Climate-induced environmental changes are known to support prevalence of disease vectors and pathogens. Temperature, rainfall, humidity and other environmental variables are considered potential drivers of population dynamics of many vectors and pathogens of health importance, especially in the tropics. This study was conducted to understand the variability and trends in atmospheric temperature and rainfall, as well as how these factors may affect the breeding of Anopheles mosquitoes in the urban areas in the future. Accra and Sekondi-Takoradi Metropolitan Areas (AMA and STMA) of coastal Ghana were the selected study sites. Anopheles larvae were sampled from pre-identified breeding sites in the two cities. Atmospheric temperature and rainfall as measured by synoptic weather stations were collected for the two cities. Again, thirty years climate data on daily minimum and maximum temperature and rainfall for both cities from Ghana Meteorological Agency (Gmet) were employed in the study. Using a statistical downscaling approach, the average of the ENSEMBLE GCM outputs AR4-BCM2 and AR4-CNCM3 scenario A1B were downscaled to match with rainfall and temperature observations of AMA and STMA. Results showed that improper solid waste management in the cities promote the breeding of Anopheles mosquitoes. Climate data analysis showed that past rainfall in the cities were below average; in the future, however, up to year 2050, the cities may experience high rainfalls and temperatures above the average. Notably, significant increases may be observed in the total monthly rainfalls as well as a slight shift of rainfall pattern in the minor season. This implies that Anopheles mosquito breeding may no longer be seasonal in the cities but perennial and malaria transmission may also follow the same trend. Poor urban dwellers who find it difficult to adopt preventative measures will be prone to persistent malaria transmission. This will increase malaria transmission among vulnerable populations in urban areas. This study recommends that city authorities must intentionally work at lowering the surface temperatures in the cities through the growing of trees and also to regularly desilt drains in order to reduce the breeding of Anopheles mosquitoes.
{"title":"2. Climate variations, urban solid waste management and possible implications for Anopheles mosquito breeding in selected cities of coastal Ghana","authors":"P. Mattah, G. Futagbi, L. Amekudzi, M. M. Mattah","doi":"10.4314/WAJAE.V28I1","DOIUrl":"https://doi.org/10.4314/WAJAE.V28I1","url":null,"abstract":"Climate-induced environmental changes are known to support prevalence of disease vectors and pathogens. Temperature, rainfall, humidity and other environmental variables are considered potential drivers of population dynamics of many vectors and pathogens of health importance, especially in the tropics. This study was conducted to understand the variability and trends in atmospheric temperature and rainfall, as well as how these factors may affect the breeding of Anopheles mosquitoes in the urban areas in the future. Accra and Sekondi-Takoradi Metropolitan Areas (AMA and STMA) of coastal Ghana were the selected study sites. Anopheles larvae were sampled from pre-identified breeding sites in the two cities. Atmospheric temperature and rainfall as measured by synoptic weather stations were collected for the two cities. Again, thirty years climate data on daily minimum and maximum temperature and rainfall for both cities from Ghana Meteorological Agency (Gmet) were employed in the study. Using a statistical downscaling approach, the average of the ENSEMBLE GCM outputs AR4-BCM2 and AR4-CNCM3 scenario A1B were downscaled to match with rainfall and temperature observations of AMA and STMA. Results showed that improper solid waste management in the cities promote the breeding of Anopheles mosquitoes. Climate data analysis showed that past rainfall in the cities were below average; in the future, however, up to year 2050, the cities may experience high rainfalls and temperatures above the average. Notably, significant increases may be observed in the total monthly rainfalls as well as a slight shift of rainfall pattern in the minor season. This implies that Anopheles mosquito breeding may no longer be seasonal in the cities but perennial and malaria transmission may also follow the same trend. Poor urban dwellers who find it difficult to adopt preventative measures will be prone to persistent malaria transmission. This will increase malaria transmission among vulnerable populations in urban areas. This study recommends that city authorities must intentionally work at lowering the surface temperatures in the cities through the growing of trees and also to regularly desilt drains in order to reduce the breeding of Anopheles mosquitoes.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"28 1","pages":"21-34"},"PeriodicalIF":0.0,"publicationDate":"2020-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45494855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study on the Songor Ramsar and UNESCO Man and Biosphere Reserve in Ghana seeks to investigate the factors that contribute to degradation of Songor Ramsar and UNESCO Man and Biosphere Reserve in Ghana through the administration of structured questionnaires using the drop-and–collect approach, face-to-face interviews and focus group discussions. The study revealed that the ranking of natural resources and occupation of the area are based on the demarcated zones within which the community is situated. Salt, fisheries and arable lands were identified as the most important natural resource in the wetland. The results on environmental degradation of the wetlands in the Songor Ramsar site in Ghana made it clear that the underlying causes of environmental degradation in the Songor Ramsar site are mainly a combination of Institutional and policy failures. It was revealed that the problem of environmental degradation is a consequence of ineffective enforcement of bye-laws. A combination of several factors such as improper waste disposal, poor attitude of residents toward environmental conservation, wildfires and shoreline recession, inadequate public education on the impact of environmental degradation, fishing and farming activities were identified during the administration of structured questionnaire, face-to-face interviews and focus group discussions. The other factors include overgrazing, over exploitation of mangroves, Predation, poaching and over fishing, uncontrolled sand and salt winning. Constraints and weaknesses to the implementation of regulations and laws with respect to conservation and protection of the wetlands identified during the study are lack of public education on the economic importance and the need to conserve the wetland, encroachment by developers, lack of enforcement of bye-laws, over-exploitation of mangroves and waste management.
{"title":"Bioenergy: Biodiesel from Freshwater Green Microalgae and a Cyanobacterium Occurring in Ghana","authors":"L. K. Doamekpor, R. Onwona-Agyeman, G. Ameka","doi":"10.4314/wajae.v27i2","DOIUrl":"https://doi.org/10.4314/wajae.v27i2","url":null,"abstract":"This study on the Songor Ramsar and UNESCO Man and Biosphere Reserve in Ghana seeks to investigate the factors that contribute to degradation of Songor Ramsar and UNESCO Man and Biosphere Reserve in Ghana through the administration of structured questionnaires using the drop-and–collect approach, face-to-face interviews and focus group discussions. The study revealed that the ranking of natural resources and occupation of the area are based on the demarcated zones within which the community is situated. Salt, fisheries and arable lands were identified as the most important natural resource in the wetland. The results on environmental degradation of the wetlands in the Songor Ramsar site in Ghana made it clear that the underlying causes of environmental degradation in the Songor Ramsar site are mainly a combination of Institutional and policy failures. It was revealed that the problem of environmental degradation is a consequence of ineffective enforcement of bye-laws. A combination of several factors such as improper waste disposal, poor attitude of residents toward environmental conservation, wildfires and shoreline recession, inadequate public education on the impact of environmental degradation, fishing and farming activities were identified during the administration of structured questionnaire, face-to-face interviews and focus group discussions. The other factors include overgrazing, over exploitation of mangroves, Predation, poaching and over fishing, uncontrolled sand and salt winning. Constraints and weaknesses to the implementation of regulations and laws with respect to conservation and protection of the wetlands identified during the study are lack of public education on the economic importance and the need to conserve the wetland, encroachment by developers, lack of enforcement of bye-laws, over-exploitation of mangroves and waste management.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"28 10 1","pages":"126-136"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70413958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Pra River Estuary, which is the second largest estuary in Ghana, has been under severe threat of siltation from illegal alluvial gold mining activities over a decade. To advocate the need for its conservation, the study assessed the ecological health status of the estuary and its connecting wetland using inhabitant benthic macroinvertebrates and prevailing physicochemical conditions as indicators. Physicochemical factors and macrozoobenthic fauna were sampled February 2012 to December 2013, and the macrozoobenthos were analysed for composition, richness, diversity and density. Results indicated low densities (<300 individuals/m2) of pollution tolerant benthic macroinvertebrates such as Capitella spp., Nereis spp., Tubifex spp. and Chironomus spp. in the estuary and wetland, suggesting a possibly low organic pollution. However, high water turbidities close to 1000 NTU remains an environmental stressor of serious concern in the estuary with possible multiplicity of repercussions on the system and its biota. A broader rehabilitation program that incorporates efforts to combat upstream illegal mining activities is therefore crucially needed to decrease turbidity levels and facilitate restoration of the estuarine ecosystem.
{"title":"Assessment of the Ecological Health Status of River Pra Estuary (Ghana) and Adjoining Wetland using Physico-chemical Conditions and Macroinvertebrate Bioindicators","authors":"I. Okyere, D. D. N. Nortey","doi":"10.4314/WAJAE.V26I2","DOIUrl":"https://doi.org/10.4314/WAJAE.V26I2","url":null,"abstract":"The Pra River Estuary, which is the second largest estuary in Ghana, has been under severe threat of siltation from illegal alluvial gold mining activities over a decade. To advocate the need for its conservation, the study assessed the ecological health status of the estuary and its connecting wetland using inhabitant benthic macroinvertebrates and prevailing physicochemical conditions as indicators. Physicochemical factors and macrozoobenthic fauna were sampled February 2012 to December 2013, and the macrozoobenthos were analysed for composition, richness, diversity and density. Results indicated low densities (<300 individuals/m2) of pollution tolerant benthic macroinvertebrates such as Capitella spp., Nereis spp., Tubifex spp. and Chironomus spp. in the estuary and wetland, suggesting a possibly low organic pollution. However, high water turbidities close to 1000 NTU remains an environmental stressor of serious concern in the estuary with possible multiplicity of repercussions on the system and its biota. A broader rehabilitation program that incorporates efforts to combat upstream illegal mining activities is therefore crucially needed to decrease turbidity levels and facilitate restoration of the estuarine ecosystem.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"26 1","pages":"44-55"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4314/WAJAE.V26I2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70413887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Small scale mining is a major threat to water resources and agricultural activities in most mining communities across Ghana. This study investigated the effect of small scale mining on the quality of water for irrigation from some selected sites along a river and a reservoir which was used as a control. The physical and chemical parameters of the water samples were measured using standard methods for water quality analysis. The samples were acid digested and assayed using Atomic Absorption Spectrophotometry (AAS). The study revealed that several of the physico-chemical parameters (turbidity, pH, conductivity, TDS) and heavy metals such as Pb and Hg were significantly higher (5% level of significance) at the river sites compared to the reservoir. Whilst most of the parameters measured were within range of the Food and Agriculture Organisation (FAO) limit for irrigation water quality, Hg, Cd, K and turbidity levels were higher than FAO permissible limits for irrigation water. Hazard assessment based on the sodium adsorption ratio (SAR), US Salinity laboratory classification and the Wilcox diagram for irrigation water quality showed the water to be within acceptable salinity and sodium limits for irrigation. It is inferred from the findings that activities of small scale miners along the river affects the quality of the water. The high turbidity and detection of some level of heavy metals in the water should be a major concern to stakeholders in the Municipality as continuous influx of small scale miners in the area could increase heavy metal concentration beyond the acceptable thresholds.
{"title":"The Impact of Small Scale Mining on Irrigation Water Quality in Asante Akim Central Municipality of Ghana","authors":"D. Nukpezah, F. A. Rahman, S. Koranteng","doi":"10.4314/WAJAE.V25I2","DOIUrl":"https://doi.org/10.4314/WAJAE.V25I2","url":null,"abstract":"Small scale mining is a major threat to water resources and agricultural activities in most mining communities across Ghana. This study investigated the effect of small scale mining on the quality of water for irrigation from some selected sites along a river and a reservoir which was used as a control. The physical and chemical parameters of the water samples were measured using standard methods for water quality analysis. The samples were acid digested and assayed using Atomic Absorption Spectrophotometry (AAS). The study revealed that several of the physico-chemical parameters (turbidity, pH, conductivity, TDS) and heavy metals such as Pb and Hg were significantly higher (5% level of significance) at the river sites compared to the reservoir. Whilst most of the parameters measured were within range of the Food and Agriculture Organisation (FAO) limit for irrigation water quality, Hg, Cd, K and turbidity levels were higher than FAO permissible limits for irrigation water. Hazard assessment based on the sodium adsorption ratio (SAR), US Salinity laboratory classification and the Wilcox diagram for irrigation water quality showed the water to be within acceptable salinity and sodium limits for irrigation. It is inferred from the findings that activities of small scale miners along the river affects the quality of the water. The high turbidity and detection of some level of heavy metals in the water should be a major concern to stakeholders in the Municipality as continuous influx of small scale miners in the area could increase heavy metal concentration beyond the acceptable thresholds.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"25 1","pages":"49-67"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4314/WAJAE.V25I2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ammonia was measured in collapsible pond, concrete tank, and earthen pond of the same size, volume and containing same fish biomass cultured under intensive system. Ammonia was also evaluated from a natural pond under extensive culture. Ammonia was measured in the afternoons for 12 weeks using Nessler method. Temperature and p H were measured in situ using Portable tester. Unionized ammonia was calculated from total ammonia using spreadsheet computation. Result showed total ammonia ranging from 1.4 to 10 mg/l with highest concentration recorded in collapsible pond and lowest found in natural pond. The unionized ammonia concentrations followed the same pattern with concentrations ranging from 0.002 to 1.13 mg/l. The trend in the total ammonia and unionized ammonia concentrations is: collapsible pond > concrete tank > earthen pond > natural pond. Temperature and p H ranged between 29.1 to 35.9 °C and 6.35 to 8.03 respectively, with the highest temperature and p H recorded in the collapsible pond and lowest temperature and p H found in natural pond. Temperature and p H followed seasonal pattern with lowest and highest temperatures and p H recorded at the end of rainy season and in the dry season respectively. High unionized ammonia recorded in the collapsible and concrete ponds was from excretion of high protein rich feed, decomposition of uneaten feed, high stocking density, low water exchange rates, water source and the alkaline medium of the systems. Low unionized ammonia in earthen pond and natural pond was attributed to the presence of phytoplankton, high water exchanges, feeding system, low acidity and relatively low temperature. Remediating measures such as the use of biofilters, aeration and reduction in feeding, temperature and p H should be employed to reduce the high concentration of unionized ammonia.
{"title":"Ammonia Concentrations in Different Aquaculture Holding Tanks","authors":"M. Mustapha, F. Akinshola","doi":"10.4314/WAJAE.V24I1","DOIUrl":"https://doi.org/10.4314/WAJAE.V24I1","url":null,"abstract":"Ammonia was measured in collapsible pond, concrete tank, and earthen pond of the same size, volume and containing same fish biomass cultured under intensive system. Ammonia was also evaluated from a natural pond under extensive culture. Ammonia was measured in the afternoons for 12 weeks using Nessler method. Temperature and p H were measured in situ using Portable tester. Unionized ammonia was calculated from total ammonia using spreadsheet computation. Result showed total ammonia ranging from 1.4 to 10 mg/l with highest concentration recorded in collapsible pond and lowest found in natural pond. The unionized ammonia concentrations followed the same pattern with concentrations ranging from 0.002 to 1.13 mg/l. The trend in the total ammonia and unionized ammonia concentrations is: collapsible pond > concrete tank > earthen pond > natural pond. Temperature and p H ranged between 29.1 to 35.9 °C and 6.35 to 8.03 respectively, with the highest temperature and p H recorded in the collapsible pond and lowest temperature and p H found in natural pond. Temperature and p H followed seasonal pattern with lowest and highest temperatures and p H recorded at the end of rainy season and in the dry season respectively. High unionized ammonia recorded in the collapsible and concrete ponds was from excretion of high protein rich feed, decomposition of uneaten feed, high stocking density, low water exchange rates, water source and the alkaline medium of the systems. Low unionized ammonia in earthen pond and natural pond was attributed to the presence of phytoplankton, high water exchanges, feeding system, low acidity and relatively low temperature. Remediating measures such as the use of biofilters, aeration and reduction in feeding, temperature and p H should be employed to reduce the high concentration of unionized ammonia.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"24 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2016-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Nude, G. Foli, S. Gawu, S. Gidigasu, P. Sakyi, D. Kwayisi
This research evaluated arsenic (As) intensity risk using sorption and geotechnical factors in the AngloGold Obuasi mine environment in Ghana. Water samples from tailings dam boreholes and surface stream were analysed for As contents over a time period of 24 months and over a distance of about 9 km respectively, under closed conditions, where there are no more discharges of waste. The porosity and bulk density of the subsurface material were also determined. Data generated from the mass-time and mass-distance analysis were used to establish As intensity risk assessment model based on documented global As impact data. From the model, a period of about 4 years is required in monitoring boreholes and a distance of about 12 km is required along the stream profile for As concentration to reduce from the maximum value of about 2.50 mg/l to 0.01 mg/l. Using the porosity, bulk density and combined degradation properties of the monitored media of the mobile As, the estimated retardation factor was 1.96 and the solute velocity estimated to be 1.53 × 10 -7 ms -1 in the borehole environment, and 1.074 and 9.25 × 10 -1 ms -1 along the streambed, respectively. This study shows that the pollution risk assessment model can be used to spatially estimate exposure to As contamination in the environment, while the transport characteristics can be used to determine clean-up criteria for effective As remediation in drainage.
本研究利用吸附和岩土因素对加纳AngloGold Obuasi矿区环境砷强度风险进行了评价。在封闭条件下，在不再排放废物的情况下，对尾矿坝钻孔水样和地表溪流水样分别进行了为期24个月和距离约9公里的砷含量分析。测定了亚表面材料的孔隙率和体积密度。利用质量-时间和质量-距离分析产生的数据，建立了基于记录在案的全球砷撞击数据的砷强度风险评估模型。从模型来看，砷浓度从峰值2.50 mg/l左右下降到0.01 mg/l，需要4年左右的监测钻孔时间，沿河流剖面需要12公里左右的距离。利用可移动As监测介质的孔隙度、容重和综合降解特性，估计其阻滞系数为1.96，井内溶质流速为1.53 × 10 -7 ms -1，沿河床溶质流速为1.074和9.25 × 10 -1 ms -1。研究表明，污染风险评估模型可用于环境中砷污染暴露的空间估计，而运移特征可用于确定排水中有效的砷修复的清理标准。
{"title":"Arsenic Intensity Risk Assessment at AngloGold Obuasi Goldmine, Ghana, West Africa: Using Sorption and Geotechnical Factors","authors":"P. Nude, G. Foli, S. Gawu, S. Gidigasu, P. Sakyi, D. Kwayisi","doi":"10.4314/WAJAE.V24I2","DOIUrl":"https://doi.org/10.4314/WAJAE.V24I2","url":null,"abstract":"This research evaluated arsenic (As) intensity risk using sorption and geotechnical factors in the AngloGold Obuasi mine environment in Ghana. Water samples from tailings dam boreholes and surface stream were analysed for As contents over a time period of 24 months and over a distance of about 9 km respectively, under closed conditions, where there are no more discharges of waste. The porosity and bulk density of the subsurface material were also determined. Data generated from the mass-time and mass-distance analysis were used to establish As intensity risk assessment model based on documented global As impact data. From the model, a period of about 4 years is required in monitoring boreholes and a distance of about 12 km is required along the stream profile for As concentration to reduce from the maximum value of about 2.50 mg/l to 0.01 mg/l. Using the porosity, bulk density and combined degradation properties of the monitored media of the mobile As, the estimated retardation factor was 1.96 and the solute velocity estimated to be 1.53 × 10 -7 ms -1 in the borehole environment, and 1.074 and 9.25 × 10 -1 ms -1 along the streambed, respectively. This study shows that the pollution risk assessment model can be used to spatially estimate exposure to As contamination in the environment, while the transport characteristics can be used to determine clean-up criteria for effective As remediation in drainage.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"24 1","pages":"1-17"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael A. Rice, F. Conteh, K. Kent, B. Crawford, B. Banja, F. Janha, I. Bojang
A successful national program to assure sanitary quality of molluscan shellfish requires a multi-disciplinary and multi-agency governmental training, data collection, policy development and management effort in collaboration with members of the shellfish industry. The Tanbi Wetlands and other estuaries of Gambia support shellfisheries for oysters, Crassostrea tulipa , and the senile ark, Senelia senilis , conducted by the TRY Oyster Women’s Association. With low shellfish prices and a small local market, a Gambian National Shellfish Sanitation Program (GNSSP) was begun as a means to boost consumer confidence and allow market access to Gambia’s robust seasonal international tourism trade. Gambian officials began training with a study tour to Rhode Island to work with counterpart officials engaged in administering the US-NSSP. Since August 2010, water was sampled bimonthly for total (TC) and fecal coliforms (FC) at stations near shellfish harvesting areas. Sanitary shoreline surveys began on 18 June 2011 to document sources of contamination and to establish priorities for remediation. Conclusions were 1) sanitary shoreline surveys identified numerous point contamination sources, 2) FC is a superior indicator of fecal contamination than TC, 3) FC values from most shellfish growing areas met or exceeded a FC standard of 14 MPN/100 ml most of the year, indicating clean growing waters, 4) highest average FC values corresponded to local rainfall maxima from July to October during the traditional off-season for shellfishing, 5) sanitary remediation (e.g. introduction of sanitary latrines at Old Jeshwang) resulted in localized water quality improvement and 6) there is enough data precision and repeatability to establish and map water quality classification zones. In areas without sanitation or near a dumpsite, FC values indicate a prohibited zone, but areas away from settlements could be certified year-around harvest sites. Postharvest shellfish sanitation and cold chain management from harvest to market remain as the key challenge of the GNSSP.
{"title":"Establishing a National Shellfish Sanitation Program in The Gambia, West Africa","authors":"Michael A. Rice, F. Conteh, K. Kent, B. Crawford, B. Banja, F. Janha, I. Bojang","doi":"10.4314/WAJAE.V23I1","DOIUrl":"https://doi.org/10.4314/WAJAE.V23I1","url":null,"abstract":"A successful national program to assure sanitary quality of molluscan shellfish requires a multi-disciplinary and multi-agency governmental training, data collection, policy development and management effort in collaboration with members of the shellfish industry. The Tanbi Wetlands and other estuaries of Gambia support shellfisheries for oysters, Crassostrea tulipa , and the senile ark, Senelia senilis , conducted by the TRY Oyster Women’s Association. With low shellfish prices and a small local market, a Gambian National Shellfish Sanitation Program (GNSSP) was begun as a means to boost consumer confidence and allow market access to Gambia’s robust seasonal international tourism trade. Gambian officials began training with a study tour to Rhode Island to work with counterpart officials engaged in administering the US-NSSP. Since August 2010, water was sampled bimonthly for total (TC) and fecal coliforms (FC) at stations near shellfish harvesting areas. Sanitary shoreline surveys began on 18 June 2011 to document sources of contamination and to establish priorities for remediation. Conclusions were 1) sanitary shoreline surveys identified numerous point contamination sources, 2) FC is a superior indicator of fecal contamination than TC, 3) FC values from most shellfish growing areas met or exceeded a FC standard of 14 MPN/100 ml most of the year, indicating clean growing waters, 4) highest average FC values corresponded to local rainfall maxima from July to October during the traditional off-season for shellfishing, 5) sanitary remediation (e.g. introduction of sanitary latrines at Old Jeshwang) resulted in localized water quality improvement and 6) there is enough data precision and repeatability to establish and map water quality classification zones. In areas without sanitation or near a dumpsite, FC values indicate a prohibited zone, but areas away from settlements could be certified year-around harvest sites. Postharvest shellfish sanitation and cold chain management from harvest to market remain as the key challenge of the GNSSP.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"23 1","pages":"1-20"},"PeriodicalIF":0.0,"publicationDate":"2015-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4314/WAJAE.V23I1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70685703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Effective control of the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) has become critical due to the genetic ability of the insect pest to develop resistance to insecticides. Alternating or rotating the use of insecticides that do not show cross-resistance is an important component of an effective resistance management strategy, as it helps prevent resistance development or regain susceptibility in an already resistant arthropod pest population. In this study, cross-resistance to selected insecticides in cartap- and esfenvalerate-selected strains of DBM was assessed in the laboratory, using the leaf-dipping method. The esfenvalerate-selected strain exhibited moderate cross-resistance to abamectin and a very low cross-resistance to cartap. The cartap-selected strain also displayed a very low cross-resistance to esfenvalerate but showed no cross-resistance to abamectin. Alternating cartap and abamectin would therefore help to effectively manage insecticide-resistance development in the DBM.
{"title":"Cross-resistance assessment in cartap- and esfenvalerateselected strains of the diamondback moth, Plutella xylostella (L.) (Lepidoptera:Plutellidae)","authors":"K. D. Ninsin","doi":"10.4314/WAJAE.V23I2","DOIUrl":"https://doi.org/10.4314/WAJAE.V23I2","url":null,"abstract":"Effective control of the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) has become critical due to the genetic ability of the insect pest to develop resistance to insecticides. Alternating or rotating the use of insecticides that do not show cross-resistance is an important component of an effective resistance management strategy, as it helps prevent resistance development or regain susceptibility in an already resistant arthropod pest population. In this study, cross-resistance to selected insecticides in cartap- and esfenvalerate-selected strains of DBM was assessed in the laboratory, using the leaf-dipping method. The esfenvalerate-selected strain exhibited moderate cross-resistance to abamectin and a very low cross-resistance to cartap. The cartap-selected strain also displayed a very low cross-resistance to esfenvalerate but showed no cross-resistance to abamectin. Alternating cartap and abamectin would therefore help to effectively manage insecticide-resistance development in the DBM.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"23 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4314/WAJAE.V23I2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A three-dimensional variable-density groundwater flow model, the SEAWAT model, was used to assess the influence of subsurface drain spacing, evapotranspiration and irrigation water quality on salt concentration at the base of the root zone, leaching and drainage in salt affected irrigated land. The study was carried out on a conceptual uniform homogenous irrigated field of shallowwatertable depth of 0.5m and aquifer salt concentration of 7200 mg/l with an impermeable layer at 10 m depth and impermeable field boundaries. The model was run for 10 years with an irrigation rate (applied recharge) of 8 mm/d and salt concentration of 1,500 mg/l, over a range of drain spacings. During the 10-year drainage period, the simulated concentrations at the base of the root zone and the discharge rates were the same at all the spacing when evapotranspiration was not included. However, upon inclusion of evapotranspiration, the simulated concentration at the base of the root zone ranged from about 5,200 to about 6200 mg/l, the discharge rate ranged from 2.3 to 1.9 mm/d. When the applied recharge concentration was changed to 1,000 mg/l and 700mg/l, but with all the other parametersmaintained, the simulated concentration at the base of the root zone ranged from 3,700 to 4,400 mg/l, and from 2,800 to 3200 mg/l for the different spacing, respectively.
{"title":"A Theoretical Study of Subsurface Drainage Model Simulation of Drainage Flow and Leaching in Salt Affected Irrigated Fields","authors":"E. A. Ampofo, T. Tanton","doi":"10.4314/WAJAE.V22I1","DOIUrl":"https://doi.org/10.4314/WAJAE.V22I1","url":null,"abstract":"A three-dimensional variable-density groundwater flow model, the SEAWAT model, was used to assess the influence of subsurface drain spacing, evapotranspiration and irrigation water quality on salt concentration at the base of the root zone, leaching and drainage in salt affected irrigated land. The study was carried out on a conceptual uniform homogenous irrigated field of shallowwatertable depth of 0.5m and aquifer salt concentration of 7200 mg/l with an impermeable layer at 10 m depth and impermeable field boundaries. The model was run for 10 years with an irrigation rate (applied recharge) of 8 mm/d and salt concentration of 1,500 mg/l, over a range of drain spacings. During the 10-year drainage period, the simulated concentrations at the base of the root zone and the discharge rates were the same at all the spacing when evapotranspiration was not included. However, upon inclusion of evapotranspiration, the simulated concentration at the base of the root zone ranged from about 5,200 to about 6200 mg/l, the discharge rate ranged from 2.3 to 1.9 mm/d. When the applied recharge concentration was changed to 1,000 mg/l and 700mg/l, but with all the other parametersmaintained, the simulated concentration at the base of the root zone ranged from 3,700 to 4,400 mg/l, and from 2,800 to 3200 mg/l for the different spacing, respectively.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"22 1","pages":"59-76"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70685900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A study of the radioactivity in groundwater from Tanke-Ilorin, Nigeria, has been carried out. Ten water samples were analyzed by ϒ-ray spectroscopy to determine the 226 Ra and 228 Ra concentrations. The activity concentration values range from 0.81 ± 0.08 to 7.4 ± 2.2 Bq/l for 226 Ra and from 1.8 ± 0.3 to 5.6 ± 2.6 Bq/l for 228 Ra. The derived Annual Effective Dose received by the population as a result of the ingestion of 226 Ra was estimated to range from 0.08 ± 0.01 to 0.12 ± 0.07 mSv/y with an average of 0.39 ± 0.11 mSv/yand 228 Ra range from 0.50 ± 0.32 to 1.42 ± 0.70 mSv/y with an average of 0.91 ± 0.31 mSv/y. Consequently, the Annual Effective Dose received, as a result of the combined ingestion of 226 Ra and 228 Ra, was found to range from 0.81 to 1.74 mSv/y with an average of 1.30 mSv/y. The mean contribution of both 226 Ra and 228 Ra activities to the committed effective dose from a year’s consumption of drinking water in the study area is, therefore, higher than the tolerable level of 1 mSv/y to the general public for prolonged exposure as recommended by ICRP, and much more than the new WHO recommended level of 0.1 mSv/y for drinking water.
{"title":"Determination of natural Radioactivity in Groundwater in Tanke - Ilorin, Nigeria","authors":"L. Nwankwo","doi":"10.4314/WAJAE.V21I1","DOIUrl":"https://doi.org/10.4314/WAJAE.V21I1","url":null,"abstract":"A study of the radioactivity in groundwater from Tanke-Ilorin, Nigeria, has been carried out. Ten water samples were analyzed by ϒ-ray spectroscopy to determine the 226 Ra and 228 Ra concentrations. The activity concentration values range from 0.81 ± 0.08 to 7.4 ± 2.2 Bq/l for 226 Ra and from 1.8 ± 0.3 to 5.6 ± 2.6 Bq/l for 228 Ra. The derived Annual Effective Dose received by the population as a result of the ingestion of 226 Ra was estimated to range from 0.08 ± 0.01 to 0.12 ± 0.07 mSv/y with an average of 0.39 ± 0.11 mSv/yand 228 Ra range from 0.50 ± 0.32 to 1.42 ± 0.70 mSv/y with an average of 0.91 ± 0.31 mSv/y. Consequently, the Annual Effective Dose received, as a result of the combined ingestion of 226 Ra and 228 Ra, was found to range from 0.81 to 1.74 mSv/y with an average of 1.30 mSv/y. The mean contribution of both 226 Ra and 228 Ra activities to the committed effective dose from a year’s consumption of drinking water in the study area is, therefore, higher than the tolerable level of 1 mSv/y to the general public for prolonged exposure as recommended by ICRP, and much more than the new WHO recommended level of 0.1 mSv/y for drinking water.","PeriodicalId":39286,"journal":{"name":"West African Journal of Applied Ecology","volume":"21 1","pages":"111-120"},"PeriodicalIF":0.0,"publicationDate":"2013-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4314/WAJAE.V21I1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70685775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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