The role of humic substances in chromium sorption onto natural organic matter (peat)

To elucidate mechanisms of Cr³⁺ sorption onto the unaltered solid natural organic matter, the comparative studies of this ion binding from a solution at pH 4.0 onto three selected particle size fractions: 2000–1000 μm, 630–200 μm and 63–20 μm of markedly different HS content and structure, separated by a wet sieving from an overall sample of peat (Brushwood Peat Humus) were carried out. Comparable patterns of COOH groups and CEC_t confirmed that for cation exchange capacity were responsible mainly cations connected with COO⁻ functional groups. It was though found that aliphatic acids in the solid state did not take part in Cr³⁺ binding, thus the finest studied fraction 63–20 μm of the highest contents of functional groups showed the lowest sorption capacity for Cr³⁺, while similar patterns of sorbed Cr³⁺, soluble HS content and base CEC₀ indicated that these parameters were directly interrelated. The base ion exchange processes determined by CEC₀ (with Ca²⁺ as a predominant exchangeable cation) appeared to be not the major mechanisms responsible for Cr³⁺ sorption. For this metal, strong binding to insoluble large molecular weight organic pool two- to threefold prevailed over the ion exchange processes. Very low acid desorption indicated generally low mobility of Cr³⁺-organic compounds.     

Controlling mechanisms of aluminium in soil solution--an evaluation of 180 podzolic forest soils.

To monitor the level of soil acidification in the county of V?rmland in the middle west of Sweden 180 podzolic forest soils were investigated. Soil solutions from four horizons were obtained by centrifugation and the soil was sampled for a determination of the exchangeable pool by extraction. The concentrations of inorganic Al and its fraction of the total Al in solution were greater in the south of the county (up to 50%). The factors influencing the total Al and free inorganic Al3+ in the soil solutions were evaluated. Saturation indices (SI) for five different mineral phases were calculated but none implied equilibrium conditions. The relationships between pAl3+ and pH (in the pH range 4-6.2) gave slopes of about 1, which indicated that ion exchange/complexation reactions may be important for determining the Al3+ concentration in the B and C horizons. In the E horizon solutions complexation with soluble organic acids seemed to be the major factor which influenced the Al3+ activity. The influence of organic matter on Al solubility was supported by partial least square (PLS) regressions.     

污泥中重金属的去除及回收试验

论述了利用离子交换技术循环使用柠檬酸去除污泥中重金属,并置换回收重金属的适宜工艺条件.经柠檬酸处理后,污泥中90%以上的重金属被去除;柠檬酸处理液中的重金属用离子交换法回收,考察了树脂种类、流速、操作方式等因素对离子交换、再生效果的影响;在适宜工艺条件下,重金属的交换率均为100%,而洗脱率均接近90%;柠檬酸及离子交换树脂循环使用,重金属也得到回收,降低了处理成本.     

Acid and aluminum effects on freshwater zooplankton: an in situ Mesocosm study

An in situ mesocosm experiment was performed to evaluate the role of aluminum toxicity in determining zooplankton community responses to take acidification. Large plastic enclosures were suspended in East Twin Lake, Ohio, USA, and duplicates were either untreated controls (pH 8.8), acidified to pH 4.5 over a 23 day period, or acidified and also spiked with incremental additions of Al, to produce a final inorganic monomeric Al level of 180 microg/liter at pH 4.5. Zooplankton abundance and species richness declined in both acid treatments, relative to the control, as numerous acid-sensitive species were eliminated. All of the acid-sensitive species were also Al-sensitive, declining in abundance more rapidly in the acid plus Al treatment than in the acid-alone treatment. Only two small cladocerans (Bosmina longirostris and Chydorus sphaericus) were acid tolerant. Both were also tolerant of elevated Al levels.     

Mg—Al水滑石对偶氮染料活性艳红X-3B的脱色性能研究

采用共沉淀法合成出一系列镁铝摩尔比不同的碳酸根型水滑石（LDHs）,经500℃高温煅烧制备出镁铝复合氧化物CLDH,并用X-射线、红外光谱对它们进行表征。考查了吸附剂投加量、反应时间、初始pH值等因素对LDHs和CLDH处理阴离子染料活性艳红X-3B模拟废水效果的影响,并对吸附机理进行探讨。实验结果表明：以镁铝摩尔比为3：1时制得的水滑石对活性艳红X-3B溶液的脱色效果最好。水滑石LDHs及其焙烧产物CLDH对活性艳红X-3B染料均具有较好的吸附性能,最佳反应时间分别为60min和30min;在较宽的pH范围内二者的脱色性能稳定,且CLDH对该染料的吸附效果要优于LDHs。LDHs及CLDH对活性艳红X-3B的吸附结果符合Langmuir吸附等温式,25℃下饱和吸附量分别为263．77mg／g和875．23mg／g。LDHs及CLDH的吸附机理分别为离子交换和层状结构重建。饱和吸附后的CLDH用高温热解法再生,吸附性能良好,随再生次数增多,脱色率下降。     

A survey of some trace elements in seaweeds from Patagonia, Argentina

Cadmium and lead concentrations were determined in some common algal species living in the southernmost coasts of Argentina. Two different sampling areas were chosen: Gulf Nuevo, a locality being influenced by a developing industrial city, and Bay Camarones, a traditional harvest area for seaweed exploitation. Selected species of the genera Lessonia, Macrocystis and Gigartina, all of commercial interest, were collected from the harvest area, and analyses showed low levels of the metals in these species. Accumulation of Pb and Cd was also evident in other common brown seaweeds from the industrial site. Analysis of Al was included in this study due to an aluminum works near one of the sampling sites. High values of this metal ranging between 300 and 3000 mg Al/kg (dry basis) were recorded in the industrialized area. Amongst all of the species studied, Colpomenia sinuosa from Gulf Nuevo exhibited the highest values of aluminum. This preliminary survey showed that, except for Al, the levels of Cd and Pb were lower than those reported in same species of seaweeds from the polluted marine waters of the rest of the world.     

The chemical species distribution and transformation of polyaluminum silicate chloride coagulant

The chemical species distributions of polyaluminum silicate chloride (PASC) and polyaluminum chloride (PACl) determined by Al-Ferron complexation timed spectrophotometric and 27Al-NMR methods, respectively, have been compared and analyzed. The experimental results show that the species distribution and transformation of PASC are different from those of PACl, due to the interaction of polysilicic acid and hydrolyzed aluminum species. At the same basicity (B), the contents of, Al(b), Al13 and the monomer species Almono (also determined by 27Al-NMR) in PASC are lower than those in PACl, while the contents of Al(c) and the Alother determined by 27Al-NMR in PASC are higher than those in PACl. The differences between PASC and PACl with respect to these species enlarge as the molar ratio of Al/Si in PASC decreases. Further, in PACl the ratio of Al13 to Al(b) closes to 1.0, indicating that the amount of the two fractions are similar. In PASC, however, such an agreement does not exist at the lower B values and Al/Si molar ratios. When the B value and Al/Si molar ratios increase, however, the amount of Al13 and Al(b) species tends to close. The study findings indicate that polysilicic acid can react with hydrolyzed aluminum species to form an aluminum silicate polymer composite and result in the change in species distribution of PASC.     

Ionic strength effects in biosorption of metals by marine algae

Biosorption, the passive accumulation of metals by biomass, can be used as a cost-effective process for the treatment of metal polluted industrial effluents. The green alga Ulva fascia and the brown seaweeds Sargassum hemiphyllum, Petalonia fascia, and Colpomenia sinuosa were characterized in terms of their number of binding sites, their charge density and intrinsic proton binding constant (pKa) using pH titrations at different ionic strengths. The determined number of binding sites decreased in the order Petalonia > or = Sargassum > Colpomenia > Ulva. Due to their high number of binding sites Sargassum and Petalonia are most promising for biosorption applications. The decrease of proton binding with increasing ionic strength and pH as well as the increase of Cu and Ni binding with increasing pH and decreasing ionic strength could be described by the Donnan model in conjunction with an ion exchange biosorption isotherm.     

Copper binding by peat fulvic and humic acids extracted from two horizons of an ombrotrophic peat bog

We studied the binding of Cu(II) to humic acids and fulvic acids extracted from two horizons of an ombrotrophic peat bog by metal titration experiments at pH 4.5, 5.0, 5.5, and 6.0 and 0.1 M KNO3 ionic strength. Free metal ion concentrations in solution were measured using an ion selective electrode. The amounts of base required to maintain constant pH conditions were recorded and used to calculate H+/Cu2+ exchange ratios. The amount of Cu(II) bound to the humic fractions was greater than the amount bound to the fulvic fractions and only at the highest concentrations of metal ion the amount of Cu(II) sorbed by both fractions became equal. The proton to metal ion exchange ratios are similar for all humic substances, with values ranging from 1.0 to 2.0, and decreasing with increased pH. The amount of Cu(II) bound is practically independent of the horizon from which the sample was extracted. The results indicate that the humic substances show similar cation binding behaviour, despite the differences in chemical composition. The copper binding data are quantitatively described with the NICA-Donnan model, which allows to characterize only the carboxylic type binding sites. The values of the binding constants are higher for the humic acids than for the fulvic acids.     

Influence of trivalent electrolytes on the humic colloid-borne transport of contaminant metals: competition and flocculation effects

With the objective to assess the relevance of competitive effects in respect of the humic colloid-borne migration of actinides in case of release, the influence of Al(III) on humate complexation of La(III) as an analogue of trivalent actinides was investigated for various humic materials by using 140La as a radioactive tracer, allowing measurements in very dilute systems to simulate realistic settings. Generally, competition by aluminium is not detectable unless the metal-loading capacity of the humic colloids is nearly exhausted. For average contents of organic carbon, a threshold value of 10(-6) M Al(III) can be specified. The metal exchange turned out to be kinetically hindered. Effects on co-adsorption of La(III) and humic acid were found to be less important. Immobilization by the concomitantly induced flocculation process outweighs the role of displacement effects. Comparative studies on complexation and flocculation of humic acid with Al(III), Ga(III), In(III), Sc(III), Y(III), and La(III) were undertaken in order to evaluate the influence of specific properties apart from ion charge and to characterize the mechanism of flocculation. In spite of considerable variations in the binding affinities among these metals, it can be inferred that the possibility of significant competitive effects in natural aquatic systems is confined to Al(III). Complex stabilities and flocculation efficiencies proved to be interrelated. Precipitation is thus attributed to homocoagulation of humic colloids induced by charge compensation, which is further supported by flocculation experiments with Al(III) depending on pH, ionic strength, and humic acid concentration.     

Distribution of inorganic arsenic species in mine tailings of abandoned mines from Korea

The main objective of the present study is to determine arsenic species in mine tailings by applying an ion exchange method. Three abandoned mines, Jingok, Cheonbo and Sino mines in Korea, which had produced mainly gold, were selected for the collection and analysis of the tailings. It was found that the arsenic speciation using an ion exchange method was effective to separate As(III) and As(V) in leachate of mine tailings. The concentration of As(V) was found to be 63-99% in the leachate, indicating that As(V) would be the major arsenic species in the mine tailings and the tailings were under oxic conditions. The total concentrations of arsenic and metal elements in the mine tailings were up to 62,350 mg/kg As, 40 wt.% Fe, 21,400 mg/kg Mn, and 7,850 mg/kg Al. Sulfate was the dominant anion throughout the leachate, reaching a maximum dissolved concentration of 734 mg/l. The results of XRD and SEM in the mine tailings showed that main arsenic-containing minerals were pyrite (FeS2) and arsenopyrite (FeAsS) which would be the source of arsenic contamination in the study area.     

Effects of experimental acidification on mobilisation of metals from sediments of limed and non-limed lakes

In order to study the influence of pH on the mobilisation of metals from lake sediments, intact sediment cores with overlying water were sampled from one lime treated lake and one acidified lake. The overlying water of two cores from each lake was successively acidified to pH 4.2 over a period of 3 months. In the acid treated samples from the limed lake, the initial concentrations of Al, Cd, Mn, Pb and Zn in the overlying water were generally lower and the final concentrations were higher than in the acid treated samples from the acidified lake. The labile inorganic fraction of Al (Al(i)) was increasingly dominating as pH decreased. Redox potential and pH in the sediment indicated that the upper two centimetres were involved in the exchange reactions. The experiment showed that mobilisation of metals from sediments can occur and the results indicated that mobilisation could contribute to increased concentrations of metals in lake water during reacidification of formerly lime treated lakes.     

Arsenic removal from water by chemisorption filters

The concept of multiple separation by chemisorptive filters was applied and investigated in the process of arsenic removal from water. Chemisorption filters were made by the paper manufacturing method and consisted of cellulose, cationic and anionic ion exchangers, activated carbon and a corresponding chemical agent. In this work chemisorption filters were activated with Ag+, Mg2+, Cu2+, Al3+ and Fe3+ ions, and their chemical contribution to total arsenic removal from the water was analyzed. It was concluded that Cu2+ ions exhibited the best removal effect. Using a chromatographic continuous system with multifunctional filters, which combines the effects of adsorption, ion exchange and filtration, a decrease in the arsenic concentration was determined; for an active layer of 8 mm and a contact time of 2 s it was more than 1000-fold. All processes were performed in batch and chromatographic continuous systems under equilibrium or dynamic conditions. The results of the investigations have shown that arsenic removal is valence dependent (the removal of pentavalent arsenic was more effective). The initial concentration, pH and pollutants in anionic forms, which affected the selectivity, were important for all the processes investigated. The mechanisms of pollutant removal were determined on the basis of measurements of active Cu2+ ion propagation inside the filter structure. By correlating the front propagation of active ions and the pollutant output concentration a more exact model for the removal process was obtained.     

Edaphological characteristics of unweathered and weathered fly ashes from Gondwana and lignite coal

Naturally weathered and unweathered samples of fly ashes produced from Gondwana and lignite coals were characterized for their edaphological properties. The particle size distribution in these fly ashes varied widely, and the percentage of [Formula: see text] size particles governed their water holding capacity. All fly ashes were noncoherent in the dry state and had lower particle density than quartz and mulite. The fly ashes were low in available N, but were sufficient in available P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and B. Among the fly ashes, unweathered lignite fly ash was the richest source of K, Ca, Mg, S and Fe, while weathered lignite fly ash had the highest amounts of Mn, Zn and B. The pH of the fly ashes was closely related to the ratio of exchangeable Ca to exchangeable Al. The fly ashes were high in soluble salt, but were poor in cation exchange capacity. As an amendment to correct soil pH, the fly ashes had a poor buffering capacity. Weathering decreased the total Fe, available S and exchangeable Na percentages, but increased the organic C content of the fly ashes. Invariably, an excess of soluble salts and exchangeable Na could limit plant growth on fly ash dumps. Toxic levels of B and Al existed in only some fly ashes.     

Ligand exchange rate of metal-nom complexes by EDTA

Metal complexation by natural ligands is important for metal transport and distribution in surface and ground water. The goal of the work was to study the ligand exchange rate for two important metal ions in natural aquatic systems (Al, Fe) was determined using EDTA and natural organic matter (NOM) of humic type as ligands. After adding EDTA to a solution containing metal-NOM complexes, these complexes dissociated and metal-EDTA complexes were formed. Metal-NOM complexes were separated from metal-EDTA complexes with the help of size-exclusion chromatography and detected by on-line inductively coupled plasma-mass spectrometry (ICP-MS). Injecting the samples into the system over time after addition of EDTA allowed us to measure the rate of the exchange of NOM by EDTA. The experiments could be well described with a first-order rate law assuming that the dissociation of the metal-NOM complexes is the rate-determining step. The exchange rate of Fe was found to be faster than that of Al. This corresponds well with the exchange rate of water molecules from the coordination sphere of the metal ions, which is also faster for Fe than for Al. Furthermore, the UV and the fluorescence signal of the chromatograms were measured. The results indicate that no disaggregation of NOM molecules took place, although about 75-85% of the aggregate-forming metal ions exchanged NOM by EDTA in their coordination sphere. This suggests clearly the fundamental role of NOM in colloidal transport of metals and in their bioavailability.     

改性天然沸石去除水中氨氮的研究

分别采用NaCl、KCl和CaCl2对黑龙江省某市天然沸石进行改性，考察了pH值、氨氮初始浓度以及温度对改性沸石交换性能的影响，并对改性沸石的交换动力学进行了研究。结果表明，NaCl和KCl改性对沸石原矿交换容量有不同程度提高，而KCl改性后容量有所降低。pH、NH4初始浓度以及温度对交换性能有明显影响，pH6．0附近沸石交换容量最大；NH4初始浓度越高，反应速度越快，相同初始浓度下，钾型沸石交换速度较快，而沸石原矿交换速度最慢。采用Langmuir型离子交换等温线进行非线性回归的结果显示，低温有利于交换反应的进行。溶液中NH4^＋在改性沸石上的离子交换反应可采用Vermeulen模型描述，沸石原矿拟合相关系数较差。改性沸石多次再生后，其交换容量均有所降低。     

改性天然沸石去除水中氨氮的研究

分别采用NaCl、KCl和CaCl2对黑龙江省某市天然沸石进行改性,考察了pH值、氨氮初始浓度以及温度对改性沸石交换性能的影响,并对改性沸石的交换动力学进行了研究.结果表明,NaCl和KCl改性对沸石原矿交换容量有不同程度提高,而KCl改性后容量有所降低.pH、NH4 初始浓度以及温度对交换性能有明显影响,pH 6.0附近沸石交换容量最大;NH4 初始浓度越高,反应速度越快,相同初始浓度下,钾型沸石交换速度较快,而沸石原矿交换速度最慢.采用Langmuir型离子交换等温线进行非线性回归的结果显示,低温有利于交换反应的进行.溶液中NH4 在改性沸石上的离子交换反应可采用Vermeulen模型描述,沸石原矿拟合相关系数较差.改性沸石多次再生后,其交换容量均有所降低.     

Organochlorine compounds (PCBs, PCDDs and PCDFs) in seafish and seafood from the Spanish Atlantic Southwest Coast

Concentrations and congener specific profiles of PCDD/Fs and PCBs were determined in edible fish and seafood species from the Coast of Huelva, in the Spanish southwest Atlantic coast. Five fish species, namely wegde sole (Dicologoglossa cuneata), common sole (Solea vulgaris), white seabream (Diplodus sargus), sardine (Sardina pilchardus), angler fish (Lophius piscatorius), two shellfish species (Donax trunculus and Chamelea gallina), common cuttlefish (Sepia officinalis) and prawns (Parapenaeus longirostris), frequently found and consumed in the area were analysed. Concentrations ranged from 861 to 23787pg/g wet weight for total PCBs, while 2,3,7,8-PCDD/Fs showed concentrations ranging from 0.2 to 1.18pg/g wet weight. WHO-TEQ concentrations ranged from 0.038 to 0.186pg WHO-TEQ(PCDD/Fs)/g wet weight, values well below the maximum concentrations established by the EU. When non- and mono-ortho PCBs were included the values increased to a maximum of 0.99pg WHO-TEQ(PCDD/Fs+PCBs)/g wet weight. The PCB and PCDD/F accumulation pattern found in the samples analysed showed a distribution typically reported for marine samples, and no remarkable differences were found between species. The PCBs were the ones contributing with the highest percentage to the total TEQ content in most species studied. Concerning the seafood, specially prawns and shellfish, the opposite was observed and PCDD/Fs were found to contribute with a higher percentage than PCBs. The congener specific contribution to the TEQ showed PCB 126 followed by 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF as the most abundant ones.     

炼油厂含油冷却水处理回用技术研究

开展了O3 氧化和强碱性阴离子交换组合工艺用于炼油厂含油冷却水回用处理的实验研究。结果表明 ,O3 氧化过程中的最佳pH值约为 10 .5 ,O3 氧化的除油效率为 86 .7% (紫外法测定 ) ,去除 1mg石油类约需消耗 5 .7mgO3 ,O3 氧化后产物以乙酸和丙酸等挥发性脂肪酸为主。离子交换处理后油的含量达到未检出的水平。研究结果表明 ,O3 氧化和离子交换组合处理技术能使炼油厂含油冷却水达到回用水水质标准。     

Congener-specific concentrations and carbon stable isotope ratios (delta13C) of two technical toxaphene products (Toxaphene and Melipax)

In this study we compared the contribution of individual congeners and the ratios of stable carbon isotopes of two technical toxaphene products. The former US-American product Toxaphene was from 1978 and the East-German product Melipax from 1979. Both technical products showed the known complexity in GC/ECD measurements. Contributions of 24 peaks to each of the technical products were determined by gas chromatography in combination high resolution electron capture negative ion mass spectrometry (GC/ECNI-HRMS). The percentages of the compounds studied in the technical mixtures ranged from approximately 0.05% to approximately 2.5% but showed some individual differences. 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9-1025 or P-62) was identified as a major congener in both mixtures. 2-Endo,3-exo,5-endo,6-exo,8,8,10,10-octachlorobornane (B8-1413 or P26) and 2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonachlorobornane (B9-1679 or P-50) were found at similar concentration in both technical products. Identical amounts of Melipax or Toxaphene were combusted to CO2 in an element analyzer and their delta13C values were determined relative to the international standard Vienna PeeDee belemnite (VPDB). The mean delta13C values of both products varied by 2.8% (determined at two different locations) which is roughly one order of magnitude more than the precision obtained in repetitive analyses of the individual products. Thus, both investigated products could be unequivocally distinguished by stable isotope ratio mass spectrometry (IRMS). IRMS analyses may thus be a suitable tool for tracing back toxaphene residues in environmental and food samples to the one or both of the products.