Heavy metal pollution monitoring using the brown seaweed Padina durvillaei in the coastal zone of the Santa Rosalía mining region, Baja California Peninsula, Mexico

Abstract

The coastal marine sediments near Santa Rosalía on the eastern coast of the Baja California Peninsula (Mexico) are heavily polluted by metals due to copper mining and smelting over the past century (up to 1984). The present study compares the accumulation of metals in the brown seaweed Padina durvillaei from the central segment of the coast of Santa Rosalía (polluted by Co, Cu, Mn and Zn) and from two segments north and south of the known "hot spot". The seaweed samples were collected in May and August 2004 and June 2005 at 13 stations located along the Santa Rosalía mining region. Heavy metal concentrations were measured by instrumental neutron activation analysis (Co and Fe) directly in dried homogenized subsamples or by flame atomic absorption spectrophotometry (Cd, Cu, Mn, Ni, Pb and Zn) after complete strong acid digestion of sub-samples. The means and standard deviations of the concentrations in dry tissues of Padina durvillaei specimens for all the studied metals and stations lie in the following sequence: Cd (3.6±1.6 mg kg −1 ) < Co (6.5±6.1 mg kg −1 ) < Pb (7.8± 6.2) < Ni (9.96±5.28 mg kg −1 ) < Cu (53±38 mg kg −1 ) < Zn (63±43 mg kg −1 ) < Mn (295±269 mg kg −1 ) < Fe (2243±2325 mg kg −1 ). This increase of the average concentrations was statistically significant. Principal Component Analysis showed that Factor 1 (36.46%) displays high positive loadings for Co, Cu, Mn and Zn, reflecting the influence of local anthropogenic pollution on the seaweed composition, while Factor 2 (26.91%) is important for Co, Fe and Ni and probably corresponds to the adsorption or accumulation of terrigenous elements of the regional origin, while Factor 3, with a high positive loading for Pb and a high negative loading for Cd, is probably controlled by local and regional anthropogenic input of Pb and episodic supply of Cd by local upwellings. The results of ANOVA for each element do not show any significant differences between the average concentrations for Cd, Fe, Ni and Pb in the seaweed of the three segments, or between the central and southern segments for Cu, Mn and Zn. Cobalt contents in the seaweed from the northern and central segments are, however, significantly different from the southern segment. This indicates that element concentrations in Padina durvillaei generally do not follow the drastic increases and gradients of Cu, Co, Mn and Zn contents detected in surface sediments. The apparent contradiction could be explained by a low geochemical mobility of these metals in the polluted sediments, composed mainly of stable residues of smelter wastes, with very low content of organic matter usually driving diagenetic mobilization of some metals into interstitial waters and then to the overlying water.

Biosorption Capacity for Cadmium of Brown Seaweed Sargassum sinicola and Sargassum lapazeanum in the Gulf of California

“…Differences in concentration of cadmium between the two species could result from differences in metabolic rates or, more likely, to the affinity of each species for cadmium. Our results ( Table 2) were above the average values reported for macroalgae (0.92±1.32 mg kg −1 ) from five regions throughout the world (Baoli and Congquiang 2004 -Figueroa et al 2009), which is contaminated by waste from copper mining. However, this value is lower than in brown and red macroalgae along the coast of Chile that is also contaminated by waste from copper mining, where Andrade et al (2006) reports 17.8 mg kg −1 in Ahnfeltiopsis sp.…”

Factor analysis and sequential extraction unveil geochemical processes relevant for trace metal distributions in fluvial sediments of a pyrite mining area, China

“…Consequently, the third factor shown by factor analysis could be related to chemical processes associated with Mn reduction/dissolution. Similar relationships between Co and Mn were also found in coastal marine sediments and urban-rural topsoil (Rodriguez-Figueroa et al 2009;Chen et al 2008). Moreover, a significant correlation between Tl and Mn was found in French agrosystems (Tremel et al 1997), and Jacobson et al (2005) also found that Mn oxides may play a dominating role in Tl retention by soils.…”

Metal mobility and bioaccumulation differences at lower trophic levels in marine ecosystems dominated bySargassumspecies

“…were all within the ranges previously reported for these and other macroalgae in the Gulf of California and along the west coast of the Baja California Peninsula, Cd: 0.03-4.60 mg g 21 , Pb: 0.1-30 mg g 21 , Cu: 0.5-82 mg g 21 , Zn: 2-96 mg g 21 and Fe: 140-2898 mg g 21 )(Huerta-Díaz et al, 2007;Jara-Marini et al, 2009;Rodríguez-Figueroa et al, 2009;Riosmena- Rodríguez et al, 2010;Patrón-Prado et al, 2011).Cadmium levels in Codium simulans were similar to findings in C. amplivesiculatum Setchell & Gardner and C. cuneatum Setchell & Gardner at sites with no or little influence of human activity but subject to natural influences, such as upwelling(Huerta-Díaz et al, 2007). Moderate upwelling has been reported in Bahía de la Paz(Jiménez-Illescas et al, 1997).…”