Research and routine analysis laboratories produce sizeable amounts of residues as a result of experiments and by-products of chemical reactions. An example of that is soil analysis, in which a sulfochromic solution is used for the determination of organic matter content. This solution contains sodium dichromate and sulfuric acid, reagents that oxidize the soil’s organic fractions and contribute to the presence of chromium in laboratory residues discharged into the environment. In an attempt to find solutions to environmental problems, the aim of the present study was to quantitatively and qualitatively characterize chromium-contaminated residues generated during soil analysis. Therefore, management methods were proposed in order to recover chromium in its trivalent form (Cr³⁺) by precipitation. The use of biochemical oxygen demand, chemical oxygen demand, nitrogen, phosphorus, and metals to characterize the samples revealed the presence of 16.76 g L⁻¹ of total chromium, with 4.19 g L⁻¹ of Cr(VI). By means of ozonation, 68 % of the chromium was converted to liquid form and, after being reduced with bisulfite, it was turned into chromium sulfate (III). The remainder, 32 %, was kept with the other metals present in the solid form (sludge).

The effectiveness of gemini-modified palygorskite (PGS) as the novel remediation material in polycyclic aromatic hydrocarbons (PAHs)-contaminated water remediation was revealed and examined. The sorption behavior of gemini surfactants at the PGS/aqueous interface was addressed using a developed two-step adsorption and partition model (TAPM). The characterizations of gemini-modified PGS were investigated using infrared spectroscopy, cationic exchange capacity, and surface area analysis. The effects of pH, ionic strength, humic acid, and temperature on sorption of phenanthrene (PHE) to untreated and modified PGS were systematically studied. Analysis of the equilibrium data indicated that the sorption isotherms of gemini fitted TAPM well. The modification of PGS with gemini surfactants provided a favorable partition medium for PHE and enhanced PHE retention in solid particles. The solution parameters played significant effects on PHE sorption to the modified PGS. The sorption isotherms of PHE on PGS at different temperatures well fitted the Freundlich equation. Thermodynamic calculations confirmed that the sorption process of PHE on modified PGS was spontaneous and exothermic from 293 to 303 K. It is revealed that the modification with gemini surfactants probably offered some unique surface characteristics to the clay mineral as a new type of remediation material. This can provide a reference to the potential application of PGS in PAH-contaminated water remediation process.

A high-dimensional driving function for Microcystis bloom warning was developed, in which both the inhibition and promotion impacts on Microcystis growth activation energy are integrally considered. Five factors, including flow disturbance, temperature, light intensity, nutrient concentration, and biological inhibition, are embedded in the equation, which results in a high-dimensional problem. The projection pursuit principle was applied for dimension reduction to resolve the numerical problem, and an integrated hydro-environmental model was established. Jinshan Lake, a typical riverside lake, was selected as the research area, and six bloom grades were determined for warning analysis. Based on the established model, the processes of Microcystis growth under varied hydrodynamic conditions were simulated. It was found that the established warning model could well reveal the Microcystis bloom processes in Jinshan Lake. The low-water year was characterized by the largest number of days on which Microcystis bloom might occur for its poor water exchange frequency; The areas where Microcystis bloom might occur in the flood seasons of high-water year, common-water year, and low-water year varied with the uneven-distributed dynamic conditions, which were respectively 0.15, 0.91, and 1.26 km².

Reducing dimensions of hyperspectral data is very important as the removal of high-dimensional spectral variables could improve the predictive ability of the model. In the current study, four different linear dimension reduction algorithms, including principal component analysis (PCA), local preserving projections (LPP), neighborhood preserving embedding (NPE), and linear discriminant analysis (LDA), were used to reduce hyperspectral dimensions, and their classification performances on the algae concentration levels in water samples using hyperspectral imaging were compared. The LPP model showed satisfactory classification accuracy of 94.296 %, which was superior to the results based on reducing spectral dimensions with LDA (94.118 %), NPE (93.353 %), and PCA (90.588 %). The results demonstrated the potential of hyperspectral imaging coupled with dimension reduction methods in classifying water bodies with different algae concentration levels.

In this study, we focused on the performance of phosphate recovery in the case of magnetic iron oxide (MIO) particles and iron oxide nanotubes (INTs) with synthetic wastewater. MIO particles were prepared by a co-precipitation method, and INTs were prepared with a potentiostatic anodization method of zerovalent iron foil in electrolyte-containing sulfate and fluoride. Although MIO had the fast adsorption rate, INT had a higher adsorption capacity per surface area rather than MIO. The adsorption isotherm of MIO and INT was approximated by a Freundlich type. Phosphate adsorbed on MIO and INT was effectively desorbed with alkaline solutions. For phosphate recovery, MIO needs a magnetic recovery device, whereas, when INT was used for phosphate recovery, another recovery step is not necessary. Both methods showed effective adsorption performance for phosphate recovery in wastewater.

To investigate the effect of different sizes, sex, and exposure time on Cu uptake capacity, mussels Mytilus galloprovincialis of different shell sizes were exposed to different Cu concentrations in different aquariums. In another experiment, mussels were exposed to stable dissolved Cu for 6 days in the laboratory. All mussels tissue concentrations were analyzed using energy dispersive X-ray fluorescence (EDXRF) spectrometry. At the end of uptake, the rate of increase of Cu level in the soft tissues of mussels in different aquariums was 3.84–7.92 times higher than before exposure. While the results of Cu concentrations were negatively correlated with the shell sizes in the control and second groups (r cₒₙₜᵣₒₗ = −0.862, r ₛₑcₒₙd = −0.851 p < 0.05), this relation was not observed in the other groups (p > 0.05). Also, results showed no significant difference between male and female (p > 0.05). On the other hand, Cu concentration values in soft tissue were monitored daily and observed to be increasing up to the third day but afterwards to be descending, thus indicating a significant effect of the exposure time-related Cu uptake by mussels. Therefore, the exposure time to Cu metal of the mussel should be taken into account in the marine pollution investigations. In addition, by using the obtained Cu heavy metal concentration results, the heavy metal intake by the human population was calculated by taking into account daily mussel consumption. The results were examined for potential human health risks and discussed. These results would be helpful to understand factors controlling Cu accumulation in mussels.

The 2′,7′-dichlorofluorescin (DCFH) assay is widely used to measure particle-bound reactive oxygen species (ROS), which are considered as a major contributor leading to the adverse health effects upon exposure to atmospheric particulate matter. DCFH, a non-fluorescent substance that can be oxidized to highly fluorescent dichlorofluorescein (DCF) in the presence of horseradish peroxidase (HRP), is usually used as a probe for ROS determination due to its response to diverse and relevant oxidant species. However, there is limited literature that reports the effects of different experimental conditions in the performance of this assay. In our work, various experimental conditions, such as pH value, incubation temperature, reagent concentration and stability, reaction time, linearity range, and extraction method, were examined and optimized as a pilot study for developing an online system for atmospheric ROS measurement. The results showed that pH value, reagent concentration, and extraction method significantly affect the performance of DCFH assay, while incubation at a specified temperature (37 °C) did not increase the oxidization extent of DCFH. After optimization, some practical samples were measured using different experimental parameters to check the performance of the optimized assay. The comparisons of these measurements showed that optimization can greatly improve the detection limit and reproducibility of the DCFH assay, which can then be employed to better the accuracy of offline and online ROS measurement.

Reference materials are an indispensable element in the quality control of analytical results and procedures. Complicated natural matrices such as soil and sediment in the environment are subject to different processes. They are a source of various biochemical reactions, degradation, and biotransformation. Subject to these processes are all organic and inorganic pollutions which affect component parts of soil and sediment. The quantity and the composition of the organic and inorganic matter forming a given matrix, its origin, and the particle size fractions—all has an immediate influence on the content and the kind of pollution. The choice of the right reference material is a condition of the correct estimation of the reliability of the results. Many of the components forming the environmental matrix have influence on the content, stability, and homogeneity of the PCBs (e.g., the organic compound content and the percentage of minerals, particle size, moisture level). Reference material must be as similar as possible to real samples tested. Unfortunately, the majority of commercially available certified reference matrices for soils and bottom sediments containing polychlorinated biphenyls (PCBs) are not fully characterized as regards their makeup and the content of mineral and organic substances. Therefore, we face the question of matching (producing) appropriate CRMs for the tested matrices (samples of soils and sediments) to obtain dependable test results. Another solution to this problem could be creation of model compositions of soils and sediments with specific physical and chemical properties.

A study was carried out to determine the pathogenicity (hemolytic activity) on corals (Turbinaria sp.) and sea bass (Lates calcarifer) of Aeromonas hydrophila from water, sediment, and coral. Samples were collected from coastal water and coral reef areas. One hundred and sixty-two isolates were successfully isolated. Out of 162, 95 were from seawater, 49 from sediment, and 18 from coral. Sixteen isolates were picked and identified. Isolates were identified using a conventional biochemical test, the API 20NE kit, and 16S rRNA nucleotide sequences. Hemolytic activity was determined. Out of 16 isolates, 14 isolates were β-hemolytic and two isolates were non-hemolytic. Corals infected with A. hydrophila suffered bleaching. Similar effect was observed for both hemolytic and non-hemolytic isolates. Intramuscular injection of A. hydrophila into sea bass resulted in muscular bleeding and death. Higher infection rates were obtained from hemolytic compared to non-hemolytic strains of A. hydrophila isolates.

To conserve water resources and guarantee food security, a new technology termed as “wet irrigation” is developed and practiced in rice fields; thus, its impact on radiative forcing derived from nitrous oxide (N₂O) and methane (CH₄) emissions merits serious attention. Dicyandiamide (DCD), a kind of nitrification inhibitor, is proposed as a viable means to mitigate greenhouse gas (GHG) emission while enhancing crop productivity. However, little is known about the response of GHG emission and grain yield to DCD application in a rice system under wet irrigation. In these regard, effects of water regime and DCD application on CH₄ and N₂O emissions, grain yield, global warming potential (GWP), and greenhouse gas intensity (GHGI) from rice fields were studied. For this study, a field experiment, designed: Treatment II (intermittent irrigation), Treatment WI (wet irrigation), Treatment IID (II plus DCD), and Treatment WID (WI plus DCD), was conducted in Jurong, Jiangsu Province, China, from 2011 to 2012. Relative to Treatment II, Treatment WI decreased CH₄ emission significantly by 49–71 % while increasing N₂O emission by 33–72 %. By integrating CH₄ and N₂O emissions and grain yield, Treatment WI was 20–28 and 11–15 % lower than Treatment II in GWP and GHGI, respectively. The use of DCD under wet irrigation reduced N₂O emission significantly by 25–38 % (p < 0.05) and CH₄ emission by 7–8 %, relative to Treatment WI, resulting in a decline of 18–30 % in GWP. Due to the increase in N use efficiency, maximal grain yield (6–7 %) and minimal GHGI (22–34 %) was observed in Treatment WID. These findings indicate that combined application of N fertilizer and DCD is a win-win strategy in water-saving high-yield rice production with less GHG emission.