Load In Water Research Articles

A baseline study of spatial variability of bacteria (total coliform, E. coli, and Enterococcus spp.) as biomarkers of pollution in ten tropical Atlantic beaches: concern for environmental and public health.

Coastal water quality in urban cities is increasingly impacted by human activities such as agricultural runoff, sewage discharges, and poor sanitation. However, environmental factors controlling bacteria abundance remain poorly understood. The study employed multiple indicators to assess ten beach water qualities in Ghana during minor wet seasons. Environmental parameters (e.g. temperature, electrical conductivity, total dissolved solids) were measured in situ using the Horiba multiple parameter probe. Surface water samples were collected to measure total suspended solids, nutrients, and chlorophyll-a via standard methods and bacteria determination through membrane filtration. Environmental parameters measured showed no significant variation for the sample period. However, bacteria loads differ significantly (p = 0.024) among the beaches and influenced significantly by nitrate (55.3%, p = 0.02) and total dissolved solids (17.1%, p = 0.017). The baseline study detected an increased amount of total coliforms and faecal indicator bacteria (Escherichia coli and Enterococcus spp.) in beach waters along the coast of Ghana, suggesting faecal contamination, which can pose health risks. The mean ± standard deviations of bacteria loads in beach water are total coliforms (4.06 × 103 ± 4.16 × 103 CFU/100 mL), E. coli (7.06 × 102 ± 1.72 × 103 CFU/100 mL), and Enterococcus spp. (6.15 × 102 ± 1.75 × 103 CFU/100 mL). Evidence of pollution calls for public awareness to prevent ecological and health-related risks and policy reforms to control coastal water pollution. Future research should focus on identifying the sources of contamination in the tropical Atlantic region.

Effects of seasonal variation and locations on microbial load in sediment and water of a polluted ecosystem

Seasonal effects on microbial load of sediment and water at different locations along Bonny Estuary of Niger Delta was investigated for a period of 12 months. All analyses followed standard procedure. Results revealed that total fungi counts in sediment and water at different locations were not significantly different (p > 0.05) at both wet and dry seasons while hydrocarbon utilizing fungi showed significant differences (p < 0.05) at both seasons in both sediment and water samples. During the wet season, total faecal counts ranged from 5.0 to 10.0 x 105 CFU/g for sediment and 4.0 to 7.0x 105 CFU/g in water. In dry season, the concentration of hydrocarbon utilizing bacteria in the sediment ranged between 0.1 x 105 CFU/ml/g and 8.0 x 105 CFU/ml/g in wet season while in dry season, the concentration in water ranged between 0.1 x 105 CFU/ml/g and 6.0 x 105 CFU/ml/g at Abuloma. At Okwujagu, total heterotrophic bacteria counts in sediment ranged from 0.1 to 8.0 x 105 CFU/g in dry season. This was higher than the range 0.1 to 6.8.0 x 105 CFU/ recorded in Abuloma, Okwujagu and Slaughter at dry season. The highest vibrio counts in water (11.0 x 105 CFU/ml) for wet and (10.0 x 105 CFU/ml) for dry seasons were recorded at Slaughter. In Oginiba, the feacal count recorded 3.0 x 105 CFU/ml in water during the wet season and 2.0 x 105 CFU/ml for dry season. Generally, there were significant differences (p < 0.05) in the bacterial concentrations in both sediment and water. This showed that different seasons favour the growth of certain microbial types.

Effects of heat treatment on corrosion fatigue and stress corrosion crack growth of additive-manufactured Alloy 800H in high-temperature water

Crack growth behaviour of additively manufactured (AM) Alloy 800H were studied under cyclic and static load in high-temperature water, focusing on heat treatment effects. Under cyclic loading, heat treatment gently affected corrosion fatigue. The growth rate is comparable to wrought 800H. As the load cycle frequency reduced to below 0.001 Hz, AM 800H exhibited inconsistent stress corrosion cracking response as compared to wrought 800H. Depending on heat treatment, inhomogeneous crack propagation and localized pinning were observed in stress-relieved and recrystallized AM 800H, attributed to carbides, microstructural inhomogeneity, and twin boundaries. Grain boundary sensitization at ˜10 wt% Cr caused fast crack growth.

Effects of Heterogeneous Stream‐Groundwater Exchange on the Source Composition of Stream Discharge and Solute Load

AbstractThe exchange of water and solutes between the stream and groundwater along a stream network affects the source composition of discharge and solute load in the stream. To date, this hydrologic turnover has only been analyzed with respect to the exchange of water. In this study, we extend the concept of hydrologic turnover to solutes and analyze the effects of different hydrologic conditions on the spatial patterns and magnitude of exchange fluxes. Based on a coupled stream‐groundwater model built in MODFLOW using the Streamflow‐routing package, we simulated stream‐groundwater exchange along a stream of 30 km in length and evaluated the evolution of stream water source composition under different precipitation and streamflow conditions. Results show that even for highly variable hydrologic conditions, the direction of stream‐groundwater exchange (loss/gain) remained unchanged in consistently gaining or losing reaches, but changed in interspersed transitional reaches. The comparison between the source composition of discharge and nitrate load in stream water revealed a decoupling of discharge and solute load contribution from groundwater to the stream, as zones of high water gains do not necessarily coincide with zones of high solute concentrations. Overall, nearly 80% of total groundwater contributions to the outflow of water from the catchment were generated over only 20% of the total stream length. Our research highlights the importance of distinguishing water and solute load contributions to streams. This in turn implies that to reduce groundwater‐borne nutrient loads to streams, measures need to focus on the specific reaches with highest load contributions.

Spatial variations and controls on the hydrochemistry of surface waters across the Ili-Balkhash Basin, arid Central Asia

Climate variability influences both water quantity and quality in lakes and rivers, e.g., shifts in salinity caused by changes in the evaporation/precipitation ratio. However, knowledge about climate and human influences on water quality in some regions is scarce, which causes uncertainty when evaluating water resources and developing water management plans. We measured the chemical composition and stable isotope values (δD and δ18O) in water samples from the Ili-Balkhash Basin, arid Central Asia, to investigate factors that control hydrologic processes in the area, and explore how the arid environment influences local hydrochemistry and water resources. Isotope values in lake waters (−24.1‰ [δD] and −1.5‰ [δ18O]) are enriched relative to river waters (−84.6‰ [δD] and −12.4‰ [δ18O]), indicating that lake waters experience intense evaporation. In the upstream Ili River, waters with lowest δD and δ18O values are supplied mainly by glacial ice and snow melt, whereas lower reaches of the river are affected increasingly by evaporation and human water extraction. Waters of the Ili River and other small rivers that drain to Lake Balkhash are chemically similar, and of the Ca-HCO3 type. Gibbs diagrams indicate that mineral weathering is the key process that controls river water chemistry. On average, carbonate and silicate weathering contribute 55.1% and 26.7%, respectively, to the total dissolved ion load in the river waters, illustrating the strong control that regional geology exerts on streamwater chemistry. In contrast, lake waters are characterized as Na-Cl type, which results mainly from evaporation and some evaporite dissolution. Weathering in the area is controlled by climate, i.e. precipitation and temperature. Moreover, a negative correlation between lake water total dissolved solids and d-excess, and a systematic increase in chemical concentrations and stable isotope values downstream in the Ili River, reflect the fact that arid climate conditions promote evaporation and affect water quality. PCA analysis and mass balance calculation of water chemistry suggests that humans contribute only 6.6% of the major ion load to waters, which display increasing concentrations in the middle and downstream regions. There, effects of human-mediated weathering and transport of salts from agricultural irrigation are reinforced by higher temperatures and evaporation.

Ozone nanobubble treatments improve survivability of Nile tilapia (Oreochromis niloticus) challenged with a pathogenic multi-drug-resistant Aeromonas hydrophila.

A rapid increase in multi-drug-resistant (MDR) bacteria in aquaculture highlights the risk of production losses due to diseases and potential public health concerns. Previously, we reported that ozone nanobubbles (NB-O3 ) were effective at reducing concentrations of pathogenic bacteria in water and modulating fish immunity against pathogens; however, multiple treatments with direct NB-O3 exposures caused alterations to the gills of exposed fish. Here, we set up a modified recirculation system (MRS) assembled with an NB-O3 device (MRS-NB-O3 ) to investigate whether MRS-NB-O3 (a) were safe for tilapia (Oreochromis niloticus), (b) were effective at reducing bacterial load in rearing water and (c) improved survivability of Nile tilapia following an immersion challenge with a lethal dose of MDR Aeromonas hydrophila. The results showed no behavioural abnormalities or mortality of Nile tilapia during the 14-day study using the MRS-NB-O3 system. In the immersion challenge, although high bacterial concentration (~2×107 CFU/ml) was used, multiple NB-O3 treatments in the first two days reduced the bacteria between 15.9% and 35.6% of bacterial load in water, while bacterial concentration increased from 13.1% to 27.9% in the untreated control. There was slight up-regulation of non-specific immune-related genes in the gills of the fish receiving NB-O3 treatments. Most importantly, this treatment significantly improved survivability of Nile tilapia with relative percentage survival (RPS) of 64.7% - 66.7% in treated fish and surviving fish developed specific antibody against MDR A.hydrophila. In summary, the result suggests that NB-O3 is a promising non-antibiotic approach to control bacterial diseases, including MDR bacteria, and has high potential for application in recirculation aquaculture system (RAS).

Institutional Barriers to On-Site Alternative Water Systems: A Conceptual Framework and Systematic Analysis of the Literature.

Scientists are increasingly exploring on-site water systems to supplement conventional centralized water and wastewater infrastructure. While major technological advancements have been achieved, we still lack a systematic view on the non-technical, or institutional, elements that constitute important barriers to the uptake of on-site urban water management systems. This paper presents a conceptual framework distinguishing between institutional barriers in six key dimensions: Equity, Knowledge and Capabilities, Financial Investment, Legal and Regulatory Frameworks, Legitimacy, and Market Structures. The analysis of the existing literature covering these barriers is translated into a typology of the socio-technical complexity of different types of alternative water systems (e.g., non-potable reuse, rainwater systems, and nutrient recovery). Findings show that socio-technical complexity increases with the pollution load in the source water, correlating to potential health risk, and the number of sectors involved in the value chain of an alternative water system. For example, greywater reuse for toilet flushing might have systematically less complex institutional barriers than source separation for agricultural reuse. This study provides practitioners with easily accessible means of understanding non-technical barriers for various types of on-site reuse systems and provides researchers with a conceptual framework for capturing socio-technical complexity in the adoption of alternative water systems.

Rotifers stimulate the specific uptake rate in lotic phototrophic biofilms

Abstract Stream biofilms can improve water quality (e.g. excessive nitrogen loads) because their microorganisms such as microphytobenthos and bacteria, are involved in self‐depuration processes in the biofilm. In marine sediments, meiofauna can influence primary productivity of phototrophic biofilms, stimulate bacterial growth, and exert a significant role on nitrogen cycling. We hypothesised that in rivers biofilms, increased meiofauna abundance in combination with nutrient enrichment can lead to improve biofilm nutrient uptake ability. River biofilms (from the Garonne River, France) were incubated in flumes supplied with natural river water. The uptake rates of the biofilms as well as the response of microorganisms were studied under different conditions of meiofaunal density and concentration over a 10‐day experiment. Rotifers dominated the meiofauna community in all biofilms. Under high nitrate conditions, the biofilm uptake rate was significantly higher in meiofauna‐enriched than non‐enriched biofilms over the first 2 days. This suggests that under high nitrate concentration conditions, high densities of rotifers enhanced the nitrogen uptake capacity of phototrophic biofilm despite a lower biomass. Densities of rotifers and bacteria in biofilms were positively correlated under enriched conditions suggesting that these two communities interacted over the experimental period. Signature pigment concentrations show that, under low concentrations of , biomasses of diatoms and green microalgae were higher in meiofaunal‐enriched than non‐enriched biofilms, indicating that rotifer activity favoured biomass accumulation of these algae. This study demonstrates that meiofauna inhabiting biofilms may contribute to the limitation of nitrogen loads in stream water and supports the thesis that the potential interactions between faunal groups and microbial communities of biofilms merits further investigation to improve our understanding of processes which regulate interactions between biofilms and the overlying water in rivers.

Comparative assessment of heavy metal bioaccumulation in skeletal muscles of softshell and hard-shell freshwater turtles

The heavy metal ions originating from the various point and nonpoint sources seriously threatening the lotic ecosystem by posing severe health crises to the aquatic organisms of higher trophic levels. The freshwater turtles with delicate body structure and devoid of any hardcovers are prone to higher heavy metal bioaccumulation risks. The present study was conducted to determine heavy metals bioaccumulation in three soft-shelled and hard-shelled freshwater turtle species in Pakistan. We collected the water samples and cadaver turtle bodies at both sites and transported them to the laboratory for heavy metal content evaluation. The skeletal muscles (1 g) and water samples (100 ml) were processed by acid digestion and prepared metals analyses by AAS. The results indicated that the mean concentrations of Copper (Cu), Zinc (Zn) and Cadmium (Cd) were significantly lower, while Nickel (Ni), Cobalt (Co), Lead (Pb) and Chromium (Cr) were significantly higher at both sites compared with world health organization (WHO, 2004) standards. Muscles of softshell turtle (Lissemys punctata) showed the maximum bioaccumulation of targeted metals than other two species of hard-shell turtles i.e. Cu (7.61 ± 1.88), Zn (49.17 ± 4.11), Ni (2.77 ± 0.41), Cd (0.21 ± 0.02), Co (3.31 ± 0.43), Pb (4.70 ± 0.62) and Cr (6.09 ± 0.39). The mean concentrations of Cu, Ni, Pb, and Cr were maximum in water and turtle species muscles collected from Trimmu Barrage. In conclusion, the heavy metal loads in water and bioaccumulation patterns in the skeletal muscles of freshwater turtle species illustrated species and location-based variations with overall similar pattern corroborations among the sequence of heavy presence levels.

Impact of mycogenic zinc nanoparticles on performance, behavior, immune response, and microbial load in Oreochromis niloticus.

This work aims to evaluate the antibacterial activity of biological zinc nanoparticles (BIO-ZnONPs) against pathogenic fish bacteria and assess the effect of BIO-ZnONPs on the performance, behavior, and immune response in Nile tilapia (Oreochromis niloticus) as compared to chemical zinc nanoparticles (CH- ZnONPs). Aspergillus niger TS16 fabricated the BIO-ZnONPs were spherical shape with the average size of 45nm and net charge of -27.23mV. Generally, the results indicate that BIO-ZnONPs were more effective than CH- ZnONPs in enhancing the performance properties of Nile tilapia. Five experimental groups of Nile tilapia (initial body weight of 20.2g) were treated with two concentrations of 0.5 and 1mg L-1 from biological and chemical ZnONPs, while the fifth group was served as a control. After ten weeks of treated water with ZnONPs, the performance, feed efficiency parameters, feeding, and swimming behaviors significantly improved in BIO-ZnONPs treated groups (P<0.05). The liver function, LYZ activity, and NBT values were significantly enhanced in the 0.5mg L-1 BIO-ZnONPS group compared to CH- ZnONPs group and control (P<0.05). Furthermore, the lowest cortisol and the highest testosterone and growth hormone levels were recorded in 1mg L-1 BIO-ZnONPs group. Regarding the antibacterial effects, BIO-ZnONPs displayed the lower total bacterial loads in water and fish tissues (intestine, gills, skin, and muscle) and the maximum antibacterial properties against pathogenic bacteria (Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Aeromonas hydrophila). Our study exemplifies novel findings of BIO-ZnONPs in the promotion of fish health and production and its antibacterial properties in Nile tilapia.

Assessment of Microbial Load in Water and Sediments of Rivers Otamiri and Nworie in Owerri, South Eastern Nigeria

Water pollution is a global problem. The study was carried out to assess the microbial constituents in water and sediment of Rivers Otamiri and Nworie during dry and rainy seasons (March and September, 2020) with comparison to WHO benchmark for drinking water .Samples were randomly collected at six (6) sampling points and analyzed using routine microbiological protocols. The results revealed detectable amount of microbial activates in surface water of both rivers during the dry and rainy season. During the rainy season, a THB bioload average of 2.02x104 and 5.1x104CFU/mL for Nworie and Otamiri river respectively were measured. For the TCC, the average was 9.8x103 and 2.5x104 CFU/mL, while in the dry period there was corresponding reduction in the bioload value for both rivers. THB average value for Nworie river was 1.34x104 CFU/mL, with corresponding 3.5x104 values for Otamiri river, while in same inclination, TCC measured 6.1x103 and 1.8x104 CFU/mL. There were noteworthy variations in the values for the two rivers as well as in the two seasons. TBC value for Otamiri measured about 1.5 folds than the value for Nworie. In same trend, TCC value for Nworie measured about 39%. All values measured were above WHO permissible limit for drinking water. The biochemical and cultural features of the isolated microorganism in water showed the presence of E. coli identified in the entire stations (100%), Salmonella and faecal coliform occurred 83.3% each, while Vibrio and Shigella were detected in 4 of the 6 stations. The mean total bacterial count, total coliform count and total E. coli, were not in conformity with World Health Organization (WHO) Standard for drinking water and thus constitute a threat to the River; these were attributed to indiscriminate waste dumps around the rivers. The study underscores the need for adequate waste management system to forestall outbreak of pathogenic diseases in the area.

The effectiveness of treating irrigation water using ultraviolet radiation or sulphuric acid fertilizer for reducing generic Escherichia coli on fresh produce-a controlled intervention trial.

AimsThe aims of this study were to: (i) estimate the effectiveness of ultraviolet radiation (UV) and sulphuric acid‐based fertilizer (SA), at reducing levels of generic Escherichia coli in surface irrigation water and on produce and surface soil in open produce fields; and (ii) describe the population dynamics of generic E. coli in produce fields.Methods and ResultsSpinach and cantaloupe plots were randomly assigned to control, UV or SA treatment groups. Irrigation water was inoculated with Rifampicin‐resistant E. coli prior to treatment. More than 75% of UV‐ and SA‐treated tank water samples had counts below the detection limit, compared to a mean count of 3·3 Log10 CFU per ml before treatment. Levels of Rifampicin‐resistant E. coli in soil and produce both increased and decreased over 10–15 days after irrigation, depending on the plot and time‐period.ConclusionsUV and SA treatments effectively reduce the levels of E. coli in surface irrigation water. Their effectiveness at reducing contamination on produce was dependent on environmental conditions. Applying wait‐times after irrigation and prior to harvest is not a reliable means of mitigating against contaminated produce.Significance and Impact of the StudyThe results are of timely importance for the agricultural industry as new FSMA guidelines require producers to demonstrate a low microbial load in irrigation water or allow producers to apply a wait‐time to mitigate the risk of contaminated produce.

A decision support system for the identification of critical zones in a watershed to implement land management practices

The increasing demand for food and clean energy, such as biofuel calls for a sustainable food-energy nexus in the agriculture sector. Mixed cropping pattern of food and biofuel crops is a viable strategy to meet the escalating demands of the biofuel production at the cost of food production. The implementation of the proposed solutions of simulation–optimization frameworks, at larger spatial scales, is a challenging task. One of the commonly adopted approaches is to implement the solution initially in critical zones that are sensitive to the land management practices and are critical for achieving the objectives. Despite the different techniques to identify the critical zones, this study proposes a new approach to identify the critical zones within a watershed, where the land use changes are essential to improve the social and physical environment while meeting the concurring demands for food and biofuel production. A decision support system (DSS), utilizing the concept of analytical hierarchy process (AHP) is developed to choose the number of optimal solutions from the Pareto-optimal Front to reduce the uncertainty involved in solution adaption by the decision-maker and identification of the critical zone. The results from the study indicate how solution strategies can influence the objective of optimal balance between crop demand and nutrient minimization using different cases. The proposed land use using the developed framework reduced the Total Nitrogen and Total Phosphorous loads by 29% and 38%, respectively from the watershed by converting about 44% of the baseline land use to different cropping patterns with the restriction on minimal food grain and biomass production. The outcome of the framework indicates that the adaptation of more robust objective function for spatial optimization through the developed DSS can reduce the nutrient load in the downstream water.

Sanitation Practices and Microbial Quality of Drinking Water in Open Defaecation Free and Open Defaecation Communities in the Savelugu Municipality

Open defaecation leads to faecal matter contamination of drinking water which can cause water borne diseases. The study assessed the linkage between sanitation practices and microbial quality of drinking water of open defaecation free and open defaecation communities in the Savelugu Municipality. A cross-sectional survey of 170 households was conducted in five open defaecation free and five open defaecation communities in the Savelugu Municipality. A total of 78 samples were collected from water sources and households and analysed for Escherichia coli, Salmonella spp and Shigella spp. Sanitation facilities used by the residents included pit latrine (88.24%), no latrine (11.17%), and flush (0.59%). The study observed improper disposal of children faeces in the communities. E. coli count ranged from 0 to 15 CFU/100 ml in open defaecation free communities and 0 to 32 CFU/100 ml in open defaecation communities. The microbial load in the drinking water from open defaecation communities was higher than open defaecation free communities. Open defaecation practice leads to contamination of household water probably due to unsanitary. Community Led Total Sanitation (CLTS) should be encouraged in open defaecation communities.

Valuation of levels of some carcinogenic metals in the water and incidences of cancer along Hadejia-Jama'are River Basin Areas

The determination of levels of some carcinogenic metals in the water and incidences of cancer was carried out in ten different local governments along Hadejia-Jama'are River Basin Areas, using standard procedures. Arsenic content was determined using UV Spectrophotometer after diazotization and heavy metals by atomic absorption spectrophotometry after acid digestion. The numbers of cancer patients were obtained from the Cancer Register of the health institutions along the basin after obtaining ethical approvals from the health institutions. The mean arsenic (As), of the water ranged from 3.35 – 10.60 µg/L, cadmium (Cd): 1.57 – 10.10 µg/L, chromium (Cr): 40.30 – 250.00 µg/L, nickel (Ni): 48.80 – 235.00 µg/L and lead (Pb): 19.50 – 38.20 µg/L. The metal concentrations in the water samples were higher in the dry season than the wet season. ANOVA showed significant differences at p&lt;0.05 for Cd, Cr, Ni and Pb. The cancer levels were determined by matching the concentration of the heavy metals from each local government with number of cancer patients in the local government along the river basin route. The cancer cases along the basin were Bunkure- 13, Wudil- 16, Ajingi11, Ringim- 9, Taura- 8, K/Hausa- 10, Hadejia- 12, Jama'are- 3, Gashua- 14 and Nguru- 10. Using the principal component analysis (PCA) there was an excellent relationship between cancer burden and metal loads in the potable water of the basin while the hierarchical cluster dendrogram (HCD) analysis reveals that arsenic, chromium and cadmium may be the major contributors to cancer incidences along the basin.

Ozonation enhancement of low cost double-stranded DNA binding dye based fluorescence measurement of total bacterial load in water.

We demonstrated the feasibility of using ozonation to enhance the performance of dsDNA binding dye SYBR Green I in the fluorescence measurement of total bacterial load in water. Unlike its membrane permeable but expensive equivalent such as SYTO82 dye, SYBR Green I is many times cheaper but membrane impermeable. Ozonation allowed SYBR Green I dye to permeate the membrane and bind with the dsDNA within by first breaching it. Using E. coli K12 bacteria at serial dilution ratios from 1/1 (980 CFU mL−1) to 1/200, we achieved corresponding quantification from 618.7 ± 9.4 to 68.0 ± 1.9 RFU (100 to 11.00% normalized RFU). In comparison, plate counting and optical density measurement were only able to quantify up till a serial dilution ratio of 1/50 (40 CFU mL−1 and 0.0421, respectively). Most importantly with ozonation, the sensitivity of SYBR Green I dye based fluorescence measurement was improved by ∼140 to 210% as compared to that without ozonation. Given its low electrical power consumption, lab-on-chip compatibility and reagent-less nature, ozonation is highly compatible with portable fluorimeters to realize low-cost monitoring of total bacterial load in water.

Noble Gases as Monitoring Tracers in CCS: A Case Study with CO2 from the Waste-to-Energy Plant Klemetsrud, Norway

To design monitoring schemes for CO2 storage sites, the composition of the injected CO2 needs to be characterized. Noble gases are one of the environmental tracers, which could be cost-effective since they are naturally inherent in the CO2 and the storage reservoir fluids. The elemental, e.g. He/Ne, He/CO2, or isotopic, e.g. 3He/4He ratios of a gas are potentially diagnostic fingerprints which can be used to discriminate gas sources in the environment, e.g. deep crustal versus shallow, biogenic gas. The waste-to-energy (WtE) plant Klemetsrud, which generates 460000 tCO2/a, was investigated as a future source of captured CO2 for storage in the up-coming large-scale CCS project ‘Longship’, in Norway, aimed to be operational by 2024. In 2019, a demonstration capture facility at the WtE plant was set up to establish the feasibility of future large-scale CO2 capture. We sampled the main gas streams on-site and present the analysis of noble gases in (I) the exhaust of the waste incineration, i.e. the flue gas stream with high concentrations of CO2, (II) the capture outlet, i.e. the CO2-depleted gas stream and (III) the captured, concentrated CO2 gas stream. Noble gas concentrations are depleted in the captured CO2 after the amine treatment by several orders of magnitude compared to the flue gas. Isotopic ratios are air-like. This behavior has been observed at other CO2 capture plants. However, absolute concentrations of noble gases measured at Klemetsrud are significantly lower for all species, except He, which is within the range of previously measured concentrations. Further, we apply phase partitioning calculations to investigate the application of inherent noble gas in CCS monitoring schemes. The low noble gas concentrations, and their associated elemental and isotopic ratios, would only be preserved when the injected CO2 remains almost pure and does not mix or interact with fluids already present in the reservoir (e.g. native gas, formation water). Interaction of the CO2 with the formation water will lead to noble gas stripping that overprints the highly depleted composition of the captured CO2 with a noble gas elemental and isotopic ratios characteristic of deep crustal fluids. This characteristic signature, especially when coupled with the distinct major gas composition of leaked CO2 (e.g. extreme CO2/CH4 ratios) may form an effective tracer to discriminate a CO2 leakage from other gas sources at the seabed (e.g. shallow biogenic, dissolved air or hydrate decomposition). To take advantage of this low cost tracer, baseline geochemical surveys should include inventories of the background dissolved noble gas load in the formation water of storage reservoirs, in other (hydrocarbon bearing) formations along the migration route and in existing seabed gas seeps overlying the storage site.

Stage-Discharge Relationships of Drawdown Plates for Denitrifying Woodchip Bioreactors

HighlightsDrawdown plates can prevent prolonged saturation in denitrifying woodchip bioreactors.Contraction coefficients for the orifice equation ranged from 0.74 to 0.76.Drawdown orifice should be sized appropriately to avoid interfering with design flow rates.Established stage-discharge relationships for drawdown orifice improve accuracy of flow monitoring.Abstract.Denitrifying woodchip bioreactors are a conservation drainage practice used to reduce nitrate loads in tile drainage water from field crops. Prolonged saturation in the woodchip media under no flow or low flow conditions can result in the production of hydrogen sulfide and methane. The US Department of Agriculture Natural Resources Conservation Service’s (NRCS) Conservation Practice Standard for denitrifying bioreactors recommends a low-level orifice at the bioreactor outlet to drain the woodchip media within 48 h to prevent prolonged stagnation. This study determined stage-discharge relationships for three drawdown configurations in an AgriDrain water level control structure (15.2 cm nominal tile size) to improve accuracy of estimating flow in field bioreactors. Tested drawdown configurations consisted of a custom-made inverted-v orifice plate currently used by the NRCS (3.6 cm2 orifice area); and a 2 and an 8 mm gap between the base of the structure and the bottom stop log (2.6 and 12.3 cm2 orifice area, respectively). The stage-discharge relationship for all three orifices was accurately described by the orifice flow equation (R2 &amp;gt; 0.99). Stage-discharge relationship for the inverted-v drawdown plate in combination with a stainless steel-edged v-notch weir was the sum of their respective stage-discharge relationships for orifice flow and flow over the weir. Contraction coefficients for the inverted-v, 2 mm gap, and 8 mm gap configurations were 0.74, 0.74, and 0.76, respectively. The stage-discharge relationships for the inverted-v, 2 mm gap, and 8 mm gap configurations were Q = 3.26*A*h0.5, Q = 3.29*A*h0.5, and Q = 3.38*A*h0.5, respectively, where Q is in m3 s-1, A is the orifice area in m2, and h is the water head differential in meters. Keywords: Denitrifying bioreactor, Drawdown plate, Flow monitoring, NRCS, Prolonged saturation.

Effects of permafrost degradation on thermokarst lake hydrochemistry in the Qinghai‐Tibet Plateau, China

AbstractThermokarst lakes play a key role in the hydrological and biogeochemical cycles of permafrost regions. Current knowledge regarding the changes caused by permafrost degradation to the hydrochemistry of lakes in the Qinghai‐Tibet Plateau (QTP) is limited. To address this gap, a systematic investigation of thermokarst lake water, suprapermafrost water, ground ice, and precipitation was conducted in the hinterland of the QTP. The thermokarst lake water in the QTP was identified to be of the Na‐HCO3‐Cl type. The mean concentrations of HCO3− and Na+ were 281.8 mg L−1 (146.0–546.2 mg L−1) and 73.3 mg L−1 (9.2–345.8 mg L−1), respectively. The concentrations of Li+, NH4+, K+, F−, NO2−, and NO3− were relatively low. Freeze‐out fractionation concentrated the dissolved solids within the lake water during winter, which was deeply deepened on lake depth and lake ice thickness. Owing to solute enrichment, the ground ice was characterized by high salinity. Conversely, repeated replenishment via precipitation led to lower solute concentrations in the ground ice near the permafrost table compared to that within the permafrost. Although lower solute concentration existed in precipitation, the soil leaching and saline ground ice melting processes enhanced the solute load in suprapermafrost water, which is considered an important water and solute resource in thermokarst lakes. The influencing mechanism of permafrost degradation on thermokarst lake hydrochemistry is presumably linked to: (1) the liberation of soluble materials sequestered in ground ice; (2) the increase of solutes in suprapermafrost water and soil pore water; and (3) the changes in lake morphometry. These results have major implications on the understanding of the effects of ground ice melting on ecosystem functions, biogeochemical processes, and energy balance in a rapidly changing climate.

Spatio-Temporal Dynamics of Algae and Macrophyte Cover in Urban Lakes: A Remote Sensing Analysis of Bellandur and Varthur Wetlands in Bengaluru, India

Rapid urbanization processes and indiscriminate disposal of urban wastewaters are major causes for anthropogenic lake-sediment deposition and eutrophication. However, information about the spatial and temporal variation of macrophyte and phytoplankton distribution as indicators for water contamination is limited. To gain insights into the dynamics, we analyzed lake-cover changes of Bellandur and Varthur Lake in the S-Indian megacity of Bengaluru for the post-rainy seasons of the years 2002–2019. Supervised maximum likelihood classifications were conducted on 62 freely available, true-color satellite images in order to distinguish between macrophytes, algae, and free water surface. The image-derived results were verified by supervised classification and manual mapping of two simultaneously recorded multispectral satellite images (Sentinel-2 and WorldView-2). Seasonal interrelations between macrophytes and algae distribution were similar for both lakes. The increase in macrophyte cover during post-rainy season negatively correlated with algal abundance. Macrophyte expansion progressively suppressed algae development at both lakes, reflective of increasing eutrophication caused by on-going wastewater input. Seasonal variation in precipitation, wind direction, and temperature seemed to trigger intra-annual shifts of macrophytes and algae while similar macrophyte spread intensities during the post-monsoon season indicated independence of nutrient loads in the lake water.