Heavy metals in sediments, mussels and oysters from Trinidad and Venezuela

Abstract: The Gulf of Paria is bordered by both Trinidad and Venezuela,from which various metallic pollutants and other contaminants can originate.The Gulf is still a significant source of fish,crabs and shellfish for human consumption to both countries,where concerns over the quality of this marine environment have been long expressed but never properly addressed.In addition,the circulatory current patterns in the Gulf ensure that contaminants originating from either country are likely to affect both countries eventually.Heavy metals were determined in oysters (Crassostrea rhizophorae and C.virginica ),green mussels (Perna viridis )and sediments from the Gulf of Paria.Samples were obtained at four sites in Trinidad and three sites in Venezuela in the Gulf of Paria,in addition to comparative samples collected from three sites on the north coast of Venezuela.Edible tissues of twelve shellfish from each location were blended and aliquots digested with concentrated nitric acid, for extraction of cadmium,chromium,copper,lead,nickel and zinc.The solutions were analysed by flame atomic absorption spectroscopy.Mercury was extracted with a mixture of nitric,hydrochloric and sulphuric acids and determined by cold vapour atomic absorption.Sediments were oven-dried at 60°C, before being similarly extracted.Results showed that mercury in sediments at all sites in Trinidad and Venezuela exceeded NOAA and Canadian sediment quality guidelines,while cadmium, copper, nickel, lead and zinc also exceeded these guidelines at several sites.Heavy metal levels in oysters and green mussels varied widely with location. However,oysters from the Gulf of Paria contained significantly higher mean levels of cadmium,copper,nickel and zinc than those from the north coast of Venezuela, but this difference was not apparent in mussels.Cadmium, mercury and zinc in sediments were significantly correlated with those of mussels,but not of oysters,in which copper and zinc at several sites in the Gulf of Paria exceeded local maximum permissible levels (Cu =20 µg g-1 wet wt; Zn =50 µg g-1 wet wt)for human consumption. These findings indicate that while mussels may be better biological indicators of heavy metal pollution in sediments than oysters,the latter may provide copper and zinc contamination.Further research is needed to determine the most appropriate biological indicators of heavy metal and other pollutants in the local marine environment and to develop protocols for their use

Heavy metals in green mussel (Perna viridis) and oysters (Crassostrea sp.) from Trinidad and Venezuela.

Heavy metal concentrations were monitored in edible soft tissues of shellfish from Trinidad and Venezuela. Oysters (Crassostrea sp.) and the green mussel (Perna viridis), which is a recently transplanted species to the Caribbean from the Far East, were collected at six locations in Venezuela and five in Trinidad, the latter along the coast line of the Gulf of Paria. Simple and low-cost methods of analysis were optimized and validated using standard reference materials. Cadmium, copper, lead, nickel, and zinc were analyzed by flame atomic absorption spectrometry. Mercury was determined by cold-vapor atomic absorption spectrometry. The present study has confirmed that oysters have a much greater capacity for accumulation of copper and zinc than does green mussel. In addition, concentrations of copper and zinc in oysters (Crassostrea sp.) at many of the sites in the Gulf of Paria exceeded local and international standards, whereas green mussel P. viridis contained generally acceptable levels for human consumption.

Maternal and foetal iron and folate activities at parturition - abstract

This study was undertaken to determine the extent to which anaemia in the mother is reflected in the neonate and to what extent iron and folate deficiency might contribute to maternal anaemia. Haemoglobin (Hb), serum iron, transferrin saturation, serum folate and red cell (RBC) folate were measured in blood samples taken from 85 mothers and from the umbilical cords at delivery. Forty-two per cent of the mothers were anaemic by WHO standards (Hb <110 g/l) and 27 per cent were anaemic using a cut-off point of 106 g/l. Twenty-eight per cent of the neonates were considered anaemic (cord Hb <136 g/l). Serum iron and folate and RBC folate were significantly higher (p<0.01) in cord than maternal blood. Only 3.5 per cent of the mothers had serum iron defiency(<8.1 æmol/l) while 35 per cent had serum folate deficiency (<6.8 æmol/l). At low (<106 g/l) compared to adequate (>110 g/l) maternal Hb, maternal mean serum iron and folate and RBC folate were all significantly lower (p<0.05). No significant differences were found in cord mean serum iron and folate and mean RBC folate between cord bloods with low Hb compared to those with adequate Hb. At deficient (<6.8 æmol/l) compared to adequate (>13.6 æmol/l) maternal serum folate, maternal mean Hb and mean RBC folate were significantly lower (p<0.001) and p<0.0001, respectively); similarly, both cord mean serum folate and mean RBC folate were significantly lower (p<0.0001 and p <0.001, respectively). These results suggest that mothers who are anaemic at parturition do not necessarily have anaemic babies except when the maternal anaemia is extremely severe. Folate deficiency appears to be a bigger contributor than iron deficiency to anaemia in pregnancy (AU)

The role of urinary calcium, magnesium, phosphate and creatinine as possible predictors of pre-eclampsia in Trinidadian parturients - abstract

One hundred pregnant women between 24 and 28 weeks' gestation attending the antenatal clinic at the Mount Hope Women's Hospital and the Port-of-Spain General Hospital were admitted to the study. Women with a history of evidence of renal disease, diabetes chronic hypertension, cardiovascular disease, proteinuria or any other chronic medical illness were excluded. Urine and blood samples were collected at the first and each subsequent visit and bi-weekly if the subject was hospitalised. The urinary and serum concentrations of total calcium, magnesium and phosphate were measured by atomic absorption spectrometry. After delivery, the patients' notes were analysed to determine the development of pre-elcampsia (PE). The purpose of the study was to evaluate urinary calcium, magnesium and phosphate as early predictors of PE. Eight women satisfied the criteria for PE and differed from the 92 normotensives as shown (Table). Urinary calcium and magnesium and birthweight were significantly lower in PE as compared to normal pregnant women. The gestational age, urinary phosphate and serum values were no different in the two groups (AU)