Natural disasters, livelihood, and healthcare challenges of the people of a riverine island in Bangladesh: A mixed-method exploration.

BACKGROUND: Bangladesh's islands, because of their geographical location, frequently encounter crises like floods and river erosion, which pose significant threats to the residents' well-being and livelihoods. To delve into the effects of these disasters on livelihood and healthcare challenges, a mixed-method study was undertaken in a riverine-island near a major river of Bangladesh. METHODOLOGY: Between February 15th and February 28th, 2023, a cross-sectional study was conducted on an island in Bangladesh. The quantitative method involved conducting a survey of 442 households, with a total of 2921 participants. Additionally, 10 in-depth interviews and 10 key-informant interviews were conducted using semi-structured guidelines. Qualitative interviews were audio-recorded, transcribed verbatim, and analyzed using a thematic analysis. Triangulation was employed in this study through the integration of qualitative and quantitative analysis, resulting in the presentation of findings that offer an in-depth comprehension of the phenomenon being investigated. RESULTS: River erosions and floods are common and recurring natural disasters that significantly impact the lives of the riverine island inhabitants. These disasters often disrupted their livelihoods, forced many residents to endure substandard living conditions or relocated during flood events. The island faced a low diagnostic prevalence of chronic diseases (e.g., 5.1% of adults were hypertension and 2.5% are diabetes) because of the absence of diagnostic facilities and a shortage of certified doctors. A significant number of chronic illness people in the community turned to alternative medicine sources (39.3%) such as homeopathy, Kabiraj, and Ayurvedic medicine, especially it gets increased during periods of natural disasters. Moreover, reproductive aged women revealed that 79.4% of them gave birth at home, with 6.0% of these home deliveries resulting in miscarriage or infant death. The destruction of crops, unstable job opportunities, an inadequate educational system, and a deficient healthcare delivery system exacerbated the hardships faced by the population affected by these disasters. CONCLUSION: The failure to seek treatment for chronic diseases and undiagnosed diseases is a significant health issue among the aging adults on the island. Island residents face the challenge of establishing effective prevention strategies for the well-being of older adults especially at the period of natural disasters. It is crucial for the government and non-governmental organizations (NGOs) to collaborate to prevent the negative effects of floods and river erosions. This should include efforts to enhance the quality of education, healthcare services, job opportunities, and financial assistance for rebuilding homes.

Flood irrigation increases the release of phosphorus from aquifer sediments into groundwater.

Nonpoint source pollution caused by agricultural activities has long attracted widespread attention from people in society and academia. Many studies have found that human activities not only convey exogenous pollutants into aquifers but also affect the mobilization and transport of geogenic pollutants in aquifers. Geogenic groundwater with high phosphorus concentrations has been found, but it is unclear whether the changes in hydrogeochemical conditions caused by flood irrigation in paddy fields affect the fate of phosphorus. We investigated the temporal and spatial distribution characteristics of phosphorus in groundwater under the influence of flood irrigation through laboratory experiments, proved its impact on phosphorus in groundwater, and explored the mechanisms influencing P concentrations. The results show that flood irrigation can increase the release of phosphorus in the aquifer media and greatly increase the phosphorus concentration in the groundwater of the study area, which has a negative impact on groundwater quality. The main mechanism of increase in phosphorus concentration in groundwater involves an increase in the reducibility of the aquifer via flood irrigation; as a result, iron oxides are reductively dissolved and iron-bound phosphorus is released into the groundwater. Changes in pH also result in the dissolution of calcium phosphate minerals and the release calcium-bound phosphorus. This study not only advances the theory of multielement-coupled hydrogeochemistry but also provides a reference for agricultural planning and groundwater pollution prevention and control in rice-growing areas.

Public Health and Health System's Responsiveness During the 2022 Floods in Pakistan: What Needs to Be Done?

OBJECTIVE: In 2022, Pakistan witnessed unprecedented flooding, submerging one-third of the country under-water, ruining millions of houses, taking lives, afflicted injuries, and displacing scores of people. Our study documents not only the public health problems that have arisen due to this natural calamity but also the state of health systems' response. METHODS: We conducted a qualitative study asking key questions around prevalent health problems, health-care seeking, government's response, resource mobilization, and roadmap for the future. We purposively selected 16 key frontline health workers for in-depth interviews. RESULTS: Waterborne and infectious diseases were rampant posing huge public health challenges. Disaster mitigation efforts and relief operations were delayed and not at scale to cover the entire affected population. Moreover, a weak economy, poverty, and insufficient livelihoods compounded the tribulations of floods. Issues of leadership and governance at state level resulted in disorganized efforts and response. CONCLUSIONS: Pakistan is famous for its philanthropy; however, lack of transparency and accountability, the actual benefits seldom reach the beneficiaries. Such climatic disasters necessitate a more holistic approach and a greater responsiveness of the health system. In addition to health services, the state must respond to financial, social, and infrastructural needs of the people suffering from the calamity.

COVID-19 disaster recovery capitals: A conceptual framework to guide holistic and strengths-based support strategies.

ISSUE ADDRESSED: The COVID-19 pandemic bears many similarities to other disasters such as bushfires, earthquakes and floods. It also has distinctive features including its prolonged and recurrent nature and the social isolation induced by pandemic responses. Existing conceptual frameworks previously applied to the study of disaster, such as the Recovery Capitals Framework (RCF), may be useful in understanding experiences of the COVID-19 pandemic and in guiding agencies and governments tasked with supporting communities. METHODS: This paper presents an analysis of interviews conducted with residents of the Australian state of Victoria in 2020-2021. The RCF was used to analyse how participant experiences and well-being were influenced by seven forms of capital-social, human, natural, financial, built, cultural and political-with particular focus on the interactions between these capitals. RESULTS: Social capital featured most prominently in participants' accounts, yet the analysis revealed important interactions between social and other capitals that shaped their pandemic experiences. The RCF supported a strengths-based and holistic analysis while also revealing how inequities and challenges were compounded in some cases. CONCLUSIONS: Findings can be leveraged to develop effective and innovative strategies to support well-being and disrupt patterns of compounding inequity. Applying the RCF in the context of COVID-19 can help to link pandemic research with research from a wide range of disasters. SO WHAT?: In an increasingly complex global landscape of cascading and intersecting disasters including pandemics, flexible and nuanced conceptual approaches such as the RCF can generate valuable insights with practical implications for health promotion efforts.

Investigating the association between floods and low birth weight in India: Using the geospatial approach.

BACKGROUND: Frequent natural disasters like floods pose a major threat to India, with significant implications for public health. Low birth weight (LBW) is a critical global health concern, contributing to neonatal mortality. However, the association between floods and LBW remains underexplored. This study aims to address this gap by investigating the association between flood hazards and LBW in India using a geospatial approach. By analyzing data from the National Family Health Survey (NFHS-5) and flood zonation maps, the study aims to uncover the spatial dynamics of this association, offering insights into the implications of floods on birth weight across diverse geographical regions. METHODS: The study used the fifth round of NFHS data, 2019-21, which involved 202,194 children selected through a multi-stage stratified sampling technique. The Vulnerability Atlas of India 2019 maps were also utilized to classify areas as flood or non-flood zones. Birth weight data from the NFHS-5 were categorized into three groups: very low, low, and normal birth weight (VLBW, LBW and NBW). Control variables including flood exposure, socio-demographic attributes, and geographic region were considered. Bivariate analysis and multinomial logistic regression were employed for statistical analysis. The spatial analysis involved Moran's I statistics and Geographically Weighted Regression to explore spatial dynamics of the association between floods and birth weight in India. RESULTS: Floods predominantly affect India's lower Himalayan belts and western coastal regions. Flood-affected areas show higher proportions of VLBW and LBW infants. Groundwater usage and unimproved sanitation are associated with higher risk of VLBW and LBW. Sex, wealth, maternal education, residence type, and geographic region significantly influence birth weights. Multinomial logistic regression reveals 8 % and 27 % higher risks for LBW and VLBW in flood-affected regions. LISA cluster maps identify high-risk areas for both LBW and floods. Geographically Weighted Regression highlights 52 % of the variability in LBW occurrences can be attributed to the influence of flood hazards. Families hailing from the poorest wealth background and exposed to flood hazards bear a 5 % heightened likelihood of delivering LBW infants, in stark contrast to their counterparts from the same economic background yet unaffected by floods. CONCLUSIONS: The significant association between floods and LBW underscores the importance of robust disaster preparedness and public health strategies. By unraveling the spatial intricacies of flood-induced LBW disparities, this research provides valuable insights for promoting healthier birth outcomes and reducing child mortality rates, particularly in flood-prone regions. These findings emphasize the importance of holistic policies that address both environmental challenges and socioeconomic inequalities to safeguard maternal and infant health across the nation.

Restricted colloidal-bound phosphorus release controlled by alternating flooding and drying cycles in an alkaline calcareous soil.

Colloid-facilitated phosphorus (P) migration plays an important role in P loss from farmland to adjacent water bodies. However, the dynamics of colloidal P (Pcoll) release as influenced by irrigation in alkaline calcareous soil remains a knowledge gap. The present study, monitored the dynamic change of Pcoll under different water management strategies: 1) control, 2) flooding, and 3) alternating flooding and drying cycles. Soil water-dispersible colloids (0.6 nm-1 µm) were extracted by combining filtration and ultrafiltration methods. The contents of P, cation and organic carbon in the water-dispersible colloids were determined and the stability and mineral composition of colloidal fractions were characterized. The results showed that Pcoll ranged from 16.5 to 25.5 mg kg-1 and represented 42.8%-64.9% of the water-extracted P in the control. Flooding significantly decreased the Pcoll content by 16.0%-62.1% (mean 32.7%) and it may be attributed to the dissolution of colloidal iron (Fe) bound P. The alternating flooding and drying treatment significantly reduced the Pcoll content by 11.6%-88.0% (mean 67.6%). The Pcoll content of the flooding event was always greater than the Pcoll content of the drying event during flooding and drying cycles. Redundancy analysis and random forest modeling showed that the colloidal calcium (Ca) and ionic strength in soil solutions had negative correlations with the Pcoll content, and pH, ionic strength and truly dissolved P were the critical factors affecting Pcoll. Drying of the flooded soil led to the decrease of pH and the increase of ionic strength, colloidal Ca content and positive charges of colloid surfaces, which promoted colloid aggregation and enhanced soil P sorption capacity. This restricted the loss potential of Pcoll. In summary, controlled flooding and drainage when managed correctly have a role to play in mitigating Pcoll loss from P-enriched calcareous soils.

Effects of water depth on the biomass of two dominant submerged macrophyte species in floodplain lakes during flood and dry seasons.

Floodplain lakes share characteristics of both deep and shallow lakes throughout any given year. Seasonal fluctuations in their water depth drive changes in nutrients and total primary productivity, which directly and indirectly affect submerged macrophyte biomass. To investigate how water depth and environmental variables affect submerged macrophyte biomass, we surveyed six sub-lakes in the Poyang Lake floodplain, China, during the flood and dry seasons of 2021. Dominant submerged macrophytes include Vallisneria spinulosa and Hydrilla verticillata. The effect of water depth on the biomass of these macrophytes varied between the flood and dry seasons. In the flood season, there was a direct effect of water depth on biomass, while in the dry season only an indirect effect was observed. During the flood season, the direct effect of water depth on the biomass of V. spinulosa was less than the indirect effect, with water depth primarily affecting the total nitrogen, total phosphorus and water column transparency. Water depth directly, positively affected H. verticillata biomass, with this effect being greater than the indirect effect by affecting the carbon, nitrogen and phosphorus content in the water column and sediment. During the dry season, water depth affected H. verticillata biomass indirectly through sediment carbon and nitrogen content, while for V. spinulosa, the effect on biomass was indirect through carbon content of the sediment and water column. The main environmental variables affecting submerged macrophyte biomass in the Poyang Lake floodplain during the flood and dry seasons, and the mechanisms through which water depth affects dominant submerged macrophyte biomass, are identified. An understanding of these variables and mechanisms will enable improved management and restoration of wetland.

Hydrological performance of rain gardens having Calendula officinalis plant with varied planting mixtures.

The rain gardens (RGs) have been one of the best management practices in cities to reduce the impact of urban flooding. However, very little is known about various design parameters of RGs, viz., the type of plantation, planting mixtures, and RG dimensions. This study pertains to examining the influence of planting mixtures on the variations of percolation rates of the RG with Calendula officinalis plant and without plants. Six types of planting mixtures in different experimental RGs have been tried. It has been observed that the percolation rate increases with a higher percentage of compost in the planting mixture for RGs with and without plants. The percolation rate is highest for the planting mixture having 25% compost. The runoff rate reduces with a higher percentage of compost in the planting mixture for RGs with C. officinalis and bare surfaces. No runoff is produced in RGs with plant having a compost of more than 20% in the planting mixture. The outcome of the study will be useful in deciding the composition of the planting mixture which will keep the RG plant healthy and at the same time improve the hydrological performance leading to lowering urban flooding magnitude.

Alum reduced phosphorus release from flooded soils under cold spring weather conditions.

The effectiveness of amendments such as alum [Al2 (SO4 )3 ·18H2 O] in reducing phosphorus (P) loss to floodwater has been reported under summer conditions and laboratory-controlled environments, but not under actual spring weather conditions in cold climate regions with high diurnal temperature variations when potential for P losses is high. The effectiveness of alum in reducing P release under Manitoba spring weather conditions was evaluated in a 42-day experiment using 15-cm soil monoliths from eight agricultural soils, which were unamended or alum-amended (5 Mg ha-1 ) and flooded to a 10-cm head. Dissolved reactive P (DRP) concentrations and pH of porewater and floodwater were determined on flooding day and every 7 days after flooding (DAF). Porewater and floodwater DRP concentrations in unamended soils increased 1.4- to 4.5-fold, and 1.8- to 15.3-fold, respectively, from 7 to 42 DAF. In alum-amended soils, DRP concentrations averaged across soils was 43%-73% (1.0-2.0 mg L-1 ) lower in porewater, and 27%-64% (0.1-1.2 mg L-1 ) lower in floodwater than unamended soils during the flooding period. The reduction of DRP by alum was more pronounced under high fluctuating diurnal spring air temperature than with controlled air temperature (4°C) in a previous similar study. Acidic pH in porewater and floodwater due to alum did not persist over 7 days. This study showed that alum application is a viable option in reducing P released to floodwater in agricultural soils of cold regions where flooding-induced P loss is prevalent in the spring.

Reservoir flood regulation affects nutrient transport through altering water and sediment conditions.

The effect of reservoir construction on nutrient dynamics is well recognized, at flood event-scale influence of reservoir flood regulation on nutrient transport however has received less attention. Taking the Three Gorges Reservoir (TGR) in the Changjiang River as an example, during the TGR's regulation on a flood in Sep., 2021, this study collected water samples along the mainstream of the reservoir as well as pre/post-dam, with the aim to identify the impact of flood regulation on nutrient (nitrogen and phosphorus) distribution and transportation. Results show that nitrate nitrogen (NO3N) and particulate phosphorus (PP) were the main fraction of the total nitrogen (TN) and total phosphorus (TP) with the proportion of 46.5%-95.6% and 57.4%-81.6%, respectively. N and P responded different to flood regulation: (i) along the stream P concentration significantly decreased due to PP deposited with sediment while N concentration barely changed during flood regulation; (ii) P concentration was significantly higher at post-dam section than at pre-dam section, while N concentration maintained the same. The diffed response to flood regulation caused TN/TP ratio increased from 4 to 8 in the reservoir tail to over 20 near the dam, which probably arise eutrophication in the reservoir head area. This study reveals the influence of flood regulation on nutrient transport in flood event and provides scientific basis for reservoir management.

[Long-term Succession Patterns and Driving Factors of Water Quality in a Flood-pulse System Lake: A Case Study of Lake Luoma, Jiangsu Province].

Lake Luoma is an important storage lake for the Eastern route of the South-to-North Water Diversion Project (NSBD), which has many functions including flood control and irrigation, drinking water supply, and ecological maintenance. In order to understand the succession patterns and driving factors of water quality in Lake Luoma, we used monthly monitoring data from 2009 to 2020 in combination with historical data from 1996 to 2008. The long-term succession patterns, seasonal dynamics, and spatial patterns of total nitrogen (TN), total phosphorus (TP), permanganate index, and ammonia nitrogen (NH+4-N) were examined, and the influence of meteorological and hydrological factors on water quality was explored through correlation analyses and generalized additive models. The results showed that it remained in the status of grade Ⅳ-inferior Ⅴ over the past 25 years. The concentration of TN, which was the main pollutant, changed significantly (1.06-3.49 mg·L-1), experiencing three stages of gradual decline (1996-2002), significant interannual fluctuation (2002-2015), and significant increase (2015-2020). Permanganate index decreased significantly (2.97-6.38 mg·L-1), whereas TP and NH+4-N concentration fluctuated slightly, ranging from 0.024-0.076 mg·L-1 and 0.11-0.69 mg·L-1, respectively. The concentration of TN and TP increased abnormally in the summer of 2017-2020, reaching 3.30 mg·L-1 and 0.14 mg·L-1 in August, respectively, which was approximately 1.5 and 2.4 times the annual average. In terms of seasonal dynamics, the seasonal variation in water quality between summer/autumn and winter/spring reversed after 2015, with water quality in summer/autumn being worse than that in winter and spring, indicating the exacerbation of eutrophication. The water quality in the southern area was obviously better than that in the northern area. The input of pollutants from the Yihe River and Middle Canal increased with water quantity since 2015, which drove the water quality deterioration through nutrients. Our results suggested that the water quality of Lake Luoma should be improved by strengthening exogenous pollution reduction, endogenous control, polder dismantling, and ecological restoration.

Study on the sediment and phosphorus flux processes under the effects of mega dams upstream of Yangtze River.

The upper Yangtze River (UYR) plays an important role in water supply, hydropower generation, environmental and ecological protection. Constructions of Mega cascade reservoirs have significantly affected the transport of sediment and P, but the evolution of sediment and P in the mega cascade reservoirs of the UYR is unclear. This study investigated the variations in sediment load and total P (TP) flux based on the flow and sediment data from 1990 to 2019 and TP concentrations from 2005 to 2019. In addition, the proportion of sediment load and TP flux from tributaries, variations in the concentrations of particulate P (PP) and dissolved P, trapping effect of dams, and statistical uncertainties were analyzed and discussed. The main results are as follows: (1) the sediment load and TP flux evidently decreased after the impoundment of reservoirs in the UYR and Jinsha River, and the contribution rate of TP flux from main tributaries (except Wu River) to mainstream increased by 3.82-24 %; (2) the error of TP flux calculated by daily and monthly data is within 30 %, which shows that the uncertainty range is clear at some degree attributed to the different monitoring frequency, and the concentration of PP in flood season is greater than that in non-flood season; (3) the total retention rates of sediment and TP in the Three Gorges Reservoir and Gezhouba were 86.78 %, and 49.83 % (2009-2012), respectively, but decreased to 82.85 % and 15.26 % (2013-2019), and the values in Xiangjiaba and Xiluodu were 97.83 % and 60.27 % (2013-2019). The retention rates of newly built reservoirs (Wudongde and Baihetan) were predicted using an empirical method, and the results revealed that new dams would facilitate long-term reduction in sediment downstream.

Comprehensive improvement of soil quality and rice yield by flooding-midseason drying-flooding.

Many water-saving technologies have been developed to reduce water input and the associated irrigation costs. However, the influence of water management technologies on soil quality is unclear. Soil quality is fundamental to rice yield and sustainable productivity of ecosystems. Therefore, it is important to understand the effect of water management on soil quality and its linkage with rice yield. In this work, a field experiment was conducted to assess the influence of water management on soil physico-chemical properties, microbial biomass, bacterial community, and rice yield in paddy fields. Three water treatments were selected for the study, including flooding-rain-fed (F-RF), flooding-midseason drying-flooding (F-D-F), and continuous flooding (CF). Total nitrogen (TN), total phosphorus (TP), dissolved carbon content (DOC), available phosphorus (AP), nitrate nitrogen (NO3-), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) contents were 11%, 20%, 29%, 30%, 11%, 183%, and 215% higher in F-D-F, respectively, than those in the CF (p < 0.05). Additionally, the bacterial diversity in F-D-F and CF was significantly higher compared to the F-RF (p < 0.05). Correspondingly, soil quality index (SQI) was higher in the F-D-F (0.8) than that of F-RF (0.53) and CF (0.5). Compared with the F-RF, water management remarkably altered bacterial community composition, with higher enrichment of anaerobic bacteria (such as Firmicutes and Chloroflexi) in flooding treatments (CF and F-D-F). Differences in the bacterial community were closely related to key soil quality indicators, such as AP. Parallel increases in soil quality and bacterial diversity resulted in increased rice yield in the F-D-F, which was 53% and 12% higher than that in F-RF and CF, respectively. Therefore, F-D-F is the suggested water management method because it can comprehensively improve soil microbial diversity, soil quality, and rice yield. KEY POINTS: • Water management changed bacterial community mainly via SMC (soil moisture content), TP, AP, and NO3-contents. • The F-D-F had greater SQI and higher rice yield in comparison with F-RF and CF.

Extreme weather layer method for implementation of nature-based solutions for climate adaptation: Case study Slupsk.

One of the most severe climate risks that is expected to affect all regions is related to stormwater. Climate models, constructed based on long-term trends, show that extreme weather events such as storms, cloudbursts and a large rise in sea level will be significant in the coming decades. Moreover, even the frequency and intensity of "normal" rainfall events, such as microbursts, are expected to be remarkably higher than today in some regions. The efficiency of urban drainage systems is affected by the land use in its whole catchment. In addition to the climate stress, there is ongoing continuous densification of urban space, resulting in more buildings and larger areas being covered with impervious surfaces. Planning decisions today approving such compaction do not consider the impacts beyond the close proximity of the land parcel. As a result, by following the current planning practices, cities are becoming extremely vulnerable to stormwater flooding (flash floods). This study presents a holistic and dynamic planning method - the Extreme Weather Layer (EWL) - that makes it possible to analyse the impact of a single development (e.g. paving a gravel parking lot with asphalt or turning an area of urban greenery into a shopping centre) on the performance of the urban drainage system and therefore on the flooding risk of the whole catchment. The EWL is based on a widely accepted drainage modelling engine coupled with GIS system and other databases which provide spatial information. Thus, the EWL combined with the systemic approach of turning from grey to green infrastructure could be a smart tool for implementing NBS solutions for stormwater management in climate adaptation in urban areas. This smart tool could indicate how much more green infrastructure is needed and which places in the city the mitigative NBS measures would help significantly.

Concurrent effects of flooding regimes and floodwater quality on sediment properties in a Yangtze River-connected floodplain wetland: Insights from field investigations during 2011-2020.

Changes in flood regimes, floodwater quality, and macrophyte types may affect sediment characteristics post-flooding. However, few studies have attempted to unravel their complex influences in floodplain wetlands. From 2011 to 2020, the physical and chemical properties of surface layer sediment pre- and post-flooding was investigated through field surveys in the Dongting Lake wetland. Results indicated that the pre-flooding soil total phosphorus (TP) and total nitrogen (TN) exhibited an increasing trend during 2011-2020. Soil TP increased post-flooding relative to that pre-flooding. The changes in TN, sediment organic matter (SOM), sediment moisture content (SMC), and sediment bulk density (SBD) fluctuated over the years. The best-fitting multi-regression model demonstrated that the changes in sediment variables post-flooding showed a parabolic trajectory along the inundation duration (ID), except for SMC. Changes in soil properties post-flooding were negatively correlated with ID for sediment with a low IDs (<148 days). Meanwhile, changes in soil properties post flooding were positively correlated with ID for sediment with a high IDs (>193 days). Changes in SBD and SOM post-flooding were positively influenced by the TP content in the floodwater. These findings indicate that changes in the flooding regime, and water quality generated by anthropogenic disturbances such as the Three Gorges Dam significantly affect sediment properties, and subsequently influence the ecological functions of the Dongting Lake wetland.

Flooding-induced inorganic phosphorus transformations in two soils, with and without gypsum amendment.

Anaerobic conditions developed during flooding can increase phosphorus (P) losses from soils to waterways. Soil amendment with gypsum (CaSO4 ·2H2 O) can effectively reduce flooding-induced P release, but its effectiveness is soil dependent, and the reasons are poorly understood. The objectives of this study were to reveal the possible inorganic P transformations during flooding of two soils (acidic-Neuenberg sandy loam [NBG-SL] and alkaline-Fyala clay [FYL-Cl]), with and without gypsum amendment prior to flooding. Porewater samples collected at 0, 35, and 70 d after flooding (DAF) from soils incubated in vessels were analyzed for dissolved reactive P (DRP); pH; and concentrations of calcium (Ca), magnesium, iron (Fe), manganese, chloride, nitrate, sulfate, and fluoride. Thermodynamic modeling using Visual MINTEQ software and chemical fractionation of soil P were used to infer P transformations. Soil redox potential (Eh) decreased with flooding and favored reductive dissolution of Fe-associated P increasing porewater DRP concentrations. Greater solubility of Ca-P under acidic pH maintained a higher DRP concentration in NBG-SL during early stages of flooding. A subsequent increase in pH with flooding and higher Ca concentration with added gypsum enhanced the stability of Ca-P (ß-tricalcium phosphate and octacalcium phosphate), reducing the DRP concentration in gypsum-amended NBG-SL. Stability of Ca-P was less affected with flooding and gypsum amendment in FYL-Cl soil because it had an alkaline pH and inherently higher Ca concentration. The FYL-Cl, with a more rapid decrease in Eh than NBG-SL, became severely reduced, releasing more P and Fe by 70 DAF. These conditions favored vivianite formation in FYL-Cl but not in NBG-SL.

Seasonal Water Quality and Algal Responses to Monsoon-Mediated Nutrient Enrichment, Flow Regime, Drought, and Flood in a Drinking Water Reservoir.

Freshwater reservoirs are a crucial source of urban drinking water worldwide; thus, long-term evaluations of critical water quality determinants are essential. We conducted this study in a large drinking water reservoir for 11 years (2010-2020). The variabilities of ambient nutrients and total suspended solids (TSS) throughout the seasonal monsoon-mediated flow regime influenced algal chlorophyll (Chl-a) levels. The study determined the role of the monsoon-mediated flow regime on reservoir water chemistry. The reservoir conditions were mesotrophic to eutrophic based on nitrogen (N) and phosphorus (P) concentrations. An occasional total coliform bacteria (TCB) count of 16,000 MPN per 100 mL was recorded in the reservoir, presenting a significant risk of waterborne diseases among children. A Mann-Kendall test identified a consistent increase in water temperature, conductivity, and chemical oxygen demand (COD) over the study period, limiting a sustainable water supply. The drought and flood regime mediated by the monsoon resulted in large heterogeneities in Chl-a, TCB, TSS, and nutrients (N, P), indicating its role as a key regulator of the ecological functioning of the reservoir. The ambient N:P ratio is a reliable predictor of sestonic Chl-a productivity, and the reservoir was P-limited. Total phosphorus (TP) had a strong negative correlation (R2 = 0.59, p < 0.05) with the outflow from the dam, while both the TSS (R2 = 0.50) and Chl-a (R2 = 0.32, p < 0.05) had a strong positive correlation with the outflow. A seasonal trophic state index revealed oligo-mesotrophic conditions, indicating a limited risk of eutrophication and a positive outcome for long-term management. In conclusion, the Asian monsoon largely controlled the flood and drought conditions and manipulated the flow regime. Exceedingly intensive crop farming in the basin may lead to oligotrophic nutrient enrichment. Although the reservoir water quality was good, we strongly recommend stringent action to alleviate sewage, nutrient, and pollutant inflows to the reservoir.

Phosphorus mobilization in unamended and magnesium sulfate-amended soil monoliths under simulated snowmelt flooding.

Enhanced release of phosphorus (P) from soils with snowmelt flooding poses a threat of eutrophication to waterbodies in cold climatic regions. Reductions in P losses with various soil amendments has been reported, however effectiveness of MgSO4 has not been studied under snowmelt flooding. This study examined (a) the P release enhancement with flooding in relation to initial soil P status and (b) the effectiveness of MgSO4 at two rates in reducing P release to floodwater under simulated snowmelt flooding. Intact soil monoliths were collected from eight agricultural fields from Southern Manitoba, Canada. Unamended and MgSO4 surface-amended monoliths (2.5 and 5.0 Mg ha-1) in triplicates were pre-incubated for 7 days, then flooded and incubated (4 °C) for 56 days. Pore water and floodwater samples collected at 7-day intervals were analyzed for dissolved reactive P (DRP), pH, Ca, Mg, Fe and Mn. Redox potential (Eh) was measured on each day of sampling. Representative soil samples collected from each field were analyzed for Olsen and Mehlich 3-P. Simulated snowmelt flooding enhanced the mobility of soil P with approximately 1.2-1.6 -fold increase in pore water DRP concentration from 0 to 21 days after flooding. Mehlich-3 P content showed a strong relationship with the pore water DRP concentrations suggesting its potential as a predictor of P loss risk during prolonged flooding. Surface application of MgSO4 reduced the P release to pore water and floodwater. The 2.5 Mg ha-1 rate was more effective than the higher rate with a 21-75% reduction in average pore water DRP, across soils. Soil monoliths amended with MgSO4 maintained a higher Eh, and had greater pore water Ca and Mg concentrations, which may have reduced redox-induced P release and favored re-precipitation of P with Ca and Mg, thus decreasing DRP concentrations in pore water and floodwater.

Ichthyological ethnoknowledge of the "piabeiros" from the Amazon region, Brazil.

BACKGROUND: The capture of ornamental fish is one of the main economic activities of riverine families in the Amazon. However, studies regarding the local ecological knowledge of workers in this activity are still incipient. In view of this, we have studied and explored the local ecological knowledge of artisanal fishers who specialize in the capture of fish for the aquarium trade in the middle part of the Negro River basin and investigated issues related to the ecological aspects of the fish species that are targeted by this trade in the region. METHODS: Therefore, we conducted semi-structured interviews and applied questionnaires to artisanal fishers of ornamental fish (N = 89), from the municipality of Barcelos, from January to April 2016. RESULTS: In total, 41 popular names were cited, which correspond to four ethnocategories and 10 families. The main species were Paracheirodon axelrodi (12.5%), Hemigrammus bleheri (8.3%), Ancistrus dolichopterus (6.4%), Symphysodon discus (5.3%), and Potamotrygon motoro (3.8%). According to the fishers, the species of fish known in the region as "piabas" have a preference for living in clusters (28.9%) and carry out migratory movements (26.1%). The diet of local fish species reported by fisheries is diverse, though mainly based on periphyton (42.2%), and the reproductive cycle directly influenced by the period of flooding of rivers in the region (37.6%) CONCLUSION: Our study revealed that the fishers possess information on the ecological aspects of local ornamental fish species, many of which are consistent with scientific literature. The information presented may assist in the decision-making process for the management of local fishery resources and contribute to the resumption of growth and sustainability in the capture of ornamental fish.