Alfonso V. Botello

Pollution by petroleum hydrocarbons in sediments from continental shelf of Tabasco state, Mexico

The Wider Caribbean is potentially one of the largest oil producing areas in the world. Major petroleum production areas include Louisiana and Texas, USA; the Bay of Campeche, Mexico; Lake Maracaibo, Venezuela; and Gulf of Paria, Trinidad; all of which are classified as production accident high-risk zones. About 5 million of barrels are transported every day in the Caribbean, thus generating an intense tanker traffic. It has been estimated that oil discharges from tank washings within the Wider Caribbean could be as high as 7 million barrels/year. For all those reasons petroleum pollution is considered as the major environmental problem in the Wider Caribbean area and increasing day to day due to the use of petroleum as the main energy source. On the other hand, the continental shelf of Tabasco state actually represents one of the most productive areas for crude oil in the Gulf of Mexico. Sediments were collected from this area and analyzed for hydrocarbons.

Metal Pollution in Coastal Areas of Mexico

Metals are natural constituents of the earth core and can be widespread in all environments, forming part of sediments, rocks, animal and plant tissues, crude oil, hemoglobin, pigments, proteins, and enzymes. However, some of these metals, such as lead, chromium, and mercury, have been widely used in industrial and human activities, thus provoking an alteration in their geochemical balance and causing high concentrations, frequently three to four orders of magnitude higher than their natural concentrations. The aggressive industrialization and urbanization of coastal areas in Mexico have given rise to singular pollution problems in which such metals play an important role. Thus, this review identifies the main sources and quantifies the concentration levels of metals in the water, sediments, and organisms of coastal ecosystems (rivers, estuaries, coastal lagoons, Continental Shelf) in the Gulf of Mexico as well as the Mexican Pacific. The results show high concentrations of lead, chromium, and nickel in sediments and animal tissues from coastal states (Tamaulipas, Veracruz, Tabasco, and Campeche) in the Gulf of Mexico, especially in areas close to industrialized towns such as Tampico, Veracruz City, and Villahermosa. On the other hand, studies conducted on Mexican Pacific coasts indicate low levels of metals in sediments and organisms, an indication that the metal pollution here is closely tied to human, industrial, and oil activities.

Pesticides distribution in sediments of a tropical coastal lagoon adjacent to an irrigation district in northwest Mexico.

This work presents the content of organochlorine (OCs) pesticides in sediments of both, agricultural drains from the Irrigation District 076, El Carrizo, Sinaloa, and of the adjacent coastal lagoon ecosystem of Agiabampo-Bacorehuis-Jitzamuri, located in northwest Mexico. A questionnaire was applied to the farmers of this irrigation district, to evaluate the usage of pesticides and to determine if banned OCs are still used. Around 31 tons of active ingredients were applied in the autumn-winter cycle (1997-1998). There were eighteen different pesticides; of them 61% are insecticides, 28% herbicides, 6% fungicides and 6% other compounds. Around 73% of the pesticides applied are organophosphorus, carbamates and sulfur, OCs are still applied and represent 4% of the total. All the pesticides applied in the irrigation district are authorized in the Official Pesticide Catalog, nevertheless forbidden and restricted compounds were detected in the sediment samples. The presence of heptachlor, heptachlor epoxide, α-endosulfan, β-endosulfan, endosulfan sulfate, α-HCH, β-HCH, lindane, δ-HCH. aldrin, dieldrin, p,p′-DDT, p,p′-DDE and p,p′-DDD was recorded in the sediment sample. The analysis of the sediments suggest that the principal pesticides input to the coastal ecosystem is mainly through three of the seven agricultural drains, that collect the excess irrigation water and runoff from the district surface. A gradient of pesticide residues in sediments exists from the agricultural drains (52 ng OCs g−1 dry weight) to the Jitzamuri bay (32 ng OCs g−1 dry weight).

Petroleum Pollution in the Gulf of Mexico and Caribbean Sea

In 1976, IOC-UNESCO and UNEP convened a meeting in Port of Spain to analyze the marine pollution problems in the region, noting that petroleum pollution was of regionwide concern and recommended initiating a research and monitoring program to determine the severity of the problem and monitor its effects. The Wider Caribbean is potentially one of the largest oil-producing areas in the world. Major production sites include Louisiana and Texas in the U.S.; the Bay of Campeche, Mexico; Lake Maracaibo, Venezuela; and the Gulf of Paria, Trinidad. All these are classified as high-risk production accident zones. Main sources of petroleum pollution in the Wider Caribbean are production, exploitation, transportation, urban and municipal discharges, refining and chemical wastes, normal loading and unloading operations, and accidental spills. About 5 million barrels of crude oil are transported daily in the Caribbean, thus generating an intense tanker traffic. It has been estimated that oil discharges from tank washings within the Wider Caribbean could be as high as 7 million barrels/yr. The results of the Caribbean Pollution Regional Program (CARIPOL) conducted between 1980 and 1987 pointed out that significant levels of petroleum pollution exist throughout the Wider Caribbean, including serious tar contamination of windward exposed beaches, high levels of floating tar within the major current systems, and very high levels of dissolved and dispersed hydrocarbons in surface waters. Major adverse effects of this type of pollution include: high tar levels on many beaches that either prevent their recreational use or require very expensive cleanup operations, distress and death for marine life, and responses in the enzyme systems of marine organisms that have been correlated with declines in reproductive success. Finally, the presence of polycyclic aromatic hydrocarbons (PAHs) in tissues of important economic species has been reported, creating a risk for public health because of the potential carcinogenic effects.

The environmental legacy of the Ixtoc-I oil spill in Campeche Sound, southwestern Gulf of Mexico

The southwestern Gulf of Mexico constitutes an important subsystem within a Large Marine Ecosystem. Due to its high biodiversity, living resources and energy resources, this region is strategic in the national plans for social and economic development of Mexico. The discovery of fossil fuel reserves in the seabed of Campeche Sound in the 1970s promoted the rapid expansion of the national oil industry in offshore waters. Unfortunately, the accidental blowout of the most productive well (Ixtoc-I) in June of 1979, caused the first–world massive oil spill in a tropical marine environment. More than 3.4 million of barrels of crude oil were liberated in an ecosystem formerly renowned for its pristine conditions. In the aftermath of this dreadful accident, an immediate concern emerged not only for the oil acute effects but also for the long-term environmental consequences derived from the residual hydrocarbon compounds accumulated in coastal environments of the southern Gulf of Mexico. The attempts to assess the magnitude of the environmental damage were strongly precluded by the lack of pre-spill information. Natural variability in the ecosystem and oil weathering-factors contributed to attenuate the acute pollution effects that lasted nine months. However, the post-spill environmental alterations caused by the Ixtoc-I blowout still remain unanswered. The sinking of the Deepwater Horizon oil platform in the deep-waters of the northern Gulf of Mexico, in 2010 rekindled our concern for the great risk involved for human lives and the health of shallow and deep sea habitats. The authors of this contribution offer their views on this environmental riddle from their own perspective as direct witnesses of the Ixtoc-I environmental tragedy.

Organic carbon isotope ratios of recent sediments from coastal lagoons of the Gulf of Mexico, Mexico

Abstract The stable carbon isotope composition sedimentary organic carbon was determined in the sediments of seven coastal lagoons of the Gulf of Mexico, Mexico. For most of the lagoons the δ 13 C values for sediments ranged from −20.1 to −23.9%. Anomalously low values, −26.8 to 29.3%. were determined in sediments of two of the studied lagoons, probably due to the presence of organic carbon from anthropogenic sources, naturally absent in these environments. The δ 13 C values determined in the tissues of oysters collected at the same time in the different lagoons were very similar to those recorded in the sediments.

Polyaromatic hydrocarbons in oysters from coastal lagoons along the eastern coast of the Gulf of Mexico, Mexico

Analytical determinations and identification of polycyclic aromatic hydrocarbons (PAH) were made in oysters from lagoons and estuaries along the eastern coast of the Gulf of Mexico. Results show that the highest concentrations were in samples taken from lagoons in an oil-producing area. The total concentrations of the PAHs in the analyzed samples were surprisingly high for oyster tissues. Clearly, no single causative factor could adequately explain environmental data of this kind because of the possibility of accidental spillages and intermittent activities that could contribute to the distortion of the results.

Presence of aliphatic and polycyclic aromatic hydrocarbons in the atmosphere of Northwestern Mexico City, Mexico

In recent years, Mexico Citys atmosphere has suffered significant changes in several of its climatological features due to the fast growth of the city and to the gradual deterioration of its air quality. The most noticeable alterations are: an increase in air temperature, increase in rain precipitation and reduction of solar radiation, produced mainly by the presence of atmospheric aerosols, particles, dusts and toxic gases originated from industrial activity besides the emanation caused by fossil hydrocarbons combustion and the supply of natural sources. Among the organic compounds present in atmospheric particles, the saturated and aromatic hydrocarbons have outstanding importance due to their carcinogenic potential and its formation from different photochemical reactions. Thus, the observed changes in the physical factors that take place in the climatic system have reached magnitudes that work as harmful agents for the inhabitants of Mexico City producing discomfort and chronic diseases of the respiratory system.

Interannual variability of soft-bottom macrobenthic communities of the NW Gulf of Mexico in relationship to the Deepwater Horizon oil spill

A 3-year research program was undertaken to assess potential environmental disturbance caused by the Deepwater Horizon oil spill to the soft-bottom macrobenthic communities within Mexican waters of the northwestern Gulf of Mexico. Community properties and temporal/spatial variability were analyzed besides toxicant parameters such as hydrocarbons and trace-metals. Overall infaunal density increased, taxa proportion changed, and small-size opportunistic organisms prevailed throughout the study. Annual abundance-biomass comparison (ABC) curves revealed progressive stress scenarios from moderate to severe. Concentrations of vanadium, nickel, cobalt, PAHs and AHs increased gradually over time. However, low correlations between benthic density and biogeochemical variables were determined. Initially, sedimentary properties were the main drivers of benthic community structure; subsequently, nickel, vanadium and PAHs, indicative of anthropogenic effect, were highlighted. Interannual variability in the macroinfauna was attributed to the synergy of several environmental factors. Undoubtedly, compounds derived from fossil fuels had a significant disturbance role, but their source remains uncertain.