Effects of substances released from a coal tar-based coating used to protect harbor structures on oysters

Cigarette butt leachates induce alterations in gene expression and damage in health status of tropical oysters

Cigarette butts (CB) are among the most frequent debris in marine litter collected in coastal areas. They are potential sources of chemical contamination by leaching process, posing risks to biota. This study aimed to evaluate the short-term impacts of CB leachates on the oyster Crassostrea brasiliana. The animals were exposed in the laboratory to different leached dilutions and assessed for bioaccumulation of polycyclic aromatic hydrocarbons (PAHs), their general health status by neutral red retention time (NRRT), and variation in expression of genes related to xenobiotic biotransformation. The results showed that CB leachates at very low dilutions impaired the general health status of oysters, with significant reductions in NRRT at 24 h (dilution 0.1 %), and that persisted at 96 h (dilution 0.01 %). Therefore, a single cigarette butt was able to make toxic 250 l of seawater after 24 h release, and 2500 l after 96hs. The gene expression indicated a decrease in gill transcripts (CYP2-like, GSTΩ, and HSP70) of C. brasiliana exposed for 24 h, with no marked trend at 96 h. Despite the low PAHs bioaccumulation, the damages observed in lysosomal membranes followed by the decreased expression of key genes involved in xenobiotic biotransformation, and the protection of protein stability, represent evidence of early effects caused by cigarette residues on marine organisms from tropical environments.

Visualization and analysis of knowledge domains for recent developments in coal mechanical properties studies

To better understand the research progress and trends in the mechanical properties of coal, and to promote theoretical research on the prevention and control of dynamic disasters, we employed the bibliometric method to analyze the research progress in this field. A total of 3450 documents from the Web of Science (WOS) core database were reviewed and analyzed. Our analysis focused on the annual distribution of literature, the distribution by country/region, organization, and author, as well as the distribution of significant source journals. We also identified research hotspots and frontiers. The results indicate a significant increase in the number of research papers on the mechanical properties of coal. China, America, Australia, India, Spain, Poland, England, Japan, South Korea, and Turkey were found to be the most active countries in this research area. The research results from China, America, and Australia were found to be the most influential, and C&BM, FUEL, INT J ROCK MECH MIN, INT J COAL GEOL, RM&RE, C&CR, and JCP were identified as the primary sources of research publications on the mechanical properties of coal. The basic theory and research system of coal mechanical properties investigation have been established, and there are numerous future research directions and areas to explore. Some current hotspots include the development of coal mechanical property models, permeability models related to mechanical properties, establishment and prediction of coal strength-temperature relationships, investigation of the proportioning scheme of granite and coal bottom ash in concrete mixes, and research on the improvement effect of fly ash on concrete manufacturing properties.

Oysters and mussels as equivalent sentinels of microplastics and natural particles in coastal environments

Filter-feeder organisms such as oyster and mussels are exposed to particles like microplastics (MPs). Although widely used to monitor MPs contamination, little is known about their performance as sentinels, which are biological monitors accumulating contaminants without significant adverse effects. This study comparatively evaluated the quantitative and qualitative accumulation of MPs by oysters (Crassostrea brasiliana) and mussels (Perna perna) along a gradient of contamination in a highly urbanized estuarine system of Brazil. In the most contaminated site, both species presented the worst status of nutrition and health, and also one of the highest MPs levels reported for molluscs to date (up to 44.1 particles·g^-1). Despite some inter-specific differences, oysters and mussels were suitable and showed an equivalent performance as sentinels, reflecting the gradient condition demonstrated for other contaminants in the region. The similarity in MPs accumulation was also observed for qualitative aspects (polymer composition, sizes, shapes and colors). Particles were mostly <1000 μm, fibrous, colorless and composed by cellulose and polymethyl methacrylate (PMMA). Thus, despite small variations, the usage of C. brasiliana and P. perna is recommended and provides reliable information for environmental levels of microplastics.

Chemical contamination in coastal areas alters shape, resistance and composition of carnivorous gastropod shells

Morphological, structural and compositional alterations in shells of molluscs have been proposed as putative biomarkers of chemical contamination in coastal zones. Despite this, few studies were carried out using top predator gastropods which tend to be more susceptible to contamination exposure. Thus, the present study assessed disturbances on shells of Stramonita brasiliensis considering compression resistance and organic and mineralogical matrix composition, related to morphometric alterations. Results showed reductions in compression resistance and organic matrix content associated with higher contaminated sites. In addition, a predominance of calcite polymorphs was seen in shells obtained in polluted areas. Such outputs were consistent with local contamination levels which may have induced the observed alterations. Thus, changes in mollusc shells showed good performance as potential biomarkers of coastal contamination, being probably observed in other species of carnivorous gastropods around the world.

Mollusc shell shape as pollution biomarkers: Which is the best biological model?

Alterations in mollusc shells have been proposed contamination biomarkers. We used geometric morphometrics analyses associated with analytical determinations of contaminants to select suitable biological models among species widely distributed on coastal zones. The study was carried out using Lottia subrugosa (herbivore limpet), Crassostrea brasiliana (filter-feeder bivalve), and Stramonita brasiliensis (carnivore gastropod) obtained along a marked contamination gradient at Santos Estuarine System (Brazil). L. subrugosa and S. brasiliensis presented distinct shapes along the gradient, while no significant differences in shell form were seen for C. brasiliana. Indeed, limpets and snails presented morphometric parameters consistent with measured contamination levels hazardous substances. Based on cross-validation models, the reliability of morphometric responses was over 75% for the herbivore and carnivore species. In addition, for S. brasiliensis, a 95.2% confidence was detected in most contaminated sites. Therefore, shell alterations on carnivorous gastropods should be further investigated, seeking to be effectively employed as pollution biomarkers.

Primary and Secondary Emissions of VOCs and PAHs in Indoor Air from a Waterproof Coal-Tar Membrane: Diagnosis and Remediation

Primary and secondary emissions of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) from a waterproof coal tar membrane and their effect on the indoor air quality were investigated through a case study in a residential building situated in Madrid, Spain. The air contaminants were analyzed in situ using photoionization method and several samples of contaminants were taken using three sorbents: activated carbon, XAD2 and Tenax GR. It was found that various VOCs such as toluene, p- and m-Xylene, PAHs such as naphthalene, methyl-naphthalenes, acenaphthene, acenaphthylene, phenanthrene and fluorine, volatile organic halogens including chloroform and trichlorofluoromethane, and alkylbenzene (1,2,4-trimethylbenzene) were found at concentrations, which exceeded the limits established by international and national agencies (WHO, EPA, OSHA). Some of the above organic compounds were found also in the samples of construction and building materials, which were obtained at different heights and places. The analysis of possible sources of the contaminants pointed at the original coal-tar membrane, which was applied on the terrace to be waterproof. During a posterior reparation the membrane was coated with a new one that hindered dissipation of emitted contaminants. The contaminants leached out and were absorbed by construction materials down in the dwelling. These materials then acted as secondary emission sources. To remediate the emission problem as the contaminated materials were removed and then a ventilation system was installed to force the gasses being emitted from the rest of contaminated slab outside. Follow-up has validated the success of the remediation procedure.

Impact of Polycyclic Aromatic Hydrocarbon Accumulation on Oyster Health

In the past decade, the Deepwater Horizon oil spill triggered a spike in investigatory effort on the effects of crude oil chemicals, most notably polycyclic aromatic hydrocarbons (PAHs), on marine organisms and ecosystems. Oysters, susceptible to both waterborne and sediment-bound contaminants due to their filter-feeding and sessile nature, have become of great interest among scientists as both a bioindicator and model organism for research on environmental stressors. It has been shown in many parts of the world that PAHs readily bioaccumulate in the soft tissues of oysters. Subsequent experiments have highlighted the negative effects associated with exposure to PAHs including the upregulation of antioxidant and detoxifying gene transcripts and enzyme activities such as Superoxide dismutase, Cytochrome P450 enzymes, and Glutathione S-transferase, reduction in DNA integrity, increased infection prevalence, and reduced and abnormal larval growth. Much of these effects could be attributed to either oxidative damage, or a reallocation of energy away from critical biological processes such as reproduction and calcification toward health maintenance. Additional abiotic stressors including increased temperature, reduced salinity, and reduced pH may change how the oyster responds to environmental contaminants and may compound the negative effects of PAH exposure. The negative effects of acidification and longer-term salinity changes appear to add onto that of PAH toxicity, while shorter-term salinity changes may induce mechanisms that reduce PAH exposure. Elevated temperatures, on the other hand, cause such large physiological effects on their own that additional PAH exposure either fails to cause any significant effects or that the effects have little discernable pattern. In this review, the oyster is recognized as a model organism for the study of negative anthropogenic impacts on the environment, and the effects of various environmental stressors on the oyster model are compared, while synergistic effects of these stressors to PAH exposure are considered. Lastly, the understudied effects of PAH photo-toxicity on oysters reveals drastic increases to the toxicity of PAHs via photooxidation and the formation of quinones. The consequences of the interaction between local and global environmental stressors thus provide a glimpse into the differential response to anthropogenic impacts across regions of the world.