Bioavailability assessment of toxic metals using the technique "acid-volatile sulfide (AVS)-simultaneously extracted metals (SEM)" in marine sediments collected in Todos os Santos Bay, Brazil.
This paper reports the bioavailability of the metals (cadmium, copper, zinc, lead, and nickel) in sediment samples collected in seven stations from the São Paulo Estuary, Todos os Santos Bay, Brazil. The bioavailability was determined by employing the technique "acid-volatile sulfide (AVS) and simultaneously extracted metal (SEM)". The elements cadmium, copper, lead, and zinc were determined using differential pulse anodic stripping voltammetry (DPASV), while nickel was quantified utilizing electrothermal atomic absorption spectrometry (ET AAS). The accuracy of these methods was confirmed using a certified reference material of estuarine sediment (NIST 1646). The sulfide was quantified using potentiometry with selective electrode and the organic matter determination employing an indirect volumetric method using potassium dichromate and iron(II) sulfate solutions. The bioavailability of the metals was estimated by relationship between the concentration of AVS and the sum of the concentrations of the simultaneously extracted metals (ΣSEM), considering a significant toxicity when (ΣSEM)/(AVS) is higher than 1. The bioavailability values in the seven stations studied varied from 0.93 to 1.31 (June, 2014) and from 0.34 to 0.58 (September, 2014). These results demonstrated a critical condition of toxicity (bioavailability >1) in six of the seven sediment samples collected during the rainy season (June, 2014). In the other period (September, 2014), the bioavailability was always lower than 1 for all sediment samples collected in the seven stations. The individual values of the concentrations of the five metals were compared with the parameters PEL (probable effects level) and TEL (threshold effects level), which are commonly employed for characterization of ecological risk in environmental systems. This comparison revealed that all metals have concentrations lower than the PEL and only zinc and lead in some stations have contents higher than the TEL. The bioavailability evaluation and the concentrations achieved for the five elements in the sediments samples analyzed demonstrated that the ecosystem studied does not present an environmental risk.
Instituto de Química, Universidade Federal da Bahia, Salvador, Bahia, 40170-270, Brazil.|Instituto Nacional de Ciência e Tecnologia, INCT, de Energia e Ambiente, Universidade Federal da Bahia, Salvador, Bahia, 40170-290, Brazil.
Jucelino B
JB
Silva
Instituto de Geociências, Universidade Federal da Bahia, Salvador, Bahia, 40170-290, Brazil.
Rodrigo A
RA
Nascimento
Instituto de Química, Universidade Federal da Bahia, Salvador, Bahia, 40170-270, Brazil.
Sergio T
ST
de Oliva
Instituto de Geociências, Universidade Federal da Bahia, Salvador, Bahia, 40170-290, Brazil.
Olívia M C
OM
de Oliveira
Instituto de Química, Universidade Federal da Bahia, Salvador, Bahia, 40170-270, Brazil. slcf@ufba.br.|Instituto Nacional de Ciência e Tecnologia, INCT, de Energia e Ambiente, Universidade Federal da Bahia, Salvador, Bahia, 40170-290, Brazil. slcf@ufba.br.
Sergio L C
SL
Ferreira
D000143:Acids / Q000032:analysis; D061006:Bays / Q000032:analysis*; D001682:Biological Availability; D001938:Brazil; D002104:Cadmium / Q000032:analysis; D003300:Copper / Q000032:analysis; D004784:Environmental Monitoring; D063366:Estuaries; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry; D000075322:Heavy Metal Poisoning; D007854:Lead / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis*; D009532:Nickel / Q000032:analysis; D011041:Poisoning; D025341:Principal Component Analysis; D013440:Sulfides / Q000032:analysis; D015032:Zinc / Q000032:analysis
D000143:Acids; D019216:Metals, Heavy; D013440:Sulfides; D002104:Cadmium; D007854:Lead; D003300:Copper; D009532:Nickel; D015032:Zinc
Acid-volatile sulfide; Bioavailability; Sediment samples; Simultaneously extracted metal; Todos os Santos Bay