Uptake of heavy metals by some edible vegetables irrigated using wastewater: a preliminary study in Accra, Ghana

The heavy metals (Fe, Zn, Pb, Ni, Cr, Co, and Cd) burden in wastewater, soil, and vegetable samples from a wastewater irrigated farm located at KorleBu, Accra has been investigated. Flame atomic absorption spectrometry after microwave digestion using a combination of HNO₃, HCl, and H₂O₂ (for water), and HNO₃ and HCl (for soil and vegetables). The mean concentrations (in milligrams per kilogram) of heavy metals in the soil samples were in the order of Fe (171?±?5.22)?>?Zn (36.06?±?4.54)?>?Pb (33.35?±?35.62)?>?Ni (6.31?±?8.15)?>?Cr (3.40?±?3.63)?>?Co (1.36?±?0.31)?>?Cd (0.43?±?0.24), while the vegetables were in the order of Fe (183.11?±?161.2)?>?Zn (5.38?±?3.50)?>?Ni (3.52?±?1.27)?>?Pb (2.49?±?1.81)?>?Cr (1.46?±?0.51)?>?Co (0.66?±?0.25)?>?Cd (0.36?±?0.15). The bioconcentration factors suggest environmental monitoring for the heavy metals as follows: Cd (0.828), Cr (0.431), Ni (0.558), Co (0.485), and Fe (1.067). Estimated daily intakes were very low for both children and adults except Fe (0.767 mg/kg/day) in children. The population that consume vegetables from the study area were, however, estimated to be safe based on the results obtained from the health risk index, which were all?<?<1. The sodium absorption ratio according to FAO (1985) classifications indicate that the wastewater in the study area is unsuitable for irrigation purposes.     

Catalytic Gasification of Coal Using Eutectic Salts: Recovery,Regeneration, and Recycle of Spent Eutectic Catalysts

Abstract

Catalyst recovery studies were conducted for gasified chars produced from steam gasification of Illinois #6 coal catalyzed with two different catalyst systems. A ternary (43.5 mol% Li₂ CO₃ –31.5 mol% Na₂ CO₃ –25 mol% K₂ CO₃ ) and a binary (29 mol% Na₂ CO₃ –71 mol% K₂ CO₃ ) eutectic catalyst system were used for gasifying coal. Various extraction schemes, such as water extraction, H₂ SO₄ extraction, and acetic acid extraction, were evaluated with respect to their extraction efficiencies. Effects of major process variables, such as solvent-to-char ratio, mixing time, temperature, and concentration, on the extraction efficiency were evaluated. A process schematic for the entire catalyst recovery, regeneration, and recycle scheme was developed and the preliminary process economics were determined based on these extraction schemes. H₂ SO₄ extraction was found to be the most desirable. It also turned out to be more attractive than a once-through throwaway system.     

Determination of levels of polychlorinated biphenyl in transformers oil from some selected transformers in parts of the Greater Accra Region of Ghana

Although polychlorinated biphenyls have never been manufactured in Ghana, it has been used extensively as dielectric fluid in electric transformers and capacitors. However, very little is known of its health and environmental impacts by both managers of these transformers and capacitors and also the general public. This work therefore seeks to explore INAA as a possible alternative to screening transformer oils for PCBs by determining the total chlorine content. The total chlorine content of transformer oil samples from Ghana that tested positive and some randomly selected samples that tested negative from screening using CLOR-N-OIL test kits, have had their total chlorine estimated. INAA using the Research Reactor located at the Ghana Atomic Energy Commission was used to estimate the total chlorine content of the oil samples. Neutron Activation and gamma ray spectroscopy using HPGe detector coupled to MAESTRO 32 software was used to determine the total chlorine content by integrating the peak area of the spectrum into a simplified program that was developed from the activation equation. Instrumental Neutron Activation Analysis was able to validate the result obtained from the test kits screening with accuracy 7.5%.The minimum total chlorine content of the positive samples determined by NAA was 71.34 μg g⁻¹.     

Persistent organochlorine pesticide residues in fish, sediments and water from Lake Bosomtwi, Ghana

Some organochlorine pesticide residues in tilapia fish (Tilapiazilli), sediment and water samples from Lake Bosomtwi (the largest natural lake in Ghana) were determined to find out the extent of pesticide contamination and accumulation in the lake. The extracted residues were analyzed on a micro-capillary gas chromatograph equipped with electron capture detector. DDE (p,p'-1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene) was the predominant residue in all the samples analyzed; detected in 82% of water samples, 98% of sediment samples and 58% of fish samples at concentrations of 0.061+/-0.03 ng g(-1), 8.342+/-2.96 ng g(-1) and 5.232+/-1.30 ng g(-1), respectively. DDT (p,p'-1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane) was detected in 78% at a mean concentration 0.012+/-0.62 ng g(-1) of water samples analyzed. The mean concentrations of DDT in sediments and fish were 4.41+/-1.54 ng g(-1) and 3.645+/-1.81 ng g(-1), respectively. The detection of lower levels of DDT than its metabolite, DDE, in the samples implies that the presence of these contaminants in the lake is as result of past usage of the pesticides.     

Public parks as an element of urban planning: a missing piece in Accra's growth and development

Public parks are important to urban environments, residents, and visitors. Among other functions, they provide environmental services, such as air and water purification, and they increase both recreational opportunities and the attractiveness of the urban environment. Because of their importance, urban parks serve as public spaces that provide visitors and urban residents with rights to the city. This paper identifies the dearth of urban public parks in Accra-Tema city-region as worrying. The Accra Plan 1958 underscored the significance of green spaces and designated the coastal strip for parks development but the areas have been lost to various urban uses. We argue that the continual neglect of public parks within urban planning and community development schemes in the Accra-Tema city-region is a major concern because it is depriving the citizens a right to the city and its public spaces. A number of factors have worked adversely against the provision of public parks and green spaces in the city-region. These include development pressures, undue political interference, a complex land delivery system, and ad hoc planning. The paper concludes by offering policy suggestions as to how to resolve the dearth of parks and green spaces in the city-region.     

Bioavailability and biological activity of bound residues of radiolabelled pirimiphos-methyl in maize grains.

Using a 14C-labelled pirimiphos-methyl preparation, the percentage of pirimiphos-methyl residues bound to maize grains after 32 weeks of storage was 13% of the applied dosage, or 38% of total terminal residues. Evidence is presented to show that bound residues of pirimiphos-methyl are bioavailable to the rat: 30%, 2% and approx. 6% of radioactivity were measured in urine expired air, and some organs respectively. A major portion of radioactivity (55%) was eliminated through faeces. Grain-bound pirimiphos-methyl residues (generated after storing whole maize grains with pirimiphos-methyl at concentrations of 10 ppm and 100 ppm) were administered to albino rats for 12 weeks. Body and organ weights, enzyme activities and blood chemistry were tested. There was a significant reduction in body weight gain in female rats. Also a significant reduction in blood cholinesterase activity was observed in both male and female rats fed on grain bound pirimiphos-methyl residues at two dose levels. The white blood cell count increased significantly in male rats fed on the high dose. No significant changes were observed in the other blood chemistry parameters tested. The results indicate that maize-bound pirimiphos-methyl residues can exert adverse biological effects in the rat.     

The impact of agricultural runoff on the quality of two streams in vegetable farm areas in Ghana

A study of two small streams at Akumadan and Tono, Ghana, was undertaken during the rain and dry season periods between February 2005 and January 2006 to investigate the impact of vegetable field runoff on their quality. In each stream we compared the concentration of current-use pesticides in one site immediately upstream of a vegetable field with a second site immediately downstream. Only trace concentrations of endosulfan and chlorpyrifos were detected at both sites in both streams in the dry season. In the wet season, rain-induced runoff transported pesticides into downstream stretches of the streams. Average peak levels in the streams themselves were 0.07 microg L(-1) endosulfan, 0.02 microg L(-1) chlorpyrifos (the Akumadan stream); 0.04 microg L(-1) endosulfan, 0.02 microg L(-1) chlorpyrifos (the Tono stream). Respective average pesticide levels associated with streambed sediment were 1.34 and 0.32 microg kg(-1) (the Akumadan stream), and 0.92 and 0.84 microg kg(-1) (the Tono stream). Further investigations are needed to establish the potential endosulfan and chlorpyrifos effects on aquatic invertebrate and fish in these streams. Meanwhile measures should be undertaken to reduce the input of these chemicals via runoff.     

Participatory incremental slum upgrading towards sustainability: an assessment of slum dwellers’ willingness and ability to pay for utility services

The concept of participatory slum upgrading has received attention in the conventional literature because it ensures and promotes the sustainability of slum-upgrading programmes. In participatory slum-upgrading programmes, slum dwellers are treated as partners, instead of recipients of the services that are provided to mitigate their deprivations. The concept thrives on the willingness and ability of slum dwellers to pay for the services. The ability of slum dwellers to pay for services, unlike their willingness to pay, has received limited research attentions. Therefore, the purpose of this study was to assess the willingness and ability of residents of a slum settlement in Kumasi in Ghana to pay for utility services. Semi-structured interview schedules were used to gather primary data from a total of 276 households. The survey data were supplemented with data from key informant interviews and focus group discussions. The results show that almost nine out of every ten households were willing to pay for water and electricity services, if these services would be supplied to them directly by the state providers. The exploitation of the residents by unregulated utility services providers partly explains their willingness to pay for the utility services. These service providers charged almost 14 times the official tariffs. The results further show that all the households who were willing to pay were also capable of paying for the services without compromising their ability to afford other life essentials. The study concludes that slum regularisation policies, programmes and projects could be designed to be incremental and participatory by making the slum dwellers, partners and drivers of the upgrading process.     

Impact of chlorine exposure time on disinfection byproduct formation in the presence of iopamidol and natural organic matter during chloramination

Chloramines,in practice,are formed onsite by adding ammonia to chlorinated drinking water to achieve the required disinfection.While regulated disinfection byproducts(DBPs)are reduced during chloramine disinfection,other DBPs such as iodinated(iodo-)DBPs,that elicit greater toxicity are formed.The objective of this study was to investigate the impact of prechlorination time on the formation of both halogen-specific total organic halogen(TOX)and iodo/chlorinated(chloro-)DBPs during prechlorination/chloramination in source waters(SWs)containing iopamidol,an X-ray contrast medium.Barberton SW(BSW)and Cleveland SW(CSW)containing iopamidol were prechlorinated for 5–60 min and afterwards chloraminated for 72 hr with ammonium chloride.Chlorine contact time(CCT)did not significantly impact total organic iodine(TOI)concentrations after prechlorination or chloramination.Concentrations of total organic chlorine(TOCl)formed during prechlorination did not significantly change regardless of pH and prechlorination time,whileTOClappearedtodecreaseafter 72 hrchloraminationperiod.Dichloroiodomethane(CHCl_2I)formation during prechlorination did not exhibit any significant trends as a function of p H or CCT,but after chloramination,significant increases were observed at pHs 6.5 and 7.5 with respect to CCT.Iodo-HAAs were not formed during prechlorination but were detected after chloramination.Significant quantities of chloroform(CHCl_3)and trichloroacetic acid(TCAA)were formed during prechlorination but formation ceased upon ammonia addition.Therefore,prechlorination studies should measure TOX and DBP concentrations prior to ammonia addition to obtain data regarding the initial conditions.     

A GAME THEORY APPROACH TO DECIDING WHO WILL SUPPLY INSTREAM FLOW WATER1

ABSTRACT: The resource management problem for the Middle Platte ecosystem is the insufficient water available to meet both instream ecological demands and out‐of‐stream economic needs. This problem of multiple interest groups competing for a limited resource is compounded by sharp disagreement in the scientific community over endangered species' needs for instream flows. In this study, game theory was used to address one dimension of this resource management problem. A sequential auction with repeated bidding was used to determine how much instream flow water each of three states — Colorado, Nebraska, and Wyoming — will provide and at what price. The results suggest that the use of auction mechanisms can improve the prospects for reaching a multi‐state agreement on who will supply instream flow water, if the auction is structured to discourage misrepresentation of costs and if political compensation is allowed.