Salinity variations of the tidal water irrigating the rice fields at Warri mangrove swamp were st... more Salinity variations of the tidal water irrigating the rice fields at Warri mangrove swamp were studied for one calendar year. It was found that the mean pH is 7.24 for low tides and 7.14 for high tides, and pH is highest in July for both high and low tides. Sodium, calcium and magnesium, the major cationic constituents of the soluble salts in the saline tidal irrigation water, as well as potassium a minor ionic constituent were all found to be highest in June at both low and high tides. Also, both the Electrical Conductivity (EC) and the derived Sodium Adsorption Ration (SAR) were highest in June. Salinity at both high and low tides is highest in June but lowest in September for high tides and in October for low tides. The indications are that the adverse effects of salinity are largely responsible for the poor initial growth and survival of the rice variety MAS 2401 during early seedling stage. From salinity point of view, it would appear that October is the most favourable month to transplant rice at the Warri mangrove swamp.
Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring ... more Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring geochemical resources. However, this has been enhanced by anthropogenic activities such as crude oil exploration and exploitation activities, resulting in pollution in the Taylor Creek aquatic ecosystem. The catfish species Bagrus bayad and other environmental segments were collected from five selected sites along Taylor Creek, southern Nigeria, and total metal concentration determined. The concentration levels of the metals in B. bayad were higher than the values reported in the literature for fresh fish and may lead to a higher risk of harmful effects. The bivariate regression models relating metals in B. bayad and metals in the surface waters were significant (R 2 ≥ 0.9002). The log (bio-concentration factor; BCF) values of Cr and Zn in B. bayad were the highest, whereas the lowest was found for Ni. The ecological distribution of the log (BCF) values was, for all the heavy metals, moderately stable over the creek. All log-transformed bio-magnification factors (BMF) in the creek were positive, which indicates that the metal concentration was greater in B. bayad than in suspended particulate matter (SPM). The absolute log (BMF) values of heavy metals can, therefore, be ranked in order of decreasing magnitude: Cr (3.26) > Zn (2.99) > Cd (2.93) > Fe (2.76) > Pb (2.66) > Mn (2.36) > Ni (2.24). This sequence indicates that toxic metals such as Cd, Cr and Pb are undergoing significant bio-reduction from SPM to B. bayad. The degree of correlation between the metals was different in B. bayad, which suggests that the sources of the metals polluting Taylor Creek were diverse.
Salinity variations of the tidal water irrigating the rice fields at Warri mangrove swamp were st... more Salinity variations of the tidal water irrigating the rice fields at Warri mangrove swamp were studied for one calendar year. It was found that the mean pH is 7.24 for low tides and 7.14 for high tides, and pH is highest in July for both high and low tides. Sodium, calcium and magnesium, the major cationic constituents of the soluble salts in the saline tidal irrigation water, as well as potassium a minor ionic constituent were all found to be highest in June at both low and high tides. Also, both the Electrical Conductivity (EC) and the derived Sodium Adsorption Ration (SAR) were highest in June. Salinity at both high and low tides is highest in June but lowest in September for high tides and in October for low tides. The indications are that the adverse effects of salinity are largely responsible for the poor initial growth and survival of the rice variety MAS 2401 during early seedling stage. From salinity point of view, it would appear that October is the most favourable month to transplant rice at the Warri mangrove swamp.
Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring ... more Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring geochemical resources. However, this has been enhanced by anthropogenic activities such as crude oil exploration and exploitation activities, resulting in pollution in the Taylor Creek aquatic ecosystem. The catfish species Bagrus bayad and other environmental segments were collected from five selected sites along Taylor Creek, southern Nigeria, and total metal concentration determined. The concentration levels of the metals in B. bayad were higher than the values reported in the literature for fresh fish and may lead to a higher risk of harmful effects. The bivariate regression models relating metals in B. bayad and metals in the surface waters were significant (R 2 ≥ 0.9002). The log (bio-concentration factor; BCF) values of Cr and Zn in B. bayad were the highest, whereas the lowest was found for Ni. The ecological distribution of the log (BCF) values was, for all the heavy metals, moderately stable over the creek. All log-transformed bio-magnification factors (BMF) in the creek were positive, which indicates that the metal concentration was greater in B. bayad than in suspended particulate matter (SPM). The absolute log (BMF) values of heavy metals can, therefore, be ranked in order of decreasing magnitude: Cr (3.26) > Zn (2.99) > Cd (2.93) > Fe (2.76) > Pb (2.66) > Mn (2.36) > Ni (2.24). This sequence indicates that toxic metals such as Cd, Cr and Pb are undergoing significant bio-reduction from SPM to B. bayad. The degree of correlation between the metals was different in B. bayad, which suggests that the sources of the metals polluting Taylor Creek were diverse.
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