Occurrence and distribution of heavy metals in indoor settled particles in Lagos Metropolis, Nigeria

The increased application of technology, industrialization and growing population has resulted in the emission of wastes such as heavy metals that pollute the environment. The occurrence and distribution of heavy metals such as cadmium (Cd), copper (Cu), chromium (Cr), iron (Fe), manganese (Mn), lead (Pb), nickel (Ni) and zinc (Zn) in settled particles (indoor) collected from selected residential in Lagos metropolis over a two- year period (February, 2007 – July, 2008) was therefore investigated. The measurements of heavy metals contents were performed using Atomic Absorption Spectroscopy (AAS). The results showed widespread heavy metals contamination especially Fe and Zn, which were present as the highest concentration while Cd was the lowest in the settled particles (dust). The order of occurrence of heavy metals in settled particles (dust) collected indoor in 2007 and 2008 respectively were as follows, Fe > Zn > Pb > Cu > Cr > Mn > Ni > Cd and Fe > Zn > Mn > Pb > Cr > Cu > Ni > Cd. The outcome of this study implied that dust represent major source of heavy metals around dwelling places in the Lagos metropolis and therefore should be monitored. Additionally, data from this study could stand as a reference point for subsequent monitoring.Keywords: Heavy metals, Settled particle, Indoor, Dust, Lagos metropolis, Dwellin

Salinity Influence on Copper Sulphate and Lead Nitrate Combined Toxicity Against Oreochromis niloticus

Brackish water ecosystems characterized by fluctuating physicochemical parameters are more susceptible to the toxic effects of heavy metals acting singly or jointly. This study investigated the effect of salinity variations on the joint action toxicity of copper sulphate (CuSO4) and lead nitrate Pb(NO3)2 against fingerlings of Oreochromis niloticus. Fingerlings were exposed to binary mixtures of CuSO4 and Pb(NO3)2 (ratios 1:1 and 1:4) at varying salinities (0‰, 2‰, 12‰ and 18‰) in laboratory bioassays. The binary mixtures of the heavy metals were least toxic to the fish at 12‰ with 96 h LC50 values of 115.558 mg l-1 and 198.274 mg l-1 compared to 8.465 mg l-1 and 16.884 mg l-1 for 0‰, 46.084 mg l-1 and 69.843 mg l-1 for 2‰ and 13.196mg l-1 and 100.567 mg l-1 for 18‰ at ratios 1:1 and 1:4 respectively. Analysis using the Synergistic Ratio Model (SR) showed that both heavy metals were less toxic to the fish species when acting jointly irrespective of ratio than when acting singly at 12‰. Therefore, the need to consider the fluctuating salinity and joint interaction of heavy metals in setting ecologically safe limits for the discharge of effluents containing heavy metals into the aquatic ecosystems is important. Key words: Salinity, Heavy Metals, Toxicity, Oreochromis niloticu

Relative toxicity of cigarette butts leachate and usefulness of antioxidant biomarker activity in Nile Tilapia Oreochromis niloticus (Trewavas, 1983)

Relative acute toxicity of cigarette butts leachate, antioxidant biomarkers; superoxide dismutase (SOD), catalase (CAT), gluthathione (GSH)activity and lipid peroxidation (LPO), an index of malondialdehyde (MDA) were evaluated in Nile Tilapia (Oreochromis niloticus) exposed to two selected commonly consumed brand of cigarettes butts in smoked and unsmoked conditions(SCB 1/ 2 and UCB 1/2) respectively. Under laboratory condition acute toxicity was conducted over a period of 96hrs. Antioxidant activity and lipid peroxidation were based on the derived 96h LC50 value over a period of 28days. On the basis of 96hrs LC50 value, SCB 1 was found to be the most toxic (1.346 cigarette butt/l) followed by SCB 2 (2.271cigarette butt/l), UCB 2 (7.313cigarette butt/l) and UCB 1 (5.559cigarette butt/l) against O. niloticus. The results of SOD and CAT activity under the sublethal concentration (1/10th and 1/100th of 96hrs LC50) of cigarette butt leachate showed significantly(P<0.05) decreased activity in liver and gills compared to the control group whereas GSH in the liver and gill was induced significantly (P < 0.05) within 7-14days compared to 21-28days. MDA increased significantly (P< 0.05) in the liver and gill compared to control group. These findings indicate high oxidant activity on the fish, explaining the enormity of the impact of cigarette butt leachates in the environment and the significance of using a set of integrated biomarker in evaluating oxidative stress in aquatic ecosystem.Keywords: Cigarette Butt Leachate, Acute toxicity, Biomarkers, Oxidative stres

Single and joint action toxicity evaluation of insecticide and laundry detergent against Poecilia reticulata

In laboratory bioassays, single action toxicities of an insecticide (Apicide [A]) and two laundry detergents (Persil [P] and Klin [K]) as well as their joint action toxicity studies in binary (1:1; 1:4) and triple (1:1:1) mixtures were evaluated against Poecilia reticulata (Guppy). Joint action toxicity mortality data was analyzed using Synergistic Ratio (SR), Concentration – Addition (RTU) and Isobolograms models. On the basis of 96hr LC50 mortality data from single action studies, showed that A was the most toxic (0.00137mg/l) followed by P (0.773mg/l) and K (28.841mg/l). The joint action toxicity data showed a synergistic effect in mixtures of insecticide and detergents in all ratios (1:1, 1:4, 1:1:1) than when acting alone. In descending order of toxicity it was revealed that Apicide/persil (1:1; 0.00079mg/l)>Apicide/ Persil/Klin (1:1:1; 0.00093mg/l)>Apicide/Klin (1:1; 0.00094mg/l)>Apicide/ Persil (1:1; 0.00098mg/l)>Apicide/ Klin (1:4; 0.00106mg/l). The subjection of the 96h LC50 values of test compound mixtures based SR and RTU showed that interaction of mixtures in various ratios (1:1, 1:4, 1:1:1) tended towards synergisms (SR>1; RTU>1) respectively. Further analysis based on the isobologram model was in conformity with RTU and SR models. The significance of this study showed the relevance of joint action toxicity studies in setting realistic safe limits in order to protect aquatic organisms. Therefore, proper disposal and management strategies for wastes should be enforced.Keywords: Bioassay, Detergent, Insecticide, Toxicity, Poecilia reticulat