Water quality is the critical environmental determinant that influences the agricultural production and therefore, the economy that solely depends on its agricultural productions. Batiaghata Upazilla is one of the maj...Water quality is the critical environmental determinant that influences the agricultural production and therefore, the economy that solely depends on its agricultural productions. Batiaghata Upazilla is one of the major crop productive areas of Khulna region and the agricultural production here largely depends on the natural water of the Shailmari River system around it. The present study was conducted to assess the suitability of this coastal river water for irrigational use. 66 water samples were collected during this study in three consecutive agricultural seasons, viz., pre-monsoon (22), monsoon (22) and post-monsoon (22) from 11 sampling stations within the river system considering the high (11) and ebb (11) tides for each station. Standard methods were followed throughout the study period for the collection of the samples and analysis of major physicochemical parameters (pH, EC, TDS, salinity, Na, K, Ca, Mg, Cl, HCO<sub>3</sub>, SO<sub>4</sub>, NO<sub>3</sub> and PO<sub>4</sub>). Hydrocehmical characterization using Piper trilinear diagram shows that the water of the river system is Na-Cl dominated saline water type in pre-monsoon, whilst most of the samples of the river and the connected channel are characterized as fresh water of Ca-Mg-Na-HCO<sub>3</sub> and Ca-Na-Mg-HCO<sub>3</sub> types in monsoon and post-monsoon respectively. The calculated values of chemical indices like SAR, %Na, KI, PI and MH using the results of the analysed parameters indicate that the river water is chemically unsuitable for use in irrigation during pre-monsoon, while in the monsoon and post-monsoon the river water is within good to permissible limit for the use in the agricultural fields. However, high %Na, KI and MH values with high salinity of the channel water limit its use in agricultural applications in monsoon and post-monsoon. The USSL (United States Salinity Laboratory) diagram depicts that the river water is C4-S4 type with very high salinity and sodium content in pre-monsoon, while in other seasons the water is mostly C1-S1, C2-S1 or C2-S2 types (low to moderate salinity and sodium) in the river. Wilcox diagram shows that the river water is “suitable” for irrigation during monsoon and post-monsoon as the most of the samples range within “Excellent to Good” and “Good to permissible” categories, while it is “unsuitable” for crop irrigation during pre-monsoon when SAR (Sodium Adsorption Ratio) and EC (Electrical Conductivity) values of the water reach to their peaks.展开更多
0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the tra...0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).展开更多
Surface water has become one of the most vulnerable resources on the earth due to deterioration of its quality from diverse sources of pollution. Understanding of the spatiotemporal distribution of pollutants and iden...Surface water has become one of the most vulnerable resources on the earth due to deterioration of its quality from diverse sources of pollution. Understanding of the spatiotemporal distribution of pollutants and identification of the sources in the river systems is a prerequisite for the protection and sustainable utilization of the water resources. Multivariate statistical techniques such as Principal Component Analysis (PCA) and Factor Analysis (FA) were applied in this study to investigate the temporal and spatial variations of water quality and appoint the major factors of pollution in the Shailmari River system. Water quality data for 14 physicochemical parameters from 11 monitoring sites over the year of 2014 in three sampling seasons were collected and analyzed for this study. Kruskal-Wallis test showed significant (p < 0.01) temporal and spatial variations in all of the water quality parameters of the river water. Principal component analysis (PCA) allowed extracting the contributing parameters affecting the seasonal water quality in the river system. Scatter plots of the PCs showed the tidal and spatial variation within river system and identified parameters controlling the behavior in each case. Factor analysis (FA) further reduced the data and extracted factors which are significantly responsible for water quality variation in the river. The results indicate that the parameters controlling the water quality in different seasons are related with salinity, anthropogenic pollution (sewage disposal, effluents) and agricultural runoff in pre-monsoon;precipitation induced surface runoff in monsoon;and erosion, oxidation or organic pollution (point and non-point sources) in post-monsoon. Therefore, the study reveals the applicability and usefulness of the multivariate statistical methods in assessing water quality of river by identifying the potential environmental factors controlling the water quality in different seasons which might help to better understand, monitor and manage the quality of the water resources.展开更多
At Shailmari River basin, located in the central Ganges Delta and the southwestern coastal Bangladesh, groundwater is the only potable source for water supply due to incompatible surface water sources. However, salini...At Shailmari River basin, located in the central Ganges Delta and the southwestern coastal Bangladesh, groundwater is the only potable source for water supply due to incompatible surface water sources. However, salinity degradation along with arsenic and iron contamination poses a serious health threat to the basin community. Considering this, an investigation was carried out along both banks of the river to assess groundwater vulnerability and its quality for drinking by conducting multi-seasonal water sampling campaigns from 20 domestic wells and analyses (both in-situ and laboratory) for several physico-chemical (pH, EC, TDS and major ions) and biological (coliforms) parameters. The results show slightly alkaline groundwater in the study area with largely variable chemical composition, i.e. EC varies from around 1900 to 2700 μS/cm. The abundance of major ions indicates as Na+ > Ca2+ > Mg2+ > K+ for cations and ?> Cl- > ?> ?> ?for anions. As per the Canadian water quality index (CCMEWQI), almost all groundwater samples concentrate in the marginal category meaning that groundwater is frequently threatened. Besides, it is not fully safe for drinking as revealed from comparison of geochemical data with national and WHO water quality standards.展开更多
Potable water is a growing requirement for sound health as contaminated water and water-borne pathogens pose serious health risks to human beings. Considering this issue, the current study aimed to assess the drinking...Potable water is a growing requirement for sound health as contaminated water and water-borne pathogens pose serious health risks to human beings. Considering this issue, the current study aimed to assess the drinking water quality served in different restaurants close to the Khulna University campus in Bangladesh. A total number of ten drinking water samples were collected from different restaurants. Afterward, the collected water samples were analyzed to examine the physico-chemical properties and microbiological contamination of the water samples. Besides, microbial properties such as Total Coliform (TC), Fecal Coliform (FC), and E. coli were analyzed by the Membrane Filtration (MF) technique. The findings suggest that all the physico-chemical attributes were within the permissible limits regarding recommended Bangladesh standards and WHO guidelines. But in case of EC, 40% of the samples exceeded the WHO permissible limits and for sodium, 10% of samples exceeded both the BD and WHO standards. In addition, the results disclosed that the drinking water served in different restaurants was contaminated by TC, FC, and E. coli. It is observed that 100% of the samples were contaminated by TC and FC whereas 70% of the samples were contaminated by E. coli. Consequently, it is clearly evident that the water is considered suitable with respect to physico-chemical analysis but this drinking water is unfit for consumption while taking into account its microbiological quality. The total coliform, fecal coliform, and E. coli count attests to the fact that anyone can become harmed at any moment by ingesting water from roadside restaurants. Finally, due to bacterial contamination, the served drinking water in these places doesn’t meet safe and suitable water excellence, therefore, consumption of this water is deleterious to public health.展开更多
The study measured the concentration of coarse particulate matter (PM10) in the ambient air of Bangladesh Small and Cottage Industries Corporation (BSCIC) Bagerhat in order to evaluate its impact on workers’ health. ...The study measured the concentration of coarse particulate matter (PM10) in the ambient air of Bangladesh Small and Cottage Industries Corporation (BSCIC) Bagerhat in order to evaluate its impact on workers’ health. 14 known-volume air samples were obtained through Envirotech APM 541 PM10 Particulate Sampler. The short-term (6 hours) samples were taken from 9 industrial units in the winter season of October, 2015 to January, 2016. Simple gravimetric analysis showed large variations in concentrations in distinct industrial units. The minimum concentration was found 33.61 μ/m3 in the outdoor premises of a coconut oil mill and the maximum was found 471.38 μ/m3 in the house of a rice mill. The pollutant sources were detected as cabinless husking machines and soot from boilers and fryers. A questionnaire survey was conducted to evaluate the mostly occurring symptoms of Chronic Obstructive Pulmonary Diseases (COPD) and bronchoconstriction among workers. The highest prevalence of symptoms of bronchoconstriction (OR = 7.1;95% CI = 2.3 - 21.9) was found among workers in rice mills and eye disturbances (OR = 2.7;95% CI = 0.9 - 8.6) had the highest prevalence in coconut mills. Monitoring of air quality, providing personal respiratory prevention and improvement in machineries were required in the study area for a healthy environment.展开更多
Arsenic is a toxic element. Chronic exposure to arsenic can pose a variety of health problems including cancers, lung disease, skin lesions, diabetes, gangrene, reproductive disorders, hypertension, and heart disease....Arsenic is a toxic element. Chronic exposure to arsenic can pose a variety of health problems including cancers, lung disease, skin lesions, diabetes, gangrene, reproductive disorders, hypertension, and heart disease. Globally the concern of arsenic is growing day by day. Addressing this concern, the study aimed to assess the arsenic level in raw rice grain and rice cooked with tubewell water and rainwater. The study was conducted at the Sholotaka Union of Gangni Upazila in Meherpur District of Khulna Division, Bangladesh in 2023. For this purpose, seven raw samples including rice grain, rainwater and tubewell water samples and six cooked rice samples were analyzed. Rice and water samples were digested using the USEPA method-3050B in Arsenic Center Jashore, under Asia Arsenic Network, Japan. The arsenic level in the samples was tested using the HG-AAS method using a Shimadzu model AA7000 (Japan) Atomic Absorption Spectrophotometer. The study’s findings revealed that arsenic concentration in rainwater samples consistently displays 0 mg/l indicating the absence of arsenic in this sample. Three (03) tube well water samples and three (03) raw rice grain samples showed a significant variation in arsenic concentration. The mean value of tubewell water samples T1, T2, and T3 was found 0.53 ± 0.003 mg/l, 0.31 ± 0.003 mg/l, and 0.65 ± 0.002 mg/l, respectively. Whereas raw rice grain samples RG1 showed a mean of 0.607 ± 0.007 mg/kg, RG2 at 0.458 ± 0.008 mg/kg, and RG3 at 0.7145 ± 0.001 mg/kg. The study found that rice cooked with tubewell water contained a higher arsenic concentration than rice cooked with rainwater. The most prominent finding of this study was that cooked rice using rainwater had a lower amount of arsenic than the raw rice grain. So, it is clearly said that using rainwater can minimize the amount of arsenic. Furthermore, the study indicates that the health risks associated with arsenic exposure have increased. Estimated daily intake (EDI) values for cooked rice samples ranged from 3.07 to 5.47 μg/kg body weight/day, exceeding safe limits. Target Hazard Quotient (THQ) values varied from 10.2 to 18.2, indicating significant potential for non-carcinogenic health effects. Lifetime Cancer Risk (LCR) values ranged from 0.461% to 0.821% exceeding the U.S. Environmental Protection Agency’s acceptable risk threshold of 0.01%, which reflects a heightened cancer risk. The study suggests that people in the study area should use rainwater instead of tubewell water for their cooking purposes. Furthermore, rainwater harvesting should be prioritized in this area to address arsenic issues.展开更多
Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static enviro...Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.展开更多
Introduction:Mangrove forests are highly productive ecosystems distributed along the tropical coast line.Nutrient biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous sources.Charac...Introduction:Mangrove forests are highly productive ecosystems distributed along the tropical coast line.Nutrient biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous sources.Characterization of organic matter in coastal ecosystems enables to understand the biogeochemical transformation of organic matter and its influence on ecosystem productivity in response to various changing environmental conditions.Therefore,the elemental and stable carbon and nitrogen levels were employed to understand the organic matter(OM)dynamics in the Sundarban mangrove ecosystem(India-Bangladesh).Results:Differences in stable isotope values indicate that variable sources influence the OM dynamics in Sundarban sediments.The progressive enrichment inδ13C levels along the land-coastal continuum indicates that the terrestrial and marine inputs are dominant at the landward and seaward ends,respectively.The CuO oxidationderived lignin phenol monomers describe significant levels of total lignin are preserved in Sundarban mangrove sediments during diagenesis.The phenol monomer ratios are lower than the plant litter explaining that aromatic ring cleavage is the dominant mechanism for the lignin degradation.Furthermore,the Ad/Al ratios were higher than the plant litter explaining the oxidation of propyl side chain of vascular OM influencing the carbon cycling in Sundarban sediments.Largely,the Ad/Al ratios describe the vascular OM degradation is through the oxidation of propyl side chain.Conclusions:The regional variability in land-use regulates the spatial variability in C,N,OC/TN ratio,δ13C andδ15N between the Indian and the Bangladesh Sundarban mangroves and indicates that in the upstream terrestrial organic matter and/or mangrove plant litter contribute significant amount of organic matter,whereas the marine POC influences the organic matter dynamics in downstream.The three end-member mixing model applying terrestrial plant litter,seston,and marine POC as end-members explains the relative contribution of OM from various sources,and marine inputs were dominant in Sundarban sediments.展开更多
文摘Water quality is the critical environmental determinant that influences the agricultural production and therefore, the economy that solely depends on its agricultural productions. Batiaghata Upazilla is one of the major crop productive areas of Khulna region and the agricultural production here largely depends on the natural water of the Shailmari River system around it. The present study was conducted to assess the suitability of this coastal river water for irrigational use. 66 water samples were collected during this study in three consecutive agricultural seasons, viz., pre-monsoon (22), monsoon (22) and post-monsoon (22) from 11 sampling stations within the river system considering the high (11) and ebb (11) tides for each station. Standard methods were followed throughout the study period for the collection of the samples and analysis of major physicochemical parameters (pH, EC, TDS, salinity, Na, K, Ca, Mg, Cl, HCO<sub>3</sub>, SO<sub>4</sub>, NO<sub>3</sub> and PO<sub>4</sub>). Hydrocehmical characterization using Piper trilinear diagram shows that the water of the river system is Na-Cl dominated saline water type in pre-monsoon, whilst most of the samples of the river and the connected channel are characterized as fresh water of Ca-Mg-Na-HCO<sub>3</sub> and Ca-Na-Mg-HCO<sub>3</sub> types in monsoon and post-monsoon respectively. The calculated values of chemical indices like SAR, %Na, KI, PI and MH using the results of the analysed parameters indicate that the river water is chemically unsuitable for use in irrigation during pre-monsoon, while in the monsoon and post-monsoon the river water is within good to permissible limit for the use in the agricultural fields. However, high %Na, KI and MH values with high salinity of the channel water limit its use in agricultural applications in monsoon and post-monsoon. The USSL (United States Salinity Laboratory) diagram depicts that the river water is C4-S4 type with very high salinity and sodium content in pre-monsoon, while in other seasons the water is mostly C1-S1, C2-S1 or C2-S2 types (low to moderate salinity and sodium) in the river. Wilcox diagram shows that the river water is “suitable” for irrigation during monsoon and post-monsoon as the most of the samples range within “Excellent to Good” and “Good to permissible” categories, while it is “unsuitable” for crop irrigation during pre-monsoon when SAR (Sodium Adsorption Ratio) and EC (Electrical Conductivity) values of the water reach to their peaks.
基金funded by the National Natural Science Foundation of China(No.42271078)the Key Research and Development Program of Shaanxi(No.2024SF-YBXM669)。
文摘0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).
文摘Surface water has become one of the most vulnerable resources on the earth due to deterioration of its quality from diverse sources of pollution. Understanding of the spatiotemporal distribution of pollutants and identification of the sources in the river systems is a prerequisite for the protection and sustainable utilization of the water resources. Multivariate statistical techniques such as Principal Component Analysis (PCA) and Factor Analysis (FA) were applied in this study to investigate the temporal and spatial variations of water quality and appoint the major factors of pollution in the Shailmari River system. Water quality data for 14 physicochemical parameters from 11 monitoring sites over the year of 2014 in three sampling seasons were collected and analyzed for this study. Kruskal-Wallis test showed significant (p < 0.01) temporal and spatial variations in all of the water quality parameters of the river water. Principal component analysis (PCA) allowed extracting the contributing parameters affecting the seasonal water quality in the river system. Scatter plots of the PCs showed the tidal and spatial variation within river system and identified parameters controlling the behavior in each case. Factor analysis (FA) further reduced the data and extracted factors which are significantly responsible for water quality variation in the river. The results indicate that the parameters controlling the water quality in different seasons are related with salinity, anthropogenic pollution (sewage disposal, effluents) and agricultural runoff in pre-monsoon;precipitation induced surface runoff in monsoon;and erosion, oxidation or organic pollution (point and non-point sources) in post-monsoon. Therefore, the study reveals the applicability and usefulness of the multivariate statistical methods in assessing water quality of river by identifying the potential environmental factors controlling the water quality in different seasons which might help to better understand, monitor and manage the quality of the water resources.
文摘At Shailmari River basin, located in the central Ganges Delta and the southwestern coastal Bangladesh, groundwater is the only potable source for water supply due to incompatible surface water sources. However, salinity degradation along with arsenic and iron contamination poses a serious health threat to the basin community. Considering this, an investigation was carried out along both banks of the river to assess groundwater vulnerability and its quality for drinking by conducting multi-seasonal water sampling campaigns from 20 domestic wells and analyses (both in-situ and laboratory) for several physico-chemical (pH, EC, TDS and major ions) and biological (coliforms) parameters. The results show slightly alkaline groundwater in the study area with largely variable chemical composition, i.e. EC varies from around 1900 to 2700 μS/cm. The abundance of major ions indicates as Na+ > Ca2+ > Mg2+ > K+ for cations and ?> Cl- > ?> ?> ?for anions. As per the Canadian water quality index (CCMEWQI), almost all groundwater samples concentrate in the marginal category meaning that groundwater is frequently threatened. Besides, it is not fully safe for drinking as revealed from comparison of geochemical data with national and WHO water quality standards.
文摘Potable water is a growing requirement for sound health as contaminated water and water-borne pathogens pose serious health risks to human beings. Considering this issue, the current study aimed to assess the drinking water quality served in different restaurants close to the Khulna University campus in Bangladesh. A total number of ten drinking water samples were collected from different restaurants. Afterward, the collected water samples were analyzed to examine the physico-chemical properties and microbiological contamination of the water samples. Besides, microbial properties such as Total Coliform (TC), Fecal Coliform (FC), and E. coli were analyzed by the Membrane Filtration (MF) technique. The findings suggest that all the physico-chemical attributes were within the permissible limits regarding recommended Bangladesh standards and WHO guidelines. But in case of EC, 40% of the samples exceeded the WHO permissible limits and for sodium, 10% of samples exceeded both the BD and WHO standards. In addition, the results disclosed that the drinking water served in different restaurants was contaminated by TC, FC, and E. coli. It is observed that 100% of the samples were contaminated by TC and FC whereas 70% of the samples were contaminated by E. coli. Consequently, it is clearly evident that the water is considered suitable with respect to physico-chemical analysis but this drinking water is unfit for consumption while taking into account its microbiological quality. The total coliform, fecal coliform, and E. coli count attests to the fact that anyone can become harmed at any moment by ingesting water from roadside restaurants. Finally, due to bacterial contamination, the served drinking water in these places doesn’t meet safe and suitable water excellence, therefore, consumption of this water is deleterious to public health.
文摘The study measured the concentration of coarse particulate matter (PM10) in the ambient air of Bangladesh Small and Cottage Industries Corporation (BSCIC) Bagerhat in order to evaluate its impact on workers’ health. 14 known-volume air samples were obtained through Envirotech APM 541 PM10 Particulate Sampler. The short-term (6 hours) samples were taken from 9 industrial units in the winter season of October, 2015 to January, 2016. Simple gravimetric analysis showed large variations in concentrations in distinct industrial units. The minimum concentration was found 33.61 μ/m3 in the outdoor premises of a coconut oil mill and the maximum was found 471.38 μ/m3 in the house of a rice mill. The pollutant sources were detected as cabinless husking machines and soot from boilers and fryers. A questionnaire survey was conducted to evaluate the mostly occurring symptoms of Chronic Obstructive Pulmonary Diseases (COPD) and bronchoconstriction among workers. The highest prevalence of symptoms of bronchoconstriction (OR = 7.1;95% CI = 2.3 - 21.9) was found among workers in rice mills and eye disturbances (OR = 2.7;95% CI = 0.9 - 8.6) had the highest prevalence in coconut mills. Monitoring of air quality, providing personal respiratory prevention and improvement in machineries were required in the study area for a healthy environment.
文摘Arsenic is a toxic element. Chronic exposure to arsenic can pose a variety of health problems including cancers, lung disease, skin lesions, diabetes, gangrene, reproductive disorders, hypertension, and heart disease. Globally the concern of arsenic is growing day by day. Addressing this concern, the study aimed to assess the arsenic level in raw rice grain and rice cooked with tubewell water and rainwater. The study was conducted at the Sholotaka Union of Gangni Upazila in Meherpur District of Khulna Division, Bangladesh in 2023. For this purpose, seven raw samples including rice grain, rainwater and tubewell water samples and six cooked rice samples were analyzed. Rice and water samples were digested using the USEPA method-3050B in Arsenic Center Jashore, under Asia Arsenic Network, Japan. The arsenic level in the samples was tested using the HG-AAS method using a Shimadzu model AA7000 (Japan) Atomic Absorption Spectrophotometer. The study’s findings revealed that arsenic concentration in rainwater samples consistently displays 0 mg/l indicating the absence of arsenic in this sample. Three (03) tube well water samples and three (03) raw rice grain samples showed a significant variation in arsenic concentration. The mean value of tubewell water samples T1, T2, and T3 was found 0.53 ± 0.003 mg/l, 0.31 ± 0.003 mg/l, and 0.65 ± 0.002 mg/l, respectively. Whereas raw rice grain samples RG1 showed a mean of 0.607 ± 0.007 mg/kg, RG2 at 0.458 ± 0.008 mg/kg, and RG3 at 0.7145 ± 0.001 mg/kg. The study found that rice cooked with tubewell water contained a higher arsenic concentration than rice cooked with rainwater. The most prominent finding of this study was that cooked rice using rainwater had a lower amount of arsenic than the raw rice grain. So, it is clearly said that using rainwater can minimize the amount of arsenic. Furthermore, the study indicates that the health risks associated with arsenic exposure have increased. Estimated daily intake (EDI) values for cooked rice samples ranged from 3.07 to 5.47 μg/kg body weight/day, exceeding safe limits. Target Hazard Quotient (THQ) values varied from 10.2 to 18.2, indicating significant potential for non-carcinogenic health effects. Lifetime Cancer Risk (LCR) values ranged from 0.461% to 0.821% exceeding the U.S. Environmental Protection Agency’s acceptable risk threshold of 0.01%, which reflects a heightened cancer risk. The study suggests that people in the study area should use rainwater instead of tubewell water for their cooking purposes. Furthermore, rainwater harvesting should be prioritized in this area to address arsenic issues.
基金the National Natural Science Foundation of China(Grant No.42271078)Key Research and Development Program of Shaanxi(2024SF-YBXM-669)。
文摘Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.
文摘Introduction:Mangrove forests are highly productive ecosystems distributed along the tropical coast line.Nutrient biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous sources.Characterization of organic matter in coastal ecosystems enables to understand the biogeochemical transformation of organic matter and its influence on ecosystem productivity in response to various changing environmental conditions.Therefore,the elemental and stable carbon and nitrogen levels were employed to understand the organic matter(OM)dynamics in the Sundarban mangrove ecosystem(India-Bangladesh).Results:Differences in stable isotope values indicate that variable sources influence the OM dynamics in Sundarban sediments.The progressive enrichment inδ13C levels along the land-coastal continuum indicates that the terrestrial and marine inputs are dominant at the landward and seaward ends,respectively.The CuO oxidationderived lignin phenol monomers describe significant levels of total lignin are preserved in Sundarban mangrove sediments during diagenesis.The phenol monomer ratios are lower than the plant litter explaining that aromatic ring cleavage is the dominant mechanism for the lignin degradation.Furthermore,the Ad/Al ratios were higher than the plant litter explaining the oxidation of propyl side chain of vascular OM influencing the carbon cycling in Sundarban sediments.Largely,the Ad/Al ratios describe the vascular OM degradation is through the oxidation of propyl side chain.Conclusions:The regional variability in land-use regulates the spatial variability in C,N,OC/TN ratio,δ13C andδ15N between the Indian and the Bangladesh Sundarban mangroves and indicates that in the upstream terrestrial organic matter and/or mangrove plant litter contribute significant amount of organic matter,whereas the marine POC influences the organic matter dynamics in downstream.The three end-member mixing model applying terrestrial plant litter,seston,and marine POC as end-members explains the relative contribution of OM from various sources,and marine inputs were dominant in Sundarban sediments.
