Variaciones morfológicas de la concha del mejillón choro, Modiolus capax, en dos poblaciones silvestres del suroeste del Golfo de California: Morphological variations of horsemussel shell, Modiolus capax, in two wild populations at southwestern Gulf of California

La forma y crecimiento de la concha de los moluscos bivalvos varía entre y dentro de cada especie, en respuesta a numerosos factores bióticos y abióticos. Se evaluaron los índices biométricos y relaciones morfométricas de la concha de dos poblaciones del mejillón Modiolus capax en el suroeste del Golfo de California. Se colectaron 60 mejillones de Santa Rosalía (SR) y Bahía de La Paz (LP) en cada estación anual, desde verano 2019 a verano 2020. La temperatura del agua, oxígeno disuelto, pH, profundidad y transparencia se determinaron en cada muestreo por localidad. Los mejillones de SR fueron más grandes y pesados, con la forma de su concha más compacta y convexa. Las interacciones morfométricas de las dimensiones de la concha para las dos poblaciones fueron lineales. Las relaciones de la altura/longitud y altura/ancho de la concha resultaron en un crecimiento relativo de tipo alométrico positivo, mientras que la longitud/ancho de la concha presentó alometría negativa. El mayor coeficiente de correlación se obtuvo para la interacción altura/ancho de la concha en ambas poblaciones. La interacción más fuerte en SR y LP se encontró durante invierno 2019 y otoño 2019, respectivamente. Las relaciones morfométricas para el total de las poblaciones mostraron el mismo patrón que las obtenidas por estación anual. Los resultados revelan diferencias en talla, morfología y morfometría de la concha entre las dos poblaciones de M. capax, lo que refleja una situación de estrés y/o adaptación de la especie a las condiciones de cada lugar

Geoquímica de los oligoelementos, elementos mayores y elementos de las tierras raras, en los sedimentos marinos del distrito minero de Santa Rosalía, B.C.S., México

IMPRESO Y PD

Niveles de contaminación por metales pesados en la zona costera de Santa Rosalía: sedimentos y macroalgas

IMPRESO Y PD

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

Heavy metal concentrations in brown seaweeds Padina durvillaei, collected in May 2004, August 2004 and June 2005 in the 13 stations located along the Santa Rosalía copper mining region on the eastern coast of the Peninsula of Baja California, were measured by instrumental neutron activation analysis (Co and Fe ) directly in dried homogenized subsamples or by flame atomic absorption spectrophotometry after complete strong acid digestion of subsamples (Cd, Cu, Mn, Ni, Pb and Zn). On a basis of the mean concentrations in dry tissues of Padina durvillaei from all stations the studied metals present the following sequence: Cd (3.6 mg kg-1) < Co (6.5 mg kg-1) < Pb (7.8 mg kg-1 ) < Ni (9.96 mg kg-1) < Cu (53 mg kg-1) < Zn (63 mg kg-1 ) < Mn ( 295 mg kg-1 ) < Fe (2243 mg kg-1 ). Obtained metal content data do not reveal any enrichment in seaweeds from the central segment of the coastal line, where the sediments are strongly polluted by Co, Cu, Mn and Zn appeared due to solid waste disposal of copper mining and smelting in past century. Such apparent contradiction could be explained by a strong fixation of metals in the residual fraction of the sediments and very low probability of the mobilizing of metals from the solid matrix to sediment interstitial waters and near bottom sea waters

Mercury dispersal to arroyo and coastal sediments from abandoned copper mine operations, El Boléo, Baja California

Evidence for mercury dispersal in an arid coastal region of central Baja California (Mexico) suggests that abandoned copper mining operations are a noticeable source of mercury in the environment. There is a generally elevated level of mercury in alluvium of arroyos throughout the mining district (0.14–0.18 mg kg-1). In the first several dozen meters surrounding two of the biggest mines, mercury levels range from 0.26 to 3.16 mg kg-1, forming a halo of anomalously high concentrations. The coastal marine sediments, particularly those close to the copper smelter in the town of Santa Rosalı´a, also display some mercury enrichment

Vertical profiles of cobalt and zinc in marine sediments of the Santa Rosalía mining region, Gulf of California, Mexico

Core sediments that were sampled from the coastal zone of the Santa Rosalía mining region and the adjacent deeper area of the Gulf of California were analysed by an instrumental neutron activation analysis (INAA). The levels of Co, Sc and Zn were used to assess the effect of pollution from the solid wastes of a copper smelter on the sediment composition in the study area. The Co/Sc and Zn/Sc ratio vertical distributions were compared to Co/Sc and Zn/Sc ratios of the earth’s crust and to a lower layer of the sediment cores and therefore less affected by pollution. The ratios of Co/Sc and Zn/Sc in cores from a predominant pollution “hot spot” near Santa Rosalía port are very high (40-150 and 150-350, respectively), suggesting that the thickness of the polluted layer exceeded the length of the cores (75-93 cm). The values of Co/Sc and Zn/Sc ratios decrease drastically in the cores collected outside the main “hot spot”. In this case, the values obtained from core depths of 20-34 cm approached the regional coastal surface sediment background (approximately 2 and 5-10 for Co/Sc and Zn/Sc, respectivelly). The Co/Sc ratios for the sediments of the deeper and further from the coast cores are slightly variable, but at sediment depths below 15 cm they are nearly constant and approximately equal to the Co/ Sc ratio of the earth´s crust. In the upper part of these cores (0-15 cm), the Zn/Sc ratios are higher (10-20) than the Zn/Sc ratio of the earth´s crust, which was probably due to the additional input of incompletely mineralised biogenic particulate Zn from the photic layer of the water column. The shape of the vertical profile the Zn/Sc ratio of SR22 sediment core (depth 360 m) in front of the main pollution “hot spot” shows that the maximum levels of pollution occurred in the past, and self-purification/restoration of the natural pollutant levels in the fine deep-water sediments can be observed during recent yearsLos sedimentos de los testigos muestreados en la zona costera de la región minera de Santa Rosalía y en el área adyacente más profunda del Golfo de California se analizaron con el análisis instrumental de la activación neutrónica (AIAN). Los niveles de Co, Sc y Zn se usaron para evaluar el efecto de la polución producida por los desechos sólidos de la fundidora de cobre sobre los sedimentos del área de estudio. Las distribuciones verticales de las relaciones Co/Sc y Zn/Sc se compararon con las relaciones Co/Sc y Zn/Sc de la corteza terrestre y con las obtenidas en la capa inferior de los testigos de sedimentos menos afectados por la polución. Las relaciones de Co/Sc and Zn/Sc en los testigos de sedimentos del área con mayor polución cerca del puerto de Santa Rosalía son muy altas, oscilando desde 40 hasta 150 y de 150 hasta 350 respectivamente, sugiriendo que el espesor de la capa altamente contaminada excede la longitud de los testigos (75-93 cm). Los valores de las relaciones Co/Sc y Zn/Sc disminuyen drásticamente en los testigos muestreados fuera de la principal área de polución. En este caso, los valores obtenidos en la profundidad de 20-34 cm del testigo se aproximan a los valores regionales de fondo de las relaciones para los sedimentos superficiales costeros (cerca a 2 para Co/Sc y a 5-10 para Zn/Sc). Las relaciones Co/Sc para los sedimentos de los testigos, muestreados a mayor profundidad y distancia de la costa son ligeramente variables, pero por debajo de 15 cm son casi constantes y aproximadamente iguales a la relación de Co/Sc para la corteza terrestre. En la parte superior (0-15 cm) de estos testigos de sedimentos, las relaciones Zn/Sc son más altas (10-20) que las relaciones Zn/Sc para la corteza terrestre, debido, probablemente, al aporte adicional del Zn biogénico particulado desde la capa fótica de la columna del agua. La forma del perfil vertical de las relaciones Zn/Sc del testigo de sedimentos SR22 (360 m de profundidad) frente al área de mayor polución muestra que los niveles máximos de polución ocurrieron en el pasado, y una autopurificación/restauración de los niveles naturales de los contaminantes en los sedimentos finos profundos se puede observar durante los últimos año

Assessment of geochemical mobility of metals in surface sediments of the Santa Rosalía mining region, western Gulf of California

To asses the geomobility of cadmium, copper, iron, manganese, nickel, lead, and zinc in marine sediments near the Santa Rosalía copper smelter, which is located on the eastern coast of the Baja California Peninsula, sequential leaching was applied to sediment samples containing different levels of Cu: (1) uncontaminated or slightly contaminated (<55 mg kg−1 Cu); (2) moderately contaminated (55–500 mg kg−1 Cu); and (3) heavily contaminated (>500 mg kg−1 Cu). Concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in four fractions of the leachate (mobile fraction F1, relatively mobile fraction F2, associated with organic matter/sulphides fraction F3, and residual fraction F4) were measured by atomic absorption spectrophotometry (AAS). The sediments with Cu concentration <500 mg kg−1 displayed prevalence of mobile acid-leachable fraction F1 and reducible fraction F2 for Cd, Cu, Mn, and Pb, whereas the relative contribution of fraction F3 was relatively low for all of the examined metals. Residual fraction F4 was highest (>65%) for Fe and Ni because both metals are associated with the crystalline matrix of natural sediments. The sediments heavily contaminated with Cu (>500 mg kg−1) had dramatically increased percentages of Cu, Mn, Pb, and Zn, ranging on average from 63 to 81%, in the residual fraction. In the case of Cu, for example, the relative abundances of this element in the different fractions of such sediments followed this sequence: residual fraction F4 (76 ± 5%) >absorbed form and carbonates fraction F1 (15 ± 5%) >Fe and Mn oxyhydroxides fraction F2 (5 ± 2%) >fraction associated with organic matter and sulphides F3 (4.5 ± 3.9%). Copper, Pb, and Zn contents in each geochemical fraction of all samples were compared with sediment-quality guideline values (“effects range low” [ERL] and “effects range medium” [ERM]) to assess their possible negative effects on biota. Copper contents in mobile fractions F1 and F2, which were moderately contaminated with Cu, were higher than ERL but lower than ERM guideline values. For heavily contaminated sediments, Zn contents of mobile fractions F1 and F2 were higher than ERL but lower than ERM guideline values. The Cu content of fraction F1 was higher than ERM guideline values, whereas for fractions F2 and F3 copper content was higher than ERL guidelines but still lower than ERM guideline values