Copper (Cu) is a vital micronutrient required for numerous fundamental biological processes, but excessive Cu poses potential detrimental effects on public and ecosystem health. However, the molecular details linking endoplasmic reticulum (ER) stress and apoptosis in duck renal tubular epithelial cells have not been fully elucidated. In this study, duck renal tubular epithelial cells exposed to Cu sulfate (CuSO₄) (0, 100 and 200 μM) and a PERK inhibitor (GSK2606414, GSK, 1 μM) for 12 h were used to investigate the crosstalk between ER stress and apoptosis under Cu exposure. Cell and ER morphological and functional characteristics, intracellular calcium (Ca²⁺) levels, apoptotic rates, ER stress and apoptosis-related mRNA and protein levels were examined. The results showed that excessive Cu could cause ER expansion and swelling, increase the expression levels of ER stress-associated genes (PERK, eIF2α, ATF4 and CHOP) and proteins (p-PERK and CHOP), induce intracellular Ca²⁺ overload, upregulate the expression levels of apoptosis-associated genes (Bax, Bak1, Caspase9 and Caspase3) and the cleaved-Caspase3 protein, downregulate Bcl-xl and Bcl2 mRNA levels and trigger apoptosis. PERK inhibitor treatment could ameliorate the above changed factors caused by Cu. In conclusion, these findings indicate that excessive Cu could trigger ER stress via activation of the PERK/ATF4/CHOP signaling pathway and that ER stress might aggravate Cu-induced apoptosis in duck renal tubular epithelial cells.

Metal pollution is a growing concern that affects the health of humans and animals globally. Copper is an essential insect micronutrient required for respiration, pigmentation and oxidative stress protection but can also act as a potentially toxic trace element. While several studies have focused on the negative fitness effects of copper on the aquatic larvae of mosquitoes, the effects of larval copper exposure on adult mosquito fitness (i.e., survival and fecundity) and their ability to transmit parasites (i.e., vector competence) remains unclear. Here, using a well-studied model vector-parasite system, the mosquito Aedes aegypti and parasite Dirofilaria immitis, we show that sublethal copper exposure in larval mosquitoes alters adult female fecundity and vector competence. Specifically, mosquitoes exposed to copper had a hormetic fecundity response and mosquitoes exposed to 600 μg/L of copper had significantly fewer infective parasite larvae than control mosquitoes not exposed to copper. Thus, exposure of mosquito larvae to copper levels far below EPA-mandated safe drinking water limits (1300 μg/L) can impact vector-borne disease dynamics not only by reducing mosquito abundance (through increased larval mortality), but also by reducing parasite transmission risk. Our results also demonstrated that larval copper is retained through metamorphosis to adulthood in mosquitoes, indicating that these insects could transfer copper from aquatic to terrestrial foodwebs, especially in urban areas where they are abundant. To our knowledge this is the first study to directly link metal exposure with vector competence (i.e., ability to transmit parasites) in any vector-parasite system. Additionally, it also demonstrates unequivocally that mosquitoes can transfer contaminants from aquatic to terrestrial ecosystems. These results have broad implications for public health because they directly linking contaminants and vector-borne disease dynamics, as well as linking mosquitoes and contaminant dynamics.

In this report, we investigated the accumulation of heavy metals in the lizard Microlophus atacamensis, in three coastal areas of the Atacama Desert, northern Chile. We captured reptiles in a non-intervened area (Parque Nacional Pan de Azúcar, PAZ), an area of mining impact (Caleta Palitos, PAL) and an active industrial zone (Puerto de Caldera, CAL). Our methods included a non-lethal sampling of reptiles’ tails obtained by autotomy and a few sacrificed animals to perform a stomach contents analysis. The concentrations of lead, copper, nickel, zinc and cadmium were measured by atomic absorption spectrophotometry in both soil and prey and compared to those recorded in the lizards’ tails. Data obtained from lizard tails captured in PAL showed significantly high concentrations of Pb, Cu, Ni, and Zn compared to the other two sites PAZ and CAL. We did not find statistically significant differences among PAZ, PAL and CAL soils, probably due to the similar geological composition of the sites. However, the regional background values for Pb indicate contamination or at least metal enrichment in soils of the three sites, for Cu the global background values indicate contamination for the three sites, and for Cd both the regional and global backgroud values show high values. The analysis of the stomach content showed differences in the food sources of the lizards among the sites studied. The concentration of heavy metal in lizard tissues versus prey delivered values of the Trophic Transfer Factor higher than one (1), suggesting that food may be a primary source of metals in the tissues of M. atacamensis. Calculations of the Bioaccumulation Factor (BAF) and the Ecological Risk (IR) resulted in values higher than one (1) indicating the relevance of this process in the sites studied. In this article, we report relationships between environmental contaminants, mainly putative preys, and concentrations found in lizard tails, which is more substantial in areas with historical heavy metal contamination such as PAL where the non-lethal technique developed in this research suggests a process of metal bioaccumulation in M. atacamensis.

Fungicide application for controlling fungal diseases can increase copper (Cu) accumulation in soil. More urgently, Cu released from fungicides can associate with soil clay and favour the mutual aggregation of Cu and soil clay, thereby potentially intensifying the accumulation of Cu. We investigated the effects of Cu salt and six common Cu-based fungicides on colloidal dynamics of a clay fraction from citrus cultivated soil. Batch experiments were carried out to provide the loading capacity of the clay fraction for Cu. The colloidal dynamic experiments were performed over a pH range from 3 to 8 following a test tube method, while surface charge, the key electrochemical factor of the solid-liquid interface, was quantified by a particle charge detector. It was found that all the studied fungicides, via releasing Cu²⁺, acted to effectively favour clay aggregation. The dissolved organic matter obtained from the dissolution of polymers in fungicides can theoretically stimulate clay dispersion. However, their effects were obscured due to the overwhelming effect of Cu²⁺. Therefore, Cu²⁺ appears as the most active agent in the fungicides that intensifies clay aggregation. These findings imply that the intensive application of fungicides for plant protection purposes can inadvertently reduce clay mobility, favour the co-aggregation of clay and fungicides, and hence potentially exacerbate the contamination of the citrus soil.

Antarctic melt streams are important ecosystems that increasingly face contaminant pressures from anthropogenic sources. Metal contaminants are often reported in the limno-terrestrial environment but their speciation is not well characterised, making environmental risk assessments difficult. This paper characterises labile metal concentrations in five melt streams and three shallow lakes around the Casey and Wilkes research stations in East Antarctica using chemical extracts and field deployments of diffusive gradients in thin-film (DGT) samplers. An acute toxicity test with field-collected Ceratadon purpeus and taxonomic identification of diatoms in melt streams were used to infer environmental risk. Copper and zinc were the most labile metals in the melt streams. DGT-labile copper concentrations were up to 3 μg Cu L⁻¹ in melt-stream waters but not labile below the sediment-water interface. DGT-labile zinc concentrations were consistent above and below the sediment-water interface at concentrations up to 14 μg Zn L⁻¹ in four streams, but one stream showed evidence of zinc mineralisation in the sediment with a flux to overlying and pore waters attributed to the reductive dissolution of iron and manganese oxides. Other metals, such as chromium, nickel, and lead were acid-extractable from the sediments, but not labile in pore waters or overlying waters. All streams had unique compositions of freshwater diatoms, but one had particularly reduced diversity and richness, which correlated to metal contamination and sediment physico-chemical properties such as a finer particle size. In laboratory bioassays with field-collected samples of the Antarctic moss C. purpeus, there was no change in photosynthetic efficiency following 28-d exposure to 700, 900, 1060, or 530 μg L⁻¹ of cadmium, copper, nickel, and zinc, respectively. This study shows that microorganisms such as diatoms may be at greater risk from contaminants than mosses, and highlights the importance of geochemical factors controlling metal lability.

Metal release into the environment from anthropogenic activities may endanger ecosystems and human health. However, identifying and quantifying anthropogenic metal bioaccumulation in organisms remain a challenging task. In this work, we assess Cu isotopes in Pacific oysters (C. gigas) as a new tool for monitoring anthropogenic Cu bioaccumulation into marine environments. Arcachon Bay was taken as a natural laboratory due to its increasing contamination by Cu, and its relevance as a prominent shellfish production area. Here, we transplanted 18-month old oysters reared in an oceanic neighbor area into two Arcachon Bay mariculture sites under different exposure levels to continental Cu inputs. At the end of their 12-month long transplantation period, the oysters’ Cu body burdens had increased, and was shifted toward more positive δ⁶⁵Cu values. The gradient of Cu isotope compositions observed for oysters sampling stations was consistent with relative geographic distance and exposure intensities to unknown continental Cu sources. A binary isotope mixing model based on experimental data allowed to estimate the Cu continental fraction bioaccumulated in the transplanted oysters. The positive δ⁶⁵Cu values and high bioaccumulated levels of Cu in transplanted oysters support that continental emissions are dominantly anthropogenic. However, identifying specific pollutant coastal source remained unelucidated mostly due to their broader and overlapping isotope signatures and potential post-depositional Cu isotope fractionation processes. Further investigations on isotope fractionation of Cu-based compounds in an aqueous medium may improve Cu source discrimination. Thus, using Cu as an example, this work combines for the first time a well-known caged bivalve approach with metal stable isotope techniques for monitoring and quantifying the bioaccumulation of anthropogenic metal into marine environments. Also, it states the main challenges to pinpoint specific coastal anthropogenic sources utilizing this approach and provides the perspectives for further studies to overcome them.

The Pearl River Estuary (PRE) is the largest estuary in southern China and under high metal stress. In the present study, we employed an integrated method of transcriptomics and proteomics to investigate the ecotoxicological effects of trace metals on the Hong Kong oyster Crassostrea hongkongensis. Three oyster populations with distinct spatial distributions of metals were sampled, including the Control (Station QA, the lowest metal levels), the High Cd (Station JZ, the highest Cd), and the High Zn–Cu–Cr–Ni (Station LFS, with the highest levels of zinc, copper, chromium, and nickel). Dominant metals in oysters were differentiated by principal component analysis (PCA), and theirgene and protein profiles were studied using RNA-seq and iTRAQ techniques. Of the 2250 proteins identified at both protein and RNA levels, 70 proteins exhibited differential expressions in response to metal stress in oysters from the two contaminated stations. There were 8 proteins altered at both stations, with the potential effects on mitochondria and endoplasmic reticulum by Ag. The genotoxicity, including impaired DNA replication and transcription, was specifically observed in the High Cd oysters with the dominating influence of Cd. The structural components (cytoskeleton and chromosome-associated proteins) were impaired by the over-accumulated Cu, Zn, Cr, and Ni at Station LFS. However, enhanced tRNA biogenesis and exosome activity might help the oysters to alleviate the toxicities resulting from their exposure to these metals. Our study provided comprehensive information on the molecular changes in oysters at both protein and RNA levels in responding to multi-levels of trace metal stress.

Heavy metal contamination has been threatening the health of human beings. To decrease the bio-toxicity of heavy metals, a thiol-functionalized nano-silica (SiO₂-SH) was adopted to remediate the soil contaminated by lead (Pb), cadmium (Cd) and copper (Cu). The remediation effect of SiO₂-SH on contaminated soils was investigated by the uptake of the heavy metals into lettuce and pakchoi in pot experiment. The bio-toxicity of the SiO₂-SH was evaluated, and its immobilization mechanisms were proposed by the fraction distribution of Cd, Pb and Cu. It was found that the SiO₂-SH can significantly reduce the uptake of Cd, Pb, Cu into pakchoi by 92.02%, 68.03%, 76.34% and into lettuce by 89.81%, 43.41%, 5.76%, respectively. The chemical species analyses of Cd, Pb, Cu indicate SiO₂-SH can transform the heavy metal in acid soluble states into reducible fraction and oxidizable fraction, thereby inhibiting the extraction of heavy metals into soil solution. The concentrations of microbial biomass carbon, organic matter, and cation exchange capacity of the soil increased while the soil bulk density decreased after remediation. Those changes demonstrate that SiO₂-SH not only has no bio-toxic impact on the soil environment but also improves the soil environment, which proves the prepared SiO₂-SH is environmental-friendly. The SiO₂-SH could be a promising amendment for heavy metal contaminated soils.

Excessive copper (Cu) in contaminated soil and groundwater has attracted continuous attentions due to the bioaccumulation and durability. In this study, the feasibility of remediation of heavy metal pollution in soil and groundwater was investigated using hydroxyapatite/calcium silicate hydrate (HAP/C–S–H) recovered from phosphorus-rich wastewater in farmland. The results show that the pH has a strong effect on copper removal from Cu-contaminated groundwater but the impact of ion strength on the removal is weak. In general, high pH and low ion strength give better results in copper removal. Kinetic and isotherm data from the study fit well with Pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity of HAP/C–S–H (138 mg/g) was higher than that of C–S–H (90.3 mg/g) when pH value, temperature, and ionic strength were 5, 308 K, and 0.01 M, respectively. Thermodynamics results indicate that Cu removal is a spontaneous and endothermic process. X-ray diffraction (XRD) results show that the mechanism of copper removal involves physical adsorption, chemical precipitation and ion exchange. For the remediation of Cu-contaminated soil, 76.3% of leachable copper was immobilized by HAP/C–S–H after 28 d. Acid soluble Cu, the main contributor to biotoxicity, decreased significantly while reducible and residual Cu increased. After immobilization, the acid neutralization capacity of the soil increased and the dissolution of copper was substantially reduced in near-neutral pH. It can be concluded that HAP/C–S–H is an effective, low-cost and eco-friendly reagent for in-situ remediation of heavy metal polluted soil and groundwater.

HKUST-1 is currently studied for a very diverse range of applications. Despite its exciting potential, significant concerns remain regarding the safety of HKUST-1. Therefore, human embryonic kidney 293 (HEK293) cells were used to verify the renal toxicity of HKUST-1. In this study, HKUST-1 induced concentration-dependent cytotoxic effects in HEK293 cells. The depolarization of mitochondrial membrane potential and formation of apoptotic bodies and autophagic vesicles were observed in HKUST-1–treated HEK293 cells. Oxidative (oxidative stress and haem oxygenase-1 activation) and inflammatory responses (NF-κB and NLRP3 activation) in HEK293 cells were induced by HKUST-1 exposure. In addition, the observed reduction in NAD(P)H levels in HKUST-1–treated HEK293 cells may be attributable to PARP-1 activation following DNA single- and double-strand breaks. The HKUST-1–induced depletion of zonula occludens proteins in HEK293 cells might lead to altered renal barrier integrity. The variations of α1-antitrypsin, oxidised α1-antitrypsin and NLRP3 protein expression in HEK293 cells suggested that HKUST-1 increases the risk of chronic kidney diseases. However, most of these adverse effects were significantly induced only by high HKUST-1 concentration (100 μg/mL), which do not reflect the actual exposure. Thus, the toxic risk of HKUST-1 appears to be negligible.