Carbon nanotubes and cyclodextrin polymers for removing organic pollutants from water

Some organic compounds are major water pollutants. They can be toxic or carcinogenic even at low concentrations. Current technologies, however, fail to remove these contaminants to parts per billion (ppb) levels. Here we report on the removal of organic pollutants from water using cross-linked nanoporous polymers that have been copolymerized with previously functionalized carbon nanotubes. These novel polymers can remove model organic species such as p-nitrophenol by as much as 99% from a 10 mg/L spiked water sample compared to granular activated carbon and native cyclodextrin polymer that removed only 47 and 58%, respectively. These polymers have also demonstrated the ability to remove trichloroethylene (10 mg/L spiked sample) to non-detectable levels (detection limit <0.01 ppb) compared to 55 and 70% for activated carbon and native cyclodextrin polymers, respectively.     

Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: I. Whole plant study

Glasshouse experiments were conducted to determine the accumulation, distribution and transformation of o,p′-DDT, p,p′-DDT and PCBs by common reed (Phragmites australis) and rice (Oryza sativa L.) under hydroponic conditions. The culture solution was spiked with the organic pollutants and samples were collected daily. Analysis of the plants at harvest showed that both species had removed DDT and PCBs from the solution. DDT appeared to have accumulated within P. australis by both passive adsorption and active absorption. Both o,p′-DDT and p,p′-DDT were transformed within P. australis. DDD was the major metabolite and the transformation was mediated by reductive dehalogenation. Plant long-distance transportation systems may be involved in the translocation of PCBs within P. australis and the affinity of the PCBs for lipids is one of the major factors affecting their uptake and translocation within the plants. Similar but less pronounced results were found in O. sativa and suggest that these wetland plants may be used for the plant-mediated remediation of persistent organic pollutants.     

Biotransfer of persistent organic pollutants from a large site in China used for the disassembly of electronic and electrical waste

Samples of groundwater, river water, river sediment, paddy soil, rice seeds, hen eggs, fish, umbilical cord blood, and newborn meconium were collected from October 2002 to October 2003 near a large site in China used for the disassembly of obsolete transformers and other electronic or electrical waste. Six indicator PCB congeners, three non-ortho dioxin-like PCB congeners, and six organochlorine pesticides were determined in the samples by GC with electron capture detector. The results demonstrated that the local environment and edible foods had been seriously polluted by toxic PCBs and organochlorine pesticides. The actual daily intakes (ADIs) of these pollutants were estimated for local residents living in the area. The intake data showed that the contents of PCBs in these local residents were substantial, as the ADI estimates greatly exceed the reference doses set by the World Health Organization and the United States Agency for Toxic Substances and Disease Registry. The presence of the indicator PCB congeners in the cord blood and the meconium samples, as well as significant correlations (r ² > 0.80, p < 0.05) between these levels, suggests a potential biotransfer of these indicators from mothers to their newborns. This preliminary study showed that obsolete transformers and other electronic or electrical waste can be an important source for the emission of persistent organic pollutants into the local environment, such as through leakage, evaporation, runoff, and leaching. Contamination from this source appears to have reached the level considered to be a serious threat to environmental and human health around the disassembly site.     

Effects of inorganic and organic phosphates on feeding, feeding absorption, nutrient allocation, growth and righting responses of the sea urchin Lytechinus variegatus

The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg l⁻¹, and triethyl phosphate (organic phosphate) concentrations of 1,000 mg l⁻¹. However, chronic exposure to low (0.8 mg l⁻¹ inorganic and 10 mg l⁻¹ organic phosphate), medium (1.6 mg l⁻¹ inorganic and 100 mg l⁻¹ organic phosphate) or high (3.2 mg l⁻¹ inorganic and 1,000 mg l⁻¹ organic phosphate) sublethal concentrations of these phosphates inhibits feeding, fecal production, nutrient absorption and allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed to medium and high concentrations of inorganic phosphates and all levels of organic phosphates. Feeding absorption efficiencies for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic phosphate. Feeding absorption efficiencies for lipids were significantly reduced in the highest inorganic phosphate concentration only, while they decreased significantly for protein with increasing phosphate exposure. Carbohydrate and lipid levels in gonad and gut tissues decreased significantly with exposure to increasing phosphate concentrations, potentially impairing both gametogenesis and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations of either phosphate. Growth rates decreased significantly under the influence of all phosphate concentrations, while increasing in seawater alone. Individuals exposed to increasing phosphate concentrations showed reduced righting responses (a measure of stress) and no acclimation in righting times during chronic exposure to phosphates over a 4 week period. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress and be inhibited in their growth and performance due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues. Received: 10 April 2000 / Accepted: 2 October 2000     

Antioxidant enzyme activities of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> in response to nonylphenols and degradation of nonylphenols by <Emphasis Type="Italic">M. aeruginosa</Emphasis>

The aim of this study was to examine the effects of chemical nonylphenols (NPs) on the antioxidant system of Microcystis aeruginosa strains. The degradation and sorption of NPs by M. aeruginosa were also evaluated. High concentrations of NPs (1 and 2 mg/l) were found to cause increases in superoxidase dismutase (SOD) and glutathione-S-transferase (GST) activities and in glutathione (GSH) levels. These results suggest that toxic stress manifested by elevated SOD and GST levels and GSH contents may be responsible for the toxicity of NPs to M. aeruginosa and that the algal cells could improve their antioxidant and detoxification ability through the enhancement of enzymatic and nonenzymatic prevention substances. The observed elevations in GSH levels and GST activities were relatively higher than those in SOD activities, indicating that GSH and GST contributed more in eliminating toxic effects than SOD. Low concentrations of NPs (0.05–0.2 mg/l) enhanced cell growth and decreased GST activity in algal cells of M. aeruginosa, suggesting that NPs may have acted as a protecting factor, such as an antioxidant. The larger portion of the NPs (>60%) disappeared after 12 days of incubation, indicating the strong ability of M. aeruginosa to degrade the moderate persistent NP compounds. The sorption ratio of M. aeruginosa after a 12-day exposure to low nominal concentrations of NPs (0.02–0.5 mg/l) was relatively high (>30%). The fact that M. aeruginosa effectively resisted the toxic effects of NPs and strongly degraded these pollutants indicate that M. aeruginosa cells have a strong ability to adapt to variations in environmental conditions and that low and moderate concentrations of organic compounds may favor its survival. Further studies are needed to provide detailed information on the fate of persistent organic pollutants and the survival of algae and to determine the possible role of organic pollutants in the occurrence of water blooms in eutrophic lakes.     

渭河水中有机物在几种土壤中的吸附特性

通过批量实验研究了渭河水中有机物在几种土壤中的吸附行为，测得吸附常数，给出吸附等温线。对吸附等温线进行分析，发现已经吸附的有机物分子会影响土壤的吸附性质。同时数据的拟合表明，有机物在不同土样中的吸附行为均可用Freundlich方程描述。吸附常数和固相一水分配系数表明4种土样中河沙的吸附能力最强，进一步的实验发现这是由于河沙中已经吸附的有机物最少，吸附位相对多，造成吸附能力强。     

几类有机污染物的微塑料/水分配系数的线性溶解能关系模型

水体中的微塑料会吸附其中的有机污染物,影响有机污染物和微塑料的环境归趋和生态毒性。研究微塑料对有机污染物的吸附行为,对于评价有机污染物和微塑料的环境赋存、迁移及生物有效性有重要意义。污染物在微塑料与水之间的平衡分配系数(Kd),是表征微塑料对有机污染物吸附能力的重要参数。实验方法难以逐个测定众多有机污染物的Kd值,有必要发展其预测模型。本研究搜集了有机污染物的线性溶解能关系(LSER)参数及Kd值,构建了可预测有机污染物在聚丙烯微塑料与海水、聚乙烯微塑料与海水、聚乙烯微塑料与淡水之间Kd值的LSER模型。模型具有良好的拟合优度(R2adj介于0.794~0.903)、稳健性(Q2LOO和Q2BOOT分别介于0.763~0.863和0.720~0.804)和预测能力(R2ext和Q2ext分别介于0.886~0.971和0.825~0.954),能够用于预测多氯联苯、多环芳烃、六氯环已烷和氯苯类有机污染物的Kd值。     

Removal of bisphenol a in soil by cyclodextrin derivatives

The apparent aqueous solubility of the endocrine disruptor in hydroxypropyl‐cyclodextrin (HP‐CD) solutions was investigated for evaluating the remediation of soil contamination and ground water pollution. The apparent solubility of bisphenol A (BPA) in water was significantly increased in HP‐CD solutions. The solubilization effect of HP‐CD's is caused by the formation of inclusion complexes of BPA and cyclodextrin. The relative aqueous‐phase concentration of BPA linearly increased with increasing HP‐CD concentration. The solubility of BPA increased in the order of the addition of HP‐a‐CD, HP‐7‐CD, and HP‐ß‐CD. However, it did not depend upon the degree of hydroxypropylation substitution. It is concluded that HP‐CD may be utilized for the remediation of soil contamination.     

人血淋巴细胞检测浊漳河地表水的遗传毒性

为评价浊漳河水体中有机污染物的致突变性,采用单细胞凝胶电泳(SCGE)技术,研究了浊漳河水体3个不同样点的有机提取物对人外周血淋巴细胞DNA损伤效应。结果显示,各水样中的有机提取物均能引起DNA损伤,且随剂量的增高,有机物对DNA的损伤加重;细胞DNA损伤与对照组相比均有显著性差异(p<0.01)。这表明人外周血淋巴细胞对水体有机污染物的毒作用非常敏感。细胞彗星尾部DNA含量(%DNAT)和染毒剂量呈极显著正相关(R2>0.8547,p<0.01)。以上结果表明,浊漳河水体受到一定程度的有机物污染,这些有机污染物可诱导淋巴细胞DNA损伤,具有遗传毒性。SCGE技术作为一种简便、快速和灵敏的检测方法在水环境遗传毒性监测方面具有较大的应用价值。     

Assessment of solid waste and dumpsite leachate and topsoil

Dumpsite leachate contains different hazardous substances, some of which threaten the environment. In this study, municipal solid waste, dumpsite leachate and topsoil from seven different dumpsites in Lagos and Ibadan, Nigeria were analysed using standard methods. The parameters analysed in the composite leachate samples collected are pH, solids, alkalinity, chloride, nitrate, sulfate, phosphate, biochemical oxygen demand, chemical oxygen demand turbidity, heavy metals (e.g. Zn, Pb, Co, Ni, Cd) and some persistent organic pollutants (e.g. polyaromatic hydrocarbons [PAHs] and polychlorinated biphenyls [PCBs]). Total organic carbon, heavy metals (e.g. Zn, Pb, Co, Ni, Cd) and organic pollutants (e.g. PAHs, PCBs) were analysed in the dumpsite topsoil and the control samples. The samples for heavy metal determination were digested using concentrated nitric acid and the digestate was analysed using atomic absorption spectrometry, whereas organic pollutants were extracted using cold extraction and quantified by gas chromatography-mass spectrometry (GC-MS). The study revealed that dumpsites in Ibadan have ～90% domestic and 10% industrial waste, whereas the figures for Lagos are 80% and 20%, respectively. In the leachate samples, concentrations of PAHs and PCBs ranged from 0.85 to 1.47 mg/L and 0.01 to 0.08 mg/L, respectively; the values were 0.94–2.79 mg/kg and 10.0–412 μg/kg in the topsoil. If not properly managed, dumpsite leachate can seep into groundwater and surface water via run-off, and can have adverse effects on human health and the entire ecosystem.     

Carboxymethyl‐β‐cyclodextrin influence on the solubility and toxicity of substituted indole compounds

The solubilization of eight selected substituted indole compounds (SICs) by carboxymethyl‐β‐cyclodextrin (CMCD) in water is reported. The results show that their solubility was well improved in CMCD aqueous solution, and the stoichiometry of inclusion complex of the studied SICs with CMCD was 1: 1. The acute toxicity to Photobacterium phosphoreum of the investigated SICs in CMCD aqueous solutions was also investigated and was compared with that in water. The results show that the toxicity of five studied SICs decreased while the toxicity of the rest three SICs increased in CMCD aqueous solutions, but neither the increase nor the decrease was significant.     

Nanosized magnetite in low cost materials for remediation of water polluted with toxic metals,azo- and antraquinonic dyes

Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsorbents include magnetic iron oxide and its modifiers/stabilizers, such as carbon, silica, clay, organic moieties (polymers, aminoacids, and fatty acids) and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial’s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.     

Renal lesions in Greenland sledge dogs ( Canis familiaris ) exposed to a natural dietary cocktail of persistent organic pollutants

Persistent organic pollutants such as Polychlorinated biphenyls (PCB) and dichloro diphenyl trichloroethane (DDT) are known to exert various adverse health effects in wildlife mammals. The impact from dietary intake of minke whale (Balaenoptera acutorostrata) blubber high in organohalogen and other chemical contaminants on renal morphology and function was investigated via a controlled study on West Greenland sledge dogs (Canis familiaris). Our results showed significantly higher frequencies of glomerular, tubular, and interstitial lesions in the exposed group. Furthermore, higher urine protein?:?creatinine ratio and plasma urea levels were found in the exposed group, which indicated a negative impact on kidney function via tubular and glomerular dysfunctions. The lesions were similar to those observed in top predator marine species–such as seals and polar bears–and humans exposed via diet to persistent environmental pollutants. The lesions may have impacts on the overall health of these animals. It is reasonable to suggest that chronic exposure to organic pollutants via a country diet of high trophic level marine organisms may have an impact on renal morphology and function in Arctic apex predators in general as well as Inuit people.     

Trace elements and organochlorine pollutants in selected fish species from Lake Phewa,Nepal

Lake water and fish livers and gills of sahar (Tor putitora), spiny eel (Mastacembelus armatus), African magur (Clarias gariepinus), and tilapia (Oreochromis niloticus) from Lake Phewa, Nepal, were assessed for the concentrations of trace metals/elements and persistent organic pollutants. The lake water was neutral with low ionic and metallic concentrations as compared to high-altitude lakes of Nepal. The four elements Cu, Zn, Se, and Cd had highest concentrations in livers, indicating uptake from diet, whereas four other metallic elements Cr, Mn, Ni, and Pb had highest concentrations in gills, indicating uptake from lake water. O. niloticus tended to have most of trace metals in the liver at higher concentrations than the other species but significant differences among the different species were found only for Mn, Ni, and Zn in the gills. A pilot study on the concentrations of persistent organic pollutants in muscle revealed that dichlorodiphenyltrichloroethane and related compounds were the dominant organochlorine pesticides, having highest concentrations in C. gariepinus and lowest in O. niloticus.     

Alkanes and hopanes for pollution source apportionment in coking plant soils

Polluted soils of former coking plants are characterized by multiple organic contributions, e.g. coal tar, coal, coke, soot, and natural organic matter, that can either be sources of polycyclic aromatic hydrocarbons (PAHs) or act as sorption surfaces for pollutants. The contamination level is usually based on the quantification of 16 PAHs but it does not provide any information on PAH sources. We studied the aliphatic fractions of 25 soil samples from a former coking plant site by microscopy and gas chromatography-mass spectrometry (GC-MS). The microscopic investigation allowed to identify four main organic contributions: coal tar, coal, coke, and natural organic matter. These isolated sources were analyzed and considered as reference materials. Although the PAH distributions were very similar in the 25 contaminated soils, alkanes and hopanes distributions were representative from various contributions characterizing the relative enrichment in coal, coal tars, or natural organic matter. Two principal component analyses based on n-alkanes and hopanes showed that three molecular indices, the carbon preference index, the low molecular weight/high molecular weight n-alkanes ratio, and the 18α(H)-22,29,30-trisnorhopane/(18α(H)-22,29,30-trisnorhopane+17α(H)-22,29,30-trisnorhopane) ratio allow to classify polluted soils according to various organic contributions.     

Rapid degradation of carbon tetrachloride by commercial micro-scale zinc powder assisted by citric acid

We developed an effective method for degradation of carbon tetrachloride (CT) in contaminated water. Zinc metal as a reducing agent for CT in aqueous solutions has been previously studied in some detail, but the rapid corrosion of zinc surface usually reduces its efficiency in removing CT. We assumed that citric acid could enhance the degradation of CT by zinc powder due to the elimination of a passivation layer of Zn(II) (hydr)oxides on the surface of zinc powder through chelating of organic ligands with Zn(II) produced from the reaction and keeping the exposure of active sites to targets. Here the influence of citric acid on the decomposing of CT by commercial micro-scale zinc powder was investigated in a pH range of 3.5–7.5 at 25°C in batch experiments. Reaction mixtures were analysed by gas chromatography/headspace analysis, and Cl⁻ concentration was determined by turbidimetry. The results demonstrate that the degradation of CT by zinc metal alone is very weak, but the addition of citric acid can assist zinc powder to decompose CT more completely and rapidly at all pHs. Degradation of CT took place mainly in the first 10 min of reaction, coupled with 75–95% of CT removal. Maximum dechlorination percentage (82.4%) of CT was obtained at pH 5.5. In that case, chloroform and dichloromethane, as main intermediates, were found at low levels during the whole reaction, suggesting that CT may be sequentially and multiply degraded so quickly that methane is yielded before the intermediates can be desorbed and released to aqueous solution. When compared with the current methods of nano-scale zinc and bimetallic systems, the application of commercial micro-scale zinc particles assisted by organic ligands is of environmental significance since it allows decontamination of aqueous chlorinated organic compounds at low cost and with high efficiency.     

Field crops for phytoremediation of metal-contaminated land. A review

The use of higher plants to remediate contaminated land is known as phytoremediation, a term coined 15 years ago. Among green technologies addressed to metal pollution, phytoextraction has received increasing attention starting from the discovery of hyperaccumulator plants, which are able to concentrate high levels of specific metals in the above-ground harvestable biomass. The small shoot and root growth of these plants and the absence of their commercially available seeds have stimulated study on biomass species, including herbaceous field crops. We review here the results of a bibliographical survey from 1995 to 2009 in CAB abstracts on phytoremediation and heavy metals for crop species, citations of which have greatly increased, especially after 2001. Apart from the most frequently cited Brassica juncea (L.) Czern., which is often referred to as an hyperaccumulator of various metals, studies mainly focus on Helianthus annuus L., Zea mays L. and Brassica napus L., the last also having the greatest annual increase in number of citations. Field crops may compensate their low metal concentration by a greater biomass yield, but available data from in situ experiments are currently very few. The use of amendments or chelators is often tested in the field to improve metal recovery, allowing above-normal concentrations to be reached. Values for Zn exceeding 1,000 mg kg⁻¹ are found in Brassica spp., Phaseolus vulgaris L. and Zea mays, and Cu higher than 500 mg kg⁻¹ in Zea mays, Phaseolus vulgaris and Sorghum bicolor (L.) Moench. Lead greater than 1,000 mg kg⁻¹ is measured in Festuca spp. and various Fabaceae. Arsenic has values higher than 200 mg kg⁻¹ in sorghum and soybean, whereas Cd concentrations are generally lower than 50 mg kg⁻¹. Assisted phytoextraction is currently facilitated by the availability of low-toxic and highly degradable chelators, such as EDDS and nitrilotriacetate. Currently, several experimental attempts are being made to improve plant growth and metal uptake, and results are being achieved from the application of organic acids, auxins, humic acids and mycorrhization. The phytoremediation efficiency of field crops is rarely high, but their greater growth potential compared with hyperaccumulators should be considered positively, in that they can establish a dense green canopy in polluted soil, improving the landscape and reducing the mobility of pollutants through water, wind erosion and water percolation.     

High levels of gene flow in the surf bivalve Donax deltoides (Bivalvia: Donacidae) on the east coast of Australia

We surveyed patterns of allelic variation within twelve samples of the pipi Donax deltoides Lamarck from beaches separated by up to 1200 km but connected to varying degrees by the East Australian Current. We used these data to test the prediction that the irregular patterns of water movement would cause genetic differentiation in pipis, so that there would be more genetic variation within and among the more southern regions than the northern regions. We found that six loci were at least moderately variable within all samples, and there were no clear geographic patterns in allelic frequencies. In general, genotype frequencies within samples were consistent with predictions for an outcrossed, sexually reproducing species, and we detected no evidence of population subdivision. Within samples, with the exception of the peptidase loci, single-locus genotype frequencies were in close agreement with expectations for Hardy–Weinberg equilibrium. We observed no significant linkage disequilibrium for any pairwise comparison of loci in any sample. Our hierarchical analysis of genetic variation revealed little variation among all samples (F st = 0.009). Loci showed consistently low levels of subdivision (F st from 0.003 to 0.018). We found almost no variation among the four geographic regions sampled (F rt = 0.001). All variation was therefore attributable to variation among samples within regions (F sr = 0.010). These data imply that larvae are moving between regions and that levels of present or recent gene flow are high, and support the conclusions of other studies which have inferred widespread gene flow for animals dispersing via planktonic, outcrossed larvae in parts of this region. This implies that the East Australian Current is sufficient to produce strong larval connections despite its intermittent nature. If existing levels of population subdivision reflect current levels of gene flow, then these data imply that D. deltoides represents a single fishery on the east coast of Australia. Received: 16 September 1996 / Accepted: 25 September 1996     

Removal of metal ions from aqueous solution by chelating polymeric hydrogel

Polysaccharide natural seed coat from the tree Magonia pubescens, in the form of hydrogel was used to remove metals in aqueous solution. Swelling tests indicate that seed coat presents hydrogel behavior, with maximum water absorption of 292 g water/g. Adsorption experiments performed using Na⁺, Mg²⁺, K⁺, Ca²⁺, Cr³⁺, Fe³⁺ and Zn²⁺ demonstrated that the polysaccharide structure has a high capacity to extract these ions from the aqueous solution. Scanning electron microscopy revealed significant morphological changes of the material before and after water contact. Differential scanning calorimetry measurements indicate a signal shift of the water evaporation temperature in the material with adsorbed zinc. X-ray photoelectron spectroscopy analysis combined with theoretical studies by the density functional theory and on Hartree–Fock (HF) level evidence that the metallic ions were adsorbed through coordination with hydroxyl groups of polysaccharide. In the case of Zn²⁺ the lowest HF energy was observed for the tetracoordination mode, where Zn²⁺ is coordinated by two hydroxyl groups and two water molecules.