Lake Water Research Articles

Lake Trafford Nutrients Budget and Influxes After Organic Sediment Dredging (South Florida, USA)

Lake Trafford, a 600-ha subtropical lake in southwestern Florida, has suffered from over 50 years of cultural eutrophication, resulting in the invasion of Hydrilla verticillata and organic sediment accumulation due to herbicide treatments. This study aimed to assess the effects of dredging on nutrient dynamics. A pre-dredging nutrient budget, developed using land use models and climatic data, estimated nutrient loads of 190 kg d−1 for total nitrogen (TN) and 18.6 kg d−1 for total phosphorus (TP), with total maximum daily loads (TMDLs) of 70.4 kg d−1 for TN and 4.15 kg d−1 for TP. Post-dredging analysis, using detailed spatiotemporal data, showed higher nutrient loads of 274.3 kg d−1 for TN and 24.2 kg d−1 for TP. While dredging reduced legacy nutrient accumulation, it led to increased nutrient influx from groundwater, caused by the exposure of organic sediment, as evidenced by increased lake water electrical conductivity. These findings demonstrate the importance of conducting thorough pre-dredging assessments to mitigate unintended consequences, offering practical insights for managing nutrient loads and improving restoration strategies in eutrophic lakes.

Synthesis of a hydrological, water chemistry, and contaminants research program in the Peace-Athabasca Delta (Canada) to inform long-term monitoring of shallow lakes

In a multistressor world, evidence-based stewardship of aquatic ecosystems requires long-term monitoring data to understand the timing and magnitude of environmental change and potential causes. At the Peace-Athabasca Delta (PAD; northeastern Alberta, Canada), concern for aquatic ecosystem degradation has triggered renewed and urgent calls by Indigenous, national, and international governance bodies for implementation of a long-term lake monitoring program capable of tracking changes in hydrological conditions and contaminant deposition attributable to major energy projects located upstream, climate change, and other unnatural and natural processes. Challenges imposed by the delta's size, hydrological complexity, inaccessibility of lakes, and other factors, however, have long impeded implementation of a delta-wide lake monitoring program. To address this pressing need, here we review and synthesize results obtained during 7 years (2015–2021) of intensive, multifaceted research at 60 shallow lakes spanning the delta's broad hydroecological gradients to inform an integrated hydrology, water chemistry, and contaminants monitoring program. The research involved systematic, repeated measurements of water isotope composition, water depth variation, water chemistry and turbidity, and metal(loid) concentrations in lake surface sediment and periphytic biofilm. Results reveal marked spatial and temporal variation of hydrological processes and their affects on lake water balance and depth, strong association between hydrological processes and lake water chemistry, and that concentrations of nickel and vanadium (key oil sands indicators) remain within the range of natural variation. Correspondence of generalized additive model trendlines for isotope-derived lake evaporation-to-inflow ratios and water chemistry with climate indices (Pacific Decadal Oscillation, Oceanic Niño Index) demonstrates the sensitivity, and predictability, of lake ecosystem processes in the delta to large-scale climatic patterns. We provide recommendations for field sampling, sample analysis, data display, and integration of information for ongoing monitoring at the PAD. These approaches are readily transferable to other complex landscapes with abundant shallow waterbodies threatened by multiple stressors that may alter hydrological regimes and contaminant delivery.

Nitrifying bacteria for the remediation of organic nitrogen‐contaminated waters: a review

AbstractThe rapid growth of the world's population and its environmental impact has increased the demand for effective water treatment methods. Surface water systems, including rivers, streams, lakes, and ponds, have suffered contamination, leading to the urgent need for effective contaminant removal. Organic nitrogen compounds and nitrates are of particular concern because they pose risks to health and can cause environmental damage. However, traditional water‐treatment methods often prove ineffective for addressing these issues. For this reason, this research focuses on harnessing the capabilities of nitrifying bacteria to denitrify organic nitrogen compounds in water, exploring various bacterial strains, their functions, and their ability to obtain sources of carbon. The study also investigates innovative approaches such as biofilm systems, mixed cultures, and combined processes, which have shown stronger potential for nitrogen removal. Overall, it provides valuable insights into the use of nitrifying bacteria‐based technologies for water remediation in the face of growing environmental challenges.

Effects of land use changes on local dust event in Urmia Lake basin

Land use change is an effective factor in climate change and global warming, which contributes to the carbon cycle, radiant energy balance, and dust production. Urmia Lake basin water balance in the Northwestern part of Iran is in a critical condition due to land use change, drought, and climate change. This process has led to the lake water area reduction and pronounced dust production. The satellite images indicate that from 1984 to 2017, 1433 Km2 rangelands and water area of the Urmia Lake basin decreased by more than 2906 Km2. The area of human settlement increased by 550 Km2, irrigated farmland and orchards, 804 Km2, and salty marsh, 3428 Km2. The outputs of the WetSpass hydrological model reveal the highest coefficient of evapotranspiration and interception variation in the East of Urmia Lake basin. The effects of these changes are observed in reduced soil moisture, increased salty marsh, and soft sediments as potential dust resources. During the study period, the frequency of dust days in the North and East of the lake increased 2.5-fold, while in the Southern and Western parts increased 6-fold. The results of the Pettitt Test indicate that these changes began to appear in 2007. The regression and correlation test confirm that salt marshes and soft sediments account for up to 75 %, and the decrease in the area of Urmia Lake for more than 64 % of the dust changes. The results of the assessments indicate the contribution of footprint in the destruction of the natural environment and the water balance of the lake basin. Revision of water resources management and environmental water rights of the lake, changes in the development strategy from agriculture to non-agriculture development based on lower water demand, and reduction of storage dams are among the recommended strategies to address this problem.

Comprehensive evaluation of water quality grades based on improved CRITIC and multidimensional connection cloud combination

AbstractThis study proposes a comprehensive water quality assessment method for nine major plateau lakes in Yunnan Province, based on an improved CRITIC method combined with a multidimensional connectivity cloud model. Key water quality monitoring indicators (NH3‐N, COD, TP, TN, permanganate index, DO, pH) were selected, and the weights were determined using the improved CRITIC method, highlighting the impact of NH3‐N, COD, and TP. These weights were then integrated with a multidimensional connectivity cloud model to classify lake water quality levels. The results indicated the following water quality grades for the lakes: Dianchi (III), Fuxian Lake (I), Erhai (II), Xingyun Lake (I), Qilu Lake (II), Yilong Lake (II), Lugu Lake (I), Yangzonghai (II), and Chenghai (II). Compared to five conventional methods, the proposed approach better addresses the issues of fuzziness, randomness, and discreteness in water quality indicators, avoiding the boundary selection problems inherent in traditional methods. By combining the improved CRITIC method with a multidimensional connectivity cloud model, the study achieves more precise and reliable evaluations through objective weighting and comprehensive consideration of multiple indicators. This method offers a more accurate reflection of lake water quality conditions and provides a scientific basis for water quality management and decision‐making, demonstrating significant potential for application in the field of environmental science.

Review of Recent Advances in Remote Sensing and Machine Learning Methods for Lake Water Quality Management

This review examines the integration of remote sensing technologies and machine learning models for efficient monitoring and management of lake water quality. It critically evaluates the performance of various satellite platforms, including Landsat, Sentinel-2, MODIS, RapidEye, and Hyperion, in assessing key water quality parameters including chlorophyll-a (Chl-a), turbidity, and colored dissolved organic matter (CDOM). This review highlights the specific advantages of each satellite platform, considering factors like spatial and temporal resolution, spectral coverage, and the suitability of these platforms for different lake sizes and characteristics. In addition to remote sensing platforms, this paper explores the application of a wide range of machine learning models, from traditional linear and tree-based methods to more advanced deep learning techniques like convolutional neural networks (CNNs), recurrent neural networks (RNNs), and generative adversarial networks (GANs). These models are analyzed for their ability to handle the complexities inherent in remote sensing data, including high dimensionality, non-linear relationships, and the integration of multispectral and hyperspectral data. This review also discusses the effectiveness of these models in predicting various water quality parameters, offering insights into the most appropriate model–satellite combinations for different monitoring scenarios. Moreover, this paper identifies and discusses the key challenges associated with data quality, model interpretability, and integrating remote sensing imagery with machine learning models. It emphasizes the need for advancements in data fusion techniques, improved model generalizability, and the developing robust frameworks for integrating multi-source data. This review concludes by offering targeted recommendations for future research, highlighting the potential of interdisciplinary collaborations to enhance the application of these technologies in sustainable lake water quality management.

Health Risk Assessment of Trace Elements in Surface Water from Dayat Roumi Lake, Morocco

To assess the human impact on the water of Dayat Roumi Lake and to develop effective management strategies to protect and restore this vital ecosystem in the region, seasonal sampling was carried out at six stations distributed around the lake. During these sampling campaigns, 24 parameters were measured, including 20 trace elements. Results showed that measured levels of trace elements increased in the following order: Cd < Be < Tl < Co < Sb < Mo < Cu < Zn < Ni < V < Rb < Mn < As < Cr < Pb < Li < Ba < Se < Pd < Sr in the lake water and that these recorded values were lower than those recommended by the Moroccan standard and the World Health Organization, except for Pb and Se. Correlation analysis revealed two principal water-contamination sources: natural geological origins and anthropogenic inputs. In addition, the Water Quality Index WQI showed that the lake’s water quality is poor, and its use can be dangerous for human and animal health. Health risk assessment associated with prolonged exposure to trace elements in lake water revealed that the Hazard quotient HQ and Hazard index HI of certain elements, such as Tl, Sb, V, As, Cr, Pb, Li, and Se, are higher than 1 in adult and children, indicating a significant risk for people living near the lake. Children are particularly vulnerable, with higher levels of HQ and HI, and selenium poses a substantial risk to their health through ingestion and skin absorption. In both adults and children, the total risk of cancer due to metals is classified as follows: CI (Cr) > CI (Ni) > CI (As) > CI (Pb) > CI (Cd). The Cr presents the highest carcinogenic risk—by ingestion or dermal route—in both groups. The total risk for these five metals exceeds 1 × 10−4, indicating a danger for residents who drink or swim in the lake.

Ore sulfur of Golovnin Volcano, Kunashir Island

Research subject. Hydrothermal deposits of Golovnin Caldera. Aim. To study the epithermal volcanogenic ore formation. Key points. Until now, there has been a consensus on the exogenous sedimentary (colloidal) genesis of sulfur in volcanic lakes. Our observations and microstructure studies indicate the presence of sulfur melt at the bottom of Kipyaschee Lake. Drops of this melt are carried to the surface of the lake as part of a light gray foam. The significant differences of sulfur spherules in the concentration of sulfide mineralization, in its composition, as well as in the presence or absence of numerous opal inclusions are most simply explained by the capture of droplets in various parts of the sulfur melt and their subsequent movement by a gas stream passing through the melt. Elemental sulfur condensate is formed in bottom sediments as a result of forced cooling of endogenous gas flows by lake water. The main condensation of sulfur occurs here (96% or more of the total potential of fluid sulfur). Residual condensation of sulfur occurs in the aquatic environment. Finely dispersed sulfur condensate in a mixture with water is unstable and breaks down over time with the release of hydrogen sulfide and the formation of sulfurous and sulfuric acids. The activity of bottom hydrotherms and coastal unrest prevents the formation of colloidal sulfur sediment at the bottom of lakes. In the crater depressions at the bottom of the lakes of the Golovnin Caldera, sulfidization of its melt occurs simultaneously with the condensation of sulfur itself. Gravitational deposition of sulfides in the sulfur melt leads to their enrichment of the root parts of crater depressions, where pyrite ore bodies are formed in real time. Terrestrial sulfur deposits, together with the modified rocks overlying them, demonstrate the full profile of endogenous apical oxidation under gas-hydrothermal action: sulfur and sulfur-opal rocks up the section are replaced by gypsum-jarosite rocks and, further, by an “iron hat” of limonite-cemented breccias of the dome mantle. Conclusions. Observations, microstructure studies and molecular chemical modeling indicate the endogenous condensate origin of ore sulfur in the Golovnin Caldera and exclude its exogenous sedimentary genesis.

Environmental DNA reveals a presence of Anser fabalis (Bean Goose) and an absence of A. erythropus (Lesser White-fronted Goose) in Finnish Northern Lapland

Abstract Detecting rare and elusive species from vast wilderness areas poses significant challenges. The Fennoscandian population of Anser erythropus (Lesser White-fronted Goose) is among the most endangered bird populations in Europe, with only 25–30 breeding pairs remaining in Northern Norway. Historically, its former breeding range extended across the mountainous regions of Fennoscandia. Thanks to targeted conservation efforts during the 21st century, A. erythropus has started to recolonize some of its former breeding areas in Norway and possibly also in Finland. Anser serrirostris rossicus (Tundra Bean Goose) is classified as Endangered (EN) in Finland, with just a few breeding pairs in northernmost Finnish Lapland with a poorly known breeding range. It breeds in higher numbers in Finnmark Norway and is listed as Vulnerable (VU) in Norway. Anser fabalis fabalis (Taiga Bean Goose), classified as Endangered in Norway, can also breed in the same area in low numbers. To locate individuals of these elusive goose species during breeding seasons, we used environmental DNA (eDNA) extracted from filtered lake water from selected lakes in northern Finland. We amplified and sequenced a short region of the mitochondrial control region to identify the species. Additionally, for positive controls, we sampled eDNA from the water of a Finnish spring staging site and known Norwegian breeding sites of the A. erythropus, from which eDNA of the A. erythropus was identified. eDNA of the A. erythropus was not detected within the former Finnish breeding range. Based on this, the A. erythropus has either not recolonized its former breeding habitats in Finland, the correct lakes were not sampled, the eDNA concentration was below detection limits, or due to other methodological issues. Anser serrirostris rossicus was detected in 3 lakes and A. fabalis fabalis in 10 lakes, providing new information about the breeding distribution of Bean Geese in Finnish Lapland.

Iron-loaded activated carbon cloth as CDI electrode material for selective recovery of phosphate.

This study investigated the efficacy of oxidised iron-loaded activated carbon cloth (Fe-ACC) for selective recovery of phosphorous. The capacitive deionisation (CDI) technology was employed, for rapid removal of phosphate, with the aim of reducing the reliance on high alkalinity environment for the regeneration of Fe-ACC electrode. Multiple experimental parameters, including applied potential, pH, and co-existing ions, were studied. Additionally, the CDI system was tested on a real water matrix (Lake Ormstrup, Denmark) to elucidate the electrodes' performance on selective recovery of phosphate. About 69 ± 10% of the adsorbed phosphate were released at pH 12 via pure chemical desorption, which was ~ 50% higher than that at pH 9. The CDI system successfully demonstrated the selective removal of phosphate from the lake water. It reduced the concentration of phosphate from 1.69 to 0.49mg/L with a 71% removal efficiency, while the removal percentages of other anions, namely chloride, sulphate, bromide, nitrite, nitrate, and fluoride, were 10%, 7%, 1%, 1.5%, 4%, and 7%, respectively.

Heating and ultraviolet irradiation: Gas pressure meter-based analytical system for on-site and rapid monitoring of permanganate index (CODMn)

Permanganate index (CODMn) is one of the important indicators of surface water quality measurement. Herein, a portable analytical system was developed for on-site and rapid analysis of CODMn, organic substances in water were oxidized and transformed into gases, so that CODMn concentration was converted into a change of gas pressure signal, the pressure signal change was further detected by a gas pressure meter. Heating method and ultraviolet (UV) irradiation method were used as assisting technologies for oxidization of organic substances by acidic KMnO4, a linear range of 2–150 mg l-1 and a detectable limit of 2 mg l-1 were obtained. Those methods were further applied to the detection of CODMn in various water samples (lake waters and domestic sewage) and certified reference water samples (BWZ 6974–2016C and BWZ 7617–2016), with recoveries of 89–111 %. Among them, a portable analytical system based on UV irradiation gas pressure meter was further established and used for the analysis of CODMn in field. It is a promising analytical system/device for CODMn monitoring in field, offering advantages of low-cost, easy-operation, portability and rapidness.

The outburst of dammed lake Maashey (North-Chuya ridge, Central Altai)

The dammed lakes are widespread in mountainous areas and usually occur when river flow is blocked by landslides, rock glaciers, etc. Among such lakes, the most dangerous are those located in the periglacial zone and blocked by rock glaciers. Continued deglaciation of mountainous areas under changing climate conditions contributes to accumulation of large volumes of melt water in lakes, which may increase pressure on the dam, cause its failure and subsequent outburst flood. In this article we describe the development of such a lake before its outburst and the process of its outburst. The object of study was Maashei Lake (North Chuya Ridge, Central Altai) located in the zone of mountain glaciation and dammed by a rock glacier, where the lake outburst occurred in July 2012. The lake area before the outburst was 259 × 103 m2 and water volume 1.21 × 106 m3. As a result of the outburst, the lake was completely drained. We analyzed the published works on Lake Maashei, materials of our own field studies in the lake basin combined with remote sensing data. We hypothesized that the mechanism of the outburst occurred in 2012 was caused by the water erosion of the filtration channel in the dam body. The mechanism of this outburst was numerically simulated using the method presented in this article. The modeling allowed to reproduce the outburst flood hydrograph, to estimate such characteristics as maximum water discharge, volume of the outburst flood, water flow velocities and the size of the formed breach. Estimated maximum discharge was 694 m3s−1, flow velocities varied from 0.2 to 5-7 m s−1, and the outburst flood period was about 5.5 hours. The breach was formed to the full height of the dam (10 m). Its calculated morphometric characteristics were as follows: average width 47.5 m (measured 41.5 m), скоss-section area 476 m2 (measured 415 m2). The discrepancy between the modeled and measured values was about 15%.

Feasibility Study on Geothermal Dolomite Reservoir Reinjection with Surface Water in Tianjin, China

Reinjection is thought to be the most effective way to maintain reservoir pressure and production capacity for hydrothermal resources. The use of external water injection to replenish deep geothermal reservoirs is a new approach in China to addressing the problems of declining groundwater levels and energy depletion caused by the excessive and uneven exploitation of geothermal resources. However, the key challenge and focus of the feasibility assessment of this method lies in the chemical compatibility of the external water with the native geothermal reservoir water and surrounding rocks. In this paper, we discuss the geochemical response of a dolomite reservoir to lake water injection based on experiments on water–rock interaction in the Wumishan formation in the Dongli Lake area of Tianjin. The results show that after reactions with dolomite, the TDS of the reacted water decreases, indicating the occurrence of precipitation. According to the calculation results obtained using the PHQREEC program, the precipitation amount is found to be quite limited. Geochemical analysis indicates that at the initial stage of the reactions, plagioclase dissolves and releases alkaline metals like Ca-, Na-, SiO2- and Al-bearing compositions, leading to the oversaturation and precipitation of dolomite and calcite. As the reaction progresses, a portion of the dolomite dissolves, while the calcite continues to precipitate at a later stage. Illite precipitates and its effects on reservoir structure depend on its shape. Based on the experimental data, it can be concluded that the dolomite reservoir will be slightly affected by the reinjection of lake water; however, it is still a good method for the sustainable development of geothermal resources.

Nutrient availability in a freshwater-to-marine continuum: cyanobacterial blooms along the Lake Okeechobee Waterway

Water from the Lake Okeechobee watershed historically flowed south through the Everglades. Hydrologic alterations created the Lake Okeechobee Waterway, where lake water is periodically shunted east to the St. Lucie Estuary (C-44 canal) and west to the Caloosahatchee River and Estuary (C-43 canal). Within the last two decades, Microcystis blooms have developed in Lake Okeechobee and been discharged to the downstream urbanized estuaries, resulting in negative environmental and human health impacts. To better understand drivers of cyanobacterial blooms across this modified waterway, two cruises were conducted from the St. Lucie Estuary through Lake Okeechobee to the Caloosahatchee River Estuary during 2019 and 2020. Stations were sampled for environmental parameters, dissolved nutrients, chlorophyll a, cyanobacterial cell concentrations, and microcystins, as well as particulate organic matter (POM) nutrient properties. Higher ammonium (NH4+), nitrate + nitrite (NO3-), dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), and POM stable N isotope (δ15N) values were observed in the estuaries and Kissimmee River than in Lake Okeechobee. The nitrogen to phosphorus ratio (N:P), microcystins, and Microcystis cell concentrations were higher in Lake Okeechobee than documented over past decades. During Microcystis blooms, high NH4+, SRP, total dissolved nitrogen (TDN), TDP, and sucralose were observed with elevated algal δ15N. These results demonstrate the importance of local basin contributions, including those within the lake, to estuarine Microcystis blooms. This suggests that decreasing nutrient loading within the St. Lucie and Caloosahatchee estuaries would help mitigate these urban blooms. High POM δ15N values, NO3- concentrations, and N:P ratios in the Kissimmee River suggest that expanding urbanization north of the lake, represents an increasing human N source contributing to cyanobacterial blooms in Lake Okeechobee.

Magnetic biochar prepared from a spent mushroom substrate as an adsorbent for the analysis of pyrethroids in environmental water samples

In this study, a spent mushroom substrate (SMS) from Lentinus edodes cultivation was used to prepare biochar (BC) and magnetic biochar (MBC) at high temperatures. The magnetic field strength of MBC was proved via VSM analysis. The results of the nitrogen adsorption‒desorption isotherms of BC and MBC showed that MBC exhibited stronger adsorption, and SEM was performed to compare the microstructures of BC and MBC. TEM was performed to compare the distributions of C, O, and Fe. The FT-IR and XRD results revealed changes in the structure and the formation of new substances after magnetization; that is, MBC was more conducive to the adsorption and recovery of pesticides. Moreover, a method for the detection of tetramethrin, beta-cypermethrin, and fenvalerate in water samples (tap water, lake water, and river water) was established, and this method combined the use of MBC as adsorbent and high-performance liquid chromatography. Moreover, great linearity of the method was obtained in the range of 0.5–2.5 μg/mL; the recoveries in real samples were in the range of 70.20–73.32%, and the RSDs were in the range of 0.22–1.09%. The method is simple and effective, is suitable for the detection of pyrethroids in water, and has certain application potential.

Structure-based design and screening of hydrogel copolymer/Fe3O4 composite microspheres for magnetic solid phase extraction of bisphenol A from aqueous samples

It is of great significance to monitor bisphenol A (BPA) in the environment because of its potential environmental and health risks. However, the detection of trace or ultratrace BPA in complicated environmental samples is challenging due to the relatively low affinity and poor selectivity of existing adsorbents used in sample pretreatment. Herein, we report a high-affinity, low environment-dependent and strong interference-resistant abiotic affinity ligand, a N-methacryloyl-l-lysine-NH2 (MLys)-based hydrogel copolymer (HP 17) screened from a small focused polymer library engineered by incorporating various combinations and ratios of candidate functional monomers. The selection of these monomers was guided by molecular mechanism between BPA and the ligand-binding pocket of its estrogen receptors. The BPA–HP17 binding is mainly a synergistic effect of π-cation and hydrophobic interactions. The screened HP 17 has high adsorption capacity (349.4 mg/g) for BPA under wide pH (3.0–10.0) and ionic strength (0–150 mM) range. To improve its practicability, a hydrogel copolymer/Fe3O4 composite microspheres (Fe3O4@HP 17) was synthesized and applied for magnetic solid phase extraction–high-performance liquid chromatography (MSPE–HPLC) analysis of BPA in tap water, lake water and industrial effluents. The method shows wide linear range (2.5⁓100 ng/mL), high sensitivity (detection limit of 0.22 ng/mL even without further concentration after desorption), high accuracies (92.6⁓103.0 %) and good precisions (0.57⁓4.53 %), indicating a great potential of this material and method in the detection of trace or ultratrace BPA in complex environmental water samples.

A Comparative Study on the Performance of Ice-Source Heat Pumps Versus Other Heat Source Heat Pumps: A Case Study in the UK

Eliminating natural gas as a fuel for heating residential and industrial units is crucial for reducing environmental pollutants. The challenge lies in finding alternative heating systems and repurposing existing infrastructures, like gas pipes. This article presents a new approach to supplying energy to heat pumps in a post-natural gas era using repurposed gas pipes to transport water for ice-source heat pumps. It highlights the advantages of ice-source heat pumps and compares their thermal performance with other types. The proposed system integrates ice-source and geothermal heat pumps, offering space efficiency, compact design, cost-effective centralization, optimized subsidies, seasonal cooling, weather resilience, and eliminates the need for new piping.This study evaluates heat pump efficiency using various low-grade heat sources: ambient air, ground, domestic wastewater, river and lake water, piped water, and latent heat. It focuses on optimizing heat pump performance under the UK's climatic conditions, addressing efficiency challenges during peak cold periods. The research demonstrates the system's robust performance in cold, densely populated areas, potentially reducing water mass for energy supply by up to 95% with a 70% ice slurry concentration. Additionally, the ice-source heat pump requires about 36.7 times less water volume than traditional systems for residential heating.

In-situ electrogenerated persulfate activated by co-existing Cu(II) for sustainable removal of sulfonamides from environmental waters

In this study, in-situ electrogenerated persulfate (E-PS) was proposed as an alternative to the conventional addition of persulfate for advanced oxidation processes (AOPs) with facilitating conversion of co-existing Cu(II) to Cu(I) to degrade antibiotics without requiring any external supply of chemical additives. The degradation rate of sulfamethoxazole (SMX) by E/Cu(Ⅱ)/Na2SO4 system (C0(Cu(Ⅱ))=1mM, C0(Na2SO4)=1mM, E=25V) was 93.3% at t=90min. Quenching combined with electron paramagnetic resonance (EPR) tests revealed that SO4•-, •OH and Cu(Ⅲ) were the primary contributors to SMX degradation. Solution pH, co-existing anions and organic matter affected the degradation performance of SMX. Four degradation pathways were proposed based on transformed products (TPs) determination, with pathways I and II being the dominant ones involving the cleavage of S-N bond in SMX. Ecological structure activity relationships (ECOSAR) program analysis implied that the TPs exhibited lower toxicity levels toward aquatic organisms compared to that of SMX. Additionally, the E/Cu(II)/Na2SO4 system achieved decomposition rates over 80% for various sulfonamides (SAs) and also demonstrated remarkable efficacy for SMX removal in different real waters, including tap water, lake water, river water and aquaculture wastewater, with all exceeding 80% at t=90min. E/Cu(Ⅱ)/Na2SO4 system developed in this study had the potential to be a prospective technique for SAs purification due to its outstanding performance in degrading and detoxifying SAs.

Highly effective fluorescence detection of UO22+ ions by an anionic Na/Eu heterometallic metal–organic framework with Lewis basic chelating sites

Uranium is a serious radioactive contaminant that can easily migrate into groundwater and surface water, posing a deadly threat to human health. Despite the development of various materials for detecting uranyl ions in water, rational design and synthesis of new uranium sensors with sensitivity, selectivity, and fast response remain challenging. Herein, we demonstrate a novel strategy for obtaining highly sensitive and selective UO22+ sensors by constructing heterometallic metal–organic framework with both an anionic skeleton and abundant chelating sites. Namely, the first anionic Na/Eu heterometallic metal–organic framework (Na/Eu-MOF) based UO22+ sensor is successfully synthesized by using sodium salt and europium salt as reactants, and abundant ether groups were introduced into its porous structure as chelating Lewis basic sites. Beneficial from the synergistic effect between the anionic skeleton and the chelating sites, Na/Eu-MOF achieved rapid, selective adsorption and fluorescence quenching toward uranyl ion. The detection limits of Na/Eu-MOF in deionized and lake water were determined to be 49.7 nM and 113.0 nM, respectively, which are lower than the maximum concentration of 130.0 nM in drinking water proposed by the United States Environmental Protection Agency, indicating potential environmental applications. The detection capability of Na/Eu-MOF is attributed to the combination system of energy competition and interactions between UO22+ ions and Na/Eu-MOF. This work offers a feasible strategy to construct an anionic heterometallic metal–organic framework with chelating sites for uranyl detection in an aqueous solution.

The MoS2/rGO embed in macro-porous PAN gel as a novel DGT binding phase for the rapid and accurate detection of trace Hg(II)

The development of binding gels with a fast uptake rate, high capacity, and good selectivity could be beneficial for trace Hg(II) detection based on the DGT technology. In this study, a novel PAN@MoS2/rGO-DGT was assembled by using the nanocomposite embedded in polyacrylonitrile membrane (PAN@MoS2/rGO) as the binding phase. The interior regular finger-like macropore of the gel provided a convenient channel for the rapid mass diffusion of Hg(II), and the abundant sulfur offered the paramount driving force for trapping Hg(II). These endowed the PAN@MoS2/rGO with an impressive reaction rate, capacity, and selectivity toward Hg(II) and featured the PAN@MoS2/rGO-DGT with excellent diffusion rate (D) and adaptability in the complex matrixes across a wide range of pH, ion strength, common cations. However, the uptake of Hg(II) was influenced by the high content of chloride, thus a calibrated model was established based on the chloride concentration to correct the accumulated mass and D. After that, the high accuracy of this method was confirmed through the good consistency between Hg(II) concentration assessed by DGT and in bulk solution when the DGT was deployed to the river water, seawater, and domestic wastewater at the static and dynamic Hg(II) concentration. Field trials in the prawn farming seawater and lake water also showed a negligible deviation of Hg(II) content from the DGT and the conventional method, acquiring the actual Hg(II) level as 1.07-3.69 ng/L. The findings highlighted the application potential of macropore PAN gel hybrid with nanocomposite as a promising binding phase for trace Hg(II) or other pollutant detection.