Climate change and pharmaceuticals contamination constitute two of the most relevant stressors on the aquatic ecosystems, however, there is a huge lack of information regarding the interactive effects of both stressors. For that, a mesocosm experiment was implemented where adult zebrafish were exposed to combined temperature and the progestin levonorgestrel (LNG) for 21 days. Considering that the liver is one of the organs where there is a greater metabolization and accumulation of toxicants, the main objective of this work was to assess the effects of both stressors on the female zebrafish hepatocytes morphology and functioning, through stereological and immunohistochemical techniques.Our results revealed an increase of coefficient of variation of the number distribution of hepatocytes volume (CVN(υ)) for individuals exposed to LNG, which denotes an increase of the hepatocytes size variability and is suggestive of functional impacts. This was corroborated by the signs of increased glycogen content with the exposure to increased LNG concentrations and temperature, indicating modified hepatocyte glycogen metabolism. Such disturbances can be considered indicators that the fish had to deal with impacts caused by the stress factors.Regarding the immunoreactivity, from the four proteins selected (catalase, CYP1A, HSP90 and Vtg), just in two of them (catalase and Vtg) were observed some responses to both stressors. For catalase there was a hormetic response, in which exposure to lower LNG concentrations caused a significant higher positive immunostaining than under higher LNG concentrations. While, for Vtg, significant effects of temperature and LNG existed, in which a decline in Vtg immunostaining was observed with exposure to higher temperature and lower LNG concentrations. These results should be seen as a warning sign about fine impacts of multiple stressors, such as temperature and progestogens, on the structure and functioning of zebrafish liver and potentially in other aquatic organisms, and on their health implications.

Natural environments are receiving an increasing number of contaminants. Therefore, the evaluation and identification of early responses to pollution in these complex habitats is an urgent and challenging task. Doñana National Park (DNP, SW Spain) has been widely used as a model area for environmental studies because, despite its strictly protected core, it is surrounded by numerous threat sources from agricultural, mining and industrial activities. Since many pollutants often induce oxidative stress, redox proteomics was used to detect redox-based variations within the proteome of Mus spretus mice captured in DNP and the surrounding areas. Functional analysis showed that most differentially oxidized proteins are involved in the maintenance of homeostasis, by eliciting mechanisms to respond to toxic substances and oxidative stress, such as antioxidant and biotransformation processes, immune and inflammatory responses, and blood coagulation. Furthermore, changes in the overall protein abundance were also analysed by label-free quantitative proteomics. The upregulation of phase I and II biotransformation enzymes in mice from Lucio del Palacio may be an alert for organic pollution in the area located at the heart of DNP. Metabolic processes involved in protein turnover (proteolysis, amino acid catabolism, new protein biosynthesis and folding) were activated in response to oxidative damage to these biomolecules. Consequently, aerobic respiratory metabolism increased to address the greater ATP demands. Alterations of cholesterol metabolism that could cause hepatic steatosis were also detected. The proteomic detection of globally altered metabolic and physiological processes offers a complete view of the main biological changes caused by environmental pollution in complex habitats.

Enhancing metals phytoextraction using gentile mobilizing agents might be an appropriate approach to increase the phytoextraction efficiency and to shorten the phytoremediation duration. The effect of sulfur-impregnated organoclay (SIOC) on the redistribution of potentially toxic elements (PTEs) among their geochemical fractions in soils and their plant uptake has not yet been studied. Therefore, our aim is to investigate the role of different SIOC application doses (1%, 3% and 5%) on operationally defined geochemical fractions (soluble + exchangeable; bound to carbonate; manganese oxide; organic matter; sulfide; poorly- and well-crystalline Fe oxide; and residual fraction) of Cd, Cr, Cu, Ni, Pb, and Zn, and their accumulation by pea (Pisum sativum) and corn (Zea mays) in a greenhouse pot experiment using a polluted floodplain soil. The SIOC caused a significant decrease in soil pH, and an increase in organic carbon and total sulfur content in the soil. The addition of SIOC increased significantly the soluble + exchangeable fraction and bioavailability of the metals. The SIOC leads to a transformation of the residual, organic, and Fe-Mn oxide fractions of Cd, Cu, Ni, and Zn to the soluble + exchangeable fraction. The SIOC addition increased the potential mobile (non-residual) fraction of Cr and Pb. The SIOC increased the sulfide fraction of Cr, Ni, and Zn, while it decreased the same fraction for Cd, Cu, and Pb. The effect of SIOC on the redistribution of metal fractions increased with enhancing application dosages. Pea accumulated more metals than corn with greater accumulation in the roots than shoots. Application of the higher dose of SIOC promoted the metals accumulation by roots and their translocation to shoots of pea and corn. Our results suggest the potential suitability of SIOC for enhancing the phytomanagement of PTEs polluted soils and reducing the environmental risk of these pollutants.

In modern society, the intense vehicle traffic and the lack of effective mitigating strategies may adversely impact freshwater systems. Road-deposited sediments (RDS) accumulate a variety of toxic substances which are transported into nature during hydrologic events, mainly affecting water bodies through stormwater runoff. The aim of this study was to evaluate the RDS metal enrichment ratio between the end of wet season and the middle of the dry season for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in samples from Natal, Brazil. Twenty RDS, drainage system and river sediment samples were collected in the wet and dry seasons using a stainless-steel pan, brush and spatula. In the laboratory, the samples were submitted to acid digestion and heavy metal concentrations were measured by atomic absorption spectrometry (AAS). A consistent RDS enrichment by heavy metals in dry season samples was followed by an increase in the finest particle size fraction (D < 63 μm). Maximum concentrations were 5, ND, 108, 23810, 83, ND, 77 and 150 mg kg⁻¹ for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn, respectively. The RDS enrichment ratio was Cr(1.3 ×), Cu(2.6 ×), Fe(3.3 ×), Mn(1.5 ×), Pb(1.5 ×) and Zn(2.1 ×). The Geo-accumulation Index values showed that RDS were moderately polluted for Cu and slighted polluted for Zn and Pb. Principal Component Analysis (PCA) showed that the accumulation of toxic heavy metals decreased according to water flow.

A study was undertaken to test the hypothesis that the presence of fly ash and other artifactual materials (AMs) significantly increases the toxicity of urban soil and street dust. AMs were distinguished as artifacts (artificial particles > 2 mm in size), and particulate artifacts (≤2 mm in size); street dust was the <63 μm fraction of street sediments. Reference artifacts, street dusts, and topsoils representing different land use types in Detroit, Michigan were analyzed for miscellaneous radionuclides, trace elements, magnetic susceptibility (MS), and acetic acid-extractable (leachable) Pb. Background levels were established using native glacial sediments. Street sediments were found to have a roadside provenance, hence street dusts inherited their contamination primarily from local soils. All soils and dusts had radionuclide concentrations similar to background levels, and radiological hazard indices within the safe range. Artifacts, fly ash-impacted soils and street dusts contained elevated concentrations of toxic trace elements, which varied with land use type, but none produced a significant amount of leachable Pb. It is inferred that toxic elements in AMs are not bioavailable because they are occluded within highly insoluble materials. Hence, these results do not support our hypothesis. Rather, AMs contribute to artificially-elevated total concentrations leading to an overestimation of toxicity. MS increased with increasing total concentration, hence proximal sensing can be used to map contamination level, but the weak correlation between total and leachable Pb suggests that such maps do not necessarily indicate the associated biohazard. Home site soils with total Pb concentrations >500 mg kg−1 were sporadically toxic. Thus, these results argue against street dust as the local cause of seasonally elevated blood-Pb levels in children. Lead-bearing home site soil tracked directly indoors to form house dust is an alternative exposure pathway.

The inorganic content of the well-preserved 3.2-m record of Las Conchas bog (NW Spain), covering 8000 cal yr BP., was analysed. To study natural vs. human contributions, we applied an innovative approach, namely the sequential study of multivariate statistics (factor analysis followed by clustering of the factor score matrix) and enrichment factors (EFs). The increasing weight of potentially toxic elements (PTEs) such as the geochemical association of Zn, Pb and Cd (EFs higher than 10, 20 and 40 in the last two centuries) was revealed, and corroborated by the contrast between the contents of anthropogenic Pb and total Rare Earth Elements (a suitable proxy for natural geogenic supplies). Furthermore, elements such as Hg, Tl and As also showed enrichment in the most recent samples of the study core. Some of them are commonly associated with global atmospheric transport; however, in this case, their increasing contents could also be explained by nearby industrial and mining activities.In summary, severe pollution was observed in the uppermost part of the record, thereby pointing to an important environmental concern. Given that local and regional sources of PTEs, such as mining and heavy industry, especially Zn smelting, were probably the main historical causes of this contamination and that some of these industries are still active, we consider that our findings deserve further attention.

Ecotoxicological studies show the association between pesticide pollution and transgenerational toxicity in aquatic organisms. However, a less considered risk is that many pesticides can be metabolized and transferred to offspring as new toxicants. In this study, we used zebrafish to evaluate the maternal transfer risk of fipronil (FIP), which is a great threat to aquatic organisms with toxic metabolite formation. After 28-day exposure to environmentally relevant concentrations (1.0, 5.0 and 10.0 μg/L) of FIP in adult female zebrafish (F0), the toxicants off-loading and transgenerational toxicity in offspring were studied. High burdens of FIP and its sulfone metabolite were found in both F0 and the embryos (F1), resulting in increased CYP450 activity. The residual levels of the metabolite were higher than those of the parent compound. Chiral analysis further showed a preferential accumulation of S-enantiomer of FIP in both F0 and F1. Maternal exposure to FIP increased the malformation rate and decreased the swim speed in larvae. Additionally, after exposure, the levels of thyroid hormones (THs), including triiodothyronine (T3) and thyroxine (T4), decreased in both generations, particularly in the F1. Gene transcription expression along the hypothalamic-pituitary-thyroid (HPT) axis was also significantly affected. Maternal exposure to FIP increased sulfone metabolite enrichment and cause multiple toxic effects in F1. Findings from this study highlight the key role of biologically active product formation in the maternal transfer of pollutants and associated risk assessment.

There are global concerns about heavy metal (HM) contamination in soils, which in turn has produced an increased demand for soil remediation. Biochar has been widely documented to effectively immobilize metals in contaminated soils and has received increasing attention for use in soil remediation. Here, we review recent progresses in understanding metal-biochar interactions in soils, potential risks associated with biochar amendment, and application of biochar in soil remediation in China. These recent studies indicate that: (1) the remediation effect depends on the characteristics of both biochar and soil and their interactions; (2) biochar applications could decrease the mobility/bioavailability of HMs in soils and HM accumulation in plants; and (3) despite its advantages, biochar applications could pose ecological and health risks, e.g., by releasing toxic substances into soils or by inhalation of biochar dust. Research gaps still exist in the development of practical methods for preparing and applying different biochars that target specific HMs. In the future, the long term effects and security of biochar applications on soil remediation, soil organisms and plant growth need to be considered.

Dichlorvos (2,2-dichlorovinyl-dimethylphosphate), an organophosphorus pesticide used for indoor insect and livestock parasite control, is among the most common commercially available pesticides. However, there are significant concerns over its toxicity, especially due to its relative stability in water, soil, and air. Zebrafish, an important developmental model, has been used for studying the effects of toxic compounds. The aim of this study was to evaluate the exposure to dichlorvos at early life stages (1 h postfertilization - 7 days postfertilization) in the zebrafish and its toxicological effects during the development, through morphological (7 days postfertilization), locomotor and social behavior analysis (7, 14, 30, 70, and 120 days postfertilization). Dichlorvos (1, 5, and 10 mg/L) exposure reduced the body length and heartbeat rate at 7 days postfertilization (dpf), as well as the surface area of the eyes (5 and 10 mg/L). The avoidance behavior test showed a significant decrease in escape responses at 7 (1, 5, and 10 mg/L) and 14 (5 and 10 mg/L) dpf zebrafish. The evaluation of larval exploratory behavior showed a reduction in distance traveled, mean speed (1, 5, and 10 mg/L) and time mobile (10 mg/L) between control and dichlorvos groups. In addition, the analysis performed on adult animals showed that the changes in distance traveled and mean speed remained reduced in 30 (1, 5, and 10 mg/L) and 70 dpf (5 and 10 mg/L), recovering values similar to the control at 120 dpf. The social behavior of zebrafish was not altered by exposure to dichlorvos in the early stages of development. Thus, the exposure to organophosphorus compounds at early stages of development induces an increased susceptibility to behavioral and neuronal changes that could be associated with several neurodegenerative diseases.

Marine fish are considered a source of high quality proteins and fatty acids. However, the consumption of fish may pose a health risk as it may have potentially toxic elements in high concentrations. In this study we quantify the multielemental composition of muscle and fins for three species of commercial marine fish from Brazil: Sphyraena guachancho (Barracuda), Priacantus arenatus (Common bigeye) and Genidens genidens (Guri sea catfish). We then assessed the potential risk of fish consumption by means of a Provisional Hazard Indices. Amongst the elements detected in fish tissue were potentially toxic elements such as Ag, Ba, Cd, Cr and Hg. Concentration differences were species-specific, and affected by the species trophic level, morphological characteristics and feeding habits. Results suggest the higher the trophic level of the fish, the higher the risk of consumption. Caution is recommended for the frequent ingestion of high trophic level fish species in Brazil.