RESUMO
The study evaluated the spatial and seasonal variations of microplastic abundances in water, sediments, and commercial fishes of a semi-urban tourist impacted estuary in the Gulf of Mexico, Mexico. The prevalence of microplastics (MPs) elucidated diffuse sources namely long-range transport, domestic, agricultural, fishing, industrial and recreational activities and the local climatic conditions. Seasonally, the mean abundances of MPs in both water and sediments were high during Nortes (strong winds) followed by the dry and rainy seasons. Overall, black and blue colored MPs dominated the region and all the recovered plastics were fibers. The commercial fishes (n = 187) contained 881 MPs in their gastrointestinal tracts, suggesting that the food web of the estuary is highly prone to microplastic contamination. SEM images of extracted plastic fibers presented surface morphologies that are impacted by physical strains. Further, the elemental characterization of fibers using EDX displayed significant peaks of Al, As, Cl, Cr, Cu, Pb, and Zn that were used as additives during the production of plastics. The main types of polymers included low-density polyethylene, polyester, polypropylene, polycarbonate, rayon, polyvinyl chloride, polyacrylonitrile, polyamide, nylon and polyethylene terephthalate. MP abundances demonstrated in this study elucidate that estuaries are a major conduit for land-derived plastics to the ocean and the results will aid in implementing remedial/clean up actions of the estuary for better conservation of the ecosystem.
Assuntos
Microplásticos , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Estuários , Golfo do México , México , Plásticos , Estações do Ano , Poluentes Químicos da Água/análiseRESUMO
Persistent organic pollutants (POP) are toxic substances for wildlife and people. The Kemp's Ridley sea turtle Lepidochelys kempii is an endangered species with limited distribution in the Gulf of Mexico (GM), a marine ecosystem that has been perturbed by a variety of anthropogenic activities. In this work, the concentrations of ten organochlorine pesticides (OP), eight polychlorinated biphenyls (PCB), and atrazine were determined in the plasma of Kemp's Ridley sea turtles that nest in Playa Rancho Nuevo Sanctuary, Tamaulipas, Mexico. Seventy-nine blood samples were collected from female turtles during the 2015-2016 nesting season. Samples were extracted with a focalized ultrasonic sound technique and analyzed through Gas Chromatography coupled to a Mass Spectrometer. POP with the highest percentage of detection were atrazine > PCB 52 > PCB 153 > DDE > alpha endosulfan > DDD > alpha HCH > DDT. There is no linear correlation between the detected POP levels in the Kemp's Ridley sea turtle plasma and its curve carapace length (CCL). When comparing 2015 and 2016 POP concentrations, there were statistically significant differences in atrazine (p < 0.05, R2 = 0.069), PCB 52 (p < 0.05, R2 = 0.0051) and ∑POP (p < 0.05, R2 = 0.0001) and, no statistically significant differences in alpha endosulfan (p < 0.05, R2 = 0.0294), DDE (p < 0.05, R2 = 0.0315) and PCB 153 (p < 0.05, R2 = 0.0036). The reported POP values of this work are one of the few registered for Kemp's Ridley sea turtle in the GM and the first for atrazine levels. These levels were higher than those reported for other sea turtle species from America, Africa, and Europe, which demonstrates a deteriorated health status of the GM marine ecosystem.
Assuntos
Poluentes Ambientais , Tartarugas , África , Animais , Ecossistema , Europa (Continente) , Feminino , Golfo do MéxicoRESUMO
Oreochromis niloticus was used to determine the effects of heavy metals and their concentration in aquatic environments. Its wide distribution, resistance, and economical importance make it a suitable biomonitor. The present study was conducted in the Tenango Dam (Puebla, Mexico) to determine water quality and its impact on O. niloticus, a species that is cultured and commercialized in this area. Five samples were collected over 1 year to evaluate the water's physicochemical parameters (temperature, dissolved oxygen, pH, and hardness) and metal contents (cadmium, chromium, copper, and lead). Metal concentrations, bioconcentration factors, and metallothionein levels were also assessed in O. niloticus livers and muscle tissues. Water and tilapia quality were estimated according to current Mexican guidelines. Results indicated that the water's physicochemical parameters were within acceptable ranges. Metal concentrations, however, suggested that this resource was not suitable for urban use. Moreover, metal levels in fish tissues exceeded the acceptable limits during two periods, rendering it unsuitable for human consumption. The bioconcentration factor indicated that the metals can potentially accumulate in organisms. Furthermore, metallothionein levels in liver and muscle showed a direct correlation with metal concentrations in these tissues. This is the first study to use tilapia as an indicator of contamination in the Tenango Dam, and also the first to describe the presence of metals in this water body.
Assuntos
Ciclídeos/metabolismo , Monitoramento Ambiental , Metais Pesados/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Cádmio/análise , Cromo/análise , Cobre/análise , Humanos , Metalotioneína/análise , Metais Pesados/análise , México , Músculos/química , Tilápia , Poluentes Químicos da Água/análiseRESUMO
Mercury and methylmercury concentrations were evaluated in two marine fish species captured and consumed in Mexico, snapper (Lutjanus sp.) and mackerel (Scomberomorus sp.), obtained from several fish ports on the Pacific Ocean and the Gulf of Mexico. Significant differences were found between the median total mercury concentrations in snapper and mackerel, which were 0.187 and 0.125 µg/g (ww), respectively. Differences in the total mercury concentration in snapper were observed between the different oceans; snappers from the Gulf of Mexico registered a higher median mercury concentration (0.233 µg/g) than those caught in the Pacific Ocean (0.150 µg/g). Ninety-three percent of all samples presented had mercury concentrations that did not exceed the maximum limit (0.5 µg/g) specified by Mexican regulations, although 21% exceeded the US EPA limit of 0.3 µg/g, and three samples had mercury concentrations that were above the FDA recommended limit of 1 µg/g. Mackerel and snapper collected in the ports of Tampico and Mazatlan (economically important industrial cities and fishing sites) had the highest concentrations of total mercury, compared with those obtained from Acapulco and Ensenada (important touristic centers), which showed the lowest values. Recommendations should be made for the maximum allowed consumption of these fish in Mexico, especially for populations settled in shorelines where fish is essential for the daily diet.
Assuntos
Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Perciformes/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Contaminação de Alimentos/análise , Golfo do México , Mercúrio/análise , Compostos de Metilmercúrio/análise , México , Oceano Pacífico , Alimentos Marinhos/análise , Poluentes Químicos da Água/análiseRESUMO
The consolidation of environmental legislation is fundamental for governments that wish to support and promote different actions focused on reducing pollution and protecting natural water resources in order to maintain the present and future benefits that water provides for human beings and wild life. Environmental laws are essential for sustaining human activities and health, preserving biodiversity and promoting sustainable development. In this context, it is important that environmental regulations concentrate on preventing or reducing the harmful impact of pollutants on organisms and ecosystems. The introduction of toxicity bioassays in environmental regulations is a positive step toward achieving this goal. In Mexico, the development of environmental legislation and the introduction of bioassays in water regulation are part of a very recent and complex journey. This article describes how aquatic ecotoxicology tools, particularly bioassays, have influenced water pollution policies in Mexico. Three scenarios are reviewed: the background of Mexican legislation on water protection and Mexico's participation in the Watertox project; the actual efforts of SEMARNAT to develop bioassay batteries for this country; and, the challenges and perspectives of ecotoxicological bioassays as regulatory instruments.