The adsorption of microcystin-LR (MCLR) by biochar has never been well understood. For the first time, the unconventional adsorption of hydrophilic MCLR on wood-based biochars was comprehensively investigated as a function of biochar properties, environmental temperature, solution pH, coexisting dissolved organic matter (DOM), and polar organic competitors. High-temperature-prepared biochar from 700 °C (BC-700) and low-temperature-prepared biochar from 300 °C (BC-300) were characterized with significantly different surface areas but similar alkaline nature. Despite a very low surface area, BC-300 exhibited very high adsorption capacity, which implies the important contribution of surface groups to biochar. MCLR adsorption on biochars was pH dependent and was strongly reduced by macromolecular DOM. Polycarboxylic aliphatic acids and 2-(2-hydroxyethyl) guanidinium cation, which are similar to specific structural groups in MCLR, exhibited an evident competitive effect. The results indicated that both carboxylic and guanidino groups of MCLR serve significant functions in MCLR adsorption to biochar. The adsorption mechanisms may be primarily related to the columbic attractions and the hydrogen bonding interactions between MCLR and biochar surface. In particular, the irreversible adsorption enhancement of MCLR was observed on BC-700, which suggests that biochar amendment can aid in immobilizing MCLR from water to sediment, thereby prolonging MCLR environmental fate in biochar-amended sediment.

Urban sprawl and increasing economical pressure on agricultural production raises new unprecedented environmental questions. The presented study proved that higher level of fertilization of the urban vegetation significantly increases the concentration of male microgametophytes in the air during the flowering season. The levels of fertilization had no significant effect on the pollen grain size, nor on the profile and content of the phenolic compounds, however, the content of tryptophan (protein with a key role in allergies) was significantly influenced. The metabolism of tryptophan and its role in human imunilogy is not yet completely understood, however, it is recommended to avoid unnecessary fertilization in urbanized areas.

Effects of invasive plants on soil properties and microbial communities have been observed, but the mechanisms driving change are less obvious. The objective of this study was to determine the short-term impacts of litter from the invasive shrub Frangula alnus on soil properties and soil microorganims. In situ soil rings (6-cm diameter by 7-cm deep) received the following aqueous treatments: deionized water, dextrose, cellulose, Quercus alba leaf extract, and F. alnus leaf extract (n = 7) and were sampled 1, 2, and 4 weeks after additions were made. Microbial biomass carbon did not respond differently to treatments containing carbon (C) sources at any sampling period, suggesting that C quality had little impact on microbial abundance at this site. However, in weeks 1 and 2, soil treated with F. alnus had significantly higher total extractable nitrogen (N) than the control, dextrose, cellulose, and Q. alba extract (all comparisons for both weeks p < 0.001). We suspect that the increase in extractable N in the F. alnus-treated soil was due to enhanced N mineralization. In addition, changes to the microbial biomass C-to-N ratio in the F. alnus-treated soil indicated that microbial function had been altered. Overall, results from this study suggest that F. alnus leaf litter has the capacity to alter soil properties and microbial function by stimulating N mineralization.

The proposed and validated method for determination of ⁹⁰Sr content in environmental samples (water, soil and plant) is based on the radiochemical analytical separation of ⁹⁰Y from the sample and measuring its activity after the establishment of radioactive equilibrium with ⁹⁰Sr. Validation is the confirmation by examination and provision of objective evidence that they meet the individual requirements stipulated for a specific use. Validation of method was done based on the blank samples for water by adding ⁹⁰Sr known activity and using reference materials of soil (IAEA-326) and plant (IAEA-330). Content of ⁹⁰Sr in environmental samples was determined by α/β low level proportional counter. The accuracy and the precision of the applied method are confirmed and the method is validated and can be used for determination of ⁹⁰Sr in environmental samples. On the other hand, participations in interlaboratory comparisons are confirmed that the adequacy of the validated method is ensured.

The article, Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility by Jae-Woo Choi, Kyu-Sang Kwon, Soonjae Lee, Byungryul An, Seok-Won Hong, Sang-Hyup Lee, is replete with some fundamental scientific flaws which have the potential to misinform readers. This comment seek to correct these flaws.

An innovative device for enhancing particle settling, referred to as the bottom grid structure (BGS), was tested in the forebay of an urban stormwater detention pond in two design variants. Results showed that compared to the simulated bare pond bottom (i.e., a reference condition), the BGSs collected more sediments during a three-month test period and also captured and retained some very fine particles (<32 μm) even under high flows. The improvements of particle removal rates expressed in multiples of removals for the bare bottom were 3.6, 7.3, and 11.2, respectively, for the particle size ranges 106 μm < D < 250 μm, 32 μm < D < 106 μm, and D < 32 μm. Because the BGS can retain much smaller particles than bare bottom sediment traps, the application of the BGS can be considered as equivalent to increasing the settling area of a particle removal facility about 5 to 60 times, depending on the size of settleable particles under consideration. This characteristic distinguishes the BGS from other sedimentation enhancement methods and makes it possible to treat stormwater with a wide particle size spectrum under high flow rates, with a relatively small footprint, and without using chemical settling aids or filtration.

Cyanobacterial toxins have caused worldwide concern because of their lethal effects, which has led to intensive search of cost-effective removal techniques. With the application of a Box–Behnken experimental design combined with response surface methodology, the adsorption process of the potent and commonly occurring microcystin-LR (MC-LR) onto nano-sized montmorillonite (NMMT) K10 was investigated through the HPLC-UV system. The quadratic statistical model was established to predict the interactive effects of pH (1–12), NMMT K10 dose (1–10 mg mL⁻¹), and MC-LR initial concentration (100–1,000 μg L⁻¹) on MC-LR adsorption and to optimize the controlling parameters. The MC-LR adsorption by NMMT K10 was pH dependent and was found to reach a maximum at pH 2.96 with a removal peak of 186.37 μg g⁻¹. The range of optimal pH for MC-LR adsorption was 2.96–3.48, and higher adsorption capacities were achieved with increasing adsorbent dose and MC-LR initial concentration. Sorption kinetics revealed that the sorption process of MC-LR on NMMT K10 was rapid (short equilibrium time) and involved several kinetic stages. The Langmuir isotherm model predicted that the theoretical maximum adsorption capacity at pH 3 was 285.20 μg g⁻¹. Alkali eluting media (0.1 M NaOH) showed the highest desorption percentage (75.3 %) during regeneration studies. The high Brunauer–Emmett–Teller (BET) specific surface area (204.65 m² g⁻¹) of NMMT K10 was also characterized. NMMT K10 was determined to be an effective and economic adsorbent for MC-LR removal on a large scale.

The fate of colored natural organic matter (CNOM) was investigated for a period of 16 months at a municipal wastewater treatment plant of a mid-sized city in Northern Ontario, Canada, using fluorescence spectroscopy. Our objectives were to assess the changes of CNOM at the inlet and outlet of the plant and to determine if these changes were correlated with parameters routinely measured at the plant. The fluorescence signals were spectrally resolved into humic-like, fulvic-like, and protein-like components using a parallel factor analysis (PARAFAC) routine. We found that the signals of the CNOM components in the raw sewage had protein-like characteristics, followed by fulvic-like and humic-like characteristics. Conversely, after treatment, the CNOM signals were dominated by fulvic-like components, followed by approximately equal signals of humic-like and protein-like components. The fluorescence signals were, on average, ∼60 % lower in the effluent for the protein-like components and ∼28 % lower for the humic-like components, suggesting a decomposition of these CNOM materials. The fluorescence signals showed a small apparent increase of fulvic-like components, by ∼4 %, suggesting that the material showing this signal is recalcitrant to decomposition, or it could be potentially produced in the process. We found weak but statistically significant correlations (R ² > 0.3) between the total fluorescence signals and total carbon (TC), the flow rate through the plant, and rainfall in the raw sewage. Similarly, correlations were found between protein-like fluorescence of the protein-like components and total Kjeldahl nitrogen (TKN) and ammonium at the effluent (R ² > 0.3).

We examined the effectiveness of rhizoaugmentation for treating water contaminated with the nitrophenols (NPs), 2-NP, 3-NP, 4-NP, and 2,4-dinitrophenol (2,4-DNP) using NP-degrading bacteria. We used 2-NP-degrading Pseudomonas sp. (strain ONR1), 3-NP-degrading Cupriavidus sp. (MFR2), 4-NP-degrading Rhodococcus sp. (PKR1), 2,4-DNP-degrading Rhodococcus sp. (DNR2), and giant duckweed (Spirodela polyrhiza). The four bacterial strains readily colonized Spirodela roots, as approximately 1 × 10⁵colony-forming units [CFUs] plant⁻¹to 10⁶–10⁷ CFU plant⁻¹. The higher populations remained stable through five sequential 2-day degradation cycles and completely removed all four NPs within each cycle. The root–bacteria association also successfully treated wastewater effluent contaminated with NPs; 52–71 % of 2-NP and 100 % of 3-NP, 4-NP, and 2,4-DNP were removed within each of five 2-day cycles. These results demonstrate the potential of rhizoaugmentation to achieve efficient and sustainable treatment of NP-contaminated waters.

To date, studies on the geological conditions in inland aquifers leading to pathways for upwelling deep saline groundwater due to pumping have not been published yet. Therefore, this paper conducted a theoretical modeling study to raise two hypotheses about deep saline-groundwater pathways leading to saltwater upconing below a pumping well in an inland aquifer based on the field situation at the Beelitzhof waterworks in southwestern Berlin (Germany), defined as follows: (1) there are windows in the Rupelian clay caused by glacial erosion, where their locations are uncertain, and (2) there are no windows in the clay, but the clay is partially thinned out but not completely removed by glacial erosion, so salt can merely come through the clay upward by diffusion and eventually accumulate on its top. These hypotheses were tested to demonstrate the impact of the lateral distance between windows in the clay and the well, as well as salt diffusion through the clay depending on its thickness on saltwater intrusion in the pumping well, respectively, using a density-dependent groundwater flow and solute transport model. Hypothesis 1 was validated with four scenarios that windows could occur in the clay at the site, and their locations under some conditions could significantly cause saltwater intrusion, while hypothesis 2 could be excluded, because salt diffusion through the clay with thickness greater than 1 m at the site was not able to cause saltwater intrusion.