To evaluate the actual status of water quality and conclude on the mains source of pollution in the Nyong estuary River, seasonal and spatial variation of water quality parameters was interpreted by multivariate stati...To evaluate the actual status of water quality and conclude on the mains source of pollution in the Nyong estuary River, seasonal and spatial variation of water quality parameters was interpreted by multivariate statistical techniques (Principal Component analysis). Nine (09) environmental variables were monitored at four surface stations in the estuary for two seasonal cycles. The fieldwork was conducted from 2018 to 2019 during high tide and low <span style="letter-spacing:0.1pt;">tide for each survey. In situ physical parameters were measured for a total of</span> 64 samples (32 samples for each tide). The laboratory works consisted of some physicochemical analyses and processing of these data by descriptive <span style="letter-spacing:0.1pt;">and multidimensional statistical analyses. Temperature, suspended particle</span> matter, nitrate, nitrite and phosphate change significantly in the estuary with season (<i>p</i> < 0.05), while salinity, dissolved oxygen, pH, and ammonium do not vary significantly with season (<i>p</i> > 0.05). Principal Component analysis found temperature, salinity, pH, ammonium to be the most important parameters contributing to the fluctuations of surface water quality in the Nyong estuary during the dry seasons whereas suspended particle matter, nitrate, and phosphate are the most important parameters contributing to the fluctuation of surface water quality in the Nyong estuary during the rainy seasons. Based on spatial variation, the Principal Component analysis found that, suspended particle matter, nitrate and phosphate contribute to the fluctuation of surface water quality parameters upstream of the estuary while downstream salinity, pH, and ammonium contribute the most to the fluctuation of surface water quality. This study shows us the usefulness of multivariate statistical techniques used in assessing water quality data sets that would help us in un<span style="letter-spacing:0.1pt;">derstanding seasonal and spatial variations of water quality parameters to</span> manage estuarine systems.展开更多
Urban areas face significant challenges in maintaining water quality amidst increasing urbanization and changing climatic patterns. This study investigates the complex interplay between meteorological variables and wa...Urban areas face significant challenges in maintaining water quality amidst increasing urbanization and changing climatic patterns. This study investigates the complex interplay between meteorological variables and water quality parameters in Nairobi City, focusing on the impacts of rainfall and temperature on surface water quality. Data from multiple sources, including the Water Resources Authority, Nairobi Water and Sewerage Company, and the World Bank’s Climate Change Knowledge Portal, were analyzed to assess the relationships between meteorological variables (rainfall and temperature) and water quality parameters (such as electroconductivity, biochemical oxygen demand, chloride, and pH). The analysis reveals varying impacts of rainfall and temperature on different water quality parameters. While parameters like iron and pH show strong relationships with both rainfall and temperature, others such as ammonia and nitrate exhibit moderate relationships. Additionally, the study highlights the influence of runoff, urbanization, and industrial activities on water quality, emphasizing the need for holistic management approaches. Recommendations encompass the establishment of annual publications on Nairobi River water quality, online accessibility of water quality data, development of hydrological models, spatial analysis, and fostering cross-disciplinary research collaborations. Implementing these recommendations can enhance water quality management practices, mitigate risks, and safeguard environmental integrity in Nairobi City.展开更多
To determine the variation of water quality in rice-crayfish(Procambarus clarkii)integrated systems(RCIS)in China,eleven water quality parameters were measured monthly in a typical RCIS located in Qianjiang City(Hubei...To determine the variation of water quality in rice-crayfish(Procambarus clarkii)integrated systems(RCIS)in China,eleven water quality parameters were measured monthly in a typical RCIS located in Qianjiang City(Hubei Province)from July 2014 to June 2015,the parameters were analyzed with principal component analysis(PCA)and compared between the trenches and rice areas during the rice fallow period(Nov-May).The trench and rice area comprehensive results showed that pH(7.48-8.68),NH_(4)^(+)-N(0.2-1.09 mg/L),NO_(2)^(-)-N(<0.052 mg/L)and conductivity(435-951μS/cm)were within the suitable ranges for P.clarkii and that turbidity(TU)was high during the crayfish harvesting and rice planting season.Annual averages of total nitrogen(TN),total phosphorus(TP),permanganate index(CODMn),and chlorophyll a(Chl.a)content were<2(except in Nov-Dec),0.25,10 mg/L,and 50 mg/m^(3)(especially in Nov-May,<10 mg/m^(3)),respectively.Dissolved oxygen(DO)was below 4 mg/L in Mar-Sep,with a minimum of~1 mg/L,and much higher in Oct-Feb.The maximum and minimum monthly average water temperature(WT)were 31.4°C in July and 5.7°C in December,while the maximum and minimum instantaneous WT were 39.7°C and 2.5°C,respectively.PCA analysis showed that the first three axes,which were mainly correlated with DO,WT and nutrient level,described most information of the parameters,and parameters showed seasonal changes.Some differences were observed in water parameters between the trenches and rice areas,i.e.,trenches generally had higher TU,WT and DO,and lower TN,TP and CODMn,although no significant differences were found in some months and some parameters.The study revealed relatively low water nutrient level,probable extreme WT and DO level in some seasons,and certain differences between the trenches and rice areas in typical CRIS in China.Accordingly,some measures should be taken to improve the negative parameters:1)enhance the water fertility;2)increase DO,especially in Mar-Sep;3)increase the trench and water depth to avoid extreme WT.And water quality management should be addressed in both trenches and rice areas.展开更多
The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed w...The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed wetlands,were investigated with laboratoryscale systems.N_(2)O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent,and the total N_(2)O emission in the system with middle COD influent concentration was the least.The relationships between N_(2)O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N_(2)O flux.The multiple linear regression model against principal components indicated that different water parameters affected N_(2)O flux with different COD concentrations in the influent,but nitrate nitrogen affected N_(2)O flux in all systems.展开更多
Using remote sensing technology for water quality evaluation is an inevitable trend in marine environmental monitoring. However, fewer categories of water quality parameters can be monitored by remote sensing technolo...Using remote sensing technology for water quality evaluation is an inevitable trend in marine environmental monitoring. However, fewer categories of water quality parameters can be monitored by remote sensing technology than the 35 specified in GB3097-1997 Marine Water Quality Standard. Therefore, we considered which parameters must be selected by remote sensing and how to model for water quality evaluation using the finite parameters. In this paper, focused on Leizhou Peninsula nearshore waters, we found N, P, COD, PH and DO to be the dominant parameters of water quality by analyzing measured data. Then, mathematical statistics was used to determine that the relationship among the five parameters was COD〉DO〉P〉N〉pH. Finally, five-parameter, fourparameter and three-parameter water quality evaluation models were established and compared. The results showed that COD, DO, P and N were the necessary parameters for remote sensing evaluation of the Leizhou Peninsula nearshore water quality, and the optimal comprehensive water quality evaluation model was the four- parameter model. This work may serve as a reference for monitoring the quality of other marine waters by remote sensing.展开更多
Climate change and variability have been inducing a broad spectrum of impacts on the environment and natural resources including groundwater resources. The study aimed at assessing the influence of weather, climate va...Climate change and variability have been inducing a broad spectrum of impacts on the environment and natural resources including groundwater resources. The study aimed at assessing the influence of weather, climate variability, and changes on the quality of groundwater resources in Zanzibar. The study used the climate datasets including rainfall (RF), Maximum and Minimum Temperature (T<sub>max</sub> and T<sub>min</sub>), the records acquired from Tanzania Meteorological Authority (TMA) Zanzibar office for 30 (1989-2019) and 10 (2010-2019) years periods. Also, the Zanzibar Water Authority (ZAWA) monthly records of Total Dissolved Solids (TDS), Electrical Conductivity (EC), and Ground Water Temperature (GWT) were used. Interpolation techniques were used for controlling outliers and missing datasets. Indeed, correlation, trend, and time series analyses were used to show the relationship between climate and water quality parameters. However, simple statistical analyses including mean, percentage changes, and contributions to the annual and seasonal mean were calculated. Moreover, t and paired t-tests were used to show the significant changes in the mean of the variables for two defined periods of 2011-2015 and 2016-2020 at p ≤ 0.05. Results revealed that seasonal variability of groundwater quality from March to May (MAM) has shown a significant change in trends ranging from 0.1 to 2.8 mm/L/yr, 0.1 to 2.8 μS/cm/yr, and 0.1 to 2.0℃/yr for TDS, EC, and GWT, respectively. The changes in climate parameters were 0.1 to 2.4 mm/yr, 0.2 to 1.3℃/yr and 0.1 to 2.5℃/yr in RF, T<sub>max</sub>, and T<sub>min</sub>, respectively. From October to December (OND) changes in groundwater parameters ranged from 0.2 to 2.5 mm/L/yr 0.1 to 2.9 μS/cm/yr, and 0.1 to 2.1℃/yr for TDS, EC, and GWT, whereas RF, T<sub>max</sub>, and T<sub>min</sub> changed from 0.3 to 1.8 mm/yr, 0.2 to 1.9℃/yr and 0.2 to 2.0℃/yr, respectively. Moreover, the study has shown strong correlations between climate and water quality parameters in MAM and OND. Besides, the paired correlation has shown significant changes in all parameters except the rainfall. Conclusively, the study has shown a strong influence of climate variability on the quality of groundwater in Zanzibar, and calls for more studies to extrapolate these results throughout Tanzania.展开更多
The oyster disease Dermo(Perkinsus marinus)affects the viability of oyster reefs of Galveston Bay,Texas.Documenting the relationships between distribution and prevalence of Dermo disease in the eastern oyster(Crassost...The oyster disease Dermo(Perkinsus marinus)affects the viability of oyster reefs of Galveston Bay,Texas.Documenting the relationships between distribution and prevalence of Dermo disease in the eastern oyster(Crassostrea virginica)and environmental conditions is beneficial to management of the eastern oyster in Galveston Bay.We sampled four sites located in Galveston Bay every other month from November 2014 through September 2015.The focus of the study was the relationship of water quality parameters(i.e.,fresh-water flow,salinity,water temperature,and water turbidity)to prevalence and parasite concentration of Dermo disease in oysters.Dermo was present in oysters at all reefs sampled,and Dermo prevalence was greatest at April Fool and Confederate reefs,but declined after heavy rainfall.Linear regression analysis indicated water variables such as temperature,salinity,turbidity,and fresh water inflow explained different amounts of the variability in the Mackin Dermo Intensity Scale among sampled reefs.We found combinations of low fresh-water inflow,high salinity,and high temperatures accounted for majority of the variance of Dermo in oysters located in Galveston Bay.展开更多
Objective:To observe the effectiveness of most widely used antibiotic,oxytetracycline(OTC)in reducing the bacterial load in rohu fish under artificial culture condition in the laboratory.Methods:The experiment was con...Objective:To observe the effectiveness of most widely used antibiotic,oxytetracycline(OTC)in reducing the bacterial load in rohu fish under artificial culture condition in the laboratory.Methods:The experiment was conducted in the Faculty Fisheries,Bangladesh Agricultural University,Mymensingh-2202.The fish were reared in 8 aquaria where fish in 5 aquaria were used for replication of the treatment(experimental group)and fish in remaining 3 aquaria were considered as a control(Control group).OTC was fed to the fish in the experimental aquarium at the rate of 2 g/kg through diet twice daily whereas fish reared under control condition was given feed without antibiotic for 20 d and bacterial content in the aquarium water,gills,skin and intestine of fish were estimated at every alternative day after onset of the experiment.Results:Rearing the fish with OTC treated feed resulted in gradual decrease of bacterial load in the aquarium water,gills,intestine and skin of the fish whereas the content remain unchanged Or little increased in the control group.W ater quality parameters such as dissolved oxygen,pH and total hardness were within the suitable range in the experimental aquarium but not in control aquaria throughout the experimental period.Conclusions:These results suggest that OTC could be a potential antibiotic to reduce the bacterial load in fish and can be used commercially for maintaining the fish health in aquarium conditions.展开更多
文摘To evaluate the actual status of water quality and conclude on the mains source of pollution in the Nyong estuary River, seasonal and spatial variation of water quality parameters was interpreted by multivariate statistical techniques (Principal Component analysis). Nine (09) environmental variables were monitored at four surface stations in the estuary for two seasonal cycles. The fieldwork was conducted from 2018 to 2019 during high tide and low <span style="letter-spacing:0.1pt;">tide for each survey. In situ physical parameters were measured for a total of</span> 64 samples (32 samples for each tide). The laboratory works consisted of some physicochemical analyses and processing of these data by descriptive <span style="letter-spacing:0.1pt;">and multidimensional statistical analyses. Temperature, suspended particle</span> matter, nitrate, nitrite and phosphate change significantly in the estuary with season (<i>p</i> < 0.05), while salinity, dissolved oxygen, pH, and ammonium do not vary significantly with season (<i>p</i> > 0.05). Principal Component analysis found temperature, salinity, pH, ammonium to be the most important parameters contributing to the fluctuations of surface water quality in the Nyong estuary during the dry seasons whereas suspended particle matter, nitrate, and phosphate are the most important parameters contributing to the fluctuation of surface water quality in the Nyong estuary during the rainy seasons. Based on spatial variation, the Principal Component analysis found that, suspended particle matter, nitrate and phosphate contribute to the fluctuation of surface water quality parameters upstream of the estuary while downstream salinity, pH, and ammonium contribute the most to the fluctuation of surface water quality. This study shows us the usefulness of multivariate statistical techniques used in assessing water quality data sets that would help us in un<span style="letter-spacing:0.1pt;">derstanding seasonal and spatial variations of water quality parameters to</span> manage estuarine systems.
文摘Urban areas face significant challenges in maintaining water quality amidst increasing urbanization and changing climatic patterns. This study investigates the complex interplay between meteorological variables and water quality parameters in Nairobi City, focusing on the impacts of rainfall and temperature on surface water quality. Data from multiple sources, including the Water Resources Authority, Nairobi Water and Sewerage Company, and the World Bank’s Climate Change Knowledge Portal, were analyzed to assess the relationships between meteorological variables (rainfall and temperature) and water quality parameters (such as electroconductivity, biochemical oxygen demand, chloride, and pH). The analysis reveals varying impacts of rainfall and temperature on different water quality parameters. While parameters like iron and pH show strong relationships with both rainfall and temperature, others such as ammonia and nitrate exhibit moderate relationships. Additionally, the study highlights the influence of runoff, urbanization, and industrial activities on water quality, emphasizing the need for holistic management approaches. Recommendations encompass the establishment of annual publications on Nairobi River water quality, online accessibility of water quality data, development of hydrological models, spatial analysis, and fostering cross-disciplinary research collaborations. Implementing these recommendations can enhance water quality management practices, mitigate risks, and safeguard environmental integrity in Nairobi City.
基金This work was financially supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201203081)the R&D Program of the Ministry of Science and Technology of China(Nos.2012BAD25B06 and 2015BAD13B02).
文摘To determine the variation of water quality in rice-crayfish(Procambarus clarkii)integrated systems(RCIS)in China,eleven water quality parameters were measured monthly in a typical RCIS located in Qianjiang City(Hubei Province)from July 2014 to June 2015,the parameters were analyzed with principal component analysis(PCA)and compared between the trenches and rice areas during the rice fallow period(Nov-May).The trench and rice area comprehensive results showed that pH(7.48-8.68),NH_(4)^(+)-N(0.2-1.09 mg/L),NO_(2)^(-)-N(<0.052 mg/L)and conductivity(435-951μS/cm)were within the suitable ranges for P.clarkii and that turbidity(TU)was high during the crayfish harvesting and rice planting season.Annual averages of total nitrogen(TN),total phosphorus(TP),permanganate index(CODMn),and chlorophyll a(Chl.a)content were<2(except in Nov-Dec),0.25,10 mg/L,and 50 mg/m^(3)(especially in Nov-May,<10 mg/m^(3)),respectively.Dissolved oxygen(DO)was below 4 mg/L in Mar-Sep,with a minimum of~1 mg/L,and much higher in Oct-Feb.The maximum and minimum monthly average water temperature(WT)were 31.4°C in July and 5.7°C in December,while the maximum and minimum instantaneous WT were 39.7°C and 2.5°C,respectively.PCA analysis showed that the first three axes,which were mainly correlated with DO,WT and nutrient level,described most information of the parameters,and parameters showed seasonal changes.Some differences were observed in water parameters between the trenches and rice areas,i.e.,trenches generally had higher TU,WT and DO,and lower TN,TP and CODMn,although no significant differences were found in some months and some parameters.The study revealed relatively low water nutrient level,probable extreme WT and DO level in some seasons,and certain differences between the trenches and rice areas in typical CRIS in China.Accordingly,some measures should be taken to improve the negative parameters:1)enhance the water fertility;2)increase DO,especially in Mar-Sep;3)increase the trench and water depth to avoid extreme WT.And water quality management should be addressed in both trenches and rice areas.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50508019)the National Natural Science Foundation of China-Japan Science and Technology Agency(NSFC-JST)Strategic Joint Research Project(Grant No.50721140117).
文摘The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed wetlands,were investigated with laboratoryscale systems.N_(2)O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent,and the total N_(2)O emission in the system with middle COD influent concentration was the least.The relationships between N_(2)O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N_(2)O flux.The multiple linear regression model against principal components indicated that different water parameters affected N_(2)O flux with different COD concentrations in the influent,but nitrate nitrogen affected N_(2)O flux in all systems.
基金The Science and Technology Project of Guangdong Province under contract No.2014A010103030the Postdoctoral Science Foundation of Zhejiang under contract No.BSH1301015the Supported by Foundation for Distinguished Young Talents in Higher Education of Guangdong Province No.GDOU2013050233
文摘Using remote sensing technology for water quality evaluation is an inevitable trend in marine environmental monitoring. However, fewer categories of water quality parameters can be monitored by remote sensing technology than the 35 specified in GB3097-1997 Marine Water Quality Standard. Therefore, we considered which parameters must be selected by remote sensing and how to model for water quality evaluation using the finite parameters. In this paper, focused on Leizhou Peninsula nearshore waters, we found N, P, COD, PH and DO to be the dominant parameters of water quality by analyzing measured data. Then, mathematical statistics was used to determine that the relationship among the five parameters was COD〉DO〉P〉N〉pH. Finally, five-parameter, fourparameter and three-parameter water quality evaluation models were established and compared. The results showed that COD, DO, P and N were the necessary parameters for remote sensing evaluation of the Leizhou Peninsula nearshore water quality, and the optimal comprehensive water quality evaluation model was the four- parameter model. This work may serve as a reference for monitoring the quality of other marine waters by remote sensing.
文摘Climate change and variability have been inducing a broad spectrum of impacts on the environment and natural resources including groundwater resources. The study aimed at assessing the influence of weather, climate variability, and changes on the quality of groundwater resources in Zanzibar. The study used the climate datasets including rainfall (RF), Maximum and Minimum Temperature (T<sub>max</sub> and T<sub>min</sub>), the records acquired from Tanzania Meteorological Authority (TMA) Zanzibar office for 30 (1989-2019) and 10 (2010-2019) years periods. Also, the Zanzibar Water Authority (ZAWA) monthly records of Total Dissolved Solids (TDS), Electrical Conductivity (EC), and Ground Water Temperature (GWT) were used. Interpolation techniques were used for controlling outliers and missing datasets. Indeed, correlation, trend, and time series analyses were used to show the relationship between climate and water quality parameters. However, simple statistical analyses including mean, percentage changes, and contributions to the annual and seasonal mean were calculated. Moreover, t and paired t-tests were used to show the significant changes in the mean of the variables for two defined periods of 2011-2015 and 2016-2020 at p ≤ 0.05. Results revealed that seasonal variability of groundwater quality from March to May (MAM) has shown a significant change in trends ranging from 0.1 to 2.8 mm/L/yr, 0.1 to 2.8 μS/cm/yr, and 0.1 to 2.0℃/yr for TDS, EC, and GWT, respectively. The changes in climate parameters were 0.1 to 2.4 mm/yr, 0.2 to 1.3℃/yr and 0.1 to 2.5℃/yr in RF, T<sub>max</sub>, and T<sub>min</sub>, respectively. From October to December (OND) changes in groundwater parameters ranged from 0.2 to 2.5 mm/L/yr 0.1 to 2.9 μS/cm/yr, and 0.1 to 2.1℃/yr for TDS, EC, and GWT, whereas RF, T<sub>max</sub>, and T<sub>min</sub> changed from 0.3 to 1.8 mm/yr, 0.2 to 1.9℃/yr and 0.2 to 2.0℃/yr, respectively. Moreover, the study has shown strong correlations between climate and water quality parameters in MAM and OND. Besides, the paired correlation has shown significant changes in all parameters except the rainfall. Conclusively, the study has shown a strong influence of climate variability on the quality of groundwater in Zanzibar, and calls for more studies to extrapolate these results throughout Tanzania.
文摘The oyster disease Dermo(Perkinsus marinus)affects the viability of oyster reefs of Galveston Bay,Texas.Documenting the relationships between distribution and prevalence of Dermo disease in the eastern oyster(Crassostrea virginica)and environmental conditions is beneficial to management of the eastern oyster in Galveston Bay.We sampled four sites located in Galveston Bay every other month from November 2014 through September 2015.The focus of the study was the relationship of water quality parameters(i.e.,fresh-water flow,salinity,water temperature,and water turbidity)to prevalence and parasite concentration of Dermo disease in oysters.Dermo was present in oysters at all reefs sampled,and Dermo prevalence was greatest at April Fool and Confederate reefs,but declined after heavy rainfall.Linear regression analysis indicated water variables such as temperature,salinity,turbidity,and fresh water inflow explained different amounts of the variability in the Mackin Dermo Intensity Scale among sampled reefs.We found combinations of low fresh-water inflow,high salinity,and high temperatures accounted for majority of the variance of Dermo in oysters located in Galveston Bay.
基金Supported in part by Bangladesh Fisheries Research Institute(BFRI).
文摘Objective:To observe the effectiveness of most widely used antibiotic,oxytetracycline(OTC)in reducing the bacterial load in rohu fish under artificial culture condition in the laboratory.Methods:The experiment was conducted in the Faculty Fisheries,Bangladesh Agricultural University,Mymensingh-2202.The fish were reared in 8 aquaria where fish in 5 aquaria were used for replication of the treatment(experimental group)and fish in remaining 3 aquaria were considered as a control(Control group).OTC was fed to the fish in the experimental aquarium at the rate of 2 g/kg through diet twice daily whereas fish reared under control condition was given feed without antibiotic for 20 d and bacterial content in the aquarium water,gills,skin and intestine of fish were estimated at every alternative day after onset of the experiment.Results:Rearing the fish with OTC treated feed resulted in gradual decrease of bacterial load in the aquarium water,gills,intestine and skin of the fish whereas the content remain unchanged Or little increased in the control group.W ater quality parameters such as dissolved oxygen,pH and total hardness were within the suitable range in the experimental aquarium but not in control aquaria throughout the experimental period.Conclusions:These results suggest that OTC could be a potential antibiotic to reduce the bacterial load in fish and can be used commercially for maintaining the fish health in aquarium conditions.