Passive Water Research Articles

CFD simulation of secondary side fluid flow and heat transfer of the passive residual heat removal heat exchanger

Abstract Passive residual heat removal heat exchanger (PRHR HX) is a key equipment in advanced passive safety pressurized water reactors (PWRs), such as AP1000. Immerged in the In-containment refueling water storage tank (IRWST), the C-shape PRHR HX removes the residual heat using natural convection and boiling heat transfer during postulated accidents. Therefore, the safety operation of the PRHR HX is very important for the nuclear power plant (NPP). In this paper, three dimensional CFD simulation of the secondary side fluid flow and heat transfer of the PRHR HX is performed. The drift flux model is used to simulate the two phase flow phenomenon in the IRWST. The tube region is modeled by the porous media approach. The flow resistance in the tube region is calculated by empirical pressure drop correlation and two phase flow multiplier. The heat transfer rate from the primary side to the secondary side fluid is also evaluated by widely used heat transfer empirical correlations. Additional source terms corresponding to the flow resistance and removed heat in the tube region are added to the momentum and energy equation, respectively. The governing equations are solved by the commercial CFD package FLUENT. Three dimensional distributions of the fluid velocity, temperature and void fraction are obtained. The heat transfer characteristics of the tube bundle is analyzed.

Experimental Investigation of Enhancing the Energy Conversion Efficiency of Solar PV Cell by Water Cooling Mechanism

Solar photovoltaic cells produce electricity by receiving solar radiation. The output power of photovoltaic cells (PV) is mainly influenced by the significant increase in cell temperature during the absorption of radiation. The solar cooling system has been considered and investigated experimentally in this research paper. A passive cooling system was designed and fabricated for efficiently cool the PV module, with inlet/outlet manifold considered for uniform flow of water at the rear side of the PV module. The experimentation was performed with and without the cooling system. In this paper, a linear trend has been established between the electrical efficiency and the temperature of the photovoltaic cells. Without a cooling system, the average cell temperature reaches to 600C, and the solar panel efficiency reduced to 8 to 16%. However, when the panel was operated under the passive water system, the temperature of the PV cell was reduced to 47°C, resulting in a 10% -21% improve in the solar PV cell efficiency. Both systems, without cooling and with cooling systems are validated experimentally.

Correction: Passive water collection with the integument: mechanisms and their biomimetic potential (doi:10.1242/jeb.153130)

There was an error published in J. Exp. Biol. (2018) 221 , [jeb153130][1] ([doi:10.1242/jeb.153130][2]). The corresponding author's email address was incorrect. It should be Philipp.Comanns{at}rwth-aachen.de. This has been corrected in the online full-text and PDF versions. We apologise to authors

Pressure-Retarded Osmosis Thermosyphon

The basis of a novel method for passive solar water heating homologous to the traditional thermosyphon but driven by salinity gradient induced by changes of salinity gradient induced by evaporation at the collector is outlined. Its purpose, likewise than a thermosyphon, is to simplify the transfer of liquid while avoiding the cost and complexity of a conventional pump. However, in this concept, the fluid motion is not obtained from the tendency of a less dense fluid to rise above a denser fluid (natural convection) but rather by taking advantage of the energy released during the spontaneous mixing of the low-concentration (evaporated fraction) solution and the high-concentration (no-evaporated fraction) solution, which have been previously separated into two streams in the evaporator module. Finally, the possibility of driving the thermal osmosis by the strong thermal dependence of the solubility featured by many solutions rather than evaporation is envisaged. One important point in favor of the proposed thermosyphon driven by thermo-osmosis is that makes possible downward heat and mass transfer, i.e., heat and mass transport from the top roofs (where solar collectors are generally placed) to the bottom (inside the homes), and then the use of expensive and voluminous tanks so characteristic of current thermosyphons driven by natural convection is no longer needed.

Passive water collection with the integument: mechanisms and their biomimetic potential.

Several mechanisms of water acquisition have evolved in animals living in arid habitats to cope with limited water supply. They enable access to water sources such as rain, dew, thermally facilitated condensation on the skin, fog, or moisture from a damp substrate. This Review describes how a significant number of animals - in excess of 39 species from 24 genera - have acquired the ability to passively collect water with their integument. This ability results from chemical and structural properties of the integument, which, in each species, facilitate one or more of six basic mechanisms: increased surface wettability, increased spreading area, transport of water over relatively large distances, accumulation and storage of collected water, condensation, and utilization of gravity. Details are described for each basic mechanism. The potential for bio-inspired improvement of technical applications has been demonstrated in many cases, in particular for several wetting phenomena, fog collection and passive, directional transport of liquids. Also considered here are potential applications in the fields of water supply, lubrication, heat exchangers, microfluidics and hygiene products. These present opportunities for innovations, not only in product functionality, but also for fabrication processes, where resources and environmental impact can be reduced.

Concentrations, fluxes and field calibration of passive water samplers for pesticides and hazard-based risk assessment

Three passive sampler types including Chemcatcher® C18, polar organic chemical integrative sampler-hydrophilic–lipophilic balance (POCIS-HLB) and silicone rubber (SR) based on polydimethylsiloxane (PDMS) were evaluated for 124 legacy and current used pesticides at two sampling locations in southern Sweden over a period of 6 weeks and compared to time-proportional composite active sampling. In addition, an in situ calibration was performed resulting in median in situ sampling rates (RS, L day−1) of 0.01 for Chemcatcher® C18, 0.03 for POCIS-HLB, and 0.18 for SR, and median in situ passive sampler-water partition coefficients (log KPW, L kg−1) of 2.76 for Chemcatcher® C18, 3.87 for POCIS-HLB, and 2.64 for SR. Deisopropylatrazine D5 showed to be suitable as a performance reference compound (PRC) for SR. There was a good agreement between the pesticide concentrations using passive and active sampling. However, the three passive samplers detected 38 pesticides (including 9 priority substances from the EU Water Framework Directive (WFD) and 2 pyrethriods) which were not detected by the active sampler. The most frequently detected pesticides with a detection frequency of >90% for both sites were atrazine, 2,6-dichlorobenzamide, bentazone, chloridazon, isoproturon, and propiconazole. The annual average environmental quality standard (AA-EQS) for inland surface waters of the EU WFD and the risk quotient (RQ) of 1 was exceeded on a number of occasions indicating potential risk for the aquatic environment.

Enhanced canopy growth precedes senescence in 2005 and 2010 Amazonian droughts

Unprecedented droughts hit southern Amazonia in 2005 and 2010, causing a sharp increase in tree mortality and carbon loss. To better predict the rainforest's response to future droughts, it is necessary to understand its behavior during past events. Satellite observations provide a practical source of continuous observations of Amazonian forest. Here we used a passive microwave-based vegetation water content record (i.e., vegetation optical depth, VOD), together with multiple hydrometeorological observations as well as conventional satellite vegetation measures, to investigate the rainforest canopy dynamics during the 2005 and 2010 droughts. During the onset of droughts in the wet-to-dry season (May–July) of both years, we found large-scale positive anomalies in VOD, leaf area index (LAI) and enhanced vegetation index (EVI) over the southern Amazonia. These observations are very likely caused by enhanced canopy growth. Concurrent below-average rainfall and above-average radiation during the wet-to-dry season can be interpreted as an early arrival of normal dry season conditions, leading to enhanced new leaf development and ecosystem photosynthesis, as supported by field observations. Our results suggest that further rainfall deficit into the subsequent dry season caused water and heat stress during the peak of 2005 and 2010 droughts (August–October) that exceeded the tolerance limits of the rainforest, leading to widespread negative VOD anomalies over the southern Amazonia. Significant VOD anomalies were observed mainly over the western part in 2005 and mainly over central and eastern parts in 2010. The total area with significant negative VOD anomalies was comparable between these two drought years, though the average magnitude of significant negative VOD anomalies was greater in 2005. This finding broadly agrees with the field observations indicating that the reduction in biomass carbon uptake was stronger in 2005 than 2010. The enhanced canopy growth preceding drought-induced senescence should be taken into account when interpreting the ecological impacts of Amazonian droughts.

Programming Water Transporter Aquaporin Z by Lipid Composition-Altered Protein Dynamics

Aquaporins (AQPs) are intrinsic membrane proteins that mediate passive bidirectional water transport across cell membranes. The rate of the said water transport varies in different membrane environments, highlighting direct effects of membrane composition. Currently, how membrane lipids directly regulate water transport is unknown. Here, we describe the dynamics and water transport of AQP in 3 different membrane-mimetic nanodiscs (DOPC, 3:1 DOPC: DOPG and E. coli polar lipid) using amide-hydrogen/deuterium exchange mass spectrometry (HDXMS). Our results reveal that membrane composition alters dynamics and modulates water transport of AqpZ. AQP dynamics correlates with water transport showing a bell-shaped curve - higher dynamics increases water transport till a certain limit, after which it inhibits water transport - suggesting that through fine balance between stabilization and fluidity, lipids can function as critical allosteric regulators of water transport across AqpZ. Hence, alteration of protein dynamics - in a membrane composition-dependent manner offers a handle to program water permeability of AqpZ. Our findings revealed a novel lipid-mediated allosteric mechanism of AqpZ, which has tremendous implications on cellular osmoregulation and selection of optimal matrix materials for fabrication of optimal AQP biomimetic membranes.

SGTR analysis on CPR1000 with a passive safety system

As the development of the nuclear industry, passive technology turns out to be a remarkable characteristic in the design of advanced nuclear power plants. Since the 20th century, much effort has been given to the passive technology, and a number of evolutionary passive systems have been developed. The CPR1000 plant, which is one kind of mature pressurized water plants in China, is proposed to be improved with some passive systems to enhance safety. The proposed passive systems include: (1) the RMT (reactor makeup tank); (2) the ACC (accumulator); (3) the IRWST (in-containment refueling water storage tank); (4) the PEFS (passive emergency feed water system), which is installed on the secondary side of SGs; (5) the PDS (passive depressurization system). In modifying the passive safety system, it is found that the actuation conditions of the passive safety system and the accident assumptions bring great effects on the accidental mitigation. It is necessary to study the influence induced by them. In this paper, the transient phenomenon of SGTR is analyzed to show the process in the modification of the actuation conditions and the assumptions. Finally, the most proper assumptions and actuation conditions are determined. Through the sensitivity analysis, it is found that the RMTs’ and PEFSs’ behaviors bring a great impact on the accident transient. The strong mutual effect between each passive safety component in the SGTR is the reason of choosing this accident to analyze in this paper.

Heat Therapy Decreases Adipose Tissue Inflammation and Improves Insulin Signaling in Polycystic Ovary Syndrome

Passive hot water immersion promotes improvements in glucose control in humans, potentially by enhancing insulin sensitivity. In animal models, this improvement is mediated by increased heat shock protein (HSP) abundance, which inhibits production of inflammatory compounds that interfere with intracellular insulin signaling. The impact of repeated passive hot water immersion (termed ‘heat therapy’) on inflammation, HSP abundance, and insulin signaling in human adipose tissue have not been explored in an insulin‐resistant population such as obese women with Polycystic Ovary Syndrome (PCOS). While exercise training can improve insulin sensitivity in PCOS, novel treatments such as heat therapy are warranted as many individuals are unable to fully benefit from a traditional exercise program due to poor exercise tolerance or capacity. Therefore, the objective of this study was to examine changes in insulin signaling, inflammatory proteins, and HSPs in subcutaneous adipose tissue of obese women with PCOS undergoing an 8–10 week heat therapy intervention. Six obese women with PCOS (Age: 26±3y, BMI 42±2 kg·m2) underwent heat therapy, consisting of 30 × 1‐hr hot tub sessions over 8–10 weeks (3–4 per week) in 40.5°C water. Subcutaneous adipose tissue biopsies were collected from the periumbilical region at the start (Pre) and end (Post) of the chronic heat intervention. Tissue samples were analyzed using immunoblotting for HSP27, HSP70, and inflammatory proteins known to be impacted by HSPs and interfere with insulin signaling, including c‐Jun‐NH2‐terminal Kinase (JNK; inhibited by HSP70) and Inhibitor of Kappa B Kinase β (IKKβ; inhibited by HSP27). Additionally, a sub‐set of primary adipocytes in n=4 subjects were serum starved for 2 hours, then exposed to 1.2 nM insulin for 5 minutes for insulin signaling (p‐AKT) analysis using immunoblotting. All targets were quantified relative to loading control and expressed as a fold change from Pre to Post. Following heat therapy, insulin signaling (p‐AKT) increased in all subjects (4.1±2.0‐fold increase, p=0.19) despite no change in BMI (p=0.42). IKKβ significantly decreased (0.50 ± 0.06‐fold decrease, p=0.02) and JNK tended to decrease (0.48 ± 0.17‐fold decrease, p=0.09) after heat therapy. Abundance of HSP27 increased in all subjects (1.27 ± 0.14‐fold increase, p=0.18), while, conversely, HSP70 abundance significantly decreased (0.42±0.12‐fold decrease; p=0.03). In these preliminary data, heat therapy appears to promote improved insulin signaling in obese women with PCOS. This improvement is likely due to observed decreases in adipose tissue inflammation, potentially mediated in part by increased HSP27 abundance. Regular heat exposure has promise as a novel treatment in insulin‐resistant individuals to improve metabolic function. Heat can potentially be implemented as a complement or as a transition to exercise training to improve metabolic health, particularly in patient populations with severe metabolic dysfunction, mobility limitations, or low exercise tolerance.Support or Funding InformationSupported by American Heart Association Predoctoral Fellowship 16PRE27780085, Eugene & Clarissa Evonuk Memorial Fellowship, and the Ken and Kenda Singer Endowment Fund.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Diffusive gradients in thin-films (DGT) for in situ sampling of selected endocrine disrupting chemicals (EDCs) in waters

A passive water sampler based on the diffusive gradients in thin-films (DGT) technique was developed and tested for 3 groups of endocrine disrupting chemicals (EDCs, including oestrogens, alkyl-phenols and bisphenols). Three different resins (hydrophilic-lipophilic-balanced (HLB), XAD18 and Strata-XL-A (SXLA)) were investigated for their suitability as the binding phase for DGT devices. Laboratory tests across a range of pH (3.5–9.5), ionic strength (0.001–0.5 M) and dissolved organic matter concentration (0–20 mg L−1) showed HLB and XAD18-DGT devices were more stable compared to SXLA-DGT. HLB-DGT and XAD18-DGT accumulated test chemicals with time consistent with theoretical predictions, while SXLA-DGT accumulated reduced amounts of chemical. DGT performance was also compared in field deployments up to 28 days, alongside conventional active sampling at a wastewater treatment plant. Uptake was linear to the samplers over 18 days, and then began to plateau/decline, indicating the maximum deployment time in those conditions. Concentrations provided by the DGT samplers compared well with those provided by auto-samplers. DGT integrated concentrations over the deployment period in a way that grab-sampling cannot. The advantages of the DGT sampler over active sampling include: low cost, ease of simultaneous multi-site deployment, in situ analyte pre-concentration and reduction of matrix interferences compared with conventional methods. Compared to other passive sampler designs, DGT uptake is independent of flow rate and therefore allows direct derivation of field concentrations from measured compound diffusion coefficients. This passive DGT sampler therefore constitutes a viable and attractive alternative to conventional grab and active water sampling for routine monitoring of selected EDCs.

The potential of energy savings and the prospects of cleaner energy production by solar energy integration in the residential buildings of Saudi Arabia

Abstract In this study, various energy conservation techniques and clean energy utilization prospects are investigated for the residential buildings of Saudi Arabia. A base case study of a distinctive residential building in Saudi Arabia is performed using simulation packages and its energy performance is optimized by incorporating the design standards of International Energy Conservation Code (IECC). The optimized results show that the energy consumed by the IECC standardized building is less by 56% for space cooling, 37% for space heating, 46% for lighting, and 27% for appliances. The IECC standardized building is integrated with a passive solar water heating system and a grid-connected solar PV system to meet the water heating load and lighting load, respectively. The use of solar water heating system shows 76% reduction in energy consumption as compared to the electric water heater. The feasibility of integrating a grid-connected solar PV system in the residential buildings is justified in terms of subsidy provided by the government and eco-environmental benefits. Finally, the prospects of utilizing solar energy in buildings are discussed with their economic and environmental benefits.

Integrating quantitative defense-in-depth metrics into new reactor designs

Risk-informed, performance-based (RIPB) methods have progressed to the point where high-level guidance can be used to augment traditional, deterministic, nuclear safety design practices in areas important to nuclear reactor safety. This paper describes an approach for augmenting the traditional defense-in-depth (DID) qualitative approach with quantitative risk information from a plant-specific probabilistic risk assessment (PRA) in a way that is structured, can be applied on a consistent basis, and allows for clear acceptance criteria. Adding performance-based targets that should be achieved is expected to result in safer and more economical plant designs. Evaluations of DID can be conducted throughout the design process as well as in support of design certification and operating license applications to identify where defense protections could be enhanced or relaxed. Consistent with the United States Nuclear Regulatory Commission's policy statement encouraging greater use of PRA to improve safety decision making and regulatory efficiency, this scenario-based DID method can be used to evaluate changes and overall plant design as part of the normal design control process. Although the RIPB method presented in this paper was developed for application to advanced passive light water reactor designs, the metrics could be tailored to other reactor designs. This risk-informed approach to DID helps to ensure that public and worker risk insights are integrated into the design process holistically.

Assessing the clogging and permeability of degrading packed bed reactors

In South Africa, the need for water treatment is increasing, especially in the mining sector. As active water treatment technologies are expensive, the mining sector has an increasing need for passive water treatment technology, with low maintenance and operating costs, yet efficient water treatment ability. Literature on passive water treatment suggests that these systems only offer a narrow range of treatment capabilities. Therefore, hybrid water treatment systems could be a solution to low-cost water treatment in South Africa. The degrading packed bed reactor (DPBR) is one of the units comprising the hybrid treatment group. The DPBR’s main action is to convert sulfates into sulfides and alkalinity, since this reduces the impact on the environment by increasing the pH and reducing the salinity. In this study, 6 small-scale DPBRs were constructed. Each was classified according to its unique organic source (manure, straw, vegetable food processing waste, wood shavings, chicken litter and a combined sample with layers of all the carbon sources). Synthetic acid mine drainage (AMD) was fed through the 6 bioreactors for a period of 3 months. Permeabilities, leachate samples and effective void volumes were measured from the DPBRs. From the experiments conducted, it was found that the manure and combination bioreactors (with equal layers of manure, straw, compost, wood shavings and chicken litter) had the lowest overall permeabilities, with straw and compost having the highest permeabilities. Linked to this, the experiments showed that the manure and combination bioreactors had the largest decreases in effective porosity with straw and compost having the least. Hydraulically, the combination bioreactor performed the best by incorporating the best attributes from each carbon source. Wood shavings preformed almost as well. Chicken litter clogged within 18 days after the initiation of the experiment and thus was the least effective substrate.

Hydrological Variability in the Arid Region of Northwest China from 2002 to 2013

The arid region of Northwest China (ANC) has a distinct and fragile inland water cycle. This study examined the hydrological variations in ANC and its three subregions from August 2002 to December 2013 by integrating terrestrial water storage (TWS) anomaly data derived from the Gravity Recovery and Climate Experiment (GRACE) satellite, soil moisture data modeled by the Global Land Data Assimilation System, and passive microwave snow water equivalent data. The results show that the TWS in ANC increased at a rate of 1.7 mm/a over the past decade, which consisted of an increasing trend of precipitation (0.12 mm/a). Spatially, in the northern ANC, TWS exhibited a significant decreasing trend of −3.64 mm/a (p<0.05) as a result of reduced rainfall, increased glacial meltwater draining away from the mountains, and intensified human activities. The TWS in southern and eastern ANC increased at a rate of 2.14 (p=0.10) and 1.63 (p<0.01) mm/a, respectively. In addition to increasing precipitation and temperature, decreasing potential evapotranspiration in Southern Xinjiang and expanding human activities in Hexi-Alashan together led to an overall increase in TWS. Increased glacier meltwater and permafrost degradation in response to climate warming may also affect the regional TWS balance. The variations in soil moisture, groundwater, and surface water accounted for the majority of the TWS anomalies in southern and eastern ANC. The proposed remote sensing approach combining multiple data sources proved applicable and useful to understand the spatiotemporal characteristics of hydrological variability in a large area of arid land without the need for field observations.

CFD investigation on thermal hydraulics of the passive residual heat removal heat exchanger (PRHR HX)

Passive residual heat removal (PRHR) system is a very important component of the passive safety systems in advanced passive safety pressurizer water reactors (PWRs) such as AP1000. The passive residual heat removal heat exchanger (PRHR HX) is a C-shape tube bundle heat exchanger immerged in the In-containment refueling water storage tank (IRWST) which removes the core decay heat during the accident transients. The performance of the PRHR HX is significant for the safety of the nuclear power plant (NPP). In this paper, the thermal hydraulics characteristics of the PRHR HX in the IRWST is analyzed using computational fluid dynamics (CFD). The tube region is modeled by the porous media approach along with the distributed resistance method. Heat transfer from the primary side fluid inside the tube to the secondary side fluid in the IRWST is considered. The simulation is carried out by the commercial CFD package FLUENT. The calculation of the flow resistance and heat transfer in the tube region is implemented using the User Defined Functions (UDF) in FLUENT based on the local flow conditions. Three dimensional distributions of the fluid velocity and temperature in the IRWST are obtained and thermal stratification is observed. The PRHR HX heat transfer capacity and the primary side fluid temperature distribution inside tubes are analyzed.

Experimental investigation of the assessment of Al2O3–H2O and CuO–H2O nanofluids in a solar water heating system

The solar water heating systems are the cheapest options to benefit from the solar energy. This paper deals with the assessment of Al2O3 and CuO nanofluids for the optimal operating conditions in a passive solar water heating system, coupled with a small storage tank. For that reason, to provide the highest amount of hot water for consumption at the desired temperature whenever the inhabitants require it, there must be the best connection between the collector and the storage tank. The experimental results present the optimum conditions of controllable variables for the highest output thermal power. Usage of Al2O3 and CuO nanofluid in the collector system, in their optimum operation, increases the power output of the system by 20.6% and 29.5%, respectively.The significance of the present study is underscored by the vital role played by the optimized heat gain of the hot water tank for water heating in residential applications.

Disentangling the mechanisms behind winter snow impact on vegetation activity in northern ecosystems.

Although seasonal snow is recognized as an important component in the global climate system, the ability of snow to affect plant production remains an important unknown for assessing climate change impacts on vegetation dynamics at high-latitude ecosystems. Here, we compile data on satellite observation of vegetation greenness and spring onset date, satellite-based soil moisture, passive microwave snow water equivalent (SWE) and climate data to show that winter SWE can significantly influence vegetation greenness during the early growing season (the period between spring onset date and peak photosynthesis timing) over nearly one-fifth of the land surface in the region north of 30 degrees, but the magnitude and sign of correlation exhibits large spatial heterogeneity. We then apply an assembled path model to disentangle the two main processes (via changing early growing-season soil moisture, and via changing the growth period) in controlling the impact of winter SWE on vegetation greenness, and suggest that the "moisture" and "growth period" effect, to a larger extent, result in positive and negative snow-productivity associations, respectively. The magnitude and sign of snow-productivity association is then dependent upon the relative dominance of these two processes, with the "moisture" effect and positive association predominating in Central, western North America and Greater Himalaya, and the "growth period" effect and negative association in Central Europe. We also indicate that current state-of-the-art models in general reproduce satellite-based snow-productivity relationship in the region north of 30 degrees, and do a relatively better job of capturing the "moisture" effect than the "growth period" effect. Our results therefore work towards an improved understanding of winter snow impact on vegetation greenness in northern ecosystems, and provide a mechanistic basis for more realistic terrestrial carbon cycle models that consider the impacts of winter snow processes.

Persistence, mobility and bioavailability of emerging organic contaminants discharged from sewage treatment plants

Little is known about the impact of emissions of micropollutants from small and large-scale sewage treatment plants (STPs) on drinking water source areas. We investigated a populated catchment that drains into Lake Mälaren, which is the drinking water source for around 2 million people including the inhabitants of Stockholm, Sweden. To assess the persistence, mobility, bioavailability and bioaccumulation of 32 structurally diverse emerging organic contaminants, sediment, integrated passive and grab water samples were collected along the catchment of the River Fyris, Sweden. The samples were complemented with STP effluent and fish samples from one sampling event. Contaminants identified as persistent, mobile, and bioavailable were 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (galaxolide), 2,4,7,9-tetramethyl-5-decyn-4,7-diol, tris(2-chloro-ethyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, and tris(1-chloro-2-propyl) phosphate. Galaxolide and 2,4,7,9-tetramethyl-5-decyn-4,7-diol were additionally found to be bioaccumulative, whereas n-butylbenzenesulfonamide was found to be only persistent and mobile. The total median mass flux of the persistent and mobile target analytes from Lake Ekoln into the drinking water source area of Lake Mälaren was estimated to be 27kg per year. Additionally, 10 contaminants were tentatively identified by non-target screening using NIST library searches and manual review. Two of those were confirmed by reference standards and further two contaminants, propylene glycol and rose acetate, were discharged from STPs and travelled far from the source. Attenuation of mass fluxes was highest in the summer and autumn seasons, suggesting the importance of biological degradation and photodegradation for the persistence of the studied compounds.

Effect of water-based recovery on blood lactate removal after high-intensity exercise.

This study assessed the effectiveness of water immersion to the shoulders in enhancing blood lactate removal during active and passive recovery after short-duration high-intensity exercise. Seventeen cyclists underwent active water- and land-based recoveries and passive water and land-based recoveries. The recovery conditions lasted 31 minutes each and started after the identification of each cyclist’s blood lactate accumulation peak, induced by a 30-second all-out sprint on a cycle ergometer. Active recoveries were performed on a cycle ergometer at 70% of the oxygen consumption corresponding to the lactate threshold (the control for the intensity was oxygen consumption), while passive recoveries were performed with subjects at rest and seated on the cycle ergometer. Blood lactate concentration was measured 8 times during each recovery condition and lactate clearance was modeled over a negative exponential function using non-linear regression. Actual active recovery intensity was compared to the target intensity (one sample t-test) and passive recovery intensities were compared between environments (paired sample t-tests). Non-linear regression parameters (coefficients of the exponential decay of lactate; predicted resting lactates; predicted delta decreases in lactate) were compared between environments (linear mixed model analyses for repeated measures) separately for the active and passive recovery modes. Active recovery intensities did not differ significantly from the target oxygen consumption, whereas passive recovery resulted in a slightly lower oxygen consumption when performed while immersed in water rather than on land. The exponential decay of blood lactate was not significantly different in water- or land-based recoveries in either active or passive recovery conditions. In conclusion, water immersion at 29°C would not appear to be an effective practice for improving post-exercise lactate removal in either the active or passive recovery modes.