*3.2.2 Metals*

*Lagoon Environments around the World - A Scientific Perspective*

five and six-ring PAHs, as well as two and three-ring ones (which originate from petrogenic sources associated to drilling activities, such as oil extraction and oil

*Individual PAHs and ERL sedimentary quality criteria in the sedimentary core of TLS.*

Most of the PAHs in the sediments proceed from pyrolytic sources, while the sources of compounds consisting of two and three rings are of petrogenic origin. The total PAHs sum was mostly contributed to by compounds consisting of four benzene rings, namely chrysene. Despite slightly higher than ERL index concentrations for anthracene, acenaphthylene, fluorene and dibenzo[α,h]anthracene, the total PAH sum did not exceed that limit. It has to be pointed that human activities are very intense in the lagoon as fisheries, shipping port, storage of petroleum and

On the other hand, TELS has been intensively studied for organic and inorganic pollutants due to its importance as a fisheries center. Thus, Ref. [42] indicates the presence of PAHs in sediments and oysters of this lagoon, reported PAHs in oyster tissue and the predominance of alkylated compounds of medium and low molecular weight indicating a petrogenic origin attributed basically to off-shore oil activities. This lagoon it is located in front of the main oil wells in the Bank of Campeche were the most intense exploration and exploitation of crude

Another study of PAHs performed on fish tissue from the western zone of TELS, showed that its concentrations exceeded the values maximum recommended by

fish [1]. In recent years [2] evaluated dissolved PAHs and mention that in Boca del Carmen, were determined high concentrations of PAHs; as well as a bacterial community that degrades very abundant PAHs. This is a clear indication that the lagoon arrive at all times dissolved/dispersed PAHs from oil activities carried out in

) for the *Petenia splendida* cichlid

spills), was minor (**Figure 2**).

agriculture.

**Figure 3.**

*3.2.1.4 TELS*

oil takes place.

the Sonda de Campeche.

international regulation (greater than 40.0 μg g<sup>−</sup><sup>1</sup>

**10**

The investigations on metals in sediments that have been carried out in three of the main coastal lagoons of the Veracruz state, show significant results: the Cd registered similar concentrations for the TLS and MLS with values of 0.46 and 0.66 μg g<sup>−</sup><sup>1</sup> respectively, and these values were below the ERL that is 1.2 μg g<sup>−</sup><sup>1</sup> , levels that produce adverse biological effects in sediments [43]. On the other hand, the highest concentration of Cr was for the TLS with 20.52 μg g<sup>−</sup><sup>1</sup> , the concentrations for ALS and MLS registered similar values with 13 μg g<sup>−</sup><sup>1</sup> . The concentrations for the three lagoons were below the limit of the ERL which is 81 μg g<sup>−</sup><sup>1</sup> . The Cu values for MLS and ALS were 15.77 and 17.49 μg g<sup>−</sup><sup>1</sup> respectively. These also stayed below the ERL which is 34 μg g<sup>−</sup><sup>1</sup> . The Pb showed values for MLS and ALS of 23.37 and 27.49 μg g<sup>−</sup><sup>1</sup> , while for TLS they recorded lower values (11.42 μg g<sup>−</sup><sup>1</sup> ). The concentrations of this metal in the three lagoons remained below the ERL which is 46.7 μg g<sup>−</sup><sup>1</sup> . They report that Zn showed similar values for ALS and MLS with 55.81 and 56.14 μg g<sup>−</sup><sup>1</sup> respectively, and their concentrations were below the ERL which is 150 μg g<sup>−</sup><sup>1</sup> . The Ni was presented with values of 71.80 and 72.26 μg g<sup>−</sup><sup>1</sup> in the lagoons of ALS and MLS respectively, and which are above the ERL which is 20.9 μg g<sup>−</sup><sup>1</sup> . The enrichment of Ni in the surface sedimentary substrate is due to the contribution of urban discharges from urban discharges and industries that are close to the coastal areas where the present study was conducted (**Figure 4**) [1, 44].

Villanueva and Ramirez [6] carried out the determination of Cd, Cr, Ni, Pb and V in sediments of the TLS, collected in seven stations. The concentrations decreased in the following order Cr > Ni > Pb > V > Cd, where the latter has not increased since 2010. Although Cd and Pb did increase in 2012, the determined values did not exceed the ecological criteria of the minimum and maximum adverse conditions for the biota (ERL and ERM), while the levels of Ni decreased compared to 2010, since they have a direct influence of the terrestrial and riparian drainages, which present higher hydrodynamics and a greater mixture due to the salt wedge coming from the sea. Likewise, there were no specific changes in metal concentrations between the years 1985 and 1988, the period in which the Thermoelectric Power Plant was built and started to operate. In the period from 1996 to 2012, the concentrations of Cd, Cr and Pb showed slight increases, while the Ni showed variation. Similarly, Vazquez-Botello et al. [23] performed the analysis of a sedimentary core in this lagoon, which concludes that there is a tendency to increase from the oldest

**Figure 4.**

*Average concentrations of metals in superficial sediments of coastal lagoons of the Veracruz state.*

stratum (1908) with surface maximums, the values of Ni and Pb are below the concentrations reported in Literature for other coastal and lacustrine systems. The basal values of Cd (0.22 μg g<sup>−</sup><sup>1</sup> ), Cr (31 μg g<sup>−</sup><sup>1</sup> ), Ni (26 μg g<sup>−</sup><sup>1</sup> ) and Pb (12 μg g<sup>−</sup><sup>1</sup> ) were also determined. From previous reports, becomes clear that the atmospheric transport is one of the main sources of Pb towards the lagoons, rivers, and oceans; and this is reflected in its levels in the sediments of the lagoons studied. For which it is recommended to analyze sedimentary nuclei and determine the origin of it. Also, the Ni detected in the studied lagoons, has a mixed origin: one part is of lithological origin and another part from the urban discharges through the particulate solids, as well as through the use of fertilizers and the mining industry and steel, and whose concentration surpasses the ELR and ERM values proposed by Long et al. [43] to the up to 100%, causing enrichment of the sedimentary substrate analyzed.
