Assessment of heavy metals in urban highway runoff from Ikorodu expressway Lagos, Nigeria

The distribution of heavy metals in the urban high way run off from Ikorodu expressway of Lagos was studied between March to May, 2004.The heavy metals studied include Pb, Cu, Cr, Zn and Cd. The levels of these selected heavy metals were determined using Atomic Absorption Spectrophotometer (Mscientific 200 Model). Trends in the heavy metal from the runoff showed significant variations between the months were values recorded in the month of April showed high values. Statistical analyses showed different mean levels of these heavy metals assessed at the five collecting points. The distribution shows Zn > Pb > Cu > Cr > Cd. Zn recorded the highest concentration levels between (53.4 ± 35.5 - 107.5 ± 80.4 μg/l), while Cd levels (ND - 6.00 μg/L) were the lowest. However, the results obtained falls within the permissible limits of FMENV effluents limits, FHWA and WHO standards of water for domestic use

Comparison of extraction and clean-up techniques for the determination of polycyclic aromatic hydrocarbons in contaminated soil samples

The development of a fast, efficient and quantitative technique for the extraction, clean-up, and preconcentration of the 16 United States Environmental Protection Agency (USEPA) priority polycyclic aromatic hydrocarbons (PAHs) was carried out on contaminated soils. The effect of Soxhlet, ultrasonication and mechanical shaking used in the extraction of a low-level PAH soil certified reference material (CRM131-100) was investigated. Six different extraction solvents: acetone, cyclohexane, 2- propanol, methanol, acetonitrile and dichloromethane, were tested to select the most suitable solvent for the extraction of the 16 PAHs from the certified soil reference material. The results were compared to determine the method with the highest extraction efficiency. The clean up and preconcentration procedures for the PAHs were optimised using the solid phase extraction (SPE). Acetonitrile, dichloromethane and tetrahydrofuran were tested as eluants for the optimisation of SPE clean up. Chromatographic conditions for the separation of PAHs using High Performance Liquid Chromatography (HPLC) using UV-DAD and fluorimetric detection with programmed excitation and emission wavelengths were also optimised. The optimised ultrasonic extraction procedure and SPE clean-up extracted the PAHs from the certified reference material with recoveries ranging from 63.6 % to over 100%.Key words: High Performance Liquid Chromatography (HPLC), mechanical shaking, polycyclic aromatic hydrocarbons (PAHs), soil, solid phase extraction (SPE), soxhlet extraction, ultrasonication

A view of canonical extension

This is a short survey illustrating some of the essential aspects of the theory of canonical extensions. In addition some topological results about canonical extensions of lattices with additional operations in finitely generated varieties are given. In particular, they are doubly algebraic lattices and their interval topologies agree with their double Scott topologies and make them Priestley topological algebras.Comment: 24 pages, 2 figures. Presented at the Eighth International Tbilisi Symposium on Language, Logic and Computation Bakuriani, Georgia, September 21-25 200

Conversion of solid waste to activated carbon to improve landfill sustainability

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Landfills’ heterogeneous composites waste were evaluated as precursors for generation of activated carbon (AC). A single step chemical activation process was applied involving irradiation with microwave energy and impregnation with KOH. The average percentage yield of AC from active landfill precursor was higher than that from closed landfill for all depths sampled. Increase in impregnation ratio and irradiation power decreased the average percentage yield for both landfill precursors (Active: 38.1 to 33.1%) (Closed 42.1: to 33.3%). The optimum pH range for adsorption of methylene blue was pH 6-7, while adsorption increased with increase in temperature over the range 30 to 50oC. Carbonyl and hydroxyl groups were the major functional groups on the surface of AC. The properties of the AC are potentially suitable for the removal of cationic dyes and pollutants. AC generated from the landfill composite were comparable to that from some other biomass being managed through AC generation. This is the first report to demonstrate the possible reuse of landfill composite as AC. The reuse option of landfill composite could provide a means of sustainable management of landfilled municipal waste

Multivariate analysis of the effects of age, particle size and landfill depth on heavy metals pollution content of closed and active landfill precursors

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Multivariate analysis of a heavy metal pollution survey of closed and active landfill precursors was carried out in order to compare environmental risk levels in relation to age, particle size and depth of the precursors. Landfill precursors (77) were collected and analyzed for 15 USEPA toxic heavy metals using ICP-MS. Heavy metals concentrations in closed landfill precursors were significantly higher than those in the active landfill for 11 of 15 heavy metals investigated (closed landfill order: Fe > Al > Mn > Cu > Pb > Ba> Co > Cr > Ni > Cd > As > Se > Ti). Cluster analysis and correlation studies indicated the distribution of the metals was more influenced by landfill precursor size than by depth of the sample. Principal component analysis (PCA) showed that 10 of 15 of heavy metals of both landfill precursors were from similar anthropogenic sources. Heavy metals pollution indices (Igeo > 5, EF > 40 and CF > 7) of both active and closed landfill precursors exceeded limits in the order of Zn > Cd > Pb > Cu > Ag, indicating a major potential health risk influenced by age and particle size of precursor. Zn, Cd, Cu and Pb of both landfill precursors exceeded the USEPA set standard for assessment of human health risk for each of the metals (1×10 -4 to 1× 10-3). This study highlights the need for the integration of a clean-up process for precursors from both types of landfill to reduce possible environmental pollution during a reuse process

An analyses of the status of landfill classification systems in developing countries: Sub Saharan Africa landfill experiences

Municipal solid waste (MSW) management remains a challenge in developing countries due to increasing waste generation, high costs associated with waste management and the structure of the containment systems implemented. This study analyses the classification of landfilling systems by using documented cases reported mainly in publications in waste management in relation to non-engineered landfilling systems/approved dumpsites in Sub Saharan African (SSA) countries from 2000 to 2018. The work identifies an existing system for the classification of landfill sites and utilises this system to determine the situation of landfill sites in SSA countries. Each article was categorised according to the main landfilling management practice reported: Uncontrolled dumping, semi controlled facility, medium controlled facility, medium/high-engineered facility or high state-of the-art facility. Findings suggested that 80% of the documented cases of landfill sites assessed in SSA countries were classified as level 0 or 1. The structure of the containment and controlled regime were identified by the focus group discussion participants as important predictors of possible strengths, weaknesses, opportunities and threats for the landfill sites considered. The study represents the first identifiable and comprehensive academic evaluation of landfill site classification based on site operations reported in the available peer reviewed literature. The information provides insight on the status of landfill sites in SSA countries with respect to the landfilling management practice and a baseline for alternative corrective measures

Factors in organisational environmental management system implementation – Developed vs. Developing country contexts

Country specificities and national cultures influence Environmental Management Systems (EMS) implementation and pro-environmental behaviour in organisations. Previous studies have focused on organisations in developed or emerging economies, creating a need to establish the extent to which findings are applicable to developing counterparts. This paper presents EMS implementation from a developing country perspective, reporting on EMS implementation factors (drivers, benefits, barriers) affecting Nigerian organisations’ pro-environmental behaviour, by analysing questionnaire responses from 136 Nigerian organisational respondents. Most commonly cited drivers were ‘environmental concern’ and ‘desire for improved organisational efficiency’. Key barriers were ‘cost of implementation/budget barriers’ and ‘regulatory agency bureaucracy’. Key benefits were ‘reduced environmental accidents and improved site safety’, ‘enhanced corporate image’ and ‘more efficient resource use’. To situate findings within a global construct, results were compared with previous studies in more developed economies. EMS implementation factors differed from those in more developed economies. Plausible explanations for differences are discussed

An essential role of human Ada3 in p53 acetylation.

The p53 tumor suppressor protein functions as a critical component of genotoxic stress response by regulating the expression of effector gene products that control the fate of a cell following DNA damage. Unstressed cells maintain p53 at low levels through regulated degradation, and p53 levels and activity are rapidly elevated upon genotoxic stress. Biochemical mechanisms that control the levels and activity of p53 are therefore of great interest. We and others have recently identified hAda3 (human homologue of yeast alteration/deficiency in activation 3) as a p53-interacting protein and enhancer of p53 activity. Here, we show that endogenous levels of p53 and Ada3 interact with each other, and by using inducible overexpression and short hairpin RNA-mediated knockdown strategies we demonstrate that hAda3 stabilizes p53 protein by promoting its acetylation. Use of a p53 mutant with mutations of known p300/CREB-binding protein acetylation sites demonstrated that hAda3-dependent acetylation is required for increase in p53 stability and target gene induction. Importantly, we demonstrate that endogenous hAda3 is essential for DNA damage-induced acetylation and stabilization of p53 as well as p53 target gene induction. Overall, our results establish hAda3, a component of coactivator complexes that include histone acetyltransferase p300/CREB-binding protein, as a critical mediator of acetylation-dependent stabilization and activation of p53 upon genotoxic stress in mammalian cells

Northern Hemisphere atmospheric stilling accelerates lake thermal responses to a warming world

Climate change, in particular the increase in air temperature, has been shown to influence lake thermal dynamics, with climatic warming resulting in higher surface temperatures, stronger stratification, and altered mixing regimes. Less-studied is the influence on lake thermal dynamics of atmospheric stilling, the decrease in near-surface wind speed observed in recent decades. Here we use a lake model to assess the influence of atmospheric stilling, on lake thermal dynamics across the Northern Hemisphere. From 1980-2016, lake thermal responses to warming have accelerated as a result of atmospheric stilling. Lake surface temperatures and thermal stability have changed at respective rates of 0.33 and 0.38°C decade-1, with atmospheric stilling contributing 15 and 27% of the calculated changes, respectively. Atmospheric stilling also resulted in a lengthening of stratification, contributing 23% of the calculated changes. Our results demonstrate that atmospheric stilling has influenced lake thermal responses to warming