(Super)paramagnetic nanoparticles as platform materials for environmental applications: From synthesis to demonstration

• The fabrication of monodisperse, (super)paramagnetic nanoparticles is summarized. • Monolayer and bilayer surface coating structures are described. • Mono/bilayer coated nanoparticles showed high sorption capacities for U, As, and Cr. Over the past few decades, engineered, (super)paramagnetic nanoparticles have drawn extensive research attention for a broad range of applications based on their tunable size and shape, surface chemistries, and magnetic properties. This review summaries our recent work on the synthesis, surface modification, and environmental application of (super)paramagnetic nanoparticles. By utilizing high-temperature thermo-decomposition methods, first, we have broadly demonstrated the synthesis of highly monodispersed, (super)paramagnetic nanoparticles, via the pyrolysis of metal carboxylate salts in an organic phase. Highly uniform magnetic nanoparticles with various size, composition, and shape can be precisely tuned by controlled reaction parameters, such as the initial precursors, heating rate, final reaction temperature, reaction time, and the additives. These materials can be further rendered water stable via functionalization with surface mono/bi-layer coating structure using a series of tunable ionic/non-ionic surfactants. Finally, we have demonstrated platform potential of these materials for heavy metal ions sensing, sorption, and separation from the aqueous phase.     

氯/溴稳定同位素分析技术及其在环境科学研究中的应用

稳定同位素分析被认为是环境污染物溯源和转化途径探究的有效工具.针对氯/溴稳定同位素研究已经开发了一些较为可靠的分析技术,被广泛应用于氯乙烯、氯苯、溴酚、多溴二苯醚和有机氯农药等有机污染物的研究.本文综述了近年来氯/溴同位素分析技术的最新进展,介绍了稳定同位素分析技术在含氯/溴有机污染物的溯源分析和降解途径识别等方面的应...     

High Cu and Cd pollution in sediments from Sisimiut, Greenland. Adsorption to organic matter and fine particles

High concentrations of Cu of up to 200 mg/kg, and Cd of up to 4.0 mg/kg, were found in sediments from the aquatic environment around Sisimiut, Greenland. These concentrations are four times higher than the limiting concentration where toxicological effects are expected. The pollution could be linked to human activities in Sisimiut, a link that have not been investigated previously in Greenland. Except from the most polluted samples there was good correlation between heavy metal concentration and organic matter. Also some relationship between fine fraction and heavy metal concentration was observed.     

绿化树种对大气金属污染物吸滞能力

研究测定了部分城市绿化树种对重金属大气铅、镉污染物的吸滞能力。结果表明：绿化树种对大气铅、镉污染物具有一定的吸收净化能力，并依污染气体和树种的不同具有明显差异；对铅吸收量高的树种有：桑树、黄金树、榆树、早树、梓树；吸镉量高的树种有：美青杨、桑树、早树、榆树、梓树、刺槐。     

Heavy metal pollution in Jamaica 1: Survey of cadmium,lead and zinc concentrations in the Kintyre and Hope Flat districts

Despite its being highly mineralised, the Hope Mine area has become a residential district. Composite soil samples taken from 91 allotments show values for cadmium: < 2–220 mg kg^–1, lead: 6–38,000 mg kg^–1, and zinc: 66–40,000 mg kg^–1. Water samples from adits contain 52–86 g kg^–1 of lead and < 1–2 hg kg^–1 of cadmium. The soil contents of cadmium and lead in at least two areas suggest that remedial actions should be considered. Blood lead levels for 33 children aged between ten months and seven years are in the range 5.7–57 g dl^–1; haemoglobin levels vary between 9.7 and 12.7 mg dl^–1. There is no obvious relationship between Pb and haemoglobin levels. Further geochemical work to define fully the spatial extent of the polluted region and epidemiological studies including intelligence testing to define further the effects of lead on children in this environment would be valuable.To whom correspondence should be addressed.     

Selective targeted adsorption and inactivation of antibiotic-resistant bacteria by Cr-loaded mixed metal oxides

• LDHs and MMOs was synthesized by ultrasound-assisted one-step co-precipitation. • MMOs performs the best for Cr(VI) and E. coli_NDM-1 simultaneous removal. • Possible antibacterial pathways of Cr-MMOs were proposed. Herein we provide a novel high-efficiency nanocomposite for bacterial capture based on mixed metal oxides (MMOs) with deleterious chromium properties. With both the layer structure of layered double hydroxides (LDHs) and the magnetic properties of Fe, MMOs enrich the location of ionic forms on the surface, providing a good carrier for adsorption of the heavy metal Cr(VI). The capacity for adsorption of Cr(VI) by MMOs can be as high as 98.80 mg/g. The prepared Cr(VI)-MMOs achieved extremely expeditious location of gram-negative antibiotic-resistant E. coli_NDM-1 by identifying lipid bilayers. Cr-MMOs with a Cr loading of 19.70 mg/g had the best bactericidal effect, and the concentration of E. coli_NDM-1 was decreased from ~10⁸ to ~10³ CFU/mL after 30 min of reaction. The binding of nitrogen and phosphorus hydrophilic groups to chromate generated realistic models for density functional theory (DFT) calculations. The specific selectivity of MMOs toward bacterial cells was improved by taking Cr(VI) as a transferable medium, thereby enhancing the antibacterial activity of Cr-MMOs. Under the combined action of chemical and physical reactions, Cr(VI)-MMOs achieved high capacity for inactivation of bacteria. Moreover, the metallic elements ratio in Cr-MMOs remained stable in their initial valence states after inactivation. This guaranteed high removal efficiency for both heavy metals and bacteria, allowing recycling of the adsorbent in practical applications.     

The size distribution of airborne bacteria and human pathogenic bacteria in a commercial composting plant

•Bacterial concentrations from eight stages were 10⁴–10⁵copies/m³. •Diameter influenced clustering of bacterial and HPB lineages. •Dg of 8 HPB ranged from 2.42 to 5.09 μm in composting areas. •Dg of 8 HPB ranged from 3.70 to 8.96 μm in packaging areas. •HPB had high concentrations and small sizes in composting areas. Composting plants are regarded as one of the important sources of environmental bioaerosols. However, limitations in the size distribution of airborne bacteria have prevented our comprehensive understanding of their risk to human health and their dispersal behavior. In this study, different sizes of airborne bacteria were collected using an eight-stage impactor from a full-scale composting facility. Size-related abundance and communities of airborne bacteria as well as human pathogenic bacteria (HPB) were investigated using 16S rRNA gene sequencing coupled with droplet digital PCR. Our results indicate that the bacterial concentrations from the eight stages were approximately 10⁴–10⁵copies/m³. Although no statistical correlation was detected between the particle size and the Shannon index, the influence of size on bacterial lineages was observed in both composting and packaging areas. For airborne bacteria from different stages, the dominant phyla were Firmicutes, Proteobacteria, and Actinobacteria, and the dominant genera was Bacillus. Seven out of eight HPB with a small geometric mean aerodynamic diameter had a high concentration in composting areas. Based on diameters of 2.42 to 5.09 μm, most HPB in the composting areas were expected to be deposited on the bronchus and secondary bronchus. However, in the packaging areas, the deposition of HPB (diameters 3.70 to 8.96 μm) occurred in the upper part of the respiratory tract. Our results on the size distribution, abundance, and diversity of these bacteria offer important information for the systematic evaluation of bacterial pathogenicity and the potential health impacts on workers in composting plants and the surrounding residents.     

Isolation and characterisation of cadmium-resistant bacteria from an industrially polluted coastal ecosystem on the southeast coast of India

A total of 35 bacterial strains were isolated from the industrially polluted Cuddalore coast, on the southeast coast of India. Of these, 17 strains were cadmium resistant and the remainder were sensitive. Six strains (C-1, C-8, C-10, C-12, C-14 and N-1) were selected based on high levels of cadmium tolerance (>150 mg L^?1) and were termed highly cadmium-resistant bacteria (HCRB). These HCRB were identified on the basis of morphological, biochemical and partial sequencing of their 16S rRNA genes. The antibiotic-susceptibility patterns and minimum inhibitory concentrations (MIC) of different metals (Cu²⁺, Pb²⁺ and Zn²⁺) against each HCRB were determined. Among the isolates, C-14 showed high degrees of metal and antibiotic resistance compared with other HCRB. Growth rates of HCRB at two different Cd²⁺ concentrations (50 and 100 mg L^?1) and under different metal conditions (Cd²⁺, Cu²⁺ and Pb²⁺) were also investigated. HCRB growth rates were lower in the metal-treated condition than in the untreated condition. Isolates C-14 and N-1 removed>80% of Cd²⁺ from cadmium-treated broth. However, isolate C-14 removed 92.3% of Cd²⁺ compared with 86.5% for isolate N-1. Bacteria showing residual growth rates under metal stress conditions might be useful in metal removal applications under growing conditions.     

紫外辐射对灯盏花附生、内生细菌数量的影响及机理

采用大田研究方法,模拟5.0kJ·m~(-2)紫外辐射(UV-B,280～315nm)增强对灯盏花Erigeronbreviscapus附生、内生细菌数量、优势种群以及类黄酮、游离氨基酸、可溶性蛋白、淀粉和可溶性糖含量的影响.UV-B辐射极显著减少灯盏花苗期叶和花期根与叶附生细菌数量(p<0.01),显著减少灯盏花果熟期根与叶附生细菌数量(p<0.05).极显著减少灯盏花苗期根与叶和花期叶与茎及果熟期茎内生细菌的数量,果熟期根内生细菌数量显著增加.灯盏花附生细菌优势种群为芽孢杆菌Bacillus和欧文氏菌Erwinia,内生细菌优势种群为芽孢杆菌;UV-B辐射可导致灯盏花附生和内生细菌优势种群数目减少.UV-B辐射还会使灯盏花生理指标发生变化,直接导致灯盏花附生细菌数量的减少,可溶性糖、游离氨基酸和可溶性蛋白含量与附生细菌数量呈显著正相关(p<0.05).UV-B辐射增加灯盏花各部位类黄酮含量,间接影响灯盏花内生细菌数量,根类黄酮含量与内生细菌数量呈极显著正相关(p<0.01).     

Acute toxicity assessment of drinking water source with luminescent bacteria: Impact of environmental conditions and a case study in Luoma Lake,East China

• Acute toxicity assessment was conducted in Luoma lake watershed, East China. • Impacts of environmental factors on the toxicity testing was fully evaluated. • Dissolve oxygen had a weak positive correlation with luminescence inhibition rate. Protecting the quality of lake watersheds by preventing and reducing their contamination is an effective approach to ensure the sustainability of the drinking water supply. In this study, acute toxicity assessment was conducted on the basis of acute bioluminescence inhibition assay using the marine bacterium Vibrio fischeri as the test organism and Luoma Lake drinking water source in East China as the research target. The suitable ranges of environmental factors, including pH value, organic matter, turbidity, hardness, and dissolved oxygen of water samples were evaluated for the toxicity testing of bioluminescent bacteria. The physicochemical characteristics of water samples at the selected 43 sites of Luoma Lake watershed were measured. Results showed that the variations in pH value (7.31–8.41), hardness (5–20 °d) and dissolved oxygen (4.44–11.03 mg/L) of Luoma Lake and its main inflow and outflow rivers had negligible impacts on the acute toxicity testing of V. fischeri. The luminescence inhibition rates ranged from -11.21% to 10.80% at the 43 sites. Pearson’s correlation analysis in the experiment revealed that temperature, pH value, hardness, and turbidity had no correlation with luminescence inhibition rate, whereas dissolved oxygen showed a weak statistically positive correlation with a Pearson correlation coefficient of 0.455 (p<0.05).     

Microscopic structure of soil Fe-Mn nodules: environmental implication

The internal structure, iron and manganese distributions of Fe-Mn nodules from imperfectly drained soils of central Greece were studied by scanning electron microscopy (SEM) and elemental analysis. Nodules exhibited a differentiated structure with discontinuous concentric rings as expression of their redox history. Fe and Mn have shown distinct repartition and were distributed mainly in concentric bands. The microstructure and the arrangement of iron—manganese compounds reflect the periodical development and the relative slow accretion rates of the studied nodules. These properties provide ample opportunity for adsorption and isolation of heavy metals from the soil system.     

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.     

Nuclear magnetic resonance studies of interactions between organic pollutants and soil components,a review

This article presents a short overview of selected recent papers using nuclear magnetic resonance (NMR) to investigate interactions between organic pollutants and soil components such as organic matter, clays, whole soils, and sediments. First, we describe solid state cross polarisation magic angle spinning (CP-MAS) experiments as the main tools to investigate covalent bonds. Second, we report NMR approaches allowing us to assess molecule mobility and to characterise non-covalent interactions. Those approaches include correlations between K _oc values and soil organic matter functions determined by CP-MAS, ²H NMR fingerprints, relaxation time measurements, ¹⁹F and ¹H high resolution (HR)-MAS experiments.     

Fungal laccases: from structure-activity studies to environmental applications

Laccases are multicopper oxidases mainly secreted by filamentous fungi. Producing radical forms from organic substrates, they are involved in numerous reactions leading to the degradation and polymerization of xenobiotics. Our studies have led to a better knowledge of the structural, catalytic and genetic properties of laccases and allowed to develop a strategy for their evolution through genetic engineering. Here, we show that fungal laccases, wild or engineered, may be potent tools to develop bioremediation processes of soils polluted by organic compounds, and assays to assess the ecotoxicological impact of these pollutants on soil fungi.     

Distribution of aromatic amines,phenols, chlorobenzenes,and naphthalenes in the surface sediment of the Dianchi Lake,China

• The total organic pollutant concentrations in sediment were 27.4-1620 ng/g. • The phenol concentrations were relatively high in the sediment of the Dianchi Lake. • Average total concentrations decreased as follows: Caohai>Waihai>Haigeng Dam. • 1,4-dichlorobenzene, 3- or 4-methylphenol, 1,2,4-trichlorobenzene might be risks. Organic pollutants are widespread environmental pollutants with high toxicity, persistence, and bioaccumulation. Our aim was to investigate the distribution of aromatic amines, phenols, chlorobenzenes, and naphthalenes in the surface sediment of the Dianchi Lake, China. Nineteen surface sediment samples were collected from the Dianchi Lake, and 40 types of organic pollutants were analyzed via gas chromatography–mass spectrometry. The total organic pollutant concentrations in the surface sediment of the Dianchi Lake varied from 27.4 to 1.62 × 10³ ng/g. The concentrations of phenols were much higher than those in other water bodies but still within a controllable range, whereas the concentrations of the other organic pollutant classes were similar or even lower. The detection ratio of 3- or 4-methylphenol was the highest (100.00%) among the pollutants. The average total organic pollutant concentrations decreased in the following order: Caohai (540 ng/g)>the middle of Waihai (488 ng/g)>the edge of Waihai (351 ng/g)>Haigeng Dam (90.4 ng/g). Pearson analysis showed a strong correlation among 1-methylnaphthalene, 2-methylnaphthalene, 1,3-dinitronaphthalene, and 1,4-dinitronaphthalene (p<0.01). Caohai, the north lakeshore of Waihai and the south of Waihai showed higher risk because of high concentration; meanwhile, 1,4-dichlorobenzene, 3- or 4-methylphenol and 1,2,4-trichlorobenzene were more likely to cause risks.     

Environmental and technological studies on the interaction of wool with some metal ions

The technical feasibility of using a suitable sorbent for the removal of some heavy metal ions from their aqueous solutions was investigated. The scope of the work covers the use of low-class native wool or wool wastes from industrial processes or from recycled woolen textiles for the removal of copper, nickel, cobalt, chromium, and zinc ions from their effluents. The sorption efficiency of the aforementioned metals by wool is in the following order: copper?>?cobalt?=?nickel?>?zinc?>?chromium.

The effect of time of sorption, temperature of the effluent, and concentration of metal ions on the rate of sorption was examined. The effect of oxidation or reduction of wool on its sorption power of copper ions is studied. The reduced wool was found to be better than native or oxidised wool in the sorption of copper metal from its effluents. The reuse of wool as metal sorber after elution of the metal, using hydrochloric acid, was also studied. It was found that wool can be reused for sorption after elution of copper up to 25 times of elution; a very limited amount of permanently fixed copper was observed. The use of sufficient woolen layers displays the best way of obtaining an effluent of zero copper content.     

铅锌污染耕地中重金属耐受细菌调查

对铅锌矿冶炼厂周围耕地中的细菌总数和抗性细菌群体数进行了调查。结果表明 ,随着污染的加重 ,土壤中可培养的细菌数量急剧减少 ,抗性细菌的比例增加。但是 ,细菌对Pb、Zn胁迫的适应进化反应不一样。经过长期的选择作用后 ,多数细菌群体能够耐受低浓度的Pb污染 (<2mmol·L-1) ,部分群体对低浓度Pb(0 .5mmol·L-1)有依赖性 ,但没有观察到能够耐受Pb浓度大于 4mmol·L-1的群体 ;0 .5mmol·L-1的Zn对细菌有抑制作用 ,但在所调查的样品中都存在能够耐受 4～ 6mmol·L-1Zn污染的群体 ,有的群体甚至能耐受 8mmol·L-1的Zn污染。能同时耐受Pb、Zn 2种重金属污染的群体数量较少 ,且耐受水平也较低 ,仅达到 2mmol·L-1。     

Sulfur mediated heavy metal biogeochemical cycles in coastal wetlands: From sediments,rhizosphere to vegetation

• In sediments, the transformation of sulfides may lead to the release of heavy metals. • In the rhizosphere, sulfur regulates the uptake of heavy metals by plants. • In plants, sulfur mediates a series of heavy metal tolerance mechanisms. • Explore interactions between sulfur and heavy metals on different scales is needed. The interactions and mechanisms between sulfur and heavy metals are a growing focus of biogeochemical studies in coastal wetlands. These issues underline the fate of heavy metals bound in sediments or released into the system through sediments. Despite the fact that numerous published studies have suggested sulfur has a significant impact on the bioavailability of heavy metals accumulated in coastal wetlands, to date, no review article has systematically summarized those studies, particularly from the perspective of the three major components of wetland ecosystems (sediments, rhizosphere, and vegetation). The present review summarizes the studies published in the past four decades and highlights the major achievements in this field. Research and studies available thus far indicate that under anaerobic conditions, most of the potentially bioavailable heavy metals in coastal wetland sediments are fixed as precipitates, such as metal sulfides. However, fluctuations in physicochemical conditions may affect sulfur cycling, and hence, directly or indirectly lead to the conversion and migration of heavy metals. In the rhizosphere, root activities and microbes together affect the speciation and transformation of sulfur which in turn mediate the migration of heavy metals. As for plant tissues, tolerance to heavy metals is enhanced by sulfur-containing compounds via promoting a series of chelation and detoxification processes. Finally, to further understand the interactions between sulfur and heavy metals in coastal wetlands, some major future research directions are proposed.     

The impact of ultrasonic treatment on activity of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in activated sludge

Conditions for ultrasonic treatment to achieve partial nitritation are optimized. Ultrasound reduces metabolic activity and releases intracellular metabolites. Mechanical shearing is essential to inhibit nitrite oxidation. The ultrasonic treatment of sludge has been considered as an effective method to facilitate the partial nitritation of municipal sewage. This study aims to reveal the effects of ultrasound on ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). The impact factors including ultrasonic irradiation time and intensity, sludge concentration, thermal effect and released free radicals were studied. The maximized difference between the changes in AOB and NOB activities were obtained with 10 g mixed liquor suspended solids (MLSS)/L, using 0.9 kJ/mL ultrasonic energy density and 12 h interval time. The increased ultrasonic intensity destroyed the floc structure of activated sludge, increased the microbial death, and decreased the cellular ATP level. Further, the mechanism exploration indicated that the mechanical shearing could be a critical factor in achieving the nitritation with inhibitory effect on nitrite oxidation.