Integrated aerobic granules were first cultivated in two sequencing batch reactors (SBRs) (A1 and A2). Then, A1’s influent organic loading rate (OLR) was changed from alternating to constant (cycling time was still 6 h), while A2’s cycling time varied from 6 to 4 h (influent OLR strategy remained alternating). After 30-day operation since the manipulative alternations, granule breakage happened in two reactors at different operational stages, along with the decrease of granule intensity. Granule diameter in A1 declined from the original 0.84 to 0.32 cm during the whole operation, while granules in A2 dwindled to 0.31 cm on day 22 with similar size to A1. Both the amount of total extracellular polymeric substances (EPSs) and the protein were declining throughout the operation, and the large molecular weight of protein was considered closely related to the stability of aerobic granules. The relative AI-2 level decreased at the same time, and influent OLR strategy might had more evident impact on quorum sensing (QS) ability of sludge compared with starvation period. Combined with microbial results, the decline of total EPS amount in two reactors could be concluded as follows: During the reactor operation, some functional bacteria gradually lost their dominance and were eliminated from the reactors, which finally caused granule disintegration. In summary, the results further confirmed that alternating OLR and proper starvation period were two major factors in effective cultivation and stability of aerobic granules from the perspective of QS.

Increased phosphorus (P) export from sediments to the overlying water column is a significant factor driving the variation of phytoplankton in productivity and community structure in lakes. However, the lack of long-term instrumental data often impeded analyses attempting to associate dynamics of phytoplankton with variation of internal P loading. Here, elements and lipid biomarkers were analyzed in a sediment core from Lake Heihai, a small, deep, and ultraoligotrophic alpine lake in Haba Mountain, Yunnan Province, SW China. The data document incredible enrichment of element iron (Fe) in the sediment, whose concentrations are much higher than those of other common major elements including titanium (Ti), aluminum (Al), calcium (Ca), and magnesium (Mg). This finding, together with the abundance correlation between P and Fe (n = 30, R ² = 0.783) suggested that P was probably retained in sediments through sorption with micro-layer of FeOOH at the sediment-water interface. The P/Ti ratios, P/Fe ratios, and P/total organic carbon (TOC) ratios all declined in the sediment since 1980, perhaps indicating increased P release from sediments to the overlying water column initiated by hypolimnion anoxia and sulfidic, which is presumably triggered by regional climate warming since the 1980s. The P-rich bottom water can be injected into photic zone during wind-driven mixing and overturn of the water column, although its frequency and intensity might decline due to stronger water column stratification in warming climate. In response, diatoms exhibited a rapid increase of productivity at this time, because diatoms have a storage vacuole and thereby nutrients such as P can be concentrated and used for cell division long after they are depleted in the bulk fluid. Elevated diatom biomass produced shading of light penetration, allowing for a low productivity for dinoflagellates. This study deepens our understanding of the impact of climate warming on lake systems and highlights the element biogeochemical cycle contributing to the variation of nutrients in the lake water column.

Water-based or flexographic inks in paper and plastic industries are more environmentally favourable than organic solvent-based inks. However, their use also creates new challenges because they remain dissolved in water and alter the recycling process. Conventional deinking technologies such as flotation processes do not effectively remove them. Adsorption, coagulation/flocculation, biological and membrane processes are either expensive or have negative health impacts, making the development of alternative methods necessary. Cellulose nanofibers (CNF) are biodegradable, and their structural and mechanical properties are useful for wastewater treatment. TEMPO-oxidised CNF have been evaluated for the decolourisation of wastewaters that contained copper phthalocyanine blue, carbon black and diarlyide yellow pigments. CNF in combination with a cationic polyacrylamide (cPAM) has also been tested. Jar-test methodology was used to evaluate the efficiency of the different treatments and cationic/anionic demand, turbidity and ink concentration in waters were measured. Results show that dual-component system for ink removal has a high potential as an alternative bio-based adsorbent for the removal of water-based inks. In addition, experiments varying CNF and cPAM concentrations were performed to optimise the ink-removal process. Ink concentration reductions of 100%, 87.5% and 83.3% were achieved for copper phthalocyanine blue, carbon black and diarlyide yellow pigments, respectively. Flocculation studies carried out show the decolourisation mechanism during the dual-component treatment of wastewaters containing water-based inks.

Consumption of psychotropic drugs is still increasing, especially in high-income countries. One of the most crucial consequences of this fact is significant release of them to the environment. Considerable amounts of atypical antipsychotics, benzodiazepines, antidepressants, and their metabolites were detected in river, lake, and sea water, as well as in tissues of aquatic organisms. Their ecotoxicity was proved by numerous studies. It should be noticed that interaction between psychotropic pharmaceuticals and radiation may lead to formation of potentially more toxic intermediates. On the other hand, photo-assisted wastewater treatment methods can be used as an efficient way to eliminate them from the environment. Many methods based on photolysis and photocatalysis were proposed and developed recently; nevertheless, the problem is still unsolved. However, according to recent studies, photocatalysis could be considered as the most promising and far more effective than regular photolysis. An overview on photolytic as well as homogenous and heterogeneous photocatalytic degradation methods with the use of various catalysts is presented. The photostability and phototoxicity of pharmaceuticals were also discussed. Various analytical methods were used for the photodegradation research, and this issue was also compared and summarized. Use of high-resolution multistage mass spectrometry (Q-TOF, ion trap, Orbitrap) was suggested. The combined techniques such as LC–MS, GC–MS, and LC–NMR, which enable qualitative and quantitative analyses in one run, proved to be the most valuable in this case. Assembling of MS/MS spectra libraries of drug molecules and their phototransformation products was identified as the future challenge.

A total of 85 PM₂.₅ samples were collected at a site located in a large industrial zone (Porto Marghera, Venice, Italy) during a 1-year-long sampling campaign. Samples were analyzed to determine water-soluble inorganic ions, elemental and organic carbon, and levoglucosan, and results were processed to investigate the seasonal patterns, the relationship between the analyzed species, and the most probable sources by using a set of tools, including (i) conditional probability function (CPF), (ii) conditional bivariate probability function (CBPF), (iii) concentration weighted trajectory (CWT), and (iv) potential source contribution function (PSCF) analyses. Furthermore, the importance of biomass combustions to PM₂.₅ was also estimated. Average PM₂.₅ concentrations ranged between 54 and 16 μg m⁻³ in the cold and warm period, respectively. The mean value of total ions was 11 μg m⁻³ (range 1–46 μg m⁻³): The most abundant ion was nitrate with a share of 44 % followed by sulfate (29 %), ammonium (14 %), potassium (4 %), and chloride (4 %). Levoglucosan accounted for 1.2 % of the PM₂.₅ mass, and its concentration ranged from few ng m⁻³ in warm periods to 2.66 μg m⁻³ during winter. Average concentrations of levoglucosan during the cold period were higher than those found in other European urban sites. This result may indicate a great influence of biomass combustions on particulate matter pollution. Elemental and organic carbon (EC, OC) showed similar behavior, with the highest contributions during cold periods and lower during summer. The ratios between biomass burning indicators (K⁺, Cl⁻, NO₃ ⁻, SO₄ ²⁻, levoglucosan, EC, and OC) were used as proxy for the biomass burning estimation, and the contribution to the OC and PM₂.₅ was also calculated by using the levoglucosan (LG)/OC and LG/PM₂.₅ ratios and was estimated to be 29 and 18 %, respectively.

Much attention has been paid to the availability of arsenic (As) in soils, while few studies were carried out on the comparison between the dry and flooded soils using different methods. In this study, chemical sequential extraction and diffusive gradients in thin films (DGT) techniques were employed to study the availability of As in soils amended with a range of exogenous As followed by one-year incubation under dry and flooded conditions, respectively. The results showed that the proportions of available solid As pools, including non-specifically adsorbed As (F1) and specifically adsorbed As (F2), had consistent increases with the increase of As amendment. The concentration of DGT-measured As (C DGT) and dissolved As in soil solution (C SOL) also increased up to 2573 (dry) and 1823 (flooded) times and 4067 (dry) and 3105 (flooded) times of the control, respectively, while their ratios (R) showing the extent of C SOL sustained from solid resupply decreased from 0.17 to 0.10 (dry) and 0.35 to 0.21 (flooded). Modelling with DGT-induced fluxes in soils (DIFS) further showed an increase of T c (the characteristic time to reach equilibrium from DGT perturbation) and decreases of desorption and adsorption rate constants (k ₁ and k ₋₁) with the increase of As amendment, reflecting a decrease in kinetic exchange rate of As between available solid As pool and soil solution. The flooded soils had greater values of R, k ₋₁ and k ₁ and lower value of T c in comparison with the dry soils, indicating a greater availability of As under the flooded condition.

This study investigated the chromium (Cr) occurrence and distribution along the Loushan River adjacent to a chromium slag heap. The speciation and chemical fractionation of Cr in different environmental media were determined. The potential ecological risks for the surrounding environment were assessed on the basis of both potential ecological risk index (RI) and risk assessment code (RAC). The results show that the surface soil experienced severe Cr contamination with Cr(T) and Cr(VI) values of 3220 ± 6266 and 64 ± 94 mg/kg, respectively, even though the chromium slag heap had already been removed. The chromium slag enhanced the Cr concentration level in the surface soil, water, and sediment samples more than the background level to different extents, which indicates that Cr released from the chromium slag actually affects the surrounding environment. The spatial distribution variety of Cr implies that their transport might have been affected by soil leaking, atmospheric transport, and fluvial hydraulics. The chemical fractionation results demonstrate that the residual fraction was the dominant form, accounting for 54.6 and 66.1% Cr(T) in surface soil and sediment samples, respectively. The content of bioavailable exchangeable Cr fraction correlated with the organic matter (OM), cation exchange capacity (CEC), and pH value. The ecological risk assessment suggests no considerable ecological risk toward the biota despite a relatively high Cr(T) level. Nevertheless, attention should be paid to the potential long-term risks owing to the slow release of oxidizable and residual fractions.

In this study, greenhouse pot experiment was carried out to investigate the Cu and Zn mobility and their accumulations in pakchoi (Brassica chinensis L.) and Chinese cabbage (Brassica rapachinensis L.) growth in Ca-bentonite-pig manure co-compost (CBC)–soil system during three consecutive planting. Five composts (0, 2.5, 5, 7.5, and 10% Ca-bentonite-pig manure co-composts) amended soil with 5% (w/w) application rate and compared to control without any additive. The results showed that the addition of CBC increased the biomass and chlorophyll content of pakchoi, and the maximum overall yield was found in 7.5% CBC treatment (12.89 ± 0.25 g), while when compared with the 0% CBC (15.89 ± 0.52 g) treatment, the Ca-bentonite amendment slightly decreased the Chinese cabbage yield (14.65 ± 0.11–15.41 ± 1.97 g). Additionally, compared to the 0% CBC treatment (11.81 ± 0.57–25.75 ± 0.89 mg/kg), the Ca-bentonite amendments showed a positive effect on restraining the diethylene triamine penta-acetic acid Zn mobilization (4.43 ± 0.41–12.48 ± 2.54 mg/kg) in pakchoi and Chinese cabbage; beside this, no obvious effect was observed on DTPA-Cu. Furthermore, there were great potential impacts for plant-available Zn in Ca-bentonite amended treatments during the consecutive planting, which decreased the content of Zn in plants. DTPA extraction results showed significantly higher Cu and Zn contents in compost–soil mixture, but its availability for grown plant was not confirmed during the consecutive planting, because of the consecutive decrease heavy metals contents in crops. Overall, the Ca-bentonite could be a useful additive for restricting the heavy metal mobility and increase the pakchoi yield.

We report on the facile and low-temperature one-pot chemical synthesis of lightly doped Zn₁₋ₓ Cu ₓ O and hybrid Au–Zn₁₋ₓ Cu ₓ O photocatalysts with low Cu molar content (0 < x < 0.7%) using 1,3-propanediol polyol simultaneously as solvent, reducing and a stabilizing agent, without any final thermal treatment. The photocatalysts have been characterized by X-ray diffraction, N₂ adsorption study, UV–vis diffuse reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy, and transmission electron microscopy. The lightly doped hybrid Au–Zn₁₋ₓ Cu ₓ O photocatalysts consisted in faceted quasi-spherical large-size Au nanoparticle cores surrounded by closely packed small-size Zn₁₋ₓ Cu ₓ O nanoparticles. Taking the photocatalytic degradation of Diuron under solar light as liquid-phase test reaction, the lightly doped Au–Zn₁₋ₓ Cu ₓ O hybrid photocatalysts with optimized x = 0.09% Cu content showed strongly enhanced photocatalytic activity when compared to the bare ZnO counterpart. The observed 16-fold higher degradation rate constant resulted jointly from the light doping of ZnO with Cu to form Zn₁₋ₓ Cu ₓ O photocatalyst and further from the addition of gold nanoparticles allowing interfacial oxide-to-metal electron transfer within the hybrid Au–Zn₁₋ₓ Cu ₓ O photocatalyst.

Chaohu Lake is the fifth largest freshwater lake in China, which tolerates substantial amount of anthropogenic discharge from surrounding cities that resulting in the degradation of water and damage of aquatic ecosystem. Metal analysis of sediment and aquatic organisms can provide important information on the environmental contamination and potential impact of aquatic food consumption. Thus, the concentrations of Cu, Pb, Zn, Cr, Cd, As, and Hg in sediment and fish from Chaohu Lake were analyzed with inductively coupled plasma mass spectrometry and atomic fluorescence spectrometry. The mean content of Cu, Pb, Zn, Cr, Cd, As, and Hg in the sediment samples were 27.4 ± 6.3, 40.5 ± 12.3, 136.8 ± 65.5, 68.5 ± 9.1, 0.357 ± 0.141, 10.8 ± 1.7, and 0.117 ± 0.049 mg/kg, respectively. The results were compared with background values and evaluation methods, to characterize the potential ecological risk. The concentrations of Cu, Pb, Zn, Cr, Cd, As, and Hg in the fish muscle samples were 1.68–5.31, 0.078–0.31, 15.55–372.98, 0.31–0.93, 0.001–0.033, 0.29–1.03, and 0.04–0.197 mg kg⁻¹ of dry mass, respectively. Most of the concentrations of the studied metals in muscles were found to be below the safe limits; however, the concentration of inorganic As (10% of total As) in two specimens exceeded the maximum allowance in fish. The ecological risk evaluation showed that the metals in sediment posed low to medium risk. The health risk assessment suggested that the consumption of fish from Chaohu Lake is currently safe with respect to the metals.