Groundwater studies often involve using any one of geophysical, geological, geochemical, or chemical data in the assessment of its characteristics. An integrated method in using all the above had been carried out for more comprehensive and confirmative assessments along the Thandava River basin, India. The geophysical data included the recording of the vertical electrical soundings by Schlumberger array configuration in 50 stations along the basin. Thirty soil samples and rainfall data of 5 years included the geological data. Chemical characterizations for 117 groundwater water samples were carried for two seasons. This study proposes the advantages besides delineating the approach in carrying integrated rather than mere single parameter-based speculative study. This correlative and computer modeling aided study led to an in-depth along with confirmative assessments on various geological, geophysical, and chemical characteristics of the groundwater along with the pollution status. Comprehensive details of groundwater like geomorphology, potential water zones, flow pattern, soil types, geochemical evolution of ions, chemical status, and suitability can be accessed by applying this type of integrated study. Graphical Abstract ᅟ

Controlling water and air pollution by photocatalysts is an advanced technique and has aroused great interest. TiO₂/hydroxyapatite (HAP) composites were successfully prepared via a one-step hydrothermal route that add a certain weight of tetrabutyl titanate to a mixed solution of Ca(NO₃)₂ and (NH₄)₂HPO₄, and then put into a Teflon-lined autoclave for hydrothermal reaction. The surface morphology, chemical composition, crystalline structure, and optical property of the TiO₂/HAP composites were characterized. The field emission-scanning electron microscopy (FE-SEM) observed the cube-like structure of crystal with the size of 10–20 μm. Energy dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD) demonstrated that Ti ₓ Ca₅₋ₓ (PO₄)₃(OH) was a unit of the crystal. UV–visible diffuse reflectance spectra show that the optical absorbance edge appeared at long wavelength (∼400 nm). Both higher temperature and longer time could contribute to the complete crystallization. Photocatalytic activity was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation and found that the TiO₂/HAP composites exhibited excellent photocatalytic activity. Therefore, these TiO₂/HAP composites were expected to become one of advanced materials removing dyes from water.

Stormwater filtration system has proven to be effective for the removal of dissolved and particulate pollutants from roadways and car parking areas. However, the long-term treatment performance of filtration systems strongly depends on the hydraulic conductivity and sorption capacity of the filter media. This paper sought to provide information regarding the hydraulic performance, characteristics and metal concentration profiles in sediments accumulated at the surface of filtration systems (SDPL) and core filter media (FMC). The lifespan of the filter media was used to estimate the lifespan of the filter media. The results showed that saturated hydraulic conductivity of the filtration systems have significantly reduced over the operational time, yet acceptable (Kf = 5.9 × 10⁻⁵ to 1.4 × 10⁻⁴ m/s). The accumulated sediments (SDPL) were predominantly composed of fine particles with 70 % < 63 μm but the heavy metals were rather uniformly distributed in the different size fractions. The concentrations of heavy metals, particularly Cu, Pb and Zn were significantly higher in the SDPL and decreased with depth of the filter bed. However, Cr and Ni increased with depth of filter media demonstrating their removal was mainly by adsorption. Concentrations of Ba, Mn, Ti and V were comparable to Zn levels indicating comparable concentrations in roadway runoff. Simultaneous adsorption of multiple heavy metals in a column experiment demonstrated that the filter media could remain operational for over 34 years. However, there is a significant concern about their lifespan, particularly due to significant reduction in the hydraulic performance and the possibility of clogging of the systems over time. Therefore, to minimize hydraulic failure, the accumulated sediment be scraped off every 7 years.

The Tula River watershed is a water flow system that runs from the State of Mexico to the south-central part of Hidalgo State in Mexico that includes the Mezquital Valley which was originally a semiarid zone and now is an important agricultural region. We studied the River Tula watershed regarding biological, chemical, and physical parameters, describing the zooplankton species list, and the levels of five metals: arsenic, cadmium, copper, lead, and zinc, in sediments, elutriates, water column, and bioaccumulation in tilapia (Oreochromis nilotica), and some zooplanktonic species using atomic absorption. Arsenic, cadmium, and lead are present in the water column in small concentrations of different reservoirs of the Tula River watershed. Concentration of these three metals in elutriates and sediments are higher than levels in water column. The effects of the presence of these three metals in the water column, elutriates, and sediments include the following: (a) Levels of lead in muscles of tilapia make this species unsafe for human consumption, and (b) arsenic, cadmium, and lead are bioaccumulated in several zooplanktonic species. We discuss these results in the context of (a) bioaccumulation through trophic levels and (b) international and Mexican national standards regarding safe levels of contaminants in fish tissues for human consumption.

The impact of nanoparticles on fish health is still a matter of debate, since nanotechnology is quite recent. In this study, freshwater benthonic juvenile fish Prochilodus lineatus were exposed through water to three concentrations of TiO₂ (0.1, 1, and 10 μg l⁻¹) and ZnO (7, 70, and 700 μg l⁻¹) nanoparticles, as well as to a mixture of both (TiO₂ 1 μg l⁻¹ + ZnO 70 μg l⁻¹) for 5 and 30 days. Nanoparticle characterization revealed an increase of aggregate size in the function of concentration, but suspensions were generally stable. Fish mortality was high at subchronic exposure to 70 and 700 μg l⁻¹ of ZnO. Nanoparticle exposure led to decreased acetylcholinesterase activity either in the muscle or in the brain, depending on particle composition (muscle—TiO₂ 10 μg l⁻¹; brain—ZnO 7 and 700 μg l⁻¹), and protein oxidative damage increased in the brain (ZnO 70 μg l⁻¹) and gills (ZnO 70 μg l⁻¹ and mixture) but not in the liver. Exposed fish had more frequent alterations in the liver (necrosis, vascular congestion, leukocyte infiltration, and basophilic foci) and gills (hyperplasia and epithelial damages, e.g., epithelial disorganization and epithelial loss) than the control fish. Thus, predicted concentrations of TiO₂ and ZnO nanoparticles caused detectable effects on P. lineatus that may have important consequences to fish health. But, these effects are much more subtle than those usually reported in the scientific literature for high concentrations or doses of metal nanoparticles.

From April 2008 to November 2009, a field decomposition experiment was conducted to investigate the effects of sediment burial on macro (C, N) and microelement (Pb, Cr, Cu, Zn, Ni, and Mn) variations in decomposing litter of Phragmites australis in the coastal marsh of the Yellow River estuary. Three one-off sediment burial treatments [no sediment burial (0 mm year⁻¹, S₀), current sediment burial (100 mm year⁻¹, S₁₀), and strong sediment burial (200 mm year⁻¹, S₂₀)] were laid in different decomposition sites. Results showed that sediment burials showed significant influence on the decomposition rate of P. australis, in the order of S₁₀ (0.001990 day⁻¹) ≈ S₂₀ (0.001710 day⁻¹) > S₀ (0.000768 day⁻¹) (p < 0.05). The macro and microelement in decomposing litters of the three burial depths exhibited different temporal variations except for Cu, Zn, and Ni. No significant differences in C, N, Pb, Cr, Zn, and Mn concentrations were observed among the three burial treatments except for Cu and Ni (p > 0.05). With increasing burial depth, N, Cr, Cu, Ni, and Mn concentrations generally increased, while C, Pb, and Zn concentrations varied insignificantly. Sediment burial was favorable for C and N release from P. australis, and, with increasing burial depth, the C release from litter significantly increased, and the N in litter shifted from accumulation to release. With a few exceptions, Pb, Cr, Zn, and Mn stocks in P. australis in the three treatments evidenced the export of metals from litter to environment, and, with increasing burial depth, the export amounts increased greatly. Stocks of Cu and Ni in P. australis in the S₁₀ and S₂₀ treatments were generally positive, evidencing incorporation of the two metals in most sampling times. Except for Ni, the variations of C, N, Pb, Cr, Cu, Zn, and Mn stocks in P. australis in the S₁₀ and S₂₀ treatments were approximated, indicating that the strong burial episodes (S₂₀) occurred in P. australis marsh in the future would have little influence on the stocks of these elements. With increasing burial depths, the P. australis was particularly efficient in binding Cu and Ni and releasing C, N, Pb, Cr, Zn, and Mn, implying that the potential eco-toxic risk of Pb, Cr, Zn, and Mn exposure might be very serious. This study emphasized the effects of different burials on nutrient and metal cycling and mass balance in the P. australis marsh of the Yellow River estuary.

Nitrogen removal by anaerobic ammonia oxidation (anammox) of granular sludge is a globally important emerging technology. The ammonium adsorption properties of anammox granular sludge were studied at varying initial ammonium concentration and sludge concentration. Factors affecting the absorption process as temperature, pH, salinity, and metal cations were also examined. The experimental results indicated that ammonium adsorption by anammox granular sludge occurred quickly (in about 20 min). The optimal pH was 7.0 and the ammonium adsorption process was significantly affected by temperature, salinity, and metal cations. The experimental data were modeled using Langmuir, Freundlich, and Temkin adsorption isotherms and the ammonium adsorption process was fit to the Freundlich isotherm. The kinetic results indicated that the experimental data fit well to a pseudo-second-order model. Both intraparticle diffusion and boundary layer diffusion could affect the ammonium adsorption rate. The thermodynamic parameters ΔG₀, ΔH₀, and ΔS₀ were evaluated and suggested that ammonium adsorption was spontaneous and exothermic. These findings indicate that the adsorption of ammonium should be incorporated into models for nitrogen removal, particularly for the use of anammox granular sludge.

Little research has been conducted on the occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment despite being increasingly impacted by these contaminants. This article reviews data on the occurrence of PPCPs in seawater, sediment, and organisms in the marine environment. Data pertaining to 196 pharmaceuticals and 37 personal care products reported from more than 50 marine sites are analyzed while taking sampling strategies and analytical methods into account. Particular attention is focused on the most frequently detected substances at highest concentrations. A snapshot of the most impacted marine sites is provided by comparing the highest concentrations reported for quantified substances. The present review reveals that: (i) PPCPs are widespread in seawater, particularly at sites impacted by anthropogenic activities, and (ii) the most frequently investigated and detected molecules in seawater and sediments are antibiotics, such as erythromycin. Moreover, this review points out other PPCPs of concern, such as ultraviolet filters, and underlines the scarcity of data on those substances despite recent evidence on their occurrence in marine organisms. The exposure of marine organisms in regard to these insufficient data is discussed.

The catalytic removal of Hg⁰ was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V₂O₅/TiO₂ and WO₃/TiO₂ catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg⁰. They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100–160 °C under the near-UV irradiation. The results indicated that V₂O₅/TiO₂ solely possessed the thermo-catalytic reactivity while WO₃/TiO₂ only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO₂, the removal efficiencies of Hg⁰ at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO₂ to nearly 90 % by WO₃/TiO₂ under the same operating conditions. The effects of doping amount of V₂O₅ and WO₃ were also investigated, and the results showed that 10 % V₂O₅ and 5 % WO₃/TiO₂ were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg⁰ was demonstrated that the highest concentration of Hg⁰ led to the best removal efficiencies for V₂O₅/TiO₂ and WO₃/TiO₂ at 140 and 160 °C, because high Hg⁰ concentration increased the mass transfer rate of Hg⁰ toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg⁰ was also investigated.

Geothermal energy is known to be a clean and renewable energy resource. However, geothermal fluid has significant impacts on surface water quality when disposed in an uncontrolled manner due to the high concentrations of numerous dissolved constituents and the elevated thermal content. The geothermal fluid in western Anatolia typically contains high concentrations of arsenic, boron, and lithium that are toxic to human and plant life. A river system in western Anatolia, Turkey, receives uncontrolled waste geothermal fluid discharge from three fields and is thermally and chemically contaminated. A one-dimensional water quality model is developed to assess the extent and strength of geothermal pollution in the river system. The calibrated and verified model results revealed that although both the point and nonpoint sources of contamination are influential in the water quality degradation, point discharges of waste geothermal fluid were responsible for dramatic increases in the contaminant concentrations and water temperature in the river. The model was later used to analyze the potential measures to improve the degraded water quality and compare the effectiveness of structural and non-structural mitigation scenarios.