Effects of waterborne Pb/Cu mixture on Chinese toad, Bufo gargarizans tadpoles: morphological, histological, and intestinal microbiota assessment.

The impact of copper exposure on Chinese toad (Bufo gargarizans) tadpoles was investigated in this study. First, the 96h LC50 value of copper was 8.697 μM, by means of a 4 d acute toxicity test. Second, we studied the chronic effects of copper on B. gargarizans tadpoles at control, 0.025, 0.1 and 1.0 μM concentration. Survival, body length, body weight, developmental stage, incidence of metamorphic climax, and size at metamorphic climax were determined. In tadpoles developed to metamorphic climax (stage G42), liver and thyroid gland were assessed histologically. Copper at 0.1 and 1.0 μM could inhibit tadpole growth and prolong tadpole metamorphic progress relative to controls. Tadpole size (total length and weight) at stage G42 is also affected in the 0.1 and 1.0 μM treatments. In addition, histological examinations have revealed that 1.0 μM copper could cause significant pathological changes and hepatocytes degeneration in liver. Furthermore, histomorphological measurements indicated that copper at 0.1 and 1.0 μM reduced thyroid gland size, diameter and number of follicle. In conclusion, our study suggests that Cu could damage the liver and thyroid gland, so growth and metamorphosis of B. gargarizans tadpoles were inhibited resulted of disrupting liver metabolism and THs homeostasis.

Bone health is closely related to national life. The pollution of heavy metals in China is extremely severe, and a variety of heavy metals in aquatic environment would have an impact on health risks for bone. At present, studies involving the relationship between heavy metals in aquatic environment and bone health have been limited. Therefore, in this study, the relationship between heavy metals and bone health based on the possible pathogenic mechanism was explored. Meanwhile, the detection technologies for heavy metals applied in aquatic environment and clinical trials were discussed to provide theoretical support for the monitoring and governance of the heavy metal pollution, and supply the prevention and treatment of bone diseases based from heavy metals for information purpose.

As the most important graphene derivate, graphene oxide (GO) is a high-efficient adsorbent for the removal of heavy metals in aquatic environment due to its abundant oxygen functional groups, enormous specific area, and strong hydrophilia. However, there are some drawbacks, such as easily aggregating and difficult separation, restricting the environmental application of GO. GO is not a suitable adsorbent by itself. Hence, some materials were used to synthesize GO composites, and GO composites are commonly characterized by high adsorption capacity to overcome the above drawbacks. This review discusses five main GO composites-GO-chitosan, GO-alginate, GO-SiO2, NZVI-rGO, and magnetic GO composites-and summarizes the synthesis methods of GO composites and its application for the removal of heavy metals in aquatic environments. The influencing factors, adsorption capacities, and mechanisms related to the removal of heavy metals by GO composites are highlighted. Lastly, the application potentials and challenges of GO composites for aqueous environmental remediation are discussed. Graphical abstract.

Microalgae account for most of the biologically sequestered trace metals in aquatic environments. Their ability to adsorb and metabolize trace metals is associated with their large surface:volume ratios, the presence of high-affinity, metal-binding groups on their cell surfaces, and efficient metal uptake and storage systems. Microalgae may bind up to 10% of their biomass as metals. In addition to essential trace metals required for metabolism, microalgae can efficiently sequester toxic heavy metals. Toxic heavy metals often compete with essential trace metals for binding to and uptake into cells. Recently, transgenic approaches have been developed to further enhance the heavy metal specificity and binding capacity of microalgae with the objective of using these microalgae for the treatment of heavy metal contaminated wastewaters and sediments. These transgenic strategies have included the over expression of enzymes whose metabolic products ameliorate the effects of heavy metal-induced stress, and the expression of high-affinity, heavy metal binding proteins on the surface and in the cytoplasm of transgenic cells. The most effective strategies have substantially reduced the toxicity of heavy metals allowing transgenic cells to grow at wild-type rates in the presence of lethal concentrations of heavy metals. In addition, the metal binding capacity of transgenic algae has been increased five-fold relative to wild-type cells. Recently, fluorescent heavy metal biosensors have been developed for expression in transgenic Chlamydomonas. These fluorescent biosensor strains can be used for the detection and quantification of bioavailable heavy metals in aquatic environments. The use of transgenic microalgae to monitor and remediate heavy metals in aquatic environments is not without risk, however. Strategies to prevent the release of live microalgae having enhanced metal binding properties are described.

The long biological half lives, non-bio-degradable nature and accumulative properties of trace and toxic heavy metals in aquatic environment has attracted great attention of environmental scientists and ecologist in recent years. Therefore, in the present investigation, we have selected Kalwa Bridge and Balkum sites along the Thane Creek to investigate pollution load due to trace and toxic heavy metals in aquatic environment. The distribution coefficient (Kd) values of metals were calculated for soil and sediment samples. It was observed that the Kd values were higher for sediment as compared to that obtained for soil samples. Also the Kd values of metals for soil and sediments were found to be lower in rainy and maximum in summer seasons.

Microplastics as a vehicle of heavy metals in aquatic environments: A review of adsorption factors, mechanisms, and biological effects

The mobility of heavy metals in aquatic environments, impacted by discharges from mining waste, is one of the major processes causing metal pollution mainly by arsenic (As), cadmium (Cd), lead (Pb), zinc (Zn) and iron (Fe), which could be risky for biota and human health. The heavy metals contained in mining waste constituted by large amounts of sulfides can reach the aquatic compartments by acid mine drainage and runoff and eventually become deposited in sediments and associated with colloidal material, being this one of the main reservoirs and ways of transport. However, the mobility of heavy metal is influenced by their specific chemical properties and undergo several physicochemical phenomena as sorption, oxidation–reduction, hydrolysis and this can be influenced by water flow, the size and composition of geological material. Hence, this work aims to review the processes and mechanism involved in the fate and transport of heavy metals from mining-waste to aquatic compartments and the methods used for identification of the specific chemical species associated with their mobility and ecological risk.

Microplastics (MPs) migrate by adsorbing heavy metals in aquatic environments and act as their carriers. However, the aging mechanisms of MPs in the environment and the interactions between MPs and heavy metals in aquatic environments require further study. In this study, two kinds of materials, polyamide (PA) and polylactic acid (PLA) were used as target MPs, and the effects of UV irradiation on the physical and chemical properties of the MPs and the adsorption behavior of Cu(II) were investigated. The results showed that after UV irradiation, pits, folds and pores appeared on the surface of aged MPs, the specific surface area (SSA) increased, the content of oxygen-containing functional groups increased, and the crystallinity decreased. These changes enhanced the adsorption capacity of aged MPs for Cu(II) pollutants. The adsorption behavior of the PA and PLA MPs for Cu(II) conformed to the pseudo-second-order model and Langmuir isotherm model, indicating that the monolayer chemical adsorption was dominant. The maximum amounts of aged PA and PLA reached 1.415 and 1.398 mg/g, respectively, which were 1.59 and 1.76 times of virgin MPs, respectively. The effects of pH and salinity on the adsorption of Cu(II) by the MPs were significant. Moreover, factors such as pH, salinity and dosage had significant effects on the adsorption of Cu(II) by MPs. Oxidative complexation between the oxygen-containing groups of the MPs and Cu(II) is an important adsorption mechanism. These findings reveal that the UV irradiation aging of MPs can enhance the adsorption of Cu(II) and increase their role as pollutant carriers, which is crucial for assessing the ecological risk of MPs and heavy metals coexisting in aquatic environments.

The increasing levels of toxic heavy metals in aquatic environments pose significant threats to ecosystems, biodiversity, and human health. The Diva-Motagaon Creek, located in Thane District, Mumbai, is one such site under investigation in this study, which aims to analyze the concentrations of various toxic heavy metals in sediment samples. As a reliable and accurate method, Atomic Absorption Spectroscopy (AAS) was used to study the effects of long-term pollution load and the buildup of heavy metal contaminants in this estuarine ecosystem.Sediment samples were collected from four strategically selected stations along the Diva-Motagaon Creek, covering four seasons from January 2023 to December 2023. The four seasons—pre-monsoon, monsoon, post-monsoon, and summer—were chosen to capture the seasonal variations in pollution levels, as aquatic environments are highly dynamic and pollutant concentrations can fluctuate due to factors like rainfall, industrial runoff, and human activities. The collected samples were analysed for the presence of chromium (Cr), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn), which are commonly found in environmental pollution, particularly industrial effluents, urban runoff, and agricultural practices.The analysis revealed notable variations in the concentrations of these heavy metals across different seasons and geographical locations within the creek. Zinc was found to be the most abundant heavy metal, followed by iron, copper, lead, and chromium, in that order. The fact that the concentration changes with the seasons suggests that the metal levels are affected by things like industrial discharges, monsoon runoff, and human activities in the area, such as religious events like immersing Ganapati idols. Among the studied metals, zinc showed the highest concentrations, which may be attributed to local industrial activities and sewage discharge into the creek.The results of this study demonstrate that heavy metal pollution in Diva-Motagaon Creek is influenced by a combination of natural processes and anthropogenic activities. High levels of metals like lead, copper, and chromium are especially bad for the environment because they can build up in aquatic organisms and make fish, invertebrates, and other marine life sick. Zinc, while essential in trace amounts for aquatic organisms, can become toxic in higher concentrations, disrupting the health of aquatic ecosystems.The study’s findings are crucial for environmental management and policy development, as they offer a scientific basis for monitoring and controlling pollution in the Diva-Motagaon Creek. The findings indicate the need for immediate action to reduce the heavy metal concentrations in the creek, particularly through effective waste management practices, industrial regulation, and pollution control strategies. The fishing industry is prevalent in the area, and the study's results emphasise the importance of protecting aquatic resources to ensure the safety of local livelihoods and the sustainability of the marine ecosystem.This study sets a baseline for the current level of pollution, which is very important for future research and actions that will be taken to help the environment and lessen the harmful effects of heavy metal pollution. The results can inform the rational planning of pollution control strategies and support efforts to restore and protect the health of Diva-Motagaon Creek. The results also show how important it is for scientists to keep an eye on things all the time to learn more about how heavy metal toxicity changes over time and how it affects marine and estuarine environments over time.The increasing levels of toxic heavy metals in aquatic environments threaten ecosystems, biodiversity, and human health. Atomic Absorption Spectroscopy (AAS) is used to look at heavy metal contamination in sediment samples from Diva-Motagaon Creek in Thane District, Mumbai. In 2023, samples were taken from four locations during four seasons: pre-monsoon, monsoon, post-monsoon, and summer. The goal was to see how the concentrations of chromium (Cr), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) changed with the seasons.Results revealed significant seasonal and spatial variations, with zinc being the most abundant metal, followed by iron, copper, lead, and chromium. High metal levels, especially during and after the monsoon season, are a sign of pollution from factories, urban runoff, and human activities like immersing Ganapati idols. While zinc is essential in trace amounts, its high concentrations, along with toxic levels of lead, copper, and chromium, pose ecological risks through bioaccumulation in aquatic organisms.These findings highlight the urgent need for pollution control measures, including industrial regulation, improved waste management, and continuous environmental monitoring. Given the creek’s significance to local fisheries, mitigating heavy metal contamination is crucial for preserving marine ecosystems and safeguarding livelihoods. This study establishes a baseline for future research and policy interventions to restore and protect Diva-Motagaon Creek.

Heavy metals are among the most persistent and hazardous pollutants affecting aquatic ecosystems worldwide. Their presence in water bodies is influenced by both natural processes and anthropogenic activities such as industrial discharge, agricultural runoff, mining, and urbanization. Seasonal variations significantly affect the concentration, distribution, and chemical behavior of heavy metals in aquatic environments by altering hydrological conditions, physicochemical parameters, and biological activity. These seasonal dynamics directly influence the bioavailability of metals and their subsequent uptake by aquatic organisms, particularly fish. Fish accumulate heavy metals in various tissues through direct absorption from water and through dietary intake, leading to seasonal variations in bioaccumulation patterns. Elevated temperatures and increased metabolic activity during warmer seasons often enhance metal uptake, while colder seasons may reduce accumulation rates. Seasonal bioaccumulation of heavy metals poses serious ecological risks to aquatic life and potential health hazards to humans through fish consumption. This theoretical review highlights the seasonal dynamics of heavy metals in aquatic environments and their bioaccumulation in fish tissues, emphasizing the importance of seasonal monitoring for environmental management and public health protection.

Water-sediment interactions and mobility of heavy metals in aquatic environments

Gut microbiota perturbations during larval stages in Bufo gargarizans tadpoles after Cu exposure with or without the presence of Pb

Cu and Zn adsorption onto non-residual and residual components in the natural surface coatings samples (NSCSs) in the Songhua River, China

The effect of fluorine exposure on morphological indicators and intestinal microbial community in Bufo gargarizans tadpoles

Gut microbiota-bile acid crosstalk contributes to intestinal damage after nitrate exposure in Bufo gargarizans tadpoles