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1.
溶解性有机质对冻融作用下污染土壤中重金属Pb的溶出释放规律 总被引：2，自引：0，他引：2
采用室内模拟实验方法研究了溶解性有机质（DOM）对冻融作用下污染土壤中重金属Pb的溶出规律。结果表明：冻融作用明显改变了土壤基本理化性质和重金属Pb的化学形态;与未冻融土壤相比,DOM明显促进了冻融土壤中Pb的溶出释放。DOM对污染土壤中Pb的溶出释放作用与土壤类型、土壤污染时间和污染程度有关：DOM对棕壤中Pb的溶出释放作用大于对黑土中Pb的溶出释放作用;而且随着土壤Pb污染时间越长和污染程度越重,DOM对土壤中Pb的溶出释放作用越大。DOM对土壤中Pb的溶出释放还与DOM质量浓度、性质和组成密切相关：DOM质量浓度的增加提高了污染土壤中Pb的溶出释放;DOM的低pH和小分子量亲水性组分利于土壤中Pb的溶出释放。 相似文献
2.
Vast amounts of knowledge about the proton- and metal-binding properties of dissolved organic matter (DOM) in natural waters have been obtained in studies on isolated humic and fulvic (hydrophobic) acids. Although macromolecular hydrophilic acids normally make up about one-third of DOM, their proton- and metal-binding properties are poorly known. Here, we investigated the acid-base and Cu-binding properties of the hydrophobic (fulvic) acid fraction and two hydrophilic fractions isolated from a soil solution. Proton titrations revealed a higher total charge for the hydrophilic acid fractions than for the hydrophobic acid fraction. The most hydrophilic fraction appeared to be dominated by weak acid sites, as evidenced by increased slope of the curve of surface charge versus pH at pH values above 6. The titration curves were poorly predicted by both Stockholm Humic Model (SHM) and NICA-Donnan model calculations using generic parameter values, but could be modelled accurately after optimisation of the proton-binding parameters (pH ? 9). Cu-binding isotherms for the three fractions were determined at pH values of 4, 6 and 9. With the optimised proton-binding parameters, the SHM model predictions for Cu binding improved, whereas the NICA-Donnan predictions deteriorated. After optimisation of Cu-binding parameters, both models described the experimental data satisfactorily. Iron(III) and aluminium competed strongly with Cu for binding sites at both pH 4 and pH 6. The SHM model predicted this competition reasonably well, but the NICA-Donnan model underestimated the effects significantly at pH 6. Overall, the Cu-binding behaviour of the two hydrophilic acid fractions was very similar to that of the hydrophobic acid fraction, despite the differences observed in proton-binding characteristics. These results show that for modelling purposes, it is essential to include the hydrophilic acid fraction in the pool of ‘active’ humic substances. 相似文献
3.
The long-term impact of irrigation on a Mediterranean sandy soil irrigated with treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 year experiment. In this second part, we focused on Cu, Cr and Pb behaviour in relation with soil organic carbon (SOC). Soil samples were collected every 3 months during 2 years at the depths 0–20, 20–40 and 40–60 cm and were analysed for exchangeable and total metals, organic carbon content, metal sequential extraction and humic substances – Humic Acids (HA), Fulvic Acids (FA) and Non-Humified Fraction (NHF). Long-term irrigation with a domestic treated wastewater (TWW) may be considered safe with regard to trace metal accumulation in soil. Irrigation lowered the HA and NHF fractions of SOC and made the FA fraction more mobile. Cu bound preferentially to the SOC fraction, Cr was found mainly in the reducible fraction and Pb was bound to all fractions indiscriminately. Cu exhibited a high affinity for the HA fraction, while Pb and Cr had a high affinity for the FA fraction, which indicates a greater mobility of the organically-bound Pb and Cr than of the organically-bound Cu. Evaluation of the potential metal mobility has to take into account not only the usual speciation between labile, reducible and oxidisable fractions, but also the nature of the SOC responsible for the oxidisable fraction. 相似文献
4.
Previous studies showed that water chemistry and concentrations of dissolved organic matter (DOM) could affect its molecular
conformation and binding characteristics with hydrophobic organic contaminants (HOCs). However, the conformational change
of DOM resultant from water chemistry and concentrations of DOM was not extensively investigated; therefore, the contradictory
reports regarding the binding property with HOCs were available in literature. In this study, the effects of ionic strength,
pH and DOM concentrations on the fluorescence properties of two humic acids (HA), namely Fluka HA and Amherst HA, were investigated
by three-dimensional excitation-emission matrix fluorescence spectroscopy (3DEEM) and steady-state fluorescence polarization
(FP) techniques. The results not only corroborated previous observations obtained by other investigators, but revealed some
new information about the fluorescence properties and molecular conformation of the humic acids under different water chemistry
and DOM concentration conditions, which could shed light on its binding mechanisms and binding properties with HOCs. 相似文献
5.
卤水中溶解性有机质(dissolved organic matter,DOM)会对盐田日晒工艺和产品质量产生不利影响,如盐田卤水的蒸发速率减缓、蒸发度减小以及提取的矿物产品带有刺鼻的气味、浓重的颜色等。因此,对具有资源开发利用价值的卤水体系中DOM结构和性质的研究可以为后续DOM的有效去除或在DOM共存体系中调控无机盐结晶工艺路线提供有效的指导意见。本文以自然界中广泛存在的两种不同类型的卤水体系,即盐湖卤水DOM(SLDOM)和油田卤水DOM(OFDOM)为研究对象,采用溶解性有机碳(dissolved organic carbon,DOC)分析、光谱学分析和平行因子分析等手段对DOM的含量、分子量分布特征、光谱学结构和光降解行为开展了研究。DOC和荧光分析表明SLDOM和OFDOM的DOC含量和生物指数(BIX)值相似;与OFDOM相比,SLDOM的腐质化指数(HIX)值和高分子量组分(HMW)比例偏高;特别吸收光谱(SUVA254)和糖类化合物含量检测结果表明,SLDOM和OFDOM的HMW组分中含有的芳香类和糖类化合物所占比例比低分子量组分(LMW)高;三维荧光谱图分析(EEM)结果表明,SLDOM主要以腐殖质类物质为主,而OFDOM以蛋白质类组分为主。此外,DOM的荧光组分在不同分子量中的分布也存在明显差异:对于SLDOM,富里酸主要分布在HMW DOM中,而腐殖酸主要在LMW DOM中;对于OFDOM,芳香胺类蛋白组分主要分布在HMW DOM中,色氨酸和酪氨酸类蛋白组分主要分布在LMM DOM中。在光降解实验中,SLDOM和OFDOM的DOC含量随光照时间增加而逐渐减少,分别下降了29.32%和15.11%。进一步的分析表明,光照过程中两种卤水中糖类化合物均减少,小分子量的DOM优先分解。此外,在光照过程中SLDOM芳香类化合物增加,腐质化程度基本不变;OFDOM芳香类化合物减少,腐质化程度增加。EEM平行因子分析(PARAFAC)结果表明,SLDOM荧光组分在光降解过程中荧光强度增加,而OFDOM荧光强度减少。 相似文献
6.
Klaus Kaiser 《Organic Geochemistry》1998,28(12):849-854
The purpose of the study was to evaluate the influence of polyvalent cations known to form complexes with natural organic substances on the operational fractionation of dissolved organic matter (DOM) using XAD-8 adsorber resin. Dissolved organic matter solutions from a forest floor were treated with increasing concentrations of polyvalent metal cations (Ca2+, Al3+, Fe3+) at different pH levels. Then the concentrations of total dissolved organic carbon (DOC) and the distribution between hydrophilic and hydrophobic DOC were determined. The concentrations of total DOC decreased slightly when the C/metal ratio was less than 10, especially for Al and Fe. Hydrophilic DOC increased and hydrophobic DOC decreased with increasing concentrations of metal cations. Effects increased in the order Ca<Al<Fe and were more pronounced at low DOC concentrations and high pH values. The reason for the reduction of the DOC concentrations seemed to be the formation of insoluble metal–DOM complexes, while soluble metal–DOM complexes may induce an alteration of the distribution between hydrophilic and hydrophobic DOC. Thus, the polyvalent cations and their concentration need to be considered when DOM fraction distributions, determined with XAD-8 resin, of different waters are compared, especially at low DOC contents and high pH. 相似文献
7.
为探究溶解性有机质(DOM)不同相对分子质量组分对药物和个人护理品(PPCPs)类污染物吸附过程的影响,以卡马西平(CBZ)为目标污染物,以石英砂代表无机矿物,用商用腐殖酸(HA)制备DOM并进行超滤分级,然后开展吸附实验,并采用荧光光谱和红外光谱表征等手段,研究了DOM不同分子质量组分对石英砂吸附CBZ的影响及机制。结果表明,以3 000和10 000的超滤膜进行分级后的不同相对分子质量HA结构有明显差别,大分子质量HA中苯环等疏水性结构以及羟基的含量较多,芳香构造化程度高,多为分子量较高、稳定性较好的疏水性有机物,但中、小分子质量HA结构差异不大,含有更多羰基、羧基等含氧官能团,主要是一些分子质量较小的亲水物质; DOM不同分子质量组分对CBZ在石英砂上的吸附有明显影响,其中大分子质量组分促进吸附,而中、小分子质量组分抑制吸附,原因在于大分子质量组分可疏水结合于矿物表面,增加介质表面的活性吸附位点,同时其芳香性或脂肪性结构可与CBZ的疏水基团发生疏水作用共吸附或累积吸附于介质表面,从而促进CBZ的吸附;而中、小分子质量DOM的极性官能团可与CBZ酰胺部分通过极性作用结合,对CBZ分子有增溶作用,从而抑制吸附。 相似文献
8.
Ultraviolet absorbance titration for the determination of conditional stability constants of Hg（Ⅱ） and dissolved organic matter 总被引：1，自引：0，他引：1
Strong interaction between natural dissolved organic matter （DOM） and Hg（Ⅱ） may influence the transport, conversion, toxicity and bio-validity of mercury in the environment. In this paper ultraviolet （UV） absorbance titration was employed for the first time for the determination of the conditional stability constants of Hg（Ⅱ） and （DOM）. With increasing Hg（Ⅱ） concentrations, the UV absorbance of fulvic acid, humic acid, and DOM in river increases progressively. By linear and non-linear model fitting, the conditional stability constants （lgK） of Hg（Ⅱ） and DOM were worked out to be 3.54-4.93 and 3.64-4.85, respectively. The results are consistent with those acquired by the typical fluorescence quenching titration method, with the maximum relative error of lgK being 2.6% and the average relative error being 0.2%. The UV absorbance titration method has the advantages of rapid determination, simple performance, and it will probably become a new approach to studying interactions between DOM and trace metallic ions. 相似文献
9.
Al(III) and Fe(III) binding by humic substances in freshwaters, and implications for trace metal speciation 总被引：2，自引：0，他引：2
Edward Tipping Carlos Rey-Castro Stephen E Bryan John Hamilton-Taylor 《Geochimica et cosmochimica acta》2002,66(18):3211-3224
Published experimental data for Al(III) and Fe(III) binding by fulvic and humic acids can be explained approximately by the Humic Ion-Binding Model VI. The model is based on conventional equilibrium reactions involving protons, metal aquo ions and their first hydrolysis products, and binding sites ranging from abundant ones of low affinity, to rare ones of high affinity, common to all metals. The model can also account for laboratory competition data involving Al(III), Fe(III) and trace elements, supporting the assumption of common binding sites. Field speciation data (116 examples) for Al in acid-to-neutral waters can be accounted for, assuming that 60-70 % (depending upon competition by iron, and the chosen fulvic acid : humic acid ratio) of the dissolved organic carbon (DOC) is due to humic substances, the rest being considered inert with respect to ion binding. After adjustment of the model parameter characterizing binding affinity within acceptable limits, and with the assumption of equilibrium with a relatively soluble form of Fe(OH)3, the model can simulate the results of studies of two freshwater samples, in which concentrations of organically complexed Fe were estimated by kinetic analysis.The model was used to examine the pH dependence of Al and Fe binding by dissolved organic matter (DOM) in freshwaters, by simulating the titration with Ca(OH)2 of an initially acid solution, in equilibrium with solid-phase Al(OH)3 and Fe(OH)3. For the conditions considered, Al, which is present at higher free concentrations than Fe(III), competes significantly for the binding of Fe(III), whereas Fe(III) has little effect on Al binding. The principal form of Al simulated to be bound at low pH is Al3+, AlOH2+ being dominant at pH >6; the principal bound form of Fe(III) is FeOH2+ at all pH values in the range 4-9. Simulations suggest that, in freshwaters, both Al and Fe(III) compete significantly with trace metals (Cu, Zn) for binding by natural organic matter over a wide pH range (4-9). The competition effects are especially strong for a high-affinity trace metal such as Cu, present at low total concentrations (∼1 nM). As a result of these competition effects, high-affinity sites in humic matter may be less important for trace metal binding in the field than they are in laboratory systems involving humic matter that has been treated to remove associated metals. 相似文献
10.
垃圾渗滤液中溶解有机质与内分泌干扰物的吸附机理 总被引：1，自引：0，他引：1
为了调查垃圾渗滤液中的溶解有机质(DOM) 及内分泌干扰物(EEDs) 的相互作用机理, 在实验室条件下研究了DOM对EEDs如双酚A (BPA)、雌二醇(E2)和雌酮(E1) 的吸附等温线, 并通过FTIR、1HNMR和ESR技术, 分析了DOM与EEDs的吸附机理.结果表明, 垃圾渗滤液中DOM对3种EEDs的吸附等温线符合Freundlich方程, 并且可用DOM与EEDs的吸附常数Kf预测EEDs的辛醇/水分配系数(Kow) 或有机碳分配系数(Kdoc), 其中直线回归方程为: lgKdoc=2.062Kf-5.065 (R2=0.9958, P=0.041 < 0.05).分析也表明DOM吸附EEDs的吸附过程至少存在离子键、共价键和电荷转移等多种吸附机制的协同作用. 相似文献
11.
1IntroductionDissolvedorganicmatter (DOM)isamixtureoforganicsubstancesconsistingmainlyofhighmolecularweightpolymericcompounds (KenandLee,1 974) .Itplaysanimportantroleincarboncyclingandbiogeochemicalmobilizationoftracemetalsandorganiccompoundsintheaquaticenvi ronment (BeffleandLeppard ,1 995) .InrecentyearsmanyresearchershavepaidattentiontothesecomplexesbasedontheMWDofDOM ,sincethefateandtransportoftracechemicalsareinfluencedbyitsmolecularsize (Chiouetal.,1 986) .Themolecularweightorfrac… 相似文献
12.
Cross polarization, magic-angle spinning 13C nuclear magnetic resonance spectroscopy was used to characterize humic fractions isolated from different soils. The acid fractions are more aromatic than the humin fractions, probably due to the higher polyssaccharide content of humins. However, fulvic acid fractions are more aromatic than the corresponding humic acid and humin fractions. These results can be interpreted in terms of the isolation procedure, because the high affinity of Polyclar AT for phenols results in higher aromaticities as compared with other isolation methods (e.g. charcoal). 相似文献
13.
A dialysis procedure was used to assess the distribution coefficients of ∼50 major and trace elements (TEs) between colloidal (1 kDa–0.22 μm) and truly dissolved (<1 kDa) phases in Fe- and organic-rich boreal surface waters. These measurements allowed quantification of both TE partitioning coefficients and the proportion of colloidal forms as a function of solution pH (from 3 to 8). Two groups of elements can be distinguished according to their behaviour during dialysis: (i) elements which are strongly associated with colloids and exhibit significant increases of relative proportion of colloidal forms with pH increase (Al, Ba, Cd, Co, Cr, Cu, Fe, Ga, Hf, Mn, Ni, Pb, rare earth elements (REEs), Sr, Th, U, Y, Zn, Zr and dissolved organic C) and (ii) elements that are weakly associated with colloids and whose distribution coefficients between colloidal and truly dissolved phases are not significantly affected by solution pH (As, B, Ca, Cs, Ge, K, Li, Mg, Mo, Na, Nb, Rb, Sb, Si, Sn, Ti, V). Element speciation was assessed using the Visual MINTEQ computer code with an implemented NICA-Donnan humic ion binding model and database. The model reproduces quantitatively the pH-dependence of colloidal form proportion for alkaline-earth (Ba, Ca, Mg, Sr) and most divalent metals (Co, Cd, Mn, Ni, Pb, Zn) implying that the complexation of these metals with low molecular weight organic matter (<1 kDa fraction) is negligible. In contrast, model prediction of colloidal proportion (fraction of 1 kDa–0.22 μm) of Cu2+ and all trivalent and tetravalent metals is much higher than that measured in the experiment. This difference may be explained by (i) the presence of strong metal-binding organic ligands in the <1 kDa fraction whose stability constants are several orders of magnitude higher than those of colloidal humic and fulvic acids and/or (ii) coprecipitation of TE with Fe(Al) oxy(hydr)oxides in the colloidal fraction, whose dissolution and aggregation controls the pH-dependent pattern of TE partitioning. Quantitative modeling of metal – organic ligand complexation and empirical distribution coefficients corroborate the existence of two colloidal pools, formerly reported in boreal surface waters: “classic” fulvic or humic acids binding divalent transition metals and alkaline-earth elements and large-size organo-ferric colloids transporting insoluble trivalent and tetravalent elements. 相似文献
14.
Markus Bauer 《Geochimica et cosmochimica acta》2009,73(3):529-9557
Due to the widespread contamination of groundwater resources with arsenic (As), controls on As mobility have to be identified. In this study we focused on the distribution of As in the dissolved, colloidal and particulate size fraction of experimental solutions rich in ferric iron, dissolved organic matter (DOM) and As(V). Size fractions between <5 kDa and >0.2 μm were separated by filtration and their elemental composition was analyzed. A steady-state particle size distribution with stable element concentration in the different size classes was attained within 24 h. The presence of DOM partly inhibited the formation of large Fe-(oxy)hydroxide aggregates, thus stabilized Fe in complexed and colloidal form, when initially adjusted molar Fe/C ratios in solution were <0.1. Dissolved As concentrations and the quantity of As bound to colloids (<0.2 μm) increased in the presence of DOM as well. At intermediate Fe/C ratios of 0.02-0.1, a strong correlation between As and Fe concentration occurred in all size fractions (R2 = 0.989). At Fe/C ratios <0.02, As was mainly present in the dissolved size fraction. These observations indicate that As mobility increased in the presence of DOM due to (I) competition between As and organic molecules for sorption sites on Fe particles; and (II) due to a higher amount of As bound to more abundant Fe colloids or complexes <0.2 μm in size. The amount of As contained in the colloidal size fractions also depended strongly on the initial size of the humic substance, which was larger for purified humic acids than for natural river or soil porewater samples. Arsenic in the particle size fraction >0.2 μm additionally decreased in the order of pH 4 ? 6 > 8. The presence of DOM likely increases the mobility of As in iron rich waters undergoing oxidation, a finding that has to be considered in the investigation of organic-rich terrestrial and aquatic environments. 相似文献
15.
Beidou Xi Chunmao Geng Yue Zhao Zimin Wei Xiaosong He 《Environmental Earth Sciences》2012,67(7):1861-1867
Dissolved organic matter (DOM) in leachate from landfills of three different ages (0, 5, and 10?year) was partitioned into hydrophobic acid, hydrophobic neutral, and hydrophilic matter fractions using the fractionation method employing XAD-8 resin. The spectroscopic characteristics of these fractions were determined through constant-wavelength synchronous fluorescence spectrometry (CWSFS). The interaction characteristic of phenanthrene with these fractions was determined through the fluorescence quenching method and CWSFS. The results revealed that the composition of DOM became complex with the increase in landfill age. The partition coefficients (K doc) for the three DOM samples of different landfill ages are in the order 10?a DOM?>?5?a DOM?>?0?a DOM. The hydrophobic fraction showed the highest K doc value among the DOM fractions. Lower linearity Stern?CVolmer plots were observed in 10?a DOM and its hydrophobic fractions. CWSFS spectra showed that a special site was fully occupied with the addition of the quencher. Desorption was found in some fractions. Therefore, CWSFS is a sensitive tool for the detection of DOM-polycyclic aromatic hydrocarbon interaction. 相似文献
16.
铁氧化物矿物对苯酚和溶解性有机质表面吸附的初步研究 总被引：2，自引：0，他引：2
文中以铁氧化物矿物对苯酚和溶解性有机质(DOM)的吸附研究为例开展生态矿物学研究。铁氧化物矿物的吸附作用存在多种机制,这些吸附机制发生作用的条件主要取决于溶液化学性质和吸附质的理化性质。批处理实验研究表明,苯酚吸附在酸性微酸性条件下不强,吸附等温线符合Langmuir方程,属于表面分子吸附模型;DOM的吸附强并发生吸附分异,配体交换、憎水键和范氏力等多种模式并存,在酸性中性条件下对DOM在针铁矿上的吸附起着重要贡献。本文实验条件下DOM吸附等温线近于线性,不能采用Langmuir方程拟合,可能原因是DOM浓度较低。矿物表面荷电性对吸附影响显著,例如,当矿物表面净电荷为零(pH=pHpzc)时,矿物表面水化膜减薄甚至消失,苯酚分子、憎水DOM分子或片断都会倾向于在矿物表面上吸附。由于苯酚吸附机制单一,其受到的影响很明显,所以苯酚在pH值7～8范围内出现吸附最大值;由于配体交换作用主要发生在酸性微酸性条件下,所以在本文pH值约7.5的实验条件下,尽管配体交换仍在发生作用,但它不是主要吸附机制,针铁矿对DOM吸附的主要贡献应是憎水键和范氏力作用,此外,DOM吸附等温方程近于线性还可能与此有关。显然,铁矿物表面作用在对有机质含量低而铁矿物含量高的红壤中污染物和DOM的固定与归宿控制中扮演着重要的角色。 相似文献
17.
18.
《Applied Geochemistry》2006,21(3):446-454
The effects of three humus fractions (fulvic acid, brown humic acid and grey humic acid) on the volatility of five types of mineral-bound Hg were investigated. Fulvic acid was found to strongly promote the volatilization of Hg bound by Fe2O3, MnO2 and kaolinite, but suppressed the volatilization of Hg bound by bentonite and CaCO3. Brown humic acid was found to enhance the volatilization of Hg bound from all the tested minerals, except for Fe2O3. Grey humic acid had the weakest effect in promoting or suppressing Hg volatilization. The influence of the various humus fractions on the volatilization of mineral-bound Hg is closely related to the complexing capacity and complex stability of the particular humus material. The higher the complexing capacity and the lower the complex stability, the more prominent is the humus material in promoting Hg volatility. The Hg sorption capacity and sorption strength of the minerals, as well as their Hg speciation characteristics, limit the effect that humus has to volatilize Hg. 相似文献
19.
Bogdan Muresan Benoît Pernet-Coudrier Daniel Cossa Gilles Varrault 《Applied Geochemistry》2011,26(12):2057-2063
Dissolved organic matter (DOM) samples were obtained from a low-density urbanized area located upstream of Paris (along the Marne River, France) and from the treated effluents at the Paris main wastewater treatment plant. These samples were then fractionated according to their hydrophobicity. DOM fractions consisted of nanomolar to sub-micromolar fresh organic substances with extremely strong Hg-complexing ligands. The conditional stability constants (i.e. ; pH ∼ 6.8, INaCl = 0.5 M, T = 25 °C) of the Hg-DOM complexes formed were greater than 1024 M−1, for the reaction Hg2+ + L = HgL (with L as ligand). For upstream of Paris, thermodynamic calculations indicated that the vast majority of Hg-DOM was associated with hydrophobic DOM. In contrast, in the Paris main wastewater treatment plant effluents, Hg-DOM was mainly bound to hydrophilic DOM. Simple dilution calculations highlighted that due to the large DOM loading of urban discharges, the hydrophilic urban DOM ligands may commonly dominate Hg-DOM speciation in the downstream Seine River, except under extreme dilution (i.e. high water episodes or floods). 相似文献
20.
A coal-based thermal power plant is situated on the bank of the Pandu River, which is a tributary to the Ganges near Kanpur. River sediments downstream from the ash pond outfall are contaminated by fly ash. In order to establish the role of soils and sediments in retaining fly ash-derived heavy metals, copper was investigated as a model metal. A maximum concentration of 70 ppm Cu could be leached from the fly ash, confirming that it is a major source of this metal. Soil samples and river sediments were examined for Cu adsorption in the natural state as well as after treatment with H2O2, EDTA, and H2O2 followed by EDTA. The organic fraction of the samples was determined, and it had a major control on removal of Cu from a solution with 10–4 M initial concentration. Further characterization of organic matter indicated that with reference to natural samples, the humic acid fraction had a copper enrichment factor in the range 9.1–15.1. The factor for fulvic acids, in contrast, was between 3.5 and 5.5. This leads to the conclusion that river deposits rich in humic acids would withstand relatively high metal loads. Only when the metal input exceeds the maximum retention potential, would the metal be fractionated into the aqueous phase and act as a potential biocide. 相似文献