHs) associated with commercial sodium humate

Examination of vapor above commercial sodium humate and above 10wt% aqueous humate solution by gas chromatography (GC) revealed the presence of chloroform and trichloroethylene. Further examination of the aqueous humate by the purge and trap procedure confirmed the association of chloroform and trichloroethylene with the humate. GC/mass spectrometry analyses of methylene chloride extract of the humate established the association of LMHs with the humate. Improved headspace capillary GC technique showed that the humate contained not only chloroform, trichloroethylene but several other LMHs in the range 190 to 4000ng·kg^‐1.     

不同生态类型富营养化湖泊沉积物中有机质赋存形态

以藻型湖泊(太湖)、草藻型湖泊(南四湖)、草型湖泊(白洋淀)湖泊沉积物为研究对象,采集了11个表层沉积物样品,测定沉积物中总氮(TN)和总磷(TP)含量并利用物理分组方法,研究了3种不同生态型湖及同一湖泊不同区域沉积物中总有机质(OM)、轻组有机质(LFOM)和重组有机质(HFOM)的赋存特征.结果表明,南四湖沉积物中总氮、总磷和总有机质含量显著高于太湖和白洋淀;尽管太湖、南四湖和白洋淀沉积物中总有机质含量较高,但是轻组有机质(LFOM)含量较低,分别占总有机质的0.95%—1.08%、0.21%—1.37%和1.4%—1.78%;重组有机质(HFOM)含量较高,分别占总有机质的83.83%—87.4%、94%—98.98%和88.2%—98.3%,表明3种不同生态型湖泊沉积物中所含有机质绝大部分为难分解的重组有机质,轻组有机质基本矿化分解.相关性分析表明,轻组有机质(LFOM)、重组有机质(HFOM)与总有机质(OM)之间均呈现显著正相关关系.