Daniele Fattorini

Arsenic represents a ubiquitous element in the environment, characterized by high mobility, complex chemical speciation and a strong sensitivity to redox conditions and biological activity, with microbial processes play a central role in its biogeochemical cycling. The present review provides a comprehensive and integrative synthesis of arsenic biogeochemical cycling across terrestrial, freshwater and marine environments, in which chemical speciation is explicitly treated as the central unifying concept controlling arsenic mobility, transformation and bioavailability, linking geological, chemical and biological processes across environmental compartments. Natural processes regulating arsenic distribution are examined from mineralogical sources and soil–water interactions to biologically mediated transformations in aquatic and marine biotic compartments, largely driven by microbial activity, highlighting the contrast between inorganic arsenic dominance in abiotic reservoirs and the prevalence of organoarsenicals in tissues of living organisms. The review further explores arsenic behaviour under natural environmental alterations and in extreme or unconventional ecosystems, where redox constraints, sulphide chemistry or intense fluid–sediment exchanges lead to deviations from the baseline speciation patterns. Against this framework, anthropogenic perturbations are discussed through several documented case studies, illustrating how industrial releases, the long-term effects of mining activities, agricultural practices and the use of synthetic arsenical compounds may change arsenic pathways primarily by altering geochemical and biological controls rather than through a generalized increase in total arsenic content. Overall, the topics covered provide an integrated framework for interpreting arsenic dynamics across environmental systems, emphasizing the complex biogeochemical processes governing arsenic cycling.

Arsenic represents a ubiquitous element in the environment, characterized by high mobility, complex chemical speciation and a strong sensitivity to redox conditions and biological activity. The present review provides an integrated synthesis of arsenic biogeochemical cycling across terrestrial, freshwater and marine ecosystems, emphasizing the central role of chemical speciation in controlling the arsenic levels, mobility and bioavailability. Natural processes regulating arsenic distribution are examined from mineralogical sources and soil–water interactions to biologically mediated transformations in aquatic and marine biotic compartments, highlighting the contrast between inorganic arsenic dominance in abiotic reservoirs and the prevalence of organoarsenicals in tissues of living organisms. The review further explores arsenic behaviour under natural environmental alterations and in extreme or unconventional ecosystems, where redox constraints, sulphide chemistry or intense fluid–sediment exchanges lead to deviations from the baseline speciation patterns. Against this framework, anthropogenic perturbations are discussed through several documented case studies, illustrating how industrial releases, the long‑term effects of mining activities, agricultural practices and the use of synthetic arsenical compounds may change the arsenic pathways primarily by altering geochemical and biological controls rather than the generalized increase of the total arsenic content. Overall, the topics covered provide an integrated framework for interpreting arsenic dynamics across environmental systems, emphasizing the complex biogeochemical processes governing arsenic cycling.

A growing scientific movement is investigating the complex and interconnected relationship between environmental degradation, infectious diseases, and global health, an approach often referred to as “One Health”. This paradigm challenges the long-held assumption that human health exists independently of the planet’s health. In the present review, three major global issues—environmental pollution, biodiversity loss, and climate change—are considered as key drivers of disease emergence and spread. Environmental pollution may affect the immune system, making living species, including humans, more vulnerable to infectious diseases. The COVID-19 pandemic highlighted this link, as studies in Italy and elsewhere correlated higher air pollution levels with increased spread and severity of the virus. Biodiversity loss, according to the “dilution effect” theory, can increase disease transmission. In ecosystems with a wide variety of species, pathogens are “diluted” because their vectors are more likely to encounter hosts that cannot transmit the disease. When biodiversity declines, however, “super-spreader” species that are effective at transmitting pathogens, such as certain rodents and bats, often dominate, increasing the risk of zoonotic spillovers. Finally, climate change exacerbates these issues by expanding the geographical range of disease vectors like mosquitoes and by creating extreme weather events that can lead to outbreaks of waterborne diseases. The present review addresses these issues by describing some key examples, such as the relationship between atmospheric contamination and the outbreak of infectious diseases, the role of biodiversity loss in Lyme disease, and the increase in the range of insect vectors of malaria and dengue associated with climate change. A multidisciplinary approach is fundamental to addressing these global challenges, suggesting collaboration between experts in human and veterinary medicine, developmental biology, environmental science and toxicology, and public policy, as well as the need to raise public awareness. This challenge could also be addressed through the advent of innovative technologies capable of significantly increasing our ability to access large multidisciplinary databases. Among these, artificial intelligence-based technologies could undoubtedly play a leading role.

Hydrocarbon contamination in marine environments poses a significant global environmental challenge, impacting ecosystems, human health, and economic activities. The present review provides a comprehensive overview of hydrocarbons in seawater, addressing their diverse sources, complex fate and transport mechanisms, ecological and toxicological impacts, and various remediation strategies. Both natural seepages from geological formations and a wide array of anthropogenic inputs are discussed as primary contributors to marine hydrocarbon burdens. Anthropogenic carbon inputs include large-scale accidental oil spills, chronic operational discharges from shipping and offshore platforms, industrial effluents, and diffuse urban runoff carrying petrogenic and pyrogenic hydrocarbons, during the past 50 years. In the sea, hydrocarbons undergo a series of interconnected physical, chemical, and biological transformations that mediate their persistence, bioavailability, and spatial distribution. The specific environmental conditions, such as temperature, nutrient availability, and microbial community composition, significantly influence the rate and extent of these natural attenuation processes. The ecological consequences range from acute lethal impacts causing immediate mortality in marine organisms to chronic sublethal effects on reproduction, growth, immune response, and behavior across a wide range of taxa, from plankton to marine mammals. Furthermore, long-term ecosystem disruptions, including habitat degradation of vital coastal areas, such as mangroves and coral reefs, and bioaccumulation within the food web, pose serious threats to ecosystem health and biodiversity. To mitigate these adverse effects, a range of remediation strategies has been developed and implemented; their mechanisms, effectiveness in various scenarios, inherent limitations, and potential secondary environmental considerations are explored in this review. Emphasis is placed on the importance of integrated approaches that combine rigorous prevention measures, rapid and effective response protocols during spill events, and sustainable, environmentally sound long-term remediation techniques. Understanding the intricate interplay between the sources, transformations, impacts, and potential solutions for hydrocarbon contamination is crucial for developing robust management plans and safeguarding the long-term health and resilience of marine ecosystems.

Microplastics (MP) can act as carriers of other contaminants, such as metals, including the metalloid arsenic (As). So, the objective of this study was to evaluate the combined effect of MP and As on the polychaete Laeonereis culveri. The animals were divided into four experimental groups: (1) exposed to MP (40 μg/L, polystyrene, 1.1 μm, spherical), (2) exposed only to As (50 μg/L as arsenite), (3) exposed to both MP and As (same concentrations as cited above), and (4) a control group (only water). The animals were exposed for 7 days and parameters related to oxidative stress and energy metabolism, as well as total arsenic content and chemical speciation, were analyzed. The results showed that coexposure to MP and As induced a decrease in GPx and GST activities, while GSH levels were reduced in the group exposed only to microplastics. MP did not induce changes in As accumulation nor did it affect As metabolization capacity. Coexposure to As and MP resulted in elevated glucose levels, lactate concentrations, and LDH activity. Hence, our findings imply that the combination of As and MP may induce a prooxidant environment in L. culveri. Such conditions could potentially compromise other long-term physiological functions.

Mussels, as filter feeders, efficiently accumulate various pollutants from the surrounding water, making them valuable bioindicators of marine environmental quality. This review focuses on their application in assessing trace element contamination in the Mediterranean Sea. Trace elements such as arsenic, cadmium, lead, mercury, and zinc are commonly identified in mussels due to their potential toxicity and bioaccumulation. Seasonal variations in trace element concentrations in mussel tissues are influenced by factors such as phytoplankton blooms, gametogenesis, temperature, and salinity. However, anthropogenic activities, including industrial discharges, mining, and urban runoff, can significantly elevate these levels. The Mediterranean Sea is particularly vulnerable to pollution due to its enclosed nature and high human population density. Natural and geological phenomena contribute to the increased bioavailability of certain elements, such as arsenic and mercury, in the Adriatic Sea and the Tyrrhenian Sea. An in-depth understanding of these phenomena is fundamental for interpreting data from scientific studies and environmental monitoring. Regions with historical mining activities, such as the Iberian Peninsula and North Africa, show elevated levels of elements such as lead and zinc. Areas with significant industrial activities, such as the Gulf of Taranto and the Gulf of Trieste (Italy), also exhibit elevated levels of trace elements in mussels. The Eastern Mediterranean, including the Aegean and Marmara Seas, is characterized by widespread pollution from urban and industrial sources, as well as maritime traffic. Mussels from these regions often exhibit high levels of trace elements, particularly in areas near major cities and industrial centers. This review examines literature from the past 25 years concerning the use of mussels as bioindicators in the study of natural and anthropogenic phenomena affecting the bioavailability of trace elements in the Mediterranean Sea, providing an overview of case studies and environmental monitoring commonly carried out in this area.

Most organisms possess the capacity to metabolize arsenic (As) accumulating compounds to less toxic forms, thus minimizing the adverse effect induced by this metalloid. However, other contaminants may to interfere with As metabolism, contributing to the accumulation of more toxic compounds. Microplastics (MPs) are omnipresent in aquatic environment and may induce toxicological effects (alone or in combination with other contaminants) on living organisms. Therefore, the objective of the present study was to evaluate the effect of the exposure of the freshwater clam Limnoperna fortunei to a combination of MP (4 and 40 μg/L of polystyrene microbeads, 1.05 μm) and As (50 μg/L) for 48 h, evaluating the accumulation and metabolization of As and oxidative stress parameters, such as catalase (CAT), glutathione-S-transferase activities, total antioxidant competence, reduced glutathione (GSH), and lipid damage in the gills and digestive glands. Results revealed that low MP concentration disrupts the redox state of the digestive gland by a decrease in the antioxidant activity (CAT and total antioxidant capacity). GSH levels in the gills of animals exposed to MP (4 μg/L) alone and the combination of MP + As increased, concomitant with an increase in the percentage of toxic compounds, indicating the effect of MP on As metabolism. Although, few studies evaluated the effect of coexposure to MP + As by considering metabolization of metalloid in freshwater bivalve, our results revealed that exposure to MP reduced the metabolization capacity of As, favoring the accumulation of more toxic compounds besides the MP alone, which showed a pro-oxidant effect in L. fortunei.