Elevated heavy metal concentrations in soils is a cause for concern as they are hazardous to soil... more Elevated heavy metal concentrations in soils is a cause for concern as they are hazardous to soil organisms including earthworms which are considered as ecosystem engineers. Current ecotoxicity tests predominantly use temperate earthworm species, and thus there is the need to include a broader genera of native species to improve ecological risk assessment. Alma nilotica, is a tropical anecic earthworm species that survives well under laboratory conditions and has potential for use in ecotoxicology testing but lacks published toxicity data for important pollutants. Growth and reproduction bioassays were carried out with Alma nilotica to determine the relationship between the concentrations of Cu, Zn, Pb and Cr in spiked soils and their bioaccumulation and toxic effects. Positive linear relationships were found between soil-metal and internal earthworm-metal concentrations. Cu did not inhibit growth up to 35 days of exposure but became toxic with longer exposure duration. Zn was not regulated by Alma nilotica although it is an essential metal that is well regulated by Eisenia sp. commonly used in standard ecotoxicity tests, showing differences in metal regulation by earthworms of different ecological functional groups. Based on bioaccumulation factors (BAFs), growth inhibition and reproduction effects the metals were ranked in decreasing toxicity as Pb > Cr > Zn > Cu. The mean 20% Internal Effects Concentrations (IEC20s) for reproduction were 1.03. 1.77, 10.2 and 218 mg metal/kg earthworm for Pb, Cr, Zn and Cu respectively. These data can contribute to the improvement of metal risk assessment particularly in tropical contexts.
The aquatic ecosystem is compromised by many contaminants that may lead to reduced ecosystem func... more The aquatic ecosystem is compromised by many contaminants that may lead to reduced ecosystem functions and severe consequences on human health. This study aimed at determining suitable bioindicators of water quality among the phytoplankton community for the biomonitoring of freshwater streams in the mono-modal agroecological zone of Cameroon. For this purpose, water physicochemical and hydrological parameters, together with the phytoplankton abundance and diversity were measured from June 2016 to May 2017 along the Benoe stream (South-West Region). The Shannon–Wiener diversity and Pielou’s evenness indices indicated a clean to mildly polluted stream with a diverse phytoplankton community which consisted of 84 species belonging to 51 families. The community was dominated by the Bacillariophyta (64%), followed by Chlorophyta (13%) and Cyanophyta (10%). Multivariate statistical analysis revealed that the total dissolved solids (TDS), electrical conductivity (EC), stream water velocity ...
Worldwide pollution of soils, rivers, streams and lakes from anthropogenic activities has been on... more Worldwide pollution of soils, rivers, streams and lakes from anthropogenic activities has been one of the most crucial environmental problems since the beginning of the 20th century. In Santa, the increasing use of agrochemicals is disturbing, as most farmers have little or no idea about application techniques or the effects of these chemicals on the environment. The objective of this work was to determine the knowledge on pesticides and fertilizer use by tracing their availability in surface and subsurface soils, in water and sediments using nitrates and phosphates, and by evaluating the quality of some water sources in Santa. Questionnaires were used to survey the knowledge of fertilizers and pesticide utilization by farmers, while water, soil and sediment samples were collected from selected field sites to determine the distribution of phosphates and nitrates. The pollution of water from some water sources in Santa was evaluated using the National Sanitation Foundation Water Qual...
We conducted a study to assess the impact of peri-urban agricultural activities of the city of Ds... more We conducted a study to assess the impact of peri-urban agricultural activities of the city of Dschang on the water quality and macroinvertebrate structure of the Menoua stream. This study covered 3 stations (one reference station at the upstream of the peri-urban agricultural activities and two downstream) with a monthly sampling frequency from March 2015 to February 2016. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. Physico-chemical parameters such as temperature, pH, conductivity, TDS (Total Dissolved Solids), salinity, turbidity, colour, SS (Suspended Solids), nitrate, ammonium and orthophosphate were analyzed. The inventory of benthic macroinvertebrates revealed a taxonomic richness of 42 families and 77 taxa and a gross abundance of 1833 individuals. Spatio-temporal monitoring of physicochemical and biological parameters provided the image of relat...
Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem an... more Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem and affect non-target organisms. This study aimed at assessing chemical pollution with pesticides using the PRIMET (Pesticides Risks in the tropics to Man, Environment and Trade) model in the Benoe stream. Ecotoxicological data on pesticides, pesticide and water physico-chemistry were used as input parameters. Water parameters were measured monthly for 06 months in 08 sampling points along the stream. Pesticide characteristics were obtained from the Pesticides Properties Data Base (PPDB) and the PRIMET software. The risk assessment was done for 44 active ingredients used in the area and whose ecotoxicological and physico-chemical data were available. Water parameters significantly (p<0.05) varied across seasons. Based on the Exposure Toxicity Ratio (ETR) pesticides to pose a definite acute risk (ETR>100), seven to pose an acute possible risk (1≤ETR≤100) and 28 to pose no risk (ETR<1). Cadusafos (ETR=5200, PEC=39µg/l) was the most risky pesticide while imazalil (ETR=0.0002, PEC=0.0053µg/l) was the least risky compound. Cypermethrin was predicted to pose both definite acute risk to water and possible chronic risk to fish, water and Daphnia. Seven active ingredients were predicted to pose possible chronic risk to Daphnia. Pesticide used in plantations near water bodies is a threat to the aquatic ecosystem augmented in case of misuse. Bioaccumulation potential and impact of these compounds on water quality and biota community structure should be examined.
International Journal of Environment and Climate Change, 2021
Aims: The aim of this study was to evaluate farmer’s pesticide use practices and their effects in... more Aims: The aim of this study was to evaluate farmer’s pesticide use practices and their effects in the wetland of Ndop. Study Design: A cross sectional study was carried out from January to August 2019 in Ndop, North West Region of Cameroon. Methodology: Questionnaires were administered separately to 382 rice and 100 vegetable farmers, and descriptive statistics was used in analyzing the results. Specifically, the Chi-squared statistic was used to determine the nature of the relationship between the variables. Results: The results showed that most of the crop fields (95.6%) lack a buffer zone since most farms were adjacent to water bodies (0 ≥farm ≥1 m). Farmers (100%) washed and rinsed knapsack sprayers in nearby water bodies. A majority of the farmers (71.3%) burnt or threw empty pesticide containers in open fields, water bodies, or nearby bushes. Both rice farmers (83.5%) and vegetable farmers (100%) reported that pesticides kill non-target organisms (fish, frogs, toad, snakes, bi...
Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem an... more Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem and affect non-target organisms. This study aimed at assessing chemical pollution with pesticides using the PRIMET (Pesticides Risks in the tropics to Man, Environment and Trade) model in the Benoe stream. Ecotoxicological data on pesticides, pesticide and water physico-chemistry were used as input parameters. Water parameters were measured monthly for 06 months in 08 sampling points along the stream. Pesticide characteristics were obtained from the Pesticides Properties Data Base (PPDB) and the PRIMET software. The risk assessment was done for 44 active ingredients used in the area and whose ecotoxicological and physico-chemical data were available. Water parameters significantly (p<0.05) varied across seasons. Based on the Exposure Toxicity Ratio (ETR)
We conducted a study to assess the impact of peri-urban agricultural activities of the city of Ds... more We conducted a study to assess the impact of peri-urban agricultural activities of the city of Dschang on the water quality and macroinvertebrate structure of the Menoua stream. This study covered 3 stations (one reference station at the upstream of the peri-urban agricultural activities and two downstream) with a monthly sampling frequency from March 2015 to February 2016. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. Physico-chemical parameters such as temperature, pH, conductivity, TDS (Total Dissolved Solids), salinity, turbidity, colour, SS (Suspended Solids), nitrate, ammonium and orthophosphate were analyzed. The inventory of benthic macroinvertebrates revealed a taxonomic richness of 42 families and 77 taxa and a gross abundance of 1833 individuals. Spatio-temporal monitoring of physicochemical and biological parameters provided the image of relat...
Pesticides are widely used to reduce crop losses due to pests. This study (an initial part of a p... more Pesticides are widely used to reduce crop losses due to pests. This study (an initial part of a project on risk assessment and biomonitoring) deals with pesticide use patterns in the South-West, Cameroon. This descriptive and cross-sectional study was done using questionnaires randomly administered to 137 respondents. Twenty-one crops were recorded in the area with a total of 107 pesticides (60 active ingredients) used. Three illegally used pesticides were recorded (lindane, dimethoate and malathion). Application of pesticides in combination was quite common (42.3%). Pesticide application was mainly manual using a sprayer (96.4%) with 54% of users experiencing health problems post-application. Because of the lack of funding and training, 19.7% sprayed pesticides without protection. For the Restricted Entry Interval (REI), 43.1% entered the field in less than 12h after pesticide application. The correlation between the REI and the number of symptoms was negative and non-significant (...
The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on be... more The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on benthic macro-invertebrate community structure of the Doulahang stream was studied from March 2015 to February 2016 on a monthly basis in three sampling stations named TS1, TS2 and TS3. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. The analysis of physico-chemical parameters revealed that the introduction of wastewater from the sandpit at the TS2 station led to an increase of the temperature, conductivity, total dissolved solids, salinity, suspended matter, turbidity and colour. The wildlife inventory identified 63 taxa divided into 4 phyla, 6 classes, 13 orders and 31 families. The lowest values of the taxonomic richness (18 taxa, against 46 taxa and 47 taxa respectively to stations TS1 and TS3), the Shannon diversity index (2.48 bits / ind.) and the Pielou'...
Fungicides are widely used in agriculture, and released in large amounts to the environment. Meth... more Fungicides are widely used in agriculture, and released in large amounts to the environment. Methods used for antifungal susceptibility testing are cumbersome and time-consuming. As a result, very little attention has been paid to including fungal tests in the routine screening of pesticides and there are no reports in the literature of fungicide focussed effects directed analysis (EDA). In addition very little is known on the toxicity of fungicides to environmentally significant fungi. Here we report a rapid microplate-based resorufin fluorescence inhibition bioassay and compare it with a 24 h microplate-based yeast growth inhibition bioassay using eight fungicides. The growth inhibition bioassay was sensitive, giving IC50 and IC90 values comparable to previously reported IC50 or MICs of these fungicides for Saccharomyces cerevisiae and other fungi. The resorufin fluorescence inhibition bioassay was both faster and more sensitive than the growth inhibition bioassay. Inhibitory concentrations obtained just after 30 min of incubation with amphotericin B (AMB) and captan were at least a hundred fold lower than IC50s in the literature for fungi. The fluorescence bioassay showed only a small response to pyrazophos and thiabendazole but these only inhibited growth at high concentrations so this may reflect low sensitivity of S. cerevisiae to these particular fungicides. This bioassay can detect toxic effects of a range of fungicides from different chemical classes with different modes of action. It will be valuable for screening chemical libraries for fungicides and as a biomarker for detecting the effects of fungicides to non-target fungi.
Elevated heavy metal concentrations in soils is a cause for concern as they are hazardous to soil... more Elevated heavy metal concentrations in soils is a cause for concern as they are hazardous to soil organisms including earthworms which are considered as ecosystem engineers. Current ecotoxicity tests predominantly use temperate earthworm species, and thus there is the need to include a broader genera of native species to improve ecological risk assessment. Alma nilotica, is a tropical anecic earthworm species that survives well under laboratory conditions and has potential for use in ecotoxicology testing but lacks published toxicity data for important pollutants. Growth and reproduction bioassays were carried out with Alma nilotica to determine the relationship between the concentrations of Cu, Zn, Pb and Cr in spiked soils and their bioaccumulation and toxic effects. Positive linear relationships were found between soil-metal and internal earthworm-metal concentrations. Cu did not inhibit growth up to 35 days of exposure but became toxic with longer exposure duration. Zn was not regulated by Alma nilotica although it is an essential metal that is well regulated by Eisenia sp. commonly used in standard ecotoxicity tests, showing differences in metal regulation by earthworms of different ecological functional groups. Based on bioaccumulation factors (BAFs), growth inhibition and reproduction effects the metals were ranked in decreasing toxicity as Pb > Cr > Zn > Cu. The mean 20% Internal Effects Concentrations (IEC20s) for reproduction were 1.03. 1.77, 10.2 and 218 mg metal/kg earthworm for Pb, Cr, Zn and Cu respectively. These data can contribute to the improvement of metal risk assessment particularly in tropical contexts.
The aquatic ecosystem is compromised by many contaminants that may lead to reduced ecosystem func... more The aquatic ecosystem is compromised by many contaminants that may lead to reduced ecosystem functions and severe consequences on human health. This study aimed at determining suitable bioindicators of water quality among the phytoplankton community for the biomonitoring of freshwater streams in the mono-modal agroecological zone of Cameroon. For this purpose, water physicochemical and hydrological parameters, together with the phytoplankton abundance and diversity were measured from June 2016 to May 2017 along the Benoe stream (South-West Region). The Shannon–Wiener diversity and Pielou’s evenness indices indicated a clean to mildly polluted stream with a diverse phytoplankton community which consisted of 84 species belonging to 51 families. The community was dominated by the Bacillariophyta (64%), followed by Chlorophyta (13%) and Cyanophyta (10%). Multivariate statistical analysis revealed that the total dissolved solids (TDS), electrical conductivity (EC), stream water velocity ...
Worldwide pollution of soils, rivers, streams and lakes from anthropogenic activities has been on... more Worldwide pollution of soils, rivers, streams and lakes from anthropogenic activities has been one of the most crucial environmental problems since the beginning of the 20th century. In Santa, the increasing use of agrochemicals is disturbing, as most farmers have little or no idea about application techniques or the effects of these chemicals on the environment. The objective of this work was to determine the knowledge on pesticides and fertilizer use by tracing their availability in surface and subsurface soils, in water and sediments using nitrates and phosphates, and by evaluating the quality of some water sources in Santa. Questionnaires were used to survey the knowledge of fertilizers and pesticide utilization by farmers, while water, soil and sediment samples were collected from selected field sites to determine the distribution of phosphates and nitrates. The pollution of water from some water sources in Santa was evaluated using the National Sanitation Foundation Water Qual...
We conducted a study to assess the impact of peri-urban agricultural activities of the city of Ds... more We conducted a study to assess the impact of peri-urban agricultural activities of the city of Dschang on the water quality and macroinvertebrate structure of the Menoua stream. This study covered 3 stations (one reference station at the upstream of the peri-urban agricultural activities and two downstream) with a monthly sampling frequency from March 2015 to February 2016. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. Physico-chemical parameters such as temperature, pH, conductivity, TDS (Total Dissolved Solids), salinity, turbidity, colour, SS (Suspended Solids), nitrate, ammonium and orthophosphate were analyzed. The inventory of benthic macroinvertebrates revealed a taxonomic richness of 42 families and 77 taxa and a gross abundance of 1833 individuals. Spatio-temporal monitoring of physicochemical and biological parameters provided the image of relat...
Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem an... more Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem and affect non-target organisms. This study aimed at assessing chemical pollution with pesticides using the PRIMET (Pesticides Risks in the tropics to Man, Environment and Trade) model in the Benoe stream. Ecotoxicological data on pesticides, pesticide and water physico-chemistry were used as input parameters. Water parameters were measured monthly for 06 months in 08 sampling points along the stream. Pesticide characteristics were obtained from the Pesticides Properties Data Base (PPDB) and the PRIMET software. The risk assessment was done for 44 active ingredients used in the area and whose ecotoxicological and physico-chemical data were available. Water parameters significantly (p<0.05) varied across seasons. Based on the Exposure Toxicity Ratio (ETR) pesticides to pose a definite acute risk (ETR>100), seven to pose an acute possible risk (1≤ETR≤100) and 28 to pose no risk (ETR<1). Cadusafos (ETR=5200, PEC=39µg/l) was the most risky pesticide while imazalil (ETR=0.0002, PEC=0.0053µg/l) was the least risky compound. Cypermethrin was predicted to pose both definite acute risk to water and possible chronic risk to fish, water and Daphnia. Seven active ingredients were predicted to pose possible chronic risk to Daphnia. Pesticide used in plantations near water bodies is a threat to the aquatic ecosystem augmented in case of misuse. Bioaccumulation potential and impact of these compounds on water quality and biota community structure should be examined.
International Journal of Environment and Climate Change, 2021
Aims: The aim of this study was to evaluate farmer’s pesticide use practices and their effects in... more Aims: The aim of this study was to evaluate farmer’s pesticide use practices and their effects in the wetland of Ndop. Study Design: A cross sectional study was carried out from January to August 2019 in Ndop, North West Region of Cameroon. Methodology: Questionnaires were administered separately to 382 rice and 100 vegetable farmers, and descriptive statistics was used in analyzing the results. Specifically, the Chi-squared statistic was used to determine the nature of the relationship between the variables. Results: The results showed that most of the crop fields (95.6%) lack a buffer zone since most farms were adjacent to water bodies (0 ≥farm ≥1 m). Farmers (100%) washed and rinsed knapsack sprayers in nearby water bodies. A majority of the farmers (71.3%) burnt or threw empty pesticide containers in open fields, water bodies, or nearby bushes. Both rice farmers (83.5%) and vegetable farmers (100%) reported that pesticides kill non-target organisms (fish, frogs, toad, snakes, bi...
Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem an... more Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem and affect non-target organisms. This study aimed at assessing chemical pollution with pesticides using the PRIMET (Pesticides Risks in the tropics to Man, Environment and Trade) model in the Benoe stream. Ecotoxicological data on pesticides, pesticide and water physico-chemistry were used as input parameters. Water parameters were measured monthly for 06 months in 08 sampling points along the stream. Pesticide characteristics were obtained from the Pesticides Properties Data Base (PPDB) and the PRIMET software. The risk assessment was done for 44 active ingredients used in the area and whose ecotoxicological and physico-chemical data were available. Water parameters significantly (p<0.05) varied across seasons. Based on the Exposure Toxicity Ratio (ETR)
We conducted a study to assess the impact of peri-urban agricultural activities of the city of Ds... more We conducted a study to assess the impact of peri-urban agricultural activities of the city of Dschang on the water quality and macroinvertebrate structure of the Menoua stream. This study covered 3 stations (one reference station at the upstream of the peri-urban agricultural activities and two downstream) with a monthly sampling frequency from March 2015 to February 2016. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. Physico-chemical parameters such as temperature, pH, conductivity, TDS (Total Dissolved Solids), salinity, turbidity, colour, SS (Suspended Solids), nitrate, ammonium and orthophosphate were analyzed. The inventory of benthic macroinvertebrates revealed a taxonomic richness of 42 families and 77 taxa and a gross abundance of 1833 individuals. Spatio-temporal monitoring of physicochemical and biological parameters provided the image of relat...
Pesticides are widely used to reduce crop losses due to pests. This study (an initial part of a p... more Pesticides are widely used to reduce crop losses due to pests. This study (an initial part of a project on risk assessment and biomonitoring) deals with pesticide use patterns in the South-West, Cameroon. This descriptive and cross-sectional study was done using questionnaires randomly administered to 137 respondents. Twenty-one crops were recorded in the area with a total of 107 pesticides (60 active ingredients) used. Three illegally used pesticides were recorded (lindane, dimethoate and malathion). Application of pesticides in combination was quite common (42.3%). Pesticide application was mainly manual using a sprayer (96.4%) with 54% of users experiencing health problems post-application. Because of the lack of funding and training, 19.7% sprayed pesticides without protection. For the Restricted Entry Interval (REI), 43.1% entered the field in less than 12h after pesticide application. The correlation between the REI and the number of symptoms was negative and non-significant (...
The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on be... more The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on benthic macro-invertebrate community structure of the Doulahang stream was studied from March 2015 to February 2016 on a monthly basis in three sampling stations named TS1, TS2 and TS3. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. The analysis of physico-chemical parameters revealed that the introduction of wastewater from the sandpit at the TS2 station led to an increase of the temperature, conductivity, total dissolved solids, salinity, suspended matter, turbidity and colour. The wildlife inventory identified 63 taxa divided into 4 phyla, 6 classes, 13 orders and 31 families. The lowest values of the taxonomic richness (18 taxa, against 46 taxa and 47 taxa respectively to stations TS1 and TS3), the Shannon diversity index (2.48 bits / ind.) and the Pielou'...
Fungicides are widely used in agriculture, and released in large amounts to the environment. Meth... more Fungicides are widely used in agriculture, and released in large amounts to the environment. Methods used for antifungal susceptibility testing are cumbersome and time-consuming. As a result, very little attention has been paid to including fungal tests in the routine screening of pesticides and there are no reports in the literature of fungicide focussed effects directed analysis (EDA). In addition very little is known on the toxicity of fungicides to environmentally significant fungi. Here we report a rapid microplate-based resorufin fluorescence inhibition bioassay and compare it with a 24 h microplate-based yeast growth inhibition bioassay using eight fungicides. The growth inhibition bioassay was sensitive, giving IC50 and IC90 values comparable to previously reported IC50 or MICs of these fungicides for Saccharomyces cerevisiae and other fungi. The resorufin fluorescence inhibition bioassay was both faster and more sensitive than the growth inhibition bioassay. Inhibitory concentrations obtained just after 30 min of incubation with amphotericin B (AMB) and captan were at least a hundred fold lower than IC50s in the literature for fungi. The fluorescence bioassay showed only a small response to pyrazophos and thiabendazole but these only inhibited growth at high concentrations so this may reflect low sensitivity of S. cerevisiae to these particular fungicides. This bioassay can detect toxic effects of a range of fungicides from different chemical classes with different modes of action. It will be valuable for screening chemical libraries for fungicides and as a biomarker for detecting the effects of fungicides to non-target fungi.
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Papers by Patricia Fai