*3.2.1.2 MLS*

*Lagoon Environments around the World - A Scientific Perspective*

and ammonium are high (**Table 1**).

tendency in time that have these compounds.

in order of decreasing followed fluorene (0.13 μg g<sup>−</sup><sup>1</sup>

**3.2 Pollutants**

*3.2.1.1 TLS*

0.29 μg g<sup>−</sup><sup>1</sup>

of 1.79 μg g<sup>−</sup><sup>1</sup>

(0.12 μg g<sup>−</sup><sup>1</sup>

tury in 0.58 μg g<sup>−</sup><sup>1</sup>

*3.2.1 Petroleum (PAHs)*

the Yucatan Peninsula, the lowlands of Tabasco and the highlands of Chiapas and Guatemala [35]. Three main rivers discharge their waters to the lagoon. The type of climate is warm sub-humid Amw [36] isothermal, with a rainy season from June to October, Northwinds from November to March and a dry season from April to June. It is influenced by extraordinary natural processes such as northerly and tropical storms and hurricanes [37]. The margins of the lagoon are covered by mangroves with a predominance of *Rhizophora mangle*, *Avicennia germinans* and *Laguncularia racemosa* [38, 39] and the seagrass *Thalassia testudinum* (**Figure 1**). Total nitrogen

Oil pollution and its derivatives are considered to be one of the biggest environmental problems in the Gulf of Mexico [40] and in its waters have been occurred the two largest oil spills at the sea, such as: the Ixtoc-1 well in the Campeche Sound and that of the Deepwater Horizon, off the coast of Louisiana, USA. Both affected significantly the diverse ecosystems of the coastal areas. Thus and in spite of the fact that the Mexican coastal lagoons settled on the margins of Veracruz, Tabasco, and Campeche, are highly productive and of high economic value. Analysis of petroleum hydrocarbons conducted in these lagoons showed important concentrations of aromatic hydrocarbons originating from the intense oil activities that develop along their coasts. In the present contribution, the updated available information on the levels of concentration of PAHs in sediments of the lagoons of Tampamachoco, Mandinga, Alvarado in the state of Veracruz and one of Terminos in Campeche is gathered. In the cases of the lagoons of Tampamachoco and Alvarado also sedimentary nuclei analysis were carried out, which give us a historical view of these pollutants for approximately 80 years old and in the same way the

The sediments of the TLS and the Tuxpan River, Veracruz, were evaluated during the end of July 2012. From the results of the 16 priority PAHs determined, the greater (1.30 μg g<sup>−</sup><sup>1</sup> ΣHAPs) was registered in the station located in front of the Thermoelectric Power Plant (CTPALM) and the minimum (0.02 μg g<sup>−</sup><sup>1</sup>

located in the north of the lagoon body. The analysis of a sedimentary core [7] in the TLS showed an average concentration of PAHs of the nucleus of 0.98 ± 0.38 μg g<sup>−</sup><sup>1</sup>

at the beginning of the last century (1908), until reaching the maximum

in 1999, and decrease towards the beginning of the twenty-first cen-

). The molecular profile in the eight analyzed strata, changed, of petro-

(2003) to show a new increase in 2010 with 0.84 μg g<sup>−</sup><sup>1</sup>

When analyzing the vertical distribution of the PAHs content, it was found that the historical pattern showed an increase from the basal level of the ΣPAHs of

pounds with the highest concentrations were, dibenzo[ah]anthracene (0.28 μg g<sup>−</sup><sup>1</sup>

genic origin in 1908, to be dominated by pyrolytic compounds and to a lesser extent by petrogenic from 1999 to the present time. It should be noted that the individual concentrations of PAHs in sediments were lower than the international sedimentary quality criterion (**Figure 3**), with less probability of causing adverse effects to the benthic community. Thus, it can be said that there is no risk derived from the intrinsic toxicity of the coastal sediments analyzed from this group of hydrocarbons.

) in site

. The com-

) and benzo[a]anthracene

.

),

**8**

In **MLS** was in which the highest values of PAHs were determined with a range of 2.2–18.2 μg g<sup>−</sup><sup>1</sup> (average 5.68 μg g<sup>−</sup><sup>1</sup> ). The compounds that stood out were chrysene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[a]anthracene, all of them considered of environmental concern. This lagoon receive directly the urban discharges of settlements south of the Port of Veracruz and refuses from steel and iron plant placed in its nearby.
