Archives of Environmental Contamination and Toxicology最新文献

The oceans become increasingly contaminated as a result of global industrial production and consumer behaviour, and this affects wildlife in areas far removed from sources of pollution. Migratory seabirds such as storm-petrels may forage in areas with different contaminant levels throughout the annual cycle and may show a carry-over of mercury from the winter quarters to the breeding sites. In this study, we compared mercury levels among seven species of storm-petrels breeding on the Antarctic South Shetlands and subantarctic Kerguelen Islands, in temperate waters of the Chatham Islands, New Zealand, and in temperate waters of the Pacific off Mexico. We tested for differences in the level of contamination associated with breeding and inter-breeding distribution and trophic position. We collected inert body feathers and metabolically active blood samples in ten colonies, reflecting long-term (feathers) and short-term (blood) exposures during different periods ranging from early non-breeding (moult) to late breeding. Feathers represent mercury accumulated over the annual cycle between two successive moults. Mercury concentrations in feathers ranged over more than an order of magnitude among species, being lowest in subantarctic Grey-backed Storm-petrels (0.5 μg g⁻¹ dw) and highest in subtropical Leach’s Storm-petrels (7.6 μg g⁻¹ dw, i.e. posing a moderate toxicological risk). Among Antarctic Storm-petrels, Black-bellied Storm-petrels had threefold higher values than Wilson’s Storm-petrels, and in both species, birds from the South Shetlands (Antarctica) had threefold higher values than birds from Kerguelen (subantarctic Indian Ocean). Blood represents mercury taken up over several weeks, and showed similar trends, being lowest in Grey-backed Storm-petrels from Kerguelen (0.5 μg g⁻¹ dw) and highest in Leach’s Storm-petrels (3.6 μg g⁻¹ dw). Among Antarctic storm-petrels, species differences in the blood samples were similar to those in feathers, but site differences were less consistent. Over the breeding season, mercury decreased in blood samples of Antarctic Wilson’s Storm-petrels, but did not change in Wilson’s Storm-petrels from Kerguelen or in Antarctic Black-bellied Storm-petrels. In summary, we found that mercury concentrations in storm-petrels varied due to the distribution of species and differences in prey choice. Depending on prey choices, Antarctic storm-petrels can have similar mercury concentrations as temperate species. The lowest contamination was observed in subantarctic species and populations. The study shows how seabirds, which accumulate dietary pollutants in their tissues in the breeding and non-breeding seasons, can be used to survey marine pollution. Storm-petrels with their wide distributions and relatively low trophic levels may be especially useful, but more detailed knowledge on their prey choice and distributions is needed.

For the first time, a global regression quantitative structure–toxicity/activity relationship (QSTR/QSAR) model was developed for the toxicity of a large data set including 1236 chemicals towards Vibrio fischeri, by using random forest (RF) regression algorithm. The optimal RF model with RF parameters of mtry = 3, ntree = 150 and nodesize = 5 was based on 13 molecular descriptors. It can achieve accurate prediction for the toxicity of 99.1% of 1236 chemicals, and yield coefficients of determination R² of 0.893 for 930 log(Mw/IBC50) in the training set, 0.723 for 306 log(Mw/IBC50) in the test se, and 0.865 for 1236 toxicity log(Mw/IBC50) in the total set. The optimal RF global model proposed in this work is comparable to other published local QSTR models on small datasets of the toxicity to Vibrio fischeri.

Mercury is a global contaminant found in the Amazon; it can be biomagnified in the aquatic trophic chain. The use of piscivorous birds for biomonitoring of mercury contamination is increasing, mainly due to the non-mobility of mercury in bird feathers. We examined the concentrations of total mercury and methylmercury in different tissues of the green kingfisher, Chloroceryle americana collected from the Teles Pires and Juruena Rivers in the southern Brazilian Amazon. We also evaluated total mercury in small Characidae fish (potential C. americana food) in the same areas. The results indicate contamination of the birds with high concentrations, on average two-times higher in the green kingfishers from the Teles Pires River compared to the Juruena River; the same results were found for the fish specimens. Fifty-eight per cent of the feather samples from the Juruena River and 90% from the Teles Pires River had total mercury concentrations above 5 µg/g, a level previously associated with adverse effects related to bird breeding. The methylmercury concentration was lowest in the liver, followed by feathers and highest in muscle. Although Juruena River bird feathers had a lower total mercury concentration, > 96% of the total mercury was methylmercury, the highest amount for specimens from both rivers. Although the concentration of Hg in the muscle of the green kingfisher is higher when compared to the feather and liver, the non-invasive monitoring through analysis of samples of feathers is an efficient biomonitoring tool for evaluation of mercury contamination in tropical birds.

Mangroves constitute a unique and important type of coastal wetlands in tropical and subtropical zones worldwide. The abundance of microplastics (MPs) in the mangrove sediments is poorly understood. This study aimed to quantify the role of mangrove root systems in effectively entrapping MPs in the mangrove areas of Tuticorin and Punnakayal Estuary. It investigated the abundance, characteristics, and weathering patterns of MPs in different mangrove sediments. Sediment samples were collected from ten mangrove sites and two control sites without mangroves. Microplastics were extracted from mangrove sediments by density separation method, and then counted and categorized according to their shape, size, and colour. Microplastics were identified in all ten sampling sites. Punnakayal Estuary has a greater MPs concentration (27 ± 2.65 items/kg dw) than Tuticorin (9.33 ± 2.52 items/kg dw). Also, microplastic concentrations are higher in the mangrove sites than in the control sites. Most MPs are fibres with size ranges of 1–2 mm and 2–3 mm dominating. Blue and transparent are the predominant colours. Four polymers were identified, namely polyethylene (PE), polypropylene (PP), polymethyl methaacrylate (PMMA), and polyurethane (PUR). The degree of weathering was confirmed by carbonyl index and the values vary between 0.28 and 1.25 for PE and 0.6 and 1.05 for PP.

Mercury contamination is a global issue because mercury concentrations in aquatic systems are influenced by both natural and anthropogenic pathways. Here, liver and muscle total mercury (THg) concentrations in black crappie Pomoxis nigromaculatus from three boreal lakes in southeastern Manitoba, Canada, were related to age, morphology and physiological traits to better understand the dynamics of mercury accumulation in an introduced generalist fish species. These THg concentrations were then compared to black crappie mercury concentrations in other Canadian water bodies and to mercury concentrations in other freshwater fishes in southeastern Manitoba. Age and size had strong positive correlations (P < 0.001, r ≥ 0.60) with muscle mercury concentrations. No evidence of acute point source contamination or physiological impairment in black crappie was found in the study area. Analysis of liver THg revealed the possible impacts of seasonal and ontogenetic differences in diet on exposure. Furthermore, THg analysis of liver and muscle tissue showed how generalist foraging may curb the progressively greater mercury exposure and resultant physiological consequences expected from ontogenetic diet shifts in black crappie. Although there appeared to be temporally varied levels of mercury exposure (i.e., liver THg) by sex, there was no sex effect observed in long-term mercury accumulation in the muscle. Black crappie bioaccumulated less mercury at age than primary piscivore species in the region. These results will help foster a better understanding of mercury biomagnification within a region impacted by legacy mercury.

Cassia fistula seed-derived coagulant has been reported to exhibit high coagulating–flocculating activity, environmental friendliness, and cost-effectiveness for the wastewater treatment, especially of textile wastewater. For heavy metal removal, however, research focusing on evaluating the feasibility of this material is still limited. Therefore, this study reports jar-test experiments in which the Zn²⁺ and Ni²⁺ removal efficiency of C. fistula coagulant was assessed. Moreover, a comparison of coagulation performance using a conventional chemical coagulant and the natural coagulant was performed. Characterization of the C. fistula seed-derived coagulant revealed the presence of important functional groups and fibrous networks with rough surfaces. A bench-scale study indicated that the coagulation performance of the two coagulants depends strongly on the initial concentration of metal ions, pH level, and coagulant dosage. The C. fistula seed-derived coagulant was found to possess higher removal efficiency than polyaluminum chloride. This natural coagulant removed over 80% of metal ions at the optimal conditions of pH 5.0, a metal ion concentration of 25 ppm, and a dosage of 0.8 and 1.6 g/L for Zn²⁺ and Ni²⁺, respectively. This study shows that C. fistula seed-derived coagulant is a potential alternative to chemical coagulants and could be developed to provide an environmentally friendly, economical, and efficient wastewater treatment.

The Red River is one of the largest rivers that plays an important role in the economic development of North Vietnam. There are many radionuclides bearing rare earth, uranium ore mines, mining industrial zones and magma intrusive formations along this river. The contamination and accumulation of radionuclides could exist at high concentration in surface sediments of this river. Thus, the present investigation aims to study the activity concentrations of ²²⁶Ra, ²³²Th (²²⁸Ra), ⁴⁰K, and ¹³⁷Cs in Red River surface sediments. Thirty sediment samples were collected, and their activity concentration was calculated using high-purity germanium gamma-ray detector. The observed results ranged from 51.0 ± 2.1 to 73.6 ± 3.7 for ²²⁶Ra, 71.4 ± 3.6 to 103 ± 5.2 for ²³²Th, 507 ± 24.0 to 846 ± 42.3 for ⁴⁰K, and ND (not detected) to 1.33 ± 0.06 Bq/kg for ¹³⁷Cs, respectively. In general, the natural radionuclides concentration of ²²⁶Ra, ²³²Th (²²⁸Ra), and ⁴⁰K is higher than the average world average values. This indicated that the natural radionuclides could contribute from similar and principal sources surrounding the upstream of Lao Cai where distributed uranium ore mines, radionuclide bearing rare earth mines, mining industrial zones and intrusive formations. Regarding the radiological hazard assessment, results of the indices computed such as absorbed gamma dose rate (D), the excess lifetime cancer risk (ELCR), and the annual effective dose equivalent (AEDE) were nearly two times higher than world average values.

The elevated use of salt as a de-icing agent on roads in Canada is causing an increase in the chloride concentration of freshwater ecosystems. Freshwater Unionid mussels are a group of organisms that are sensitive to increases in chloride levels. Unionids have greater diversity in North America than anywhere else on Earth, but they are also one of the most imperiled groups of organisms. This underscores the importance of understanding the effect that increasing salt exposure has on these threatened species. There are more data on the acute toxicity of chloride to Unionids than on chronic toxicity. This study investigated the effect of chronic sodium chloride exposure on the survival and filtering activity of two Unionid species (Eurynia dilatata, and Lasmigona costata) and assessed the effect on the metabolome in L. costata hemolymph. The concentration causing mortality after 28 days of exposure was similar for E. dilatata (1893 mg Cl⁻/L) and L. costata (1903 mg Cl⁻/L). Significant changes in the metabolome of the L. costata hemolymph were observed for mussels exposed to non-lethal concentrations. For example, several phosphatidylethanolamines, several hydroxyeicosatetraenoic acids, pyropheophorbide-a, and alpha-linolenic acid were significantly upregulated in the hemolymph of mussels exposed to 1000 mg Cl⁻/L for 28 days. While no mortality occurred in the treatment, elevated metabolites in the hemolymph are an indicator of stress.

The traditional application for quantitative structure–property/activity relationships (QSPRs/QSARs) in the fields of thermodynamics, toxicology or drug design is predicting the impact of molecular features using data on the measurable characteristics of substances. However, it is often necessary to evaluate the influence of various exposure conditions and environmental factors, besides the molecular structure. Different enzyme-driven processes lead to the accumulation of metal ions by the worms. Heavy metals are sequestered in these organisms without being released back into the soil. In this study, we propose a novel approach for modeling the absorption of heavy metals, such as mercury and cobalt by worms. The models are based on optimal descriptors calculated for the so-called quasi-SMILES, which incorporate strings of codes reflecting experimental conditions. We modeled the impact on the levels of proteins, hydrocarbons, and lipids in an earthworm's body caused by different combinations of concentrations of heavy metals and exposure time observed over two months of exposure with a measurement interval of 15 days.

Ho Chi Minh City (HCMC) is one of the main socioeconomic and financial centers of Vietnam. The city also faces serious air pollution. However, the city polluted with benzene, toluene, ethylbenzene, and xylene (BTEX) has rarely been studied. We used positive matrix factorization (PMF) to analyze BTEX concentrations measured at two sampling locations to identify the main sources of BTEX in HCMC. The locations represented residential area (i.e., To Hien Thanh) and industrial area (i.e., Tan Binh Industrial Park). At the To Hien Thanh location, the average concentrations of benzene, ethylbenzene, toluene, and xylene were 6.9, 14.4, 4.9, and 12.7 µg/m³, respectively. At the Tan Binh location, the average concentrations of benzene, ethylbenzene, toluene, and xylene were 9.8, 22.6, 2.4, and 9.2 µg/m³, respectively. The results showed that PMF was a reliable model for source apportionment in HCMC. Traffic activities were the main sources of BTEX. Besides, industrial activities also contributed to BTEX emissions, especially the location near the industrial park. The majority of BTEXs at the To Hien Thanh sampling site come from traffic sources accounting for 56.2%. Activities from traffic and photochemical reactions (42.7%) and industrial sources (40.5%) were the main sources affecting BTEX emissions at the sampling site of Tan Binh Industrial Park. This study can be used as a reference for mitigation solutions to reduce the BTEX emission in HCMC.