Potentially toxic elements and biochemical components in surface sediments of NW Mexico: An assessment of contamination and trophic status.

Concentrations of Potentially Toxic Elements (PTEs) were determined in sediments from Santa María La Reforma (SAMARE) coastal lagoon and Mocorito River, Mexico. Furthermore, biochemical composition of organic matter in sediments was analyzed to assess their trophic status. The PTEs concentrations followed the order Fe > Pb ∼ Zn > Cr ∼ Cu > Ni ∼ As ∼ Co > Cd. Except for As, PTEs showed correlation between them indicating a common source. As and Pb were above the threshold levels of toxic effect, but they did not exceed the levels of probable effect for biota. Metals were correlated with carbohydrates and As with lipids. Low protein/carbohydrate ratios suggest that decomposed detritus of nitrogen-rich algae as well as fresh mangrove litter can be present. These biochemical proxies suggest that meso-oligotrophic conditions prevail in SAMARE. Considering that fishing activities are practiced and that the northern portion of SAMARE was classified as a RAMSAR site, the information presented is useful to generate strategies for the management of this ecosystem. • Except for As, the PTEs showed correlation among them indicating a common source. • Arsenic and Pb concentrations were above the threshold levels of toxic effect. • The PTEs were correlated with carbohydrates main component of labile organic matter. • Low PRT/CHO ratios suggest a mixture of nitrogen-rich algae and mangrove residues. • These biochemical proxies suggest that meso-oligotrophic conditions prevail in SAMARE. [ABSTRACT FROM AUTHOR]