Derick Carboo

Quantification of neonicotinoid insecticide residues in soils from cocoa plantations using a QuEChERS extraction procedure and LC-MS/MS.

The use of neonicotinoids as an insecticide group in Ghana has been quite significant particularly in cocoa production. The high usage has been mainly as a result of a government policy of free insecticide spraying on cocoa farms, in an effort to curb declining yields caused by pests and diseases and to prevent the use of unapproved or banned insecticides on cocoa farms. However the scale of cocoa farming, the frequency and intensity of usage coupled with the mode of application may result in large physical volumes of insecticides in the environment. This makes the knowledge of the concentration and fate of neonicotinoids in the environment extremely important. The present study was aimed at assessing the levels of five major neonicotinoids in soils from cocoa farmlands in Ghana. Extraction and cleanup of analytes were performed by use of a method based on the original QuEChERS procedure after optimizing salts, sorbents and instrumental conditions. Analyte extraction with NaCl and MgSO4 in acidified acetonitrile followed by cleanup with primary secondary amine (PSA) presented the optimum conditions for extraction. Quantification was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Validation of the procedure showed average recoveries ranging from 72.0 to 104.8% for all analytes at all fortification levels with relative standard deviation (RSD) ≤ 15.0. Limits of quantitation were <10 μg kg(-1) for all neonicotinoids studied. The results obtained from the analysis of 52 samples from cocoa farms revealed imidacloprid as the predominant neonicotinoid with concentrations ranging from 4.3 to 251.4 μg kg(-1) in >50% of samples analyzed.

Evaluation of municipal solid wastes (MSW) for utilisation in energy production in developing countries

In countries such as Ghana, which are still undergoing restructuring in their economies, low-cost energy supplies are most vital for development initiatives and may not only be the main constraint to their economic growth, but a principal source of conflicts in this century. But whether a meaningful and sustainable economic growth would be achieved or not rests exclusively on the removal of these energy constraints either by way of substitution for increasingly expensive conventional energy sources or new discoveries of cheaper alternatives that would power their industries. Such alternative sources should not only be cheap with great capability of promoting viable economies of scale, but also should be eco-efficient. Today, the traditional energy sources such as hydroelectric power, wood fuel, and oils are increasingly less attractive with a grown knowledge of their effects on the natural environment. This paper discusses research experiences gathered during a study that was undertaken in Accra, Ghana, to explore the potential for utilising municipal solid waste (MSW) for energy generation in a low-income economy and at the same time, address worsening MSW problems in the major cities. The results show that MSW in a typical low-income country is wet with low calorific values between 14 MJ/kg and 20 MJ/kg and an average energy recovery efficiency of about 40%.

Speciation of As(III) and As(V) in some ghanaian gold tailings by a simple distillation method

As(III) and As(V) in goldtailings and river-bedsediments from Obuasi were determined by distillationof arsenic as AsCl3. Results yielded 3750±426 mg kg-1 (45.2%) for As(V) and 3050±66 mg kg-1 (36.7%) for As(III) in the tailings. In the river-bed sediments, one spot yielded: As(III) 0 mg kg-1 (0%) and As(V) 1447±51 mg kg-1 (100%), whilst a second spot yielded: As(III) 0 mg kg-1 (0%) and As(V) 2976±51 mg kg-1 (100%). Using arsenic oxide standards, the recovery of As(III) and As(V) in the trioxide were 94.8 and 0.6% respectively. In a mixture of the two oxides, the recovery of As(III) was 87.6% with practically no interference from As(V). Total As content of the tailings was determined by neutron activation analysis (NAA) to be 8305±75 mg kg-1.

Atmospheric burden of organochlorine pesticides in Ghana

Organochlorine pesticides (OCPs) are subject to the Stockholm Convention on POPs and have been banned or restricted globally. In Ghana, concerns of illicit applications of some OCPs have been raised in recent times. Applying polyurethane foam (PUF) disk passive air samplers (PAS), the levels of OCPs in the atmosphere and their spatial resolution were investigated. It was the first nationwide coverage of OCPs monitoring in Ghana. ∑DDTs and endusulfans constituted the highest burden of atmospheric OCPs in Ghana, at average concentrations of 156±36 and 153±28 pg m(-3), respectively. Mirex had the lowest concentration (0.2±0.01 pg m(-3)). From the chemical signatures of the various OCPs, we deduced that DDT, endosulfans and heptachlor were freshly applied at certain sites, which were all agricultural sites. The OCPs were spatially resolved as a function of the types of crops cultivated in different areas, legacy issues and recent applications.

Assessing Municipal Solid Wastes (MSWs) for composting programmes in rapidly urbanising areas: a case study from Accra, Ghana

A complete understanding of all physico-chemical and biochemical attributes of waste stream materials is necessary for successful implementation of waste management programmes in given context because of their influence on the behaviour of these materials in the natural environment. This paper discusses these properties of Municipal Solid Waste (MSW) to gauge its suitability for sustainable composting programmes in Accra, a rapidly urbanising city. The results showed that the MSW was very wet at 60% moisture content by weight. Additionally, the proportion of the biologically originated carbon was considerably high compared with nitrogen thus giving high values of carbon to nitrogen (C : N) ratios (i.e., roughly 27 : 1-100 : 1).

Sorption and degradation of neonicotinoid insecticides in tropical soils

ABSTRACT Neonicotinoids are the most widely applied class of insecticides in cocoa farming in Ghana. Despite the intensive application of these insecticides, knowledge of their fate in the Ghanaian and sub-Saharan African environment remains low. This study examined the behavior of neonicotinoids in soils from cocoa plantations in Ghana by estimating their sorption and degradation using established kinetic models and isotherms. Studies of sorption were conducted using the batch equilibrium method on imidacloprid, thiamethoxam, clothianidin, acetamiprid and thiacloprid, while degradation of imidacloprid, thiamethoxam and their respective deuterated counterparts was studied using models proposed by the European forum for coordination of pesticide fate and their use (FOCUS). Analytes were extracted using the quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure and quantified by liquid chromatography-tandem mass spectrometry (LC–MS/MS). Average recoveries were high (≥ 85%) for all analytes. The findings from the study suggest that neonicotinoid insecticides may be persistent in the soils studied based on estimated half-lives > 150 days. The study also revealed generally low-sorption coefficients for neonicotinoids in soils, largely influenced by soil organic carbon.

A study of autopsy procedures in Ghana: Implications for the use of autopsy data in epidemiological analyses

The study of cause of death certification remains a largely neglected field in many developing countries, including Ghana. Yet, mortality information is crucial for establishing mortality patterns over time and for estimating mortality attributed to specific causes. In Ghana, autopsies remain the appropriate option for determining the cause of deaths occurring in homes and those occurring within 48 hours after admission into health facilities. Although these organ-based autopsies may generate convincing results and are considered the gold standard tools for ascertainments of causes of death, procedural and practical constraints could limit the extent to which autopsy results can be accepted and/or trusted. The objective of our study was to identify and characterise the procedural and practical constraints as well as to assess their potential effects on autopsy outcomes in Ghana. We interviewed 10 Ghanaian pathologists and collected and evaluated procedural manuals and operational procedures for the conduct of autopsies. A characterisation of the operational constraints and the Delphi analysis of their potential influence on the quality of mortality data led to a quantification of the validity threats as moderate (average expert panel score = 1) in the generality of the autopsy operations in Ghana. On the basis of the impressions of the expert panel, it was concluded that mortality data generated from autopsies in urban settings in Ghana were of sufficiently high quality to guarantee valid use in health analysis.