Global deposition of potentially toxic metals via faecal material in seabird colonies.

Seabirds are known to play an important role in the geochemical cycling of macronutrients; however, their role in cycling elements of environmental interest has not been investigated. Guano is an important source of marine-derived nutrients and trace metals in seabird nesting areas, but most of the available information on this topic is derived from local studies. In the present study, we used a bioenergetic model to estimate the amounts of cadmium (Cd), mercury (Hg) and lead (Pb) that are deposited via faecal material in seabird colonies worldwide.

Heavy metal concentrations in the Pacific sharpnose shark Rhizoprionodon longurio from the Santa Rosalia mining zone, Baja California Sur, Mexico.

Rhizoprionodon longurio is an important commercial species captured in an area with heavy metal presence due to the mining waste from Santa Rosalia, Gulf of California, and levels of heavy metals in its muscle remain unknown. This study aimed to investigate whether contamination levels are below the limits allowed for human consumption and to prevent health damage. Concentrations of essential (Cu, Fe, Mn, and Zn) and non-essential (Ag, Cd, and Pb) trace elements were determined in fifty-seven muscle samples of R.

Sediment trace metal levels in the Ojo de Liebre Lagoonal Complex (Baja California, Mexico), a marine wildlife protected area.

Surficial sediment quality in the Ojo de Liebre Lagoon (OLL), Mexico, was evaluated via five geochemical indices. Results indicate that concentrations of the elements Ag, As, Cu, Fe, Mn, Mo, Ni, Sb, U, V and Zn do not exert adverse biological effects in this ecosystem. However, minor enrichment was observed for Ba (mean ± SD: 1.

Seabird colonies as important global drivers in the nitrogen and phosphorus cycles.

Seabirds drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil, sediment, and water eutrophication (hereafter termed ornitheutrophication). Here, we report worldwide amounts of total nitrogen (N) and total phosphorus (P) excreted by seabirds using an inventory of global seabird populations applied to a bioenergetics model. We estimate these fluxes to be 591 Gg N y and 99 Gg P y, respectively, with the Antarctic and Southern coasts receiving the highest N and P inputs.

Biosorption removal of benzene and toluene by three dried macroalgae at different ionic strength and temperatures: Algae biochemical composition and kinetics.

Release of low-molecular aromatic hydrocarbons (HC) into natural waters brings severe consequences to our environment. Unfortunately very limited information is available regarding the treatment of these pollutants. This work evaluated the use of brown, green and red macroalgae biomass as biosorbents of benzene and toluene, two of the most soluble HC.

Calibration of handheld X-ray fluorescence (XRF) equipment for optimum determination of elemental concentrations in sediment samples.

Handheld X-ray fluorescence spectrometers (XRFs) represent a more practical, efficient and economic tool to determine the elemental composition of solid inorganic and organic samples than conventional analytical techniques. The objective of this work was to demonstrate that handheld XRFs could be a precise, accurate and reliable tool to analyze up to 27 different elements. This objective was accomplished through the optimization of an empirical calibration curve that, in addition to include certified reference materials (CRM), it also introduced new approaches, such as the use of solid CRM mixtures and combinations of organic and inorganic matrices.

Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.

Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors.

Trace metal enrichments in nearshore sediments and accumulation in mussels (Modiolus capax) along the eastern coast of Baja California, Mexico: environmental status in 1995.

The biogeochemistry of trace metals in nearshore sediments and mussel was studied at 15 stations along a 1000 km long transect paralleling the west coast of the Gulf of California (GOC). Total trace metal (Me) and enrichment factor (EF(Me)) values in sediments were low due to negligible anthropogenic influence in the region. Past copper mining, however, near Santa Rosalia caused concentrations of Pb, Mn, Co, Zn and Cu which were 10-3.

Historical trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in three dated sediment cores from Mexico.

This paper describes the first report of dioxins and furans (PCDDs/Fs) in sediment cores from Mexico. Sedimentation rates and vertical fluxes were estimated using (210)Pb dating. Two cores correspond to marine sediments and one to an endorheic lake.

Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico.

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)sample ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors.