Coastal groundwater aquifer characterization from geoelectrical measurements- A case study at Kalapara, Patuakhali, Bangladesh.

Vertical electrical sounding has been carried out in a coastal area in the southern part of Bangladesh to locate the groundwater aquifers containing fresh water. The Interpex1X1Dv3 computer program was used to process the field apparent resistivity data sets obtained from the vertical electrical sounding.  Geoelectric layers were identified in the context of resistivity and thickness from the vertical electrical sounding data. From the initial parameters layered model was achieved using the inversion technique. Correlation of the obtained layer model with a nearby lithologic log concludes the groundwater aquifer system of the area. From the electrical properties of the subsurface layers, water bearing layers were detected and characterized. Very fine sand geoelectric layer with a thickness varying from 20 to 143 meters is an upper aquifer and has 0.66–14.02 Ωm apparent resistivity value. Fine sand geoelectric layer with 0.21-5.99 Ωm apparent resistivity value is lower aquifer with maximum thickness ~250 meters. From the resistivity value, it is observed that the upper aquifer contains saline to brackish-fresh water while the resistivity value of the lower aquifer indicates that it contains saline water. The water quality of the upper zone varies geographically from the southern to the northern part in the investigated area. The water quality of the upper aquifer is fresh in the northern part of the study while lower aquifer contains saline water there

A 30-day follow-up study on the prevalence of SARS-COV-2 genetic markers in wastewater from the residence of COVID-19 patient and comparison with clinical positivity

Wastewater based epidemiology (WBE) is an important tool to fight against COVID-19 as it provides insights into the health status of the targeted population from a small single house to a large municipality in a cost-effective, rapid, and non-invasive way. The implementation of wastewater based surveillance (WBS) could reduce the burden on the public health system, management of pandemics, help to make informed decisions, and protect public health. In this study, a house with COVID-19 patients was targeted for monitoring the prevalence of SARS-CoV-2 genetic markers in wastewa-ter samples (WS) with clinical specimens (CS) for a period of 30 days. RT-qPCR technique was employed to target non-structural (ORF1ab) and structural-nucleocapsid (N) protein genes of SARS-CoV-2, according to a validated experimental protocol. Physiological, environmental, and biological parameters were also measured following the American Public Health Association (APHA) standard protocols. SARS-CoV-2 viral shedding in wastewater peaked when the highest number of COVID-19 cases were clinically diagnosed. Throughout the study period, 7450 to 23,000 gene copies/1000 mL were detected, where we identified 47 % (57/120) positive samples from WS and 35 % (128/360) from CS. When the COVID-19 patient number was the lowest (2), the highest CT value (39.4; i.e., lowest copy number) was identified from WS. On the other hand, when the COVID-19 patients were the highest (6), the lowest CT value (25.2 i.e., highest copy numbers) was obtained from WS. An advance signal of increased SARS-CoV-2 viral load from the COVID-19 patient was found in WS earlier than in the CS. Using customized primer sets in a traditional PCR approach, we confirmed that all SARS-CoV-2 variants identified in both CS and WS were Delta variants (B.1.617.2). To our knowledge, this is the first follow-up study to determine a temporal relationship be-tween COVID-19 patients and their discharge of SARS-CoV-2 RNA genetic markers in wastewater from a single house including all family members for clinical sampling from a developing country (Bangladesh), where a proper sewage system is lacking. The salient findings of the study indicate that monitoring the genetic markers of the SARS-CoV-2 virus in wastewater could identify COVID-19 cases, which reduces the burden on the public health system during COVID-19 pandemics.Peer reviewe

Wastewater-based epidemiological surveillance to monitor the prevalence of SARS-CoV-2 in developing countries with onsite sanitation facilities

Wastewater-based epidemiology (WBE) has emerged as a valuable approach for forecasting disease outbreaks in developed countries with a centralized sewage infrastructure. On the other hand, due to the absence of well-defined and systematic sewage networks, WBE is challenging to implement in developing countries like Bangladesh where most people live in rural areas. Identification of appropriate locations for rural Hotspot Based Sampling (HBS) and urban Drain Based Sampling (DBS) are critical to enable WBE based monitoring system. We investigated the best sampling locations from both urban and rural areas in Bangladesh after evaluating the sanitation infrastructure for forecasting COVID-19 prevalence. A total of 168 wastewater samples were collected from 14 districts of Bangladesh during each of the two peak pandemic seasons. RT-qPCR commercial kits were used to target ORF1ab and N genes. The presence of SARS-CoV-2 genetic materials was found in 98% (165/168) and 95% (160/168) wastewater samples in the first and second round sampling, respectively. Although wastewater effluents from both the marketplace and isolation center drains were found with the highest amount of genetic materials according to the mixed model, quantifiable SARS-CoV-2 RNAs were also identified in the other four sampling sites. Hence, wastewater samples of the marketplace in rural areas and isolation centers in urban areas can be considered the appropriate sampling sites to detect contagion hotspots. This is the first complete study to detect SARS-CoV-2 genetic components in wastewater samples collected from rural and urban areas for monitoring the COVID-19 pandemic. The results based on the study revealed a correlation between viral copy numbers in wastewater samples and SARS-CoV-2 positive cases reported by the Directorate General of Health Services (DGHS) as part of the national surveillance program for COVID-19 prevention. The findings of this study will help in setting strategies and guidelines for the selection of appropriate sampling sites, which will facilitate in development of comprehensive wastewater-based epidemiological systems for surveillance of rural and urban areas of low-income countries with inadequate sewage infrastructure.This research was supported by Water Aid Bangladesh, North South University, Dhaka, COVID-19 Diagnostic Lab, Department of Microbiology, Noakhali Science and Technology University (NSTU), Noakhali, Bangladesh, the International Training Network of Bangladesh University of Engineering and Technology (ITN-BUET) - Centre for Water Supply and Waste Management, and KTH Royal Institute of Technology, Sweden. We acknowledge the sincere help and support of the staff and volunteers of NSTU-COVID-19 Diagnostic Lab, Noakhali Science and Technology University, Bangladesh during the different phases of the study. PB and MTI acknowledge the Life Science Technology Platform, Science for Life Laboratory for the seed funding to initiate the wastewater-based epidemiological studies for SARS-CoV-2 in Bangladesh. We would also like to acknowledge the two anonymous reviewers for their critical comments as well as their thoughtful insights, which has significantly improved the manuscript.Peer reviewe

Exploring impacts and livelihood vulnerability of riverbank erosion hazard among rural household along the river Padma of Bangladesh

Abstract Background Riverbank erosion has both direct and indirect effects on human life and socio-economy of Bangladesh. The present study investigated the riverbank erosion hazard in study area, its impacts on local people and livelihood vulnerability due to land loss. Methods To evaluate the riverbank erosion hazard in the study area, data have been collected from relevant scientific literatures, different government and non-government organizations, informal interview, questionnaire survey and Focused Group Discussion; and analyzed through different computer program and index. Results From the study, it was found that from 1973 to 2011, about 189.4 km2 lands was eroded from the left bank section and only 23.66 km2 was accreted with a net loss of 155 km2. Instead, right bank of the Padma River behaved in the opposite manner with 166.53 km2 erosion and 134.45 km2 accretions. Comparing to the right bank, left bank was more vulnerable to erosion which destroyed the permanent stable lands. However, the value of the newly accreted char land is very low compare to the main land. Thus this hazard creates a great loss in the local economy. Within the studied time range the monetary loss is about 1414.81 million BDT (17,422,937.16 $). Many wealthy farmers of the study area turn into marginal farmer and even landless due to the erosional hazard. Agricultural land becomes barren land by huge siltation and the cropping pattern has been changed significantly. In addition, the infrastructure and property losses are enormous. From the results of vulnerability index (IPCC-VI) it suggests that the most vulnerable areas are identified as Boyra (0.061), Kanchanpur (0.062), Lesragonj (0.064), Azimnagar (0.067), Sutalori (0.071) and Dhulsonra (0.076) because of more sensitivity and less adaptive capacity. On the other hand, Balara (− 0.017) and Balla (− 0.019) are comparatively least vulnerable comparing to the previous sites. Conclusions As, riverbank erosion is one of the most hazardous disasters in the study area; so treating independent separate policies and program for the vulnerable areas might helpful to support the affected community

Water Quality Criteria and Ecological Risk Assessment of Typical Transition Metals in South Asia

Transition metal pollution in rivers in South Asia is more serious than in other regions because of the lack of adequate freshwater management measures. Water quality criteria (WQC) for South Asia is urgently needed to protect regional aquatic environments because of the occurrence of transboundary rivers. The present study established non-parametric kernel density estimation species sensitivity distribution (NPKDE-SSD) models and then derived the acceptable hazardous concentration for protection of 95% of all aquatic species (HC5) and WQC of six typical transition metals in South Asia. The results showed that the order of acute and chronic WQC was Mn > Fe > Cd > Zn > Cu > Hg and Cu > Fe > Cd, respectively. A risk assessment of these metals in the Indus River, the Ganges River, the Brahmaputra River, the Meghna River, and the Bagmati River was also carried out. Based on the results, these major rivers in South Asia were highly polluted with transition metals, with significant ecological risks for a large number of aquatic species. This study can contribute to a better understanding of ecological risks in South Asia and provide a scientific basis for the updating of water quality standards and the increase in overall water quality

A Soil Health Card (SHC) for soil quality monitoring of agricultural lands in south-eastern coastal region of Bangladesh

Abstract Background The present study introduces an alternate tool of laboratory analysis named Soil Health Card (SHC) for soil quality monitoring and routine field observations by farmers. Results Different physicochemical and nutrient contents of soil, i.e. pH, electric conductivity, soil organic matter, organic carbon, total nitrogen, phosphorous, sulfur and boron were assessed by laboratory analysis collected from the different fields of Noakhali district of Bangladesh. These parameters were scored according to the soil fertility standards according to Bangladesh Agriculture Research Council. Results found that, the soil quality of all the studied fields are medium category. Again, a SHC was prepared using soil structure, subsurface compaction, aggregate stability, status of ground cover, soil smell, soil pH, color, organic matter content, drainage capacity, diversity of micro-life, earthworm contents, infiltration rate, soil aeration, crop coverage and leaf color. The result of SHC is interestingly similar to the laboratory experiment results. Conclusions Analyzing these two methods it was found that, the SHC is truly representative, much convenient, precise, coast effective and easily understandable to the marginal farmers. However, SHC can be an alternative to farmer for sustainable farm management

A 30-day follow-up study on the prevalence of SARS-COV-2 genetic markers in wastewater from the residence of COVID-19 patient and comparison with clinical positivity

Wastewater based epidemiology (WBE) is an important tool to fight against COVID-19 as it provides insights into the health status of the targeted population from a small single house to a large municipality in a cost-effective, rapid, and non-invasive way. The implementation of wastewater based surveillance (WBS) could reduce the burden on the public health system, management of pandemics, help to make informed decisions, and protect public health. In this study, a house with COVID-19 patients was targeted for monitoring the prevalence of SARS-CoV-2 genetic markers in wastewa-ter samples (WS) with clinical specimens (CS) for a period of 30 days. RT-qPCR technique was employed to target non-structural (ORF1ab) and structural-nucleocapsid (N) protein genes of SARS-CoV-2, according to a validated experimental protocol. Physiological, environmental, and biological parameters were also measured following the American Public Health Association (APHA) standard protocols. SARS-CoV-2 viral shedding in wastewater peaked when the highest number of COVID-19 cases were clinically diagnosed. Throughout the study period, 7450 to 23,000 gene copies/1000 mL were detected, where we identified 47 % (57/120) positive samples from WS and 35 % (128/360) from CS. When the COVID-19 patient number was the lowest (2), the highest CT value (39.4; i.e., lowest copy number) was identified from WS. On the other hand, when the COVID-19 patients were the highest (6), the lowest CT value (25.2 i.e., highest copy numbers) was obtained from WS. An advance signal of increased SARS-CoV-2 viral load from the COVID-19 patient was found in WS earlier than in the CS. Using customized primer sets in a traditional PCR approach, we confirmed that all SARS-CoV-2 variants identified in both CS and WS were Delta variants (B.1.617.2). To our knowledge, this is the first follow-up study to determine a temporal relationship be-tween COVID-19 patients and their discharge of SARS-CoV-2 RNA genetic markers in wastewater from a single house including all family members for clinical sampling from a developing country (Bangladesh), where a proper sewage system is lacking. The salient findings of the study indicate that monitoring the genetic markers of the SARS-CoV-2 virus in wastewater could identify COVID-19 cases, which reduces the burden on the public health system during COVID-19 pandemics.Peer reviewe