Sediment cores from the Colorado River (CR) remnant delta were used to assess the changing sedimentation and pollutant deposition processes in response to extensive human manipulation of the river. The cores are formed of alternating layers of clays and silts, with isolated sandy horizons. The clayey units are interpreted as periods of flood flows into this low gradient and meandering estuary after dam construction in the United States. The geochemistry of these sediments is particular because of the association of MnO with CaO rather than with the Fe(2)O(3)-rich clays. Past pollution of the CR delta by As, and probably also Pb and Cu, is recorded in some cores. Enrichment factors (EFs) >1 for these elements and their statistical association suggest anthropogenic inputs. The most likely sources for these element enrichments (especially As) are the arsenate-based pesticides used intensively in the area during the first half of the 20th century. The transport of these elements from the nearby agricultural lands into the present river reaches appears to have been driven in part by flooding events of the CR. Flushing by river and tide flows appear to be responsible of a lower pollutant deposition in the CR compared to the adjacent Hardy River (HR). Arsenic in the buried clay units of the HR has concentrations above the probable toxic effect level (PEL) for dwelling organisms, with maximum concentrations of 30 microg g(-1). Excess (210)Pb activities ((210)Pb(xs)) indicate that fluxes of this unsupported atmospheric isotope were not constant in this estuarine environment. However, the presence of (210)Pb(xs) does indicate that these sediments accumulated during the last ~100 years. Aproximate sediment ages were estimated from the correlation of historic flooding events with the interpretation of the stratigraphic record. They are in fair agreement with the reported onset of DDT metabolites at the bottom of one core.
<p><strong>Background:</strong> The agri-food sector, which includes fishing and aquaculture, poses challenges in improving the food quality and restructure markets. Currently, we have the opportunity to understand the food crisis associated with the COVID-19 pandemic, and to promote a paradigm shift in food and markets, which leads to the changes generation in the food economic system, transformation of markets and rapprochement of producers with consumers. One of the ways to bring the producer and the consumer closer to each other, is precisely to know and characterize their consumption, by conducting market studies. A market study is a systematic investigation based on the information collection and data analysis related to the outstanding characteristics of the market to which a company or a sector is directed, which allows us to know and characterize the tastes and preferences in the population consumption. <strong>Objective:</strong> To diagnose the perceptions and preferences on the fish and shellfish consumption in the Mexicali city, Baja California, Mexico. <strong>Methodology:</strong> To get the required information, surveys were applied at four points in Mexicali. The study was carried out with cluster analysis using the statistical package for social sciences. It was obtained that three clusters were separated from each other and are statistically different (98.5% of the analyzed data). <strong>Results: </strong>The first conglomerate comprises 61.77% of those surveyed, while the second 27.94% and the remaining 10.29% were in the third conglomerate. Cluster 2 represents the population that consumes the most fish and shellfish, followed by cluster 1 and those of cluster 3, which consumes less fish and/or shellfish. In order of importance, the most relevant variables to explain on the three clusters are: differences between fishery products vs aquaculture, presentation of consumption and date of acquisition. <strong>Implications: </strong>This study provides a baseline for future market research in Baja California where trends in consumer buying behavior are analyzed, as well as contributing to the recognition of problems, identification of opportunities and improvement in decision-making by consumers, aquaculture producers and fishermen (or fishing sector). <strong>Conclusions:</strong> The results show that there is a lack of knowledge in the population on fishery and aquaculture products. Therefore, there is a tremendous area of opportunity to publicize information about the fishery and aquaculture products in the different media communication. Especially to their nutritional and health benefits.</p>
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