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Proximal VIS-NIR spectrometry to retrieve substance concentrations in surface waters using partial least squares modelling
摘要： Many water quality parameters such as concentrations of suspended matter, nutrients and algae directly or indirectly change the electromagnetic reflectance and transmission properties of surface water bodies. Optical measurement approaches have shown great potential to partially substitute water sampling and laboratory analyses, but are obstructed by limited flexibility or high maintenance demands. In order to overcome these problems and to bridge the gap between in situ and remote sensing measurements, the use of close-range, above-surface reflectance measurements in the VIS-NIR domain to measure water quality parameters in surface water bodies was investigated. Remote sensing reflectance in a 1 m3 water tank with increasing, known concentrations of suspended solids was measured. A partial least squares model was trained to predict concentrations from reflectance curves, which performed well, considering the wide range of concentrations and illumination conditions (R2cal ? 0.96, R2val ? 0.97). The approach was then transferred to the field and further parameters were tested. Using a semi-autonomous spectrometer mounted to a boom stand on a motor boat, we traced substance concentrations in close intervals along a longitudinal gradient from inflow to dam in a drinking water reservoir in Brazil. The method is suitable for parameters directly influencing the reflection properties of the water body (e.g. suspended solids (R2cal ? 0.93), chlorophyll-a (R2cal ? 0.74)), or for parameters closely related to those (e.g. total phosphorus (R2cal ? 0.97)). For chemical oxygen demand, the method is not well suited (R2cal ? 0.14, R2val ? 0.45). Once calibrated to the local conditions, the spectrometer can be used stationary or on moving platforms to map and monitor surface waters. The integration of the procedure into acoustic and imaging techniques is further investigated.
关键词： water quality,suspended solids,hyperspectral,reservoir,partial least squares,proximal sensing
更新于2025-09-23 15:22:29
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Synthesis of a novel visible light responsive <i>γ</i> -Fe2O3/SiO2/C-TiO2 magnetic nanocomposite for water treatment
摘要： This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by FTIR, XRD, TEM and EDS substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15–22 nm with a quasi-spherical shape. BET surface area analysis revealed an average surface area of 55.20 m2/g which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g) and an average pore diameter of 8.36 nm. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation, which was 19.7% greater than using the same photo-catalyst under strict UV light irradiation. Photo-catalysis using these nanoparticles was observed to be very effective. The prepared novel visible light active nanocomposite has great potential for incorporation into water treatment systems because it exhibits good stability and magnetism as well as high photocatalytic efficiency.
关键词： methylene blue,titanium dioxide,water treatment,maghemite,photo-catalysis,magnetic nanocomposite
更新于2025-09-23 15:22:29
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A Study on Hydrodynamic Behavior of Fine Sediment in Retention Structure Using Particle Image Velocimetry
摘要： Detention ponds are one type of stormwater best management practices (BMPs) that can be used for the quantity control of stormwater. The pond works by reducing peak discharge downstream through temporary storage and gradual release. In this paper, a new experimental procedure using particle image velocimetry (PIV) is introduced for a two-dimensional study of the hydrodynamic behavior of fine particles in a specially designed sediment basin. The hydrodynamic behavior of fine particles under different hydraulics parameters was achieved by shifting outlet placement, using different particle-size diameters, varying the distance of the inlet from the water surface, and varying the flow rate. The same inlet and outlet level reduced fine-particle dispersion and a lower flow rate assisted with controlling high siltation. Furthermore, smaller spherical particles had more influence on fine particle suspension. Therefore, controlling the hydraulic parameters can decrease the siltation problem level. Water Environ. Res., 88, 2309 (2016).
关键词： stormwater best management practices (BMPs),fine particle,siltation,particle image velocimetry (PIV),water surface
更新于2025-09-23 15:22:29
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Ni doped noble-metal-free CdZnNiS photocatalyst for high-efficient photocatalytic hydrogen evolution reduction by visible light driving
摘要： In this paper, we report a method that the transition element nickel is doped into the interstitial position of CdZnS (CZS) nanoparticles for their photocatalytic hydrogen evolution activity boosting. It is demonstrated that CdZnNiS nanocrystalline materials (with 0.5 wt% of Ni) could achieve the highest photocatalytic H2-evolution activity of 25.4 mmol·g?1·h?1 in sulfide and sulfite solution under visible light which value is 1.16 times higher than that of Pt modified CdZnS particles (with 3 wt% of Pt). This work evidences the possibility of substitution of noble metal cocatalyst by adding a suitable inexpensive Ni to achieve high-efficient visible light driven water splitting hydrogen production.
关键词： Semiconductors,CdZnNiS nanocrystalline materials,Noble-metal-free cocatalyst,Gap doping,Nanocomposites,Water splitting
更新于2025-09-23 15:22:29
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Network Structured CuWO4/BiVO4/Co-Pi Nanocomposite for Solar Water Splitting
摘要： A network structured CuWO4/BiVO4 nanocomposite with a high specific surface area was prepared from CuWO4 nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO4/BiVO4 exhibited high catalytic activity toward photoelectrochemical (PEC) water oxidation. When cobalt phosphate (Co-Pi) was coupled with CuWO4/BiVO4, the activity of the resulting CuWO4/BiVO4/Co-Pi composite for the oxygen evolution reaction (OER) was further improved. The photocurrent density (Jph) for OER on CuWO4/BiVO4/Co-Pi is among the highest reported on a CuWO4-based photoanode in a neutral solution. The high activity for the PEC OER was attributed to the high specific surface area of the composite, the formation of a CuWO4/BiVO4 heterojunction that accelerated electron–hole separation, and the coupling of the Co-Pi co-catalyst with CuWO4/BiVO4, which improved the charge transfer rate across composite/solution interface.
关键词： copper tungstate,cobalt phosphate,oxygen evolution reaction,bismuth vanadate,photoelectrochemical water splitting
更新于2025-09-23 15:22:29
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Radiometric Cross-Calibration of Tiangong-2 MWI Visible/NIR Channels over Aquatic Environments using MODIS
摘要： The Moderate-Resolution Wide-Wavelength Imager (MWI), onboard the Tiangong-2 (TG-2) Space Lab, is an experimental satellite sensor designed for the next-generation Chinese ocean color satellites. The MWI imagery is not sufficiently radiometrically calibrated, and therefore, the cross-calibration is urgently needed to provide high quality ocean color products for MWI observations. We proposed a simple and effective cross-calibration scheme for MWI data using well calibrated Moderate Resolution Imaging Spectroradiometer (MODIS) imagery over aquatic environments. The path radiance of the MWI was estimated using the quasi-synchronized MODIS images as well as the MODIS Rayleigh and aerosol look up tables (LUTs) from SeaWiFS Data Analysis System 7.4 (SeaDAS 7.4). The results showed that the coefficients of determination (R2) of the calibration coefficients were larger than 0.97, with sufficient matched areas to perform cross-calibration for MWI. Compared with the simulated Top of Atmosphere (TOA) radiance using synchronized MODIS images, all errors calculated with the calibration coefficients retrieved in this paper were less than 5.2%, and lower than the lab calibrated coefficients. The Rayleigh-corrected reflectance (ρrc), remote sensing reflectance (Rrs) and total suspended matter (TSM) products of MWI, MODIS and the Geostationary Ocean Color Imager (GOCI) images for Taihu Lake in China were compared. The distribution of ρrc of MWI, MODIS and GOCI agreed well, except for band 667 nm of MODIS, which might have been saturated in relatively turbid waters. Besides, the Rrs used to retrieve TSM among MWI, MODIS and GOCI was also consistent. The root mean square errors (RMSE), mean biases (MB) and mean ratios (MR) between MWI Rrs and MODIS Rrs (or GOCI Rrs) were less than 0.20 sr?1, 5.52% and within 1 ± 0.023, respectively. In addition, the derived TSM from MWI and GOCI also agreed with a R2 of 0.90, MB of 13.75%, MR of 0.97 and RMSE of 9.43 mg/L. Cross-calibration coefficients retrieved in this paper will contribute to quantitative applications of MWI. This method can be extended easily to other similar ocean color satellite missions.
关键词： atmospheric correction,cross calibration,total suspended matter,open oceans,inland water
更新于2025-09-23 15:22:29
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WaterSpy: A High Sensitivity, Portable Photonic Device for Pervasive Water Quality Analysis
摘要： In this paper, we present WaterSpy, a project developing an innovative, compact, cost-effective photonic device for pervasive water quality sensing, operating in the mid-IR spectral range. The approach combines the use of advanced Quantum Cascade Lasers (QCLs) employing the Vernier effect, used as light source, with novel, fibre-coupled, fast and sensitive Higher Operation Temperature (HOT) photodetectors, used as sensors. These will be complemented by optimised laser driving and detector electronics, laser modulation and signal conditioning technologies. The paper presents the WaterSpy concept, the requirements elicited, the preliminary architecture design of the device, the use cases in which it will be validated, while highlighting the innovative technologies that contribute to the advancement of the current state of the art.
关键词： Quantum Cascade Lasers,photonics,water quality monitoring,photodetectors
更新于2025-09-23 15:22:29
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A Sensitive Near-Infrared Fluorescent Probe for Detecting Heavy Metal Ag+ in Water Samples
摘要： Silver is a common catalyst in industrial production, and the frequent use of Ag+ can cause water pollution. Thus, the detection of Ag+ in the environment is necessary to determine the level of pollution from silver. In this work, we designed a new, highly selective near-infrared (NIR) fluorescent probe QCy to detect Ag+. The probe exhibits 'turn-off' fluorescence quenching responses at 760 nm towards Ag+ over other relevant cations, with outstanding sensitivity and a low detection limit (0.03 μM), which is considerably lower than the standard of the World Health Organization (WHO) for drinking water (0.9 μM). Meanwhile, QCy showed a very good linearity at a low concentration of Ag+ with a 'naked eye' visible color change of solution from blue to red. The probe has been applied successfully for the detection of Ag+ in real water samples.
关键词： selectivity,fluorescence probe,Ag+,sensitivity,water samples
更新于2025-09-23 15:22:29
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Nanoporous water oxidation electrodes with a low loading of laser-deposited Ru/C exhibit enhanced corrosion stability
摘要： For the oxidation of water to dioxygen, oxide-covered ruthenium metal is known as the most efficient catalyst, however, with limited stability. Herein, we present a strategy for incorporating a Ru/C composite onto a novel nanoporous electrode surface with low noble metal loading and improved stability. The Ru/C is coated on the pore walls of anodic alumina templates in a one-step laser-induced deposition method from Ru3(CO)12 solutions. Scanning electron microscopy proves the presence of a continuous Ru/C layer along the inner pore walls. The amorphous material consists of metallic Ru incorporated in a carbonaceous C matrix as shown by X-ray diffraction combined with Raman and X-ray photoelectron spectroscopies. These porous electrodes reveal enhanced stability during water oxidation as compared to planar samples at pH 4. Finally, their electrocatalytic performance depends on the geometric parameters and is optimized with 13 μm pore length, which yields 2.6 mA cm?2, or 49 A g?1, at η = 0.20 V.
关键词： ruthenium catalyst,nanostructures,water splitting,electrochemistry,noble metals
更新于2025-09-23 15:22:29
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Assessing UV Inactivation of Adenovirus 41 Using Integrated Cell Culture Real-Time qPCR/RT-qPCR
摘要： Enteric adenoviruses are among most UV-resistant viruses in water. Cytopathic effects (CPE)-based cell culture TCID50 assay as a conventional virus assessment approach has major drawbacks for enteric adenovirus since it is selective on cell lines and takes longer time to show CPE. Integrated cell culture real-time quantitative PCR (ICC-qPCR) and reverse transcriptase (RT)-qPCR were applied in this study, in comparison with TCID50, to assess UV inactivation of adenovirus type 41 (Ad41) in water. Adenovirus type 41 was exposed to UV doses of 40, 80, 160, and 320 mJ/cm2 using a collimated beam apparatus. There was no significant difference of inactivation at conducted UV doses between measurements using TCID50 assay and ICC-RT-qPCR. Both assays fitted the Chick–Watson model at 95% confidence level. The inactivation measured by ICC-qPCR did not fit the Chick–Watson model. In summary, ICC-RT-qPCR is the most appropriate alternate to CPE-based assay for assessing UV inactivation of enteric adenoviruses. Water Environ. Res., 89, 323 (2017).
关键词： cytopathic effects,cell culture,real-time quantitative PCR/RT-PCR,adenovirus type 41,water,UV inactivation
更新于2025-09-23 15:22:29