Unveiling the fast adsorption and desorption of heavy metals on/off nanoplastics by real-time in-situ potentiometric sensing.

Nanoplastics (<1 µm) can serve as a transport vector of environmental pollutants (e.g., heavy metals) and change their toxicities and bioavailabilities. Up to date the behaviors of adsorption and desorption heavy metals on/off nanoplastics are largely unknown. Herein, polymeric membrane potentiometric ion sensors are proposed for in-situ assessment of the real-time kinetics of heavy metal adsorption and desorption on/off nanoplastics. Results show that nanoplastics can adsorb and release heavy metals in a fast manner, indicating their superior ability in transferring heavy metals. The adsorption behaviors are closely related to the characteristics of nanoplastics and background electrolytes. Particle aggregation and increases in salinity and acidity suppress the adsorption of heavy metals on nanoplastics. The desorption efficiencies of different heavy metals are Pb2+ (31 %) < Cu2+ (40 %) < Cd2+ (97 %). Our proposed method is applicable for the detection of the plastic pollutants with size <100 nm and of the samples with high salinities (e.g., seawater). This work would provide new insights into the assessment of environmental risks posed by nanoplastics and heavy metals.

Use of plant growth-promoting bacteria to facilitate phytoremediation.

Here, phytoremediation studies of toxic metal and organic compounds using plants augmented with plant growth-promoting bacteria, published in the past few years, were summarized and reviewed. These studies complemented and extended the many earlier studies in this area of research. The studies summarized here employed a wide range of non-agricultural plants including various grasses indigenous to regions of the world. The plant growth-promoting bacteria used a range of different known mechanisms to promote plant growth in the presence of metallic and/or organic toxicants and thereby improve the phytoremediation ability of most plants. Both rhizosphere and endophyte PGPB strains have been found to be effective within various phytoremediation schemes. Consortia consisting of several PGPB were often more effective than individual PGPB in assisting phytoremediation in the presence of metallic and/or organic environmental contaminants.

Assessing the potential of portable X-ray fluorescence (XRF) as a rapid, onsite screening tool in the assessment of cadmium surface decontamination effectiveness.

Portable X-ray fluorescence has successfully been used to effectively evaluate occupational exposure to airborne and surface metal contaminants nondestructively. Traditional methods of assessing metal surface contamination involve the costly, time-consuming collection and laboratory analysis of wipe samples, making portable X-ray fluorescence an attractive alternative method for screening worksites by reducing delays in risk assessment decision-making. Existing research into this use of portable X-ray fluorescence has primarily been centered on the analysis of airborne and surface lead contamination. The extant literature is sparse on the use of portable X-ray fluorescence with other metals for surface contamination with respect to occupational exposure. The present study evaluated the use of portable X-ray fluorescence in the screening of cadmium surface contamination to determine if the effectiveness of decontamination measures can be ascertained by this technique. Wipe samples were collected and screened with portable X-ray fluorescence before being sent to the laboratory for definitive analysis to assess the correlation between portable X-ray fluorescence readings in percent mass with laboratory results in µg/ft2. Portable X-ray fluorescence readings demonstrated a strong linear correlation with laboratory results, as indicated by the R2 value of 0.993. Therefore, this technique may be further developed and deployed as a screening tool for wipe samples used for evaluating contamination and decontamination of metal-contaminated areas.

Assessment of herbaceous community structure for identifying metal-tolerant species at different land uses in and around Varanasi city.

Plant community structure under different land uses provides an important understanding of vegetation dynamics to safeguard future restoration programmes and balance ecosystem services. Therefore, this study was carried out to estimate the alterations in soil properties and contamination by potentially toxic metals at different land uses (industrial, brick kiln, highway, and residential areas) compared to the reference (botanical garden area) site coupled with their subsequent influence on herbaceous community structure, bioconcentration, translocation, and extraction amount of metals in different plant species. Most of the total and phytoavailable metals (Co, Cr, Cd, Cu, Ni, Pb, Mn, and Zn) were higher at the contaminated sites compared to the reference site. The number of herbaceous species was highest at the reference site and minimum at the industrial site. Dominant and tolerant species were Cyanodon dactylon, Croton bonaplandianus, Achyranthus aspera, Malvestrum coromendelianum, Dicanthium annulatum, Nicotiana hindostana, Sporobolus virginicus, and Parthenium hysterophorus, found at the industrial, brick kiln, and highway sites. Based on transfer coefficients, C. bonaplandianus, D. annulatum, and Eleusine indica were recognized as potential accumulators, whereas C. dactylon, Commelina benghalensis, A. aspera, Amaranthus sessilis, and M. coromendelianum were found as excluder species for different metals. The identified tolerant herbaceous species could be used for future phytoremediation strategies and the prevention of hazardous risks to living components of contaminated sites.

Contrasting copper concentrations and isotopic compositions in two Great Lakes watersheds.

Copper (Cu) stable isotopes can elucidate the biogeochemical controls and sources governing Cu dynamics in aquatic environments, but their application in larger rivers and catchments remains comparatively scarce. Here, we use major and trace element hydrogeochemical data, Cu isotope analyses, and mixing modeling, to assess Cu loads and sources in two major river systems in Ontario, Canada. In both the Spanish River and Trent River catchments, aqueous hydrochemical compositions appeared reasonably consistent, but Cu concentrations were more variable spatially. In the Spanish River, waters near (historic) industrial mining activities displayed positive Cu isotope compositions (δ65CuSRM-976 between +0.75 ‰ and +1.01 ‰), but these signatures were gradually attenuated downstream by mixing with natural background waters (δ65Cu -0.65 ‰ to -0.16 ‰). In contrast, Trent River waters exhibited more irregular in-stream Cu isotope patterns (δ65Cu from -0.75 ‰ to +0.21 ‰), beyond the variability in Cu isotope signatures observed for adjacent agricultural soils (δ65Cu between -0.26 ‰ and +0.30 ‰) and lacking spatial correlation, reflective of the more diffuse sourcing and entwined endmember contributions to Cu loads in this catchment. This work shows that metal stable isotopes may improve our understanding of the sources and baseline dynamics of metals, even in large river systems.

Moringa oleifera Lam. Commercial Beverages: A Multifaceted Investigation of Consumer Perceptions, Sensory Analysis, and Bioactive Properties.

This study employs a multidisciplinary approach to evaluate consumers' perceptions and acceptance of Moringa oleifera Lam. beverages, examining sensory attributes, chemical composition, and bioactivities. High-performance liquid chromatography with diode array detection (HPLC-DAD) analyses revealed significant chemovariation in phenolic compositions among commercial moringa beverages. A soluble moringa powder drink exhibited the greatest concentrations of phenolic and flavonoid compounds, along with powerful antioxidant capacity powers assessed with ABTS•+, DPPH•, FRAP assays, •NO, and H2O2 scavenging activities. However, this sample was the least preferred and presented high Cd levels, exceeding WHO-acceptable values of 0.3 mg/kg. Sensory testing indicated that sweet and floral flavors contributed to beverages being liked, while green, grass, herbal flavors, sour, bitter, and precipitate presence were considered unfavorable sensory attributes. Health claims positively influenced acceptance, particularly among women. Consumers associated feelings of health, wellness, relaxation, and leisure with moringa beverages. During purchase, the most observed information included the ingredient list, health benefits, and type/flavor. These findings emphasize the importance of consumer awareness in reading labels, verifying product origins, and ensuring the absence of contaminants. By understanding consumer preferences and the impact of health claims, producers can better tailor M. oleifera beverages to meet consumer expectations while maintaining safety and quality standards.

Membrane-based microfluidic solvent extraction of Ga-68 from aqueous Zn solutions: towards an automated cyclotron production loop.

BACKGROUND: The radionuclide Ga-68 is commonly used in nuclear medicine, specifically in positron emission tomography (PET). Recently, the interest in producing Ga-68 by cyclotron irradiation of [68Zn]Zn nitrate liquid targets is increasing. However, current purification methods of Ga-68 from the target solution consist of multi-step procedures, thus, leading to a significant loss of activity through natural decay. Additionally, several processing steps are needed to recycle the costly, enriched target material. RESULTS: To eventually allow switching from batch to continuous production, conventional batch extraction and membrane-based microfluidic extraction were compared. In both approaches, Ga-68 was extracted using N-benzoyl-N-phenylhydroxylamine in chloroform as the organic extracting phase. Extraction efficiencies of up to 99.5% ± 0.6% were achieved within 10 min, using the batch approach. Back-extraction of Ga-68 into 2 M HCl was accomplished within 1 min with efficiencies of up to 94.5% ± 0.6%. Membrane-based microfluidic extraction achieved 99.2% ± 0.3% extraction efficiency and 95.8% ± 0.8% back-extraction efficiency into 6 M HCl. When executed on a solution irradiated with a 13 MeV cyclotron at TRIUMF, Canada, comparable efficiencies of 97.0% ± 0.4% were achieved. Zn contamination in the back-extracted Ga-68 solution was found to be below 3 ppm. CONCLUSIONS: Microfluidic solvent extraction is a promising method in the production of Ga-68 achieving high efficiencies in a short amount of time, potentially allowing for direct target recycling.

N6-methyladenosine upregulates ribosome biogenesis in environmental carcinogenesis.

Many trace metal pollutants in surface water, the atmosphere, and soil are carcinogenic, and ribosome biogenesis plays an important role in the carcinogenicity of heavy metals. However, the contradiction between upregulated ribosome biogenesis and decreased ribosomal DNA copy number in environmental carcinogenesis is not fully understood. Here, from a perspective of the most predominant and abundant RNA epigenetic modification, N6-methyladenosine (m6A), we explored the reason behind this contradiction at the post-transcriptional level using arsenite-induced skin carcinogenesis models both in vitro and in vivo. Based on the m6A microarray assay and a series of experiments, we found for the first time that the elevated m6A in arsenite-induced transformation is mainly enriched in the genes regulating ribosome biogenesis. m6A upregulates ribosome biogenesis post-transcriptionally by stabilizing ribosomal proteins and modulating non-coding RNAs targeting ribosomal RNAs and proteins, leading to arsenite-induced skin carcinogenesis. Using multi-omics analysis of human subjects and experimental validation, we identified an unconventional role of a well-known key proliferative signaling node AKT1 as a vital mediator between m6A and ribosome biogenesis in arsenic carcinogenesis. m6A activates AKT1 and transmits proliferative signals to ribosome biogenesis, exacerbating the upregulation of ribosome biogenesis in arsenite-transformed keratinocytes. Similarly, m6A promotes cell proliferation by upregulating ribosome biogenesis in cell transformation induced by carcinogenic heavy metals (chromium and nickel). Importantly, inhibiting m6A reduces ribosome biogenesis. Targeted inhibition of m6A-upregulated ribosome biogenesis effectively prevents cell transformation induced by trace metals (arsenic, chromium, and nickel). Our results reveal the mechanism of ribosome biogenesis upregulated by m6A in the carcinogenesis of trace metal pollutants. From the perspective of RNA epigenetics, our study improves our understanding of the contradiction between upregulated ribosome biogenesis and decreased ribosomal DNA copy number in the carcinogenesis of environmental carcinogens.

Interactions of microplastics with contaminants in freshwater systems: a review of characteristics, bioaccessibility, and environmental factors affecting sorption.

Microplastics (MPs), plastic particles of 1 nm to <5 mm, have been identified in the atmosphere, soil, and aquatic environments across the globe. MPs may act as vectors to transport environmental contaminants to sensitive receptors, including humans. In this review, the capability of MPs to sorb persistent organic pollutants (POPs) and metals is investigated, along with how sorption is affected by factors, such as pH, salinity, and temperature. Sensitive receptors may take up MPs through incidental ingestion. In the gastrointestinal tract (GIT), contaminants may desorb from MPs, and this desorbed portion is then considered bioaccessible. Understanding the sorption and bioaccessibility of such contaminants is important in determining potential risks of exposure to MPs. Thus, a review is presented on the bioaccessibility of contaminants sorbed to MPs in the human and avian GIT s. The current state of knowledge on MP-contaminant interactions in freshwater systems is limited; these interactions can differ considerably from those in marine environments. The bioaccessibility of contaminants sorbed to MPs can vary significantly, from near zero to 100%, depending on MP type, contaminant characteristics, and the digestive phase. Further research is needed to characterize the bioaccessibility and the potential risks, especially for POPs associated with MPs.

Efficient and easily scaled-up biosorbent based on natural and chemically modified macauba (Acrocomia aculeata) to remove Al3+, Mn2+ and Fe3+ from surface water contaminated with iron mining tailings.

The ruptures of tailings mine dams in the cities of Mariana and Brumadinho contaminated local Brazilian Rivers with toxic metals. Herein, we describe a scaled-up biosorbent based on natural macauba endocarp (NTE) and macauba endocarp chemically treated (TE) to remove Al3+, Mn2+ and Fe3+ from aqueous solutions. For the TE material: the variation of pH and temperature of water did not cause significant sorption interferences; the kinetics studies suggest a pseudo-second-order model; the adsorption isotherms revealed that the Langmuir equation was the best fit for Al3+ and Mn2+, while the Freundlich equation best described the Fe3+; and the maximum adsorption capacities were between 0.268 mg g-1 and 1.379 mg g-1. A scaled-up was carried out using an adsorption column to remove the metals from Rio Paraopeba River water samples and the results showed that both NTE and TE are potentially low cost biosorbents for removing Al3+, Mn2+ and Fe3+.

Multiple contaminant ecological risk evaluation in small craft harbour sediments in Nova Scotia, Canada.

Small craft harbours are vital for the fishing industry and have high socioeconomic and cultural importance for surrounding communities. Presence of potential contaminants of concern in small craft harbour sediments can have significant impacts in biota and humans, including fishing activities and the local economy. While single contaminant sediment concentrations may be below sediment quality guidelines, the interaction of multiple contaminants in sediments may potentially exacerbate chemical ecological risk. An ecological risk evaluation for four classes of contaminants (i.e., petroleum hydrocarbons, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and metals) was conducted in 31 small craft harbours in Nova Scotia, Canada, using two approaches (i.e., mean probable effect level quotient and number and frequency of sediment quality guideline exceedances). Most small craft harbours showed a low ecological risk to marine biota, with only two small craft harbours suggesting high risk. While urgent action is not needed, monitoring is recommended for these small craft harbours to confirm that pollution is not increasing, and to potentially identify and control contamination sources.

Mass-Balance Modeling of Metal Loading Rates in the Great Lakes.

Major elements and nutrients are key water quality monitoring targets in the Great Lakes, but large-scale and long-term data for (trace) metals remains comparatively scarce. Consequently, the sources and processes controlling metal loading rates and potential accumulation in the lakes are not as well constrained. Here, we present a comprehensive assessment of select metal loads in the Great Lakes basin, aggregating tributary and connecting channel loads as well as estimates for atmospheric input and sedimentation. In total, 26,845 hydrometric and water quality datapoints from major environmental surveillance programs were compiled into mass-balance calculations and dynamic simulations for 1980-2020. Conservative element (Na, Cl) loads were used to calibrate the black-box approach, and mass-balance for these elements could be achieved at ≥90% and long-term trends accurately reproduced. In contrast, biogeochemically reactive (trace) metals Cu, Ni, Zn and Pb displayed highly variable source-sink behavior across the Great Lakes. Our results show that i) atmospheric inputs, tributary loads, and sedimentation all affect the concentrations and temporal trends of the studied metals but differently in the upper versus lower lakes, ii) smaller tributaries can be disproportionately important to lake-wide metal budgets, and iii) current loading rates may yield increasing lake-wide average Cl concentrations (e.g., up to 2.3 mg/L in Lake Superior) but decreasing metal concentrations (e.g., down to <0.25 µg/L Cu in Lake Ontario) by 2100. This work provides important quantitative baselines for metal loads in the Great Lakes and may help optimize surveillance and management strategies for the preservation of Great Lakes water quality.

Systematic Review and Meta-analysis of Environmental Toxic Metal Contaminants and the Risk of Ischemic Stroke.

Background: Stroke is the second largest cause of mortality (WHO 2014) and long-lasting disability worldwide. Many risk factors are associated with stroke, such as age, gender, chronic illnesses, cardiovascular disease, lifestyle, and smoking. With global industrialization, the roles of environmental contaminants and their association with stroke are still unclear and have attracted much more attention. Materials and Methods: We conducted a systematic review on the environmental toxic metal contaminants and the risk of ischemic stroke. A comprehensive literature search was carried out till June 30, 2021 from databases such as PubMed, Science Direct, Embase, and Scopus. The quality of all the articles which met our inclusion criteria was assessed using Newcastle-Ottawa scaling, and four eligible studies were included for our systematic review. Results: The serum and urine cadmium concentrations were positively associated with the risk of ischemic stroke. There was an inverse association of serum and urine concentrations of mercury (Hg), serum concentration of gold and cerium with ischemic stroke, and the serum and urine concentrations of lead (Pb) had no association with ischemic stroke risk. Conclusion: The study showed strong associations between heavy metals and ischemic stroke, but more studies are required to prove the associations.

The influence of preferred habitat and daily range of the European hare on its contamination by heavy metals: a case study from the West Carpathians.

The Spisská Magura mountain range, located in the Middle Spis, is one of the regions in Slovakia most contaminated by heavy metals resulting from mining and smelting activities. Heavy metals and other potentially toxic elements have accumulated in mountain areas via atmospheric transport. The influence of the daily range size of the European hare on its contamination by heavy metals was investigated in three habitat types (forest, woodland edge, meadow) in the Spisská Magura mountain range in the West Carpathians. Individual hares (n = 21) were traced and located by GPS following snowfall. Pair samples of their faeces (n = 64) and food (n = 64) were collected from feeding sites. The maps created were used for determination of the size of the daily range as being small or large. All hares that have a small daily range avoid meadows and open spaces due to the higher predation risk. However, individuals with a large daily range feed in all habitats, including meadows. Hares with a small daily range in a forest habitat ingested higher amounts of bio-elements Ca, Cr, S, and Mn as well as higher amounts of heavy metals Ba and Pb than hares with a large daily range. Moreover, dominant hares with a small daily range, with access to abundant food sources in a forest habitat, may gradually take on higher levels of bio-elements including heavy metals that are present in their food source. In contrast, in the woodland edge, hares with a small daily range had a smaller concentration of Ca, Cr, Mn, S, Ba, and Pb compared to hares with a large daily range. Caecotrophy plays a very significant role as far as the intake of nutrients and other elements is concerned. We found significant dependence between concentrations of the elements Cr, S, Ba, Pb, and Cd in the food of European hares and in their faeces.

Microbial Sensing and Removal of Heavy Metals: Bioelectrochemical Detection and Removal of Chromium(VI) and Cadmium(II).

The presence of inorganic pollutants such as Cadmium(II) and Chromium(VI) could destroy our environment and ecosystem. To overcome this problem, much attention was directed to microbial technology, whereas some microorganisms could resist the toxic effects and decrease pollutants concentration while the microbial viability is sustained. Therefore, we built up a complementary strategy to study the biofilm formation of isolated strains under the stress of heavy metals. As target resistive organisms, Rhizobium-MAP7 and Rhodotorula ALT72 were identified. However, Pontoea agglumerans strains were exploited as the susceptible organism to the heavy metal exposure. Among the methods of sensing and analysis, bioelectrochemical measurements showed the most effective tools to study the susceptibility and resistivity to the heavy metals. The tested Rhizobium strain showed higher ability of removal of heavy metals and more resistive to metals ions since its cell viability was not strongly inhibited by the toxic metal ions over various concentrations. On the other hand, electrochemically active biofilm exhibited higher bioelectrochemical signals in presence of heavy metals ions. So by using the two strains, especially Rhizobium-MAP7, the detection and removal of heavy metals Cr(VI) and Cd(II) is highly supported and recommended.

Review of Biochar Properties and Remediation of Metal Pollution of Water and Soil.

BACKGROUND: Mining, waste disposal, and agrochemical residues have contributed to pollution of water and soil with toxic metals in most low- and middle-income countries, raising concerns of ecological safety and public health. This has prompted many studies into the production and utilization of biochars to adsorb toxic metal contaminants from soil and water. OBJECTIVE: The present study presents a review of biochar properties, the mechanisms of toxic metal adsorption onto biochar, and sorption of toxic metal contaminants in water and soil in small scale applications and laboratory experiments. METHODS: A total of 305 articles were collected, and after screening for relevance, a final of 164 articles from both high- and low- and middle-income countries were used in this review paper. DISCUSSION: Biochar for sorption has proven effective and its raw materials are readily available, cost effective, environmentally stable and a good form of waste management. CONCLUSIONS: Different techniques of biochar production influence the properties of biochar and adsorption of toxic metals from water and soil. COMPETING INTERESTS: The authors declare no competing financial interests.

Comprehensive review of the basic chemical behaviours, sources, processes, and endpoints of trace element contamination in paddy soil-rice systems in rice-growing countries.

Rice is the leading staple food for more than half of the world's population, and approximately 160 million hectares of agricultural area worldwide are under rice cultivation. Therefore, it is essential to fulfil the global demand for rice while maintaining food safety. Rice acts as a sink for potentially toxic metals such as arsenic (As), selenium (Se), cadmium (Cd), lead (Pb), zinc (Zn), manganese (Mn), nickel (Ni), and chromium (Cr) in paddy soil-rice systems due to the natural and anthropogenic sources of these metals that have developed in the last few decades. This review summarizes the sources and basic chemical behaviours of these trace elements in the soil system and their contamination status, uptake, translocation, and accumulation mechanisms in paddy soil-rice systems in major rice-growing countries. Several human health threats are significantly associated with these toxic and potentially toxic metals not only due to their presence in the environment (i.e., the soil, water, and air) but also due to the uptake and translocation of these metals via different transporters. Elevated concentrations of these metals are toxic to plants, animals, and even humans that consume them regularly, and the uniform deposition of metals causes a severe risk of bioaccumulation. Furthermore, the contamination of rice in the global rice trade makes this a critical problem of worldwide concern. Therefore, the global consumption of contaminated rice causes severe human health effects that require rapid action. Finally, this review also summarizes the available management/remediation measures and future research directions for addressing this critical issue.

Effect of bioturbation on contaminated sediment deposited over remediated sediment.

A challenge to all sediment remediation technologies is the continued influx of contaminants from uncontrolled sources following remediation. However, contaminants deposited on sediments remediated with chemically active sequestering agents may be affected by the sequestering agents resulting in reduced impacts. We deposited sediment contaminated with As, Cd, Cu, Ni, Pb, and Zn over clean sediment capped with the sequestering agent, apatite, and clean uncapped sediment in laboratory mesocosms to simulate the recontamination of remediated sediment by influxes of particle-bound contaminants. Cap effectiveness was assessed in the presence and absence of the bioturbating organism Corbicula fluminea based on metal fluxes to sediment pore water and surface water, the distribution of mobile contaminants in sediment and surface water measured by Diffusive Gradients in Thin Films, and contaminant bioaccumulation by Lumbriculus variegatus. The metal sequestration capacity of apatite caps was unaffected or improved by bioturbation for all elements except As. Effects with uncapped sediment were metal specific including reductions in the bioavailable pool for Ni, Cd, and to a lesser extent, Pb, increases in the bioavailable pool for As and Cu, and little effect for Zn. It is likely that the reductions observed for some metals in uncapped, clean sediment were the result of burial and dilution of contaminated sediment combined with chemical processes such as sequestration by minerals and other compounds. These results indicate that apatite caps can control recontamination by metals regardless of bioturbation but point to the complexity of sediment recontamination and the need for further study of this problem.

Simultaneous removal of cationic and anionic heavy metal contaminants from electroplating effluent by hydrotalcite adsorbent with disulfide (S2-) intercalation.

Hydrotalcite materials are generally utilized for anionic pollutants due to its interlayered anion exchange ability. Their potentiality for cationic contaminants is rarely explored. In this study, disulfide (S2-) intercalated LDH material demonstrated capability to remove both heavy metal cations and oxyanions simultaneously from water. The S2- intercalation of LDH significantly improved its adsorption capability towards both heavy metal cations (Co2+ and Ni2+) and oxyanion (CrO42-). The adsorption amount of S-LDH towards Co2+ and Ni2+ reached 88.6mg/g and 76.2mg/g, which are 405% and 281% higher than that of pristine LDH. For CrO42- removal, the adsorption amount reached 34.7mg/g, 402% higher than that of pristine LDH. The cations capture mechanism mainly depends on the novel layer sheet cation substitution mechanism based on irreversible precipitation and the generation of metal sulfide precipitates. Meanwhile, the interlayered S2- can be easily replaced by CrO42- to realize the simultaneous removal of both heavy metal cations and oxyanions. In the fixed-bed column experiments, 448 bed volume (BV) (672 mL) of simulating electroplating wastewater can be efficiently treated by yielding only 1 BV(15 mL) of chemical sludge, which is practically acceptable. This work provided a highly practical adsorption technology based on the S2- modification hydrotalcite material for the purification of heavy metal ions contaminated wastewater.

Ecological risk assessment of metals in small craft harbour sediments in Nova Scotia, Canada.

Ecological risk assessment of metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in surface sediments from 31 small craft harbours (SCHs) in Nova Scotia, Canada was conducted using multiple risk assessment approaches. Approaches used were contamination factor, pollution load index, geoaccumulation index, potential ecological risk factor for individual metals, comprehensive potential ecological risk index, mean probable effect level quotient and mean effects range median quotient. Results indicated most SCHs exhibited low ecological risk from sediment metal concentrations, except for two harbours. Metal contamination was highest in Canso Harbour, followed by Clarks Harbour. SCH sediments were only slightly contaminated with low probability of pollution according to mean probable effect level and mean effects range median quotients. However, pollution load and geoaccumulation indexes indicated Cd and Hg had the highest metal contamination across SCH sediments. Cadmium and Hg had the highest potential ecological risk, respectively compared to other metals.