Supramolecular interactions of humic acids with organic and inorganic xenobiotics studied by capillary electrophoresis

Methodology based on capillary electrophoresis (CE) to study humic acids (HAs)-xenobiotics interactions is proposed. The interactions of HAs with organic and inorganic xenobiotics like paraquat, diquat, p,p(')-DDE, p,p(')-DDT, potassium ferrocyanide, potassium ferricyanide, chloride, 4-nitrocatechol and other organic compounds were studied. They were found to be of different kind depending on the structure of the xenobiotic molecule and on its charge (neutral, positive or negative). Ion binding, hydrogen bonding, van der Waals forces, ligand exchange, hydrophobic and hydrophilic adsorption, charge-transfer complexes and sequestration are some of the different mechanisms proposed to bind inorganic and organic compounds to HAs.It was also observed that some of the pollutants are strongly complexed (bound) only with some of the HA fractions forming quite stable entities of supramolecular kind, which can migrate independently. In addition, the stability constant of HA-Cl (negatively charged species) was estimated to be logk=3.1+/-0.95. In order to explain the interaction between negatively charged HAs and inorganic anions (like Cl(-), [Fe(CN)(6)](3-) and [Fe(CN)(6)](4-)), it is proposed that macropolycyclic polyamine structures are present in HA supramolecules, and that they are responsible for such strong binding.     

Contaminant-induced irreversible changes in properties of the soil-vadose-aquifer zone: an overview

Most studies on contaminant interactions with the subsurface environment focus on contaminant transport, retention and persistence, and on potential remediation of polluted soils, vadose zones and aquifers. Changes in the soil-vadose-aquifer zone (SVAZ) matrix and properties, caused by human activities, are thus usually considered to be deviations from a normal geochemical environment, which will disappear by natural processes or by specific remediation procedures. However, contaminants may also cause, under specific conditions, irreversible changes in SVAZ properties. In this critical overview, we discuss a different aspect of contaminant-SVAZ interactions: irreversible changes in natural SVAZ properties as a result of anthropogenically-induced chemical contamination. We survey selected research results that illustrate various aspects of such phenomena, in soils, aquifers and the vadose zone. Grouping contaminants according to major and trace elements, we observe that major elements can irreversibly affect water transmission and other physical and chemical properties of the SVAZ, mainly in the liquid phase, while trace elements affect mostly the solid phase matrix.     

Integrated assessment: rhetoric of models and perceptions of world futures

Integrated assessment of climate change implies the construction of models describing the very complex interactions among economic processes, geochemical or geophysical phenomena and ecological processes at the Earth level. This attempt is unprecedented in the history of science. To build models of a unique, very large and extremely complex object, the whole Earth, supposes the definition of concepts allowing the comparison of these models through their structures and not only comparisons of their numerical results. The purpose of this paper is to give some preliminary elements of such a structural comparison.     

高铁酸钾预氧化并复合高岭土与PAC絮凝去除水中的颤藻

对高铁酸钾预氧化并复合高岭土与PAC絮凝法除水中颤藻的效果进行了研究。通过正交实验得出了在实验水质条件下,去除颤藻的最佳条件为:高铁酸钾的投加量2.4 mg/L、高岭土24 mg/L、PAC 5 mg/L及pH值为6.5。在此条件下,K2FeO4除藻效果明显优于传统的PAC絮凝工艺。考察了K2FeO4对接种到培养液中的颤藻生长活性的影响,结果表明,随着K2FeO4量的增加,颤藻生长活性抑制时间增长。数码生物显微镜观察表明:K2FeO4在低浓度2.4 mg/L下不能破坏颤藻细胞结构,高浓度50 mg/L下可使其细胞破裂死亡。     

Control of ammonia toxicity to Hyalella azteca by sodium, potassium and pH

The toxicity of ammonia to Hyalella azteca at constant pH in artificial media was controlled by sodium and potassium, and not by calcium, magnesium, or anions. Small increases in the LC50 for total ammonia (from 0.15 to 0.5 mM) occurred as sodium was increased from 0.1 to 1 mM and above, but major increases in the LC50 (to over 10 mM total ammonia) required the addition of potassium. Potassium was, however, more effective at reducing ammonia toxicity at high (1 mM) sodium than at low (0.1 mM) sodium. Ammonia toxicity was independent of pH at low sodium and potassium concentrations, when ammonia toxicity appeared to be associated primarily with aqueous ammonium ion concentrations. At high sodium and potassium concentrations, the toxicity of ammonia was reduced to the point where un-ionized ammonia concentrations also affected toxicity, and the LC50 became pH dependent. A mathematical model was produced for predicting ammonia toxicity from sodium and potassium concentrations and pH.     

Effect of fertilisation on the potassium and radiocaesium distribution in tree stands (Pinus sylvestris L.) and peat on a pine mire

This paper compares the effects of single and repeated fertilisation on the contents of potassium, 134Cs and 137Cs in different Scots pine compartments at different levels above ground and in the peat profile 9 years after the Chernobyl disaster. The material was collected from a ditch spacing and fertilisation experiment in Finland. Above a needle potassium concentration of 3.0 mg g(-1) in composed crown samples, 137Cs and 134Cs concentrations remained at about the same level but below that the values were higher on average. This potassium value corresponded to the potassium concentrations of 3.5-3.6 mg g(-1) in the current-year needles of two topmost whorls. The result indicates an enhanced radiocaesium uptake by pine trees under severe potassium deficiency. Fertilisation with potassium-containing fertilisers decreased the caesium uptake considerably. The inhibiting effect of fertilisation on caesium uptake by trees seemed to be fairly long lasting. Fertilisation had sped up the penetration of caesium downwards in the peat profile and its moving out of the active circulation of elements between soil and plants.     

Effect of potassium inhibition on the thermophilic anaerobic digestion of swine waste.

The inhibition effects of high potassium concentration on thermophilic anaerobic digestion of swine waste were studied. A continuous stirred tank reactor (CSTR), operated at a hydraulic retention time of 10 days and chemical oxygen demand loading of 7.2 to 7.5 g/L/d, was used to digest swine waste and cultivate thermophilic anaerobic microorganisms. To evaluate the toxicity of potassium, batch inhibition tests were also conducted. Without acclimation to potassium, the inhibition threshold beyond which methane production decreased significantly was 3 g K+/L. Volatile fatty acids accumulation was observed during the decline of methane production. Propionic acid was the dominant fatty acid, indicating that propionic acid utilizers were more sensitive to potassium inhibition than acetoclastic methanogens. To test the effect of acclimation on potassium inhibition, the potassium concentration in the CSTR was increased to 6 and 9 g K+/L. Acclimation to 6 g K+/L increased the tolerance of anaerobic inocula to potassium inhibition without significantly reducing the methanogenic activity. The inhibition threshold was increased from 3 g K+/L for unacclimated inocula, to 6 g K+/L for inocula acclimated to 6 g/L of potassium. Acclimation of inocula to 9 g/L potassium further increased the inhibition threshold to 7.5 g K+/L. However, the overall methanogenic activity in the last case was lower than that of unacclimated and 6 g K+/L acclimated inocula.     

高铁酸钾降解苯胺废水的机制研究

研究了高铁酸钾投加量、初始pH及苯胺初始浓度对苯胺降解效果的影响.结果表明.苯胺废水的COD去除事随高铁酸钾投加量和苯胺初始浓度的增大而升高,而初始pH对COD去除率影响不明显.对高铁酸钾降解苯胺废水后的产物进行了气相色谱/质谱(GCIMS)分析.在此基础上详细探讨了高铁酸钾降解苯胺的机制.     

The composition of rime ice as an indicator of the quality of winter deposition

Rime ice deposition and snow chemistry has been determined over a 4-year period on the summit of Cairngorm Mountain, NE Scotland. The direction of ice deposition reflected the dominant air mass movement over the summit. Sea salt concentrations in the rime ice were approximately 2.5 times greater than in snow deposited over the same period. Excess sulphate concentrations were double, and those of nitrate nearly four times higher. The direction of deposition influenced concentrations of excess sulphate and nitrogen species (nitrate and ammonium) in rime ice. The same directional effect was found in the snow chemistry indicating increased entrapment of pollutants, or a more polluted air mass, when it prevailed from a Southerly or Easterly direction. The potential surface reactions involving gaseous species of S and N may increase the ionic loading to the rime and reflect natural ionic enrichment of the rimed snowpack surface. Because of such phenomena, rime ice is proposed as a further indicator of winter air quality revealing important information on ionic interactions and total deposition flux measurement, especially at high altitudes.     

Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol in supercritical water

Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol (o-CP) in supercritical water (SCW) were studied in this paper under the conditions of 450 degrees C and 25 MPa. Experimental results indicated that the dechlorination of o-CP can be accelerated significantly by all alkalis investigated. The dechlorination of o-CP proceeded mainly via two pathways: hydrodechlorination and hydrolysis. Both of the two pathways can be promoted by alkalis, and the dechlorination of o-CP can be accelerated by both the cations and hydroxide ion dissociated from alkalis. The overall dechlorination of o-CP can be accelerated by cations via promoting the hydrodechlorination pathway, while, hydroxide ion via promoting the hydrolysis pathway. In addition, the hydrodechlorination can be accelerated faster by sodium alkalis than that by potassium ones, while, the hydrolysis can be promoted faster by potassium alkalis. This difference may be caused by the different charge density between potassium ion and sodium ion, and the different solubility and dissociation constant between potassium alkalis and sodium alkalis in SCW. Dechlorination of o-CP with addition of alkalis prior to supercritical water oxidation (SCWO) process not only can avoid the reactor corrosion caused by the generated hydrochloric acid in direct SCWO of o-CP, but also can reduce the formation of toxic chlorinated byproducts compared with direct SCWO process or SCWO of o-CP with addition of alkali.     

Distribution of peroxidase activity and polyamine pattern of Heliotropium europeum in potassium deficiency conditions

Polyamines, especially putrescine, are reported to increase in higher plants in response to various stressors, in particular mineral deficiency, low pH and different atmospheric pollutants. Peroxidases are another stress indicator in plants. The aim of this study is to establish the relationship between polyamine content and peroxidase activity in potassium deficiency conditions. In this study, potassium deficiency increased the free and bound Put and Spd contents. We estimated more stimulation in free Put synthesis (300%) in potassium deficiency. We also determined increment in POD activity in whole plant, especially root POD activity increased much more compared to stem and leaf.     

紫外光协助高锰酸钾降解四环素的研究

高锰酸钾氧化法在实际水处理中得到了一定的应用,但对有机污染物的去除和降解能力相对有限,为此提出了以外加紫外光照射协助高锰酸钾氧化的方法。以四环素作为模型污染物,考察了四环素浓度、高锰酸钾浓度、反应时间、初始pH条件和不同紫外光照射等的影响。结果表明,高锰酸钾能够氧化并去除四环素,紫外光照射明显提高了高锰酸钾对四环素的降解效果,并且254 nm紫外光照射对降解的促进作用远大于365 nm紫外光。在所考察的pH范围内,无论紫外光照射与否,高锰酸钾在酸性条件下的降解效率最高,中性条件较高,碱性条件次之。     

Decolorization of dyes and textile wastewater by potassium permanganate

Decolorization of 10 types of dye solutions by potassium permanganate was studied. Effects of reaction conditions on the decolorization efficiency were examined in batch experiments. The pH value had a significant effect on the decolorization efficiency. When pH value <1.5, the decolorization efficiency was very high. When pH value >4.0, the dye solutions were almost not decolorized. Concentration of potassium permanganate and temperature also showed significant effects on the decolorization efficiency. The decolorization rate of dye solutions by potassium permanganate was rapid, and most of dye solutions can be decolorized effectively. The results of total organic carbon indicated that dye solutions were degraded incompletely by potassium permanganate. The results of treatment of textile wastewater by potassium permanganate indicated that the oxidation with potassium permanganate might be used as a pre-treatment process before biological treatment.     

Genetic and DNA-methylation changes induced by potassium dichromate in Brassica napus L

This study evaluated genetic and DNA methylation alteration induced by potassium dichromate in Brassica napus L. plants. Amplified fragment length polymorphism (AFLP) and selective amplification of polymorphic loci (SAMPL) tests revealed dose-related increases in sequence alterations in plantlets exposed to 10-200 mg/l potassium dichromate. Individual plantlets exposed to chromium under similar conditions showed different AFLP and SAMPL DNA profiles. These observations suggest random DNA mutation in response to potassium dichromate and argue against preferential sites for mutation. DNA methylation changes in response to chromium treatment were also evaluated. Two complementary approaches were applied: (i) immunolabelling, using a monoclonal antibody against 5-methylcytosine; and (ii) methylation-sensitive amplified polymorphism (MSAP). Immunolabelling showed cytosine-hypermethylation in the Brassica napus L. genome when plants were treated with potassium dichromate. MSAP analysis showed extensive methylation changes in CCGG-sequences, with the net result being genome-wide hypermethylation. These results showed a clear DNA alteration in plants as a response to chromium exposure and the effect was dose-dependent. DNA polymorphism detected by different markers supports the effectiveness of the use of these tools for the investigation of environmental toxicology and for evaluating the concentration of pollutants by DNA analysis in plants.     

Urban environmental geochemistry of trace metals

As the world's urban population continues to grow, it becomes increasingly imperative to understand the dynamic interactions between human activities and the urban environment. The development of urban environmental geochemistry has yielded a significant volume of scientific information about geochemical phenomena found uniquely in the urban environment, such as the distribution, dispersion, and geochemical characteristics of some toxic and potentially toxic trace metals. The aim of this paper is to provide an overview of the development of urban environmental geochemistry as a field of scientific study and highlight major transitions during the course of its development from its establishment to the major scientific interests in the field today. An extensive literature review is also conducted of trace metal contamination of the urban terrestrial environment, in particular of urban soils, in which the uniqueness of the urban environment and its influences on trace metal contamination are elaborated. Potential areas of future development in urban environmental geochemistry are identified and discussed.     

Removal of <Emphasis Type="Italic">Anabaena spiroides</Emphasis> by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.     

Indoor/outdoor connections exemplified by processes that depend on an organic compound's saturation vapor pressure

Outdoor and indoor environments are profitably viewed as parts of a whole connected through various physical and chemical interactions. This paper examines four phenomena that share a dependence on vapor pressure—the extent to which an organic compound in the gas phase sorbs on airborne particles, sorbs on surfaces, sorbs on particles collected on a filter or activates trigeminal nerve receptors. It also defines a new equilibrium coefficient for the partitioning of organic compounds between an airstream and particles collected by a filter in that airstream. Gas/particle partitioning has been studied extensively outdoors, but sparingly indoors. Gas/surface partitioning occurs primarily indoors while gas/filter partitioning occurs at the interface between outdoors and indoors. Activation of trigeminal nerve receptors occurs at the human interface. The logarithm of an organic compound's saturation vapor pressure correlates in a linear fashion with the logarithms of equilibrium coefficients characteristic of each of these four phenomena. Since, to a rough approximation, the log of an organic compound's vapor pressure scales with its molecular weight, molecular weight can be used to make first estimates of the above processes. For typical indoor conditions, only larger compounds with lower-saturation vapor pressures (e.g., tetracosane, pentacosane, or di-2-ethylhexyl phthalate) have airborne particle concentrations comparable to or larger than gas phase concentrations. Regardless of a compound's vapor pressure, the total mass sorbed on indoor airborne particles is quite small compared to the total sorbed on indoor surfaces, reflecting the large difference in surface areas between particles within a room and surfaces within a room. If the actual surface areas are considered, accounting for roughness and porosity, the surface concentration of organics sorbed on typical airborne particles appears to be comparable to the surface concentration of organics sorbed on indoor carpets, walls and other materials (based on data from several studies in the literature). Mirroring the importance of phase distributions outdoors, an organic compound's indoor lifetime, fate and even health impacts depend on its distribution between phases and among surfaces.     

Municipal waste compost as an alternative to cattle manure for supplying potassium to lowland rice

The importance of the use of potassium in agriculture is increasing in South Asia for making most productive use of the nutrient in terms of economic returns. Nutrient supply traditionally by cattle manure is constrained by its insufficient availability. Municipal waste compost may be an alternative source of nutrient supplements. Field experiments were conducted at the Experimental Farm of Calcutta University, West Bengal, India during the wet seasons of 1997, 1998 and 1999 on flooded lowland rice. Potassium fractions in municipal waste compost and cattle manure were determined by sequential extraction and also the potassium uptake by rice to compare the effectiveness of municipal waste compost with traditional manure. Potassium was significantly bound to the organic matter in municipal waste compost. Potassium uptake by rice grain and straw increased significantly with the combined application of organics and fertilizers and it was higher in grain than in straw. Water-soluble and non-exchangeable potassium contents of municipal waste compost and cattle manure were highly correlated with the uptake of potassium by straw and grain. Exchangeable and residual potassium were also significantly correlated with the uptake of potassium by straw and grain of rice. Much higher uptake of K in rice straw and rain resulted from applying the manures in conjunction with fertilizers than when applied singly.     

钛白副产硫酸亚铁的综合利用研究

以钛白副产硫酸亚铁、氯化钾和氨水为原料，采用硫酸钾铵法制取硫酸钾。实验结果表明，该工艺生产的产品，其质量达到ZBG-21006-89国家标准，且此工艺流程简单、操作方便、条件易控制，无二次污染。     

不同释钾菌对粉煤灰的生态效应

粉煤灰治理难度大,但它含有植物生长必需的营养元素钾,将其就地资源化生物利用是一条较好的途径。释钾菌是一种能把矿物中的难溶性钾转化为有效钾的细菌,从土壤中筛选出2种释钾菌,经过在粉煤灰基质中的驯化培养,通过盆栽试验种植紫花苜蓿,比较不同菌株对粉煤灰的改良作用及其对植物生长的影响。结果表明,筛选出的菌株C6对粉煤灰中速效钾的释放效果明显,降低了基质pH,显著地促进了植物的生长,对粉煤灰生态修复具有重要意义。