*4.2.2 Metals*

*Lagoon Environments around the World - A Scientific Perspective*

English that has a value of 1 ng g<sup>−</sup><sup>1</sup>

ERL, that is, 2.07 and 2.2 ng g<sup>−</sup><sup>1</sup>

since from 0.02 ng g<sup>−</sup><sup>1</sup>

**4. Discussion**

initially in the TLS since 2009.

**4.1 Physicochemical composition**

in these important systems.

alteration and of potential risk to human health since various benthic organisms of these coastal sites are for food consumption [47]. Another similar case is that which occurs for *p,p'*-DDT since in the sediments of the ALS, it exceeded the biological damage threshold established in 1.19 ng/gas well as a second ecotoxicological criterion, the ERL was known as the level of effect low by its acronym in

in this analysis was much higher than the environmental references TEL and

already been described, means that, in spite of the biogeochemical transformation of *p,p'*-DDT in *p,p'*-DDE, the benthic toxicity continues for this ecosystem that harbors several species of edible mollusks such as oysters and clams. It is worth mentioning the case of Dieldrin in the context of biotic damage since, despite not having presented large concentrations in the analyzed systems, its environmental reference concentrations are very low, evidencing the danger it has for organisms

The study and protection of coastal systems, such as coastal lagoons, wetlands,

Although Mexican coastal lagoons are important sites for fishing, aquaculture, the development of communities and that provide economic resources of great value, reports on increasing levels not only in nutrients, hydrocarbons, metals and pesticides two, that appear in the literature every day and lately plastics and micro-

and estuaries, should be a priority for countries that have benefited from an extensive coastal zone such as Mexico. However, the accelerated development and industrialization of these areas have led to processes of degradation and alteration

plastics that impact them and put at risk environmental and human health. The coastal system of Gulf of Mexico has different climate, morphology and complex river flow which discharges to the lagoons, resulting in wide natural physicochemical water composition, but it must be considered the high urban settlement with their economic activities as different industry that incremented the concentration of certain chemical compounds. This is the case of inorganic nutrients that in the present work included four coastal aquatic system (Tampamachoco, Mandinga, Alvarado and Terminos lagoons), all of them with a eutrophication conditions by high total nitrogen, total phosphorus and ammonium result of urban, agriculture and others economic activities, settlement in the margin of the river and lagoons and the residual water that are dispose to this system. This situation is in a great number of many lagoon system in the Gulf of Mexico; for example: la Mancha, Farallon, El Llano and El Verde located at the north of the Gulf of Mexico, in which were register high concentration of nitrogen,

phosphorus and ammonia that result in eutrophication two [40, 48].

The results on PAHs indicate that these compounds are widely distributed in coastal areas and are stored in lagoons, estuaries, and wetlands. There is abundant

; of this aromatic family, the *p,p'*-DDE reported

respectively for what was reported in ALS, as has

can cause harmful effects (ERL) so, this risk already exists

**14**

**4.2 Pollutants**

*4.2.1 Petroleum (PAHs)*

Comparing the concentrations of metals in the sediments listed in **Table 2**, the Yucateco and Mecoacan lagoons report high levels with respect to the three lagoons considered in this study. The Cd presented up to an order of magnitude higher (1.84 and 1.46 μg g<sup>−</sup><sup>1</sup> ), this shows that Cd has a lithological as well as anthropogenic origin. The Cr and Pb are up to 100% above the areas of this study (36.32 and 48.30 μg g<sup>−</sup><sup>1</sup> ), while Pb has a natural origin, by atmospheric transport, as well as anthropogenic. However, the V was the one that reported the highest concentrations in the Mecoacan lagoon with 18.78 μg g<sup>−</sup><sup>1</sup> . What is clear is that part of the Ni and V has their origin in the composition of the dominant oil in the area. These levels can be considered normal and expected, since there are oil wells in the vicinity of the Yucateco lagoon and Mecoacan lagoon. In **Table 2**, it is clearly observed how the variations in the concentrations of the metals analyzed are influenced by the


**Table 2.**

*Average levels of pollutants in sediments of the four lagoons analyzed.*

activities carried out in each of the surrounding areas, as well as the special and temporary hydrodynamic predominant according to the different seasons of the year [50, 51].
