Vanadium and Cadmium in Water from the Perdido Area, Northwest of the Gulf of Mexico: 2 years' Monitoring and Current Status.

Surface water samples from the Perdido study area presented Cd and V concentrations similar to those reported internationally for waters with: (1) fossil fuel extraction, processing and burning, and (2) sites polluted by anthropogenic wastewater. Results showed an order of magnitude increase in time for Cd, therefore, no general average value was established. For V, however, results of this study suggest a general average value of 1.4 µg L-1 for the area. The observed spatial variation of concentrations could be the result of: (1) temporal variation of external inputs to the area, and coincide with previously reported hydrodynamic patterns of dispersion related to significant river contributions and accumulation areas indicative of eddy circulation or fronts. The Perdido area showed Cd and V concentrations in surface water reflective of anthropogenic impacts, while its spatial and temporal variation could depend significantly on the hydrodynamics of the area.

Spatial and Temporal Distribution of Trace Metals in Shallow Marine Sediments of the Yucatan Shelf, Gulf of Mexico.

We investigated the spatial and temporal distribution of V and Cd in surface sediments of the Yucatan Shelf to establish current average values for the area. V and Cd concentrations are similar to those reported internationally for limestone rocks and surface marine sediments. The observed variability of V concentrations between cruises may be the result of changes in ocean current direction in summer (SW-S) and strong prevailing winds in autumn (N-NE). In addition to the hydrodynamics described above, Cd variations may also be associated with inputs of particulate material by upwelling events and subsequent transport and distribution to the shelf by the Yucatan Channel current (autumn). Considering that both metals showed significant spatial and temporal differences, a range of values for V (0.4-1.5 µg g-1) and Cd (0.05-0.2 µg g-1) are proposed as baseline reference for sediments of the Yucatan Shelf.

Vanadium and Cadmium in Shallow Marine Sediments: Spatial and Temporal Behavior in the Tamaulipas Continental Platform, Gulf of Mexico, Mexico.

This study analyzed 27 surface sediment samples from the Tamaulipas Continental shelf to determine the spatial-temporal distribution of V and Cd (spring-summer 2016; summer 2017). Average V concentrations (99 ± 18 mg g-1) were similar to that previously reported values for the area, while average Cd concentrations reflect uncontaminated sediments at surface level of the shelf. Inputs of V and Cd may be related to hydrocarbon and anthropogenic contributions from South and North of the Gulf of Mexico. The variability shown by both elements results from the hydrodynamics and hydrology of the area produced by local currents, eddies of the Loop Current, resuspension of fine sediments and contribution of terrigenous material. Considering that both metals showed significant differences (Shapiro-Wilk, p = 0), baseline concentrations could not be established, instead a reference interval of 79-122 µg g-1 for V and 0.121-0.258 µg g-1 for Cd in sediments from the Tamaulipas platform is suggested.

Spatial and Temporal Variations of Vanadium and Cadmium in Surface Water from the Yucatan Shelf.

Surface water samples from the Yucatan shelf presented Cd concentrations similar to those reported internationally for non-polluted coastal and marine waters. V concentrations, on the other hand, fall within the range of anthropogenically polluted waters (25% of the sampling sites). In the study area, the probable sources of V could be: (1) carbonate sediments leaching V into the water column and co-transported with fine sediments resuspending as a result of the complex hydrodynamics in the area or, (2) accidental spills from cargo ships transporting oil between the Atlantic and the Gulf of Mexico. Significant spatial and temporal differences were found for both metals; therefore, a regional interval concentration is suggested for V from 1.28 to 1.84 µg L-1 and Cd from 0.003 to 0.09 µg L-1. These differences could primarily be the result of the observed hydrology and hydrodynamics created by the Yucatan current, submarine groundwater discharges and upwelling.

Brominated Flame Retardants in Sediments of Four Coastal Lagoons of Yucatan, Mexico.

We examined the sediments of four coastal lagoons (Ria Lagartos, Bocas de Dzilam, Laguna de Chelem and Ria Celestun) from the state of Yucatan, Mexico, for three widely used commercial polybrominated diphenyl ethers formulations (penta-, octa- and deca-BDE). The most commonly found congeners in all four lagoons were BDEs 47, 99 and 100 (all in the penta-BDE formulation) and BDE209 (deca-BDE formulation). The greatest variety and highest concentrations of brominated flame retardants were found in Ria Lagartos, which also showed the highest BDE 100 concentration (24.129 ng/g). Hexabromocyclododecane was found in all lagoons, but at lower concentrations than those of the various polybrominated diphenyl ethers. Dispersal routes of these compounds are discussed, such as a ring of sinkholes (cenotes) adjacent to the lagoons. Moreover, electronic waste is a serious problem because municipal landfills have been the primary disposal method for these wastes and therefore represent a reservoir of brominated fire retardants.

Expression of metallothionein type 2 and 3 genes in Prosopis glandulosa leaves treated with copper.

For a better understanding of the strategies that are used by Prosopis glandulosa in heavy metal tolerance, the present study evaluated the gene expression of three metallothioneins (MTs; PgMt2-1, PgMt2, and PgMt3) in plants exposed to sub-lethal concentrations of copper. The PgMt2-1, PgMt2, and PgMt3 sequences were homologous to the MT type 2 (isoform 1), Mt2, and Mt3 sequences of other plant species found in GenBank. A reverse transcriptase-polymerase chain reaction showed that treatment with 100 mM Cu2+ induced a significant increase in PgMt2 and PgMt3 expression during the first 4 h of exposure compared to that of PgMt2-1. However, after 8 h of exposure, the expression levels of PgMt2 and PgMt3 were significantly lower than those of PgMt2-1. PgMt transcript levels only increased significantly during the first hour after exposure to copper, suggesting that PgMts could play a key role in the plant's detoxification mechanism. However, additional studies are required to confirm MTs as a mechanism of heavy metal tolerance and accumulation in this species.

Petroleum hydrocarbons, fluorescent aromatic compounds in fish bile and organochlorine pesticides from areas surrounding the spill of the Kab121 well, in the Southern Gulf of Mexico: a case study.

In October 2007, a light crude oil spill took place in the off shore Kab121 oil well, 32 km north of the mouth of the Grijalva River, Tabasco, Mexico. In order to estimate the possible effects of oil spill on the biota in the area surrounding the spilled well, the level of different fractions of petroleum hydrocarbons were measured in fish, as well as the concentration of some chlorinated hydrocarbons and PCBs. The organisms examined were cat fish (Ariopsis felis), in addition fluorescent aromatic compounds in bile, the contaminants above mentioned and their relationship with cyotochrome P-450 and Ethoxyresorufin-O-deethylase, Glutathion-S-Transferase and catalase activities in liver were determined. The concentration of most pollutants were low, except PAHs. Spatial distribution of these compounds, as well as most biomarkers, reflected the highest exposure of fish to pollutants in the area adjacent to well, as well as in the proximity of rivers. The profile of exposure to this environment was chronic in nature and not temporary.

The influence of radical architecture on cadmium bioaccumulation in the black mangrove, Avicennia germinans L.

Two groups of Avicennia germinans plants with differences in the radical architecture were exposed under hydroponic conditions to 95ppm of cadmium (Cd) for a period of 24h. Later, Cd concentration in roots, stems and leaves was determined by graphite furnace atomic absorption spectrophotometry. Our results showed that, for both groups of plants, the roots accumulated higher concentration of Cd as compared to stems and leaves, though, the plants of group B displayed enhanced radical architecture, better growth performance, and lower Cd concentration as compared to plants of group A. In contrast, low values of leaves/roots Cd transportation index, and bioaccumulation factor were found in plants of group B. These results suggest that the higher radical architecture developed in plants of group B might better adjust the uptake of Cd as a result of an integrated network of multiple response processes for instances, production of organic acids, antioxidative replay, cell-wall lignification and/or suberization. Further studies will be focused in understanding the role of the radical system in mangrove plants with the rhizosphere activation and root adsorption to soil Cd under natural conditions.

Pollutants and biomarker responses in two reef fish species (Haemulon aurolineatum and Ocyurus chrysurus) in the Southern Gulf of Mexico.

The environmental quality differences between two groups of reefs in the Veracruz Reef System were evaluated. The North group of reefs is very close to Veracruz, an urban and port zone, whereas the South group is more isolated, with minor anthropogenic disturbances. To prove the hypothesis that the North group is more affected by anthropogenic activities, the concentrations of hydrocarbons in liver, metals and metalloids such as Se, As, Ba, Cd, Hg and V in muscle, and PAH metabolites in bile were evaluated, and related to biomarkers (transcript abundance of cytochrome P4501A, Vitellogenin, and Glutathione-S-transferase) in two species of fish: Haemulon aurolineatum and Ocyurus chysurus. H. aurolineatum presents the highest concentrations for many pollutants, but O. chysurus shows the most significant differences in pollutant concentrations and biomarkers between the two reef groups, suggesting that this species could be used as a sentinel in future studies in the Gulf of Mexico.

Toxicity of sediments from Bahía de Chetumal, México, as assessed by hepatic EROD induction and histology in nile tilapia Oreochromis niloticus.

The effect of environmental pollutants present in sediments obtained from Bahía de Chetumal, a bay on the border between Mexico and Belize, was studied in nile tilapia (Oreochromis niloticus) intraperitoneally injected with sediment extracts from six different sites of the Bay. Sediment samples used for the study contained a variety of organic chemicals such as organochlorine pesticides, polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs). Total cytochrome P-450 and EROD activity were measured in fish liver. Haematological and histological analyses were also carried out. Hepatic P-450 content in treated fish increased from 43 to 240%, and EROD activity from 85 to 160% compared to controls. Extracts from two sampling sites inhibited EROD activity. There were positive significant correlations between P-450 content and the levels of PCBs 44 and 128. EROD activity correlated to HCB, op'-DDE, pp'-DDE, pp'-DDD, mirex and PCB 18 concentrations. Blood examination showed cell degeneration and binucleated leukocytes with abnormal chromatin. Extract treatment also resulted in foci of hyperplasia on the basement of gill lamellae, hypertrophy and oedema in gills and liver necrosis. Control fish showed no abnormalities. The results demonstrate that sediments from Bahía of Chetumal have the potential to cause histopathological, haematological and biochemical alterations in fish. The administration of sediment extracts to fish may serve as a useful test to screen the toxicity of sediments from different areas.

Persistent organic pollutants and histological lesions in Mayan catfish Ariopsis assimilis from the Bay of Chetumal, Mexico.

Livers of catfish (Ariopsis assimilis) from the Bay of Chetumal were analyzed for organochlorine compounds and hydrocarbons as part of a study to diagnose the environmental health of the Bay after a catfish mass mortality that occurred in 1996. The presence of histological lesions in several organs of the fish as result of chemical exposure was also evaluated. The concentrations of organic pollutants found in the Bay may be considered high if compared to the levels reported for sites affected by chemical pollution. High prevalences of cellular alteration histopathologies were found in liver, including hepatic tumors. The presence of some lesions may be related statistically to environmental pollution in the Bay, specially with chlorinated compounds.

The Pb-hyperaccumulator aquatic fern Salvinia minima Baker, responds to Pb(2+) by increasing phytochelatins via changes in SmPCS expression and in phytochelatin synthase activity.

The relationship between accumulation of Pb(2+) and the activation of chelation and metal sequestration mechanisms mediated by phytochelatins (PC) was analyzed in the Pb(2+) hyperaccumulator aquatic fern Salvinia minima, after exposure to 40microM Pb(NO(3))(2). The tissue accumulation pattern of lead and the phytochelatin biosynthesis responses were analyzed in both, S. minima submerged root-like modified fronds (here named "roots"), and in its aerial leaf-like fronds ("leaves"). S. minima roots accumulated a significantly higher concentrations of Pb(+2) than leaves did. Accumulation of Pb(2+) in roots was bi-phasic with a first uptake phase reached after 3h exposure and a second higher uptake phase reached after 24h exposure. In leaves, a single delayed, smaller uptake phase was attained only after 9h of exposure. In roots lead accumulation correlated with an increased phytochelatin synthase (PCS) activity and an enhanced PC production. A higher proportion of polymerized PC(4) was observed in both tissues of exposed S. minima plants relative to unexposed ones, although a higher concentration of PC(4) was found in roots than in leaves. PCS activity and Pb(2+) accumulation was also higher in roots than in leaves. The expression levels of the S. minima PCS gene (SmPCS), in response to Pb(2+) treatment, were also evaluated. In S. minima leaves, the accumulation of Pb(2+) correlated with a marked increase in expression of SmPCS, suggesting a transcriptional regulation in the PCS activation and PC accumulation in this S. minima tissue. However, in roots, the basal expression of SmPCS was down-regulated after Pb(2+) treatment. This fact did not correlate with the later but strong increase in both, PCS activity and PC production; suggesting that the PC biosynthesis activation in S. minima roots occurs only by post-translational activation of PCS. Taken together, our data suggest that the accumulation of PC in S. minima is a direct response to Pb(2+) accumulation, and phytochelatins do participate as one of the mechanism to cope with Pb(2+) of this Pb-hyperaccumulator aquatic fern.

Preliminary studies of biochemical changes (ethoxycoumarin O-deethylase activities and vitellogenin induction) in two species of shrimp (Farfantepenaeus duorarum and Litopenaeus setiferus) from the Gulf of Mexico.

Several investigations have demonstrated that the increase in chemicals in the environment may have caused effects on aquatic life and wildlife. The impact from oil production activities on the benthic community structure and shrimp (Farfantepenaeus duorarum and Litopenaeus setiferus) biochemical markers were studied in the Gulf of Mexico, which is heavily contaminated by polycyclic aromatic hydrocarbons and heavy metals. Shrimp were collected from a control area and from an area close to oil production platforms during October and November 2002. There was no spatial difference in exposure and response probably because shrimp migrate, as results did not show significant differences in cytochrome P4501A (as measured by ethoxycoumarin O-deethylase (ECOD) metabolism) between the two sites. In October, shrimp ECOD activities were higher and statistically different from those measured in the samples taken in November. As for ECOD activities, with the concentration of vitellogenin as another biomarker, there were no differences between the shrimp collected from the control area and the shrimp collected on the oil production platforms. In this case the concentrations were higher in shrimp collected in November vs. shrimp collected in October. However, there are significant correlations between contaminants and responses (biomarkers), indicating an effect of pollution. One of the most important considerations brought up by this kind of study is that, although the majority of groups studying the effects of endocrine disruption have focused almost exclusively on human health or vertebrate wildlife-related issues, it is necessary to increase research focused on understanding the function of hormones in invertebrate species exposed in the field to different kinds of pollutants.

Effect of pyrene on hepatic cytochrome P450 1A (CYP1A) expression in Nile Tilapia (Oreochromis niloticus).

The effect of pyrene on the regulation of the gene expression of cytochrome P4501A ( CYP1A) was studied in tilapia (Oreochromis niloticus), a tropical fish of great ecological and economical importance. To evaluate CYP1A mRNA, tilapia CYP1A cDNA was cloned, sequenced, and compared with those CYP1A reported sequences in the GeneBank DNA database. The top seven matches corresponded to CYP1A from other teleosts. Hepatic CYP1A mRNA levels showed a significant increase at day 1 after pyrene injection (20 mg kg(-1) body weight [BW]), and this CYP1A mRNA levels did not return to basal levels for up to 5 days. The immunoblot analysis of CYP1A protein levels using polyclonal rabbit-anti-trout antibodies in the liver of pyrene-treated (20 mg kg(-1) BW) tilapias showed a 1.9-fold increase at day 3 after injection. Ethoxyresorufin- O-deethylase (EROD) activity increased 18-fold with respect to control fish at day 3 after injection. CYP1A protein and EROD activity remained increased for 5 days after a single pyrene IP administration. Similarly, the highest concentration of 1-hydroxypyrene (1-OH pyrene) in bile was observed in fish sacrificed at day 3 after injection. EROD activity and 1-OH pyrene concentration showed a statistically significant correlation (r = 0.85) according to the Spearman test, suggesting the participation of this cytochrome in the biotransformation of pyrene.