Organochlorine contaminants in sediments and factors influencing their distribution in the natural marine protected area in the gulf of Mexico.

The aim of this study was to determine the concentration of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in marine sediments of a natural marine protected area (NMPA), Veracruz Reef System (VRS), in the Gulf of Mexico (GoM). This NMPA represents one of the first coastal sites with port activity in Mexico, which causes a range of human activities that require adequate planning so as not to impact and destroy this marine protected area; In this sense, this work represents the first effort aimed at diagnosing the presence of organochlorine contaminants in reef sediments from the mainland, both from the adjacent port area and from more distant regions with dominant agricultural activities that ultimately affect this NMPA. Content of organic matter (OM), carbonates and grain-size composition were determined to investigate their influence on compounds distribution in the sediment through multivariate analysis. The potential risk represented by organochlorines concentrations was evaluated taking as reference Sediment Quality Guidelines (SQGs). Levels of ∑PCBs, ∑DDTs, ∑HCHs and ∑Cyclodienes ranged from 11.59 to 29.79, < 0.01 to 34.11, 22.10 to 102.80, and 17.21-104.45 ng g-1 dry weight (DW), respectively. The statistical analysis revealed that the content of mud and organic matter were the parameters that might influence PCBs distribution in the sediment while OCPs could be influenced by sand and carbonate. The theoretical risk assessment estimated with the results obtained showed that concentrations of lindane, endrin, dieldrin and p,p'-DDT could have an adverse effect on the reef benthic community and continued monitoring is required. The data obtained on the organochlorine contaminants (OCs) considered in this work will contribute to support the strategies proposed by the Mexican federal government entity to continue with the conservation and surveillance of this NMPA and thereby guarantee the least impact derived mainly from port and related agricultural activities.

210Pb geochronology and metal concentrations in sediment cores recovered in the Alvarado Lagoon system, Veracruz, Mexico.

Three sediment cores recovered from the Alvarado Lagoon System (ALS) in the Gulf of Mexico were used to reconstruct the history of metals and metalloids and their environmental importance. The sedimentary profiles were dated with 210Pb and verified with 137Cs. Maximum ages of 77 and 86 years were estimated. Sediment provenance was described by sedimentological and geochemical proxies. The chemical alteration index (CIA) and weathering index (CIW) revealed moderate to high intensity of weathering in the source area that is controlled tropical climatic conditions, runoff, and precipitation in the basin that feeds sediments to this coastal lagoon. The Al2O3/TiO2 ratios indicated that the sediments were derived from intermediate igneous rocks. The enrichment factor values revealed the lithogenic and anthropic contribution of metals and metalloids. Cd is classified under the category extremely severe enrichment; agricultural activities, fertilizers, herbicides, and pesticides containing Cd are expected to supply this metal to the ecosystem. Factor Analysis and Principal Components provided two main factors, terrigenous and biological origins; ANOVA indicated that there are significant differences between the cores for the parameters analyzed and revealed that there are differences in depositional environments between the recovery zones of the cores. The ALS presented natural variations associated with the climatic conditions, terrigenous input, and its relationship with the hydrological variations of the main rivers. The contribution of this work was to identify the magnitude of the natural component versus the human contribution, mainly of risk metals such as Cd, to support better management of the hydrological basin that affects the ALS.

Potential of the HSP70 protein family as biomarker of Crassostrea virginica under natural conditions (Ostreoida: Ostreidae)

The HSP70 proteins are used as exposure biomarkers, and the oyster Crassostrea virginica is considered as a bioindicator organism in environmental assessment. According to the season, the level of expression of the HSP70 family in wild oysters has not been characterized before. The aim of this work was to analyze the expression of the HSP70 family as an exposure biomarker using C. virginica gills from individuals and groups of oysters from the Tampamachoco Lagoon under natural conditions. Ninety oyster samples were collected at locations from the Tampamachoco Lagoon during the dry and "north winds" seasons. One group of oysters was maintained under laboratory conditions and exposed to thermal stress. The pH, temperature, salinity, and dissolved oxygen (DO2) were measured inside the brackish Tuxpam-Tampamachoco system. Salinity and DO2 were outside the limits recommended for brackish systems in both seasons. The electrophoresis and immunodetection assay of HSP70 were performed using proteins from oyster gills. The HSP73, HSP72 and HSP69 isoforms were expressed in dry season tissue samples, while only the HSP73 and HSP72 isoforms were detected in north winds season tissue samples and positive control tissue samples. The HSP73 isoform has not been previously reported in C. virginica. To evaluate the expression of HSP70 protein family at individual and group levels from wild animals, it is also important to determine a seasonal baseline expression.

Las proteínas HSP70 se utilizan como biomarcadores de exposición y el ostión Crasostrea virginica es considerado como un organismo bioindicador en evaluaciones ambientales. De acuerdo con la estación, el nivel de expresión de la familia de las HSP70 en ostiones silvestres no ha sido caracterizado. El objetivo de este trabajo fue analizar la expresión de la familia de las proteínas HSP70 como un biomarcador de exposición utilizando branquias de C. virginica de manera individual y grupal bajo condiciones naturales. Noventa muestras de ostión se recolectaron en un sitio dentro de la Laguna Tampamachoco durante las estaciones de secas y "nortes". Un grupo se mantuvo bajo condiciones de laboratorio y expuesto a estrés térmico. El pH, la temperatura, la salinidad y el oxígeno disuelto (DO2) se midieron dentro del sistema salobre Tuxpan-Tampamachoco. La salinidad y el DO2 estuvieron fuera de los límites recomendados para sistemas salobres en ambas estaciones. La electroforesis y el ensayo de inmunodetección se llevaron a cabo con branquias de ostiones. Las isoformas HSP73, HSP72 y HSP69 se expresaron en tejido de las muestras de la época de secas, mientras que solamente las isoformas HSP73 y HSP72 se detectaron en tejido de las muestras de época de nortes y control positivo. La isoforma HSP73 no ha sido reportada previamente en C. virginica. Para evaluar la expresión de la familia de las proteínas HSP70 a nivel individual y grupal de organismos silvestres es importante determinar una línea de base de expresión estacional.

Presence of Oil Mineral Aggregates (OMAs) in Surface Sediments from Mexico's Exclusive Economic Zone, NW Gulf of Mexico.

We assessed the presence and distribution of oil mineral aggregates (OMAs) in surficial sediments of Mexican waters in the NW Gulf of Mexico, their potential sources and their correlation with polycyclic aromatic hydrocarbons (PAH). In summer of 2010, OMAs were detected in three shallow sites. In winter of 2011, OMAs were observed in ten sites, two of them in the northernmost area at > 1500 m depth. These particles were possibly advected from the north Gulf and Mississippi area following the deep-water currents of the zone. The OMAs from shallower sites may reflect local pollution sources. PAHs displayed low concentrations in both surveys (from 0.01 to 0.7 µg g-1 in summer, and from 0.01 to 0.51 µg g-1 in winter), and showed rather a local origin. The expansion of the oil and port industry in the region is accountable for most of the OMAs detected.

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.

Pollution by organochlorine pesticides in Navachiste-Macapule, Sinaloa, Mexico.

The lagoon system of Navachiste-Macapule is located in northern Mexico, in the state of Sinaloa, with an area of 24,000 ha. The main economic activity in the area is agriculture, and the lagoon lies next to the irrigation district ID-063 which covers 116,615 ha. The purpose of this study is to evaluate the levels of pollution generated by organochlorine pesticides (OC) in the surface sediments of the lagoon and in the agricultural drains of the ID-063 that are supposedly transported into the system as a result of agricultural activities and runoff from adjacent land. For this, between 2006 and 2007, 45 surface sediment samples were collected (warm dry, rainy and cold dry) from 15 sampling sites, during the three climatic seasons. Of these, eight were located inside the lagoon in marine conditions (salinity >31 PSU) and seven in the agricultural drains of the ID-063 in freshwater conditions (salinity <5 PSU). The average concentration of the OC in the sediments was 44.75 ng g(-1), among which the group of the alicyclic compounds presented the greatest concentrations. The average value of the total organic carbon (TOC) in the sediments of the system was 0.90%. The sediments collected inside the lagoon had an average OC concentration of 18.97 ng g(-1), and the predominant type of sediment was fine to very fine sand. The average OC concentration in the sediments collected in the agricultural drains was 75.69 ng g(-1), where fine sediments (silt) were predominant. The presence of methoxychlor, endrin and heptachlor suggested that these compounds were continuously used in the system, even though their use is forbidden in Mexico.

Organochlorine pesticides in lacustrine sediments and tilapias of Metztitlan, Hidalgo, Mexico

The organochlorine pesticides (OP) are very stable molecules, due to this stability; they are very resistant in the environment and highly related to fat tissues with a wide diffusion property and an average time life higher then 10 years. We studied sediments (November 2001, April and June 2002) and organisms collected in April and July (2002) from the lacustric zone of Metzitlán, Hidalgo, Mexico. The analysis was performed according to UNEP/IAEA (1982) (sediments) and UNEP/FAO/IOC/IAEA (1986) (organisms) methods. Three chemical families of organochlorine pesticides were identified and analyzed to determine posible toxicological risk. The principal organochlorine compounds found in sediments were g-HCH, d-HCH, p,p’-DDT and the endosulfan sulfate; these xenobiotics come from agriculture lands near the river and lake, used intensively, and most probably carried by the rain and rain flows into the main water body. In the tilapias tissue, p,p’-DDD y d-HCH were detected. The average concentrations of organochlorine pesticides in sediments were within the internacional limits for freshwater benthonic fauna, although lindane (g-HCH) was near the limit. The fish were above the criteria established in the local legislation (NOM-027-SSA1-1993 y NOM-028-SSA1-1993). Rev. Biol. Trop. 56 (3): 1381-1390. Epub 2008 September 30.

El presente trabajo se llevó a cabo en la cuenca lacustre de Metztitlán, Hgo. Se realizaron tres colectas de sedimentos recientes en noviembre (2001), abril y julio (2002) y dos colectas para organismos en abril y julio (2002). Los análisis se hicieron siguiendo la metodología para sedimentos propuesta por UNEP/IAEA (1982) y para tejido de organismos por UNEP/FAO/IOC/IAEA (1986). Se identificaron y cuantificaron tres familias químicas de plaguicidas organoclorados, para determinar el posible riesgo toxicológico de los sedimentos y de organismos en capturas comerciales. Los principales compuestos clorados en sedimentos fueron el g-HCH, d-HCH, p,p’-DDT y el sulfato de endosulfán; estos xenobióticos provienen de las zonas de cultivos aledañas al río y al lago, con un uso intensivo, probablemente transportados por lluvias y descargas fluviales hacia el cuerpo lacustre y en el tejido de organismos se detectaron principalmente el p,p’-DDD y d-HCH. Las concentraciones promedio de plaguicidas clorados en sedimentos no rebasaron los límites establecidos en los criterios de calidad ambiental internacionales para provocar efectos nocivos en la biota bentónica de los sistemas dulceacuícolas, aunque de manera puntual el lindano (g-HCH) registró niveles cercanos a dichos límites. Las tilapias rebasaron los criterios existentes en las Normas Oficiales Mexicanas (NOM-027-SSA1-1993 y NOM-028SSA1-1993).

Organochlorine pesticides in lacustrine sediments and tilapias of Metztitlan, Hidalgo, Mexico.

The organochlorine pesticides (OP) are very stable molecules, due to this stability; they are very resistant in the environment and highly related to fat tissues with a wide diffusion property and an average time life higher then 10 years. We studied sediments (November 2001, April and June 2002) and organisms collected in April and July (2002) from the lacustric zone of Metzitlán, Hidalgo, Mexico. The analysis was performed according to UNEP/IAEA (1982) (sediments) and UNEP/FAO/IOC/IAEA (1986) (organisms) methods. Three chemical families of organochlorine pesticides were identified and analyzed to determine posible toxicological risk. The principal organochlorine compounds found in sediments were gamma-HCH, delta-HCH, p,p'-DDT and the endosulfan sulfate; these xenobiotics come from agriculture lands near the river and lake, used intensively, and most probably carried by the rain and rain flows into the main water body. In the tilapias tissue, p,p'-DDD y delta-HCH were detected. The average concentrations of organochlorine pesticides in sediments were within the internacional limits for freshwater benthonic fauna, although lindane (gamma-HCH) was near the limit. The fish were above the criteria established in the local legislation (NOM-027-SSA1-1993 y NOM-028-SSA1-1993).

Effect of cadmium, chromium, lead and metal mixtures on survival and growth of juveniles of the scallop Argopecten ventricosus (Sowerby II, 1842).

The effects of Cd, Cr, Pb and their mixtures on the growth and sensitivity of the scallop Argopecten ventricosus were analyzed in this study. Cadmium showed to be more toxic metal to juveniles (96 hour median lethal concentration (LC(50)) = 0.396 mg Cd/L), followed by lead (LC(50) = 0.830 mg Pb/L) and chromium (LC(50) = 3.430 mg Cr/L). Cadmium toxicity was 8 times higher than chromium and 2 times than lead. The most toxic combination was Cd + Cr + Pb. (LC(50) = 0.302 mg/L). Based on toxic units analyses (T.U.), a synergistic effect was observed for Cr + Pb and Cd + Cr + Pb. (T.U. = 0.374; T.U. = 0.403), and antagonic effects for Cd + Cr and Cd + Pb (T.U. = 1.26; T.U. = 1.43) respectively. The level of effect (from high to low) on the growth of A. ventricosus juveniles was: Cd > Cd + Cr + Pb > Cr > Pb. The EC(50) (metal concentration where a reduction of 50% growing rate is observed) obtained were: Cd = 0.018 mg/L, Cd + Cr + Pb = 0.104 mg/L, Cr = 0.51 mg/L and Pb = 4.21 mg/L. These results suggest that A. ventricosus juveniles are more sensitive to these metals in comparison to other juveniles from other bivalve species (e.g., A. irradians, Mytillus edulis, Crassostrea virginica).