Fluoride retention from water is nowadays a serious health problem. This study reports the potential of a newly developed nano-hydrotalcite/hydroxyapatite (n-HT/HAp) composite, and its constituent materials, hydrotalcite (HT) and hydroxyapatite (HAp), in fluoride removal. Calcined hydrotalcites (cHT) showed a remarkable fluoride removal ability from water through memory effect mechanism. HAp, the mineral compound of bones, adsorbs fluoride as well but through ion exchange mechanism. Fluoride substitutes hydroxyls to produce fluorapatite. Among the tested calcined hydrotalcites, cHT Mg-Al (4:1) sample, composed of magnesium divalent cation to aluminum ratio of 4, was identified as the best-performing hydrotalcite. The differences among cHT samples in fluoride removal capacities are attributed to hydrotalcite composition as well as to particle size. The performance of these materials is compared with that of n-HT/HAp composite whose main features are basic acidic material and not yet tested in fluoride retention. Interestingly, n-HT/HAp also performs best, 98 %, slightly higher than the best cHT Mg-Al (4:1) sample with 97 % fluoride removal efficiency from such a high initial fluoride solution of 20 mg/L at 10 g/L dose, yielding the final residual fluoride concentrations of 0.36 and 0.6 mg/L, respectively; both meet the WHO standard for drinking water. Besides, the uncalcined hydrotalcite constituent added virtue to the advantage of using n-HT/HAp in fluoride removal as the efficiency was compensated by the nanometric size of the hydrotalcite particle.

Effects of low-temperature thermal desorption (LTTD) treatment on the ecological properties of soil contaminated by petroleum hydrocarbons were assessed. For this purpose, various ecological properties related to soil health and physicochemical properties of the oil-contaminated soil before and after LTTD treatment were investigated. Total petroleum hydrocarbon concentration, electrical conductivity, organic matter, and total nitrogen decreased while water-holding capacity and available P₂O₅ increased. The soil color was also changed but textural class was not changed after LTTD. The microbial number and dehydrogenase activity increased following LTTD, but there was no significant difference in the β-glucosidase and acid phosphatase activities. Seed germination succeeded after LTTD, but the germination rate was still lower than that in non-contaminated soil as the growth of plants and earthworms was. The results showed that overall soil health related to biological productivity and environmental functions was improved after LTTD and suggested that LTTD could be a better alternative to other harsh remediation methods. However, ecological indicators still show differences to the adjacent non-contaminated level. Therefore, to ensure safe soil reuse, the change in eco-physiochemical properties as well as contaminant removal efficiency during the remediation process should be considered.

The mass spectrometric analysis of the impact of sulfur dioxide and dust emission on carbon and oxygen stable isotopic compositions of glucose hydrolysed from α-cellulose samples extracted from Scots pine growing in the vicinity of “Huta Katowice” steelworks was the main aim of this study. The annual rings covered the time span from 1975 to 2012 AD. The relationships between climatic conditions, sulfur dioxide, and industrial dust emission and oxygen and carbon isotopic compositions were analyzed using correlation function methods. This study shows the first analysis of carbon and oxygen stable isotopes in glucose as the bio-indicators of CO₂, sulfur dioxide, and industrial dust emission. The anticoincidence trend of δ¹⁸O and δ¹³C and dust and sulfur dioxide confirms that the decreases of dust and sulfur dioxide industrial emission increase δ¹⁸O and δ¹³C values in glucose.

Three experiments were performed to compare the P availability between struvite and the commercial fertilizer monoammonium phosphate (MAP). Experiment 1 evaluated triticale grown in a commercial potting medium and fertilized with struvite and MAP at 0, 56, 112, and 224 kg P₂O₅ ha⁻¹. Struvite was comparable for dry matter (DM) yield (P < 0.01) and resulted in greater concentrations of P (P < 0.005) compared to MAP. Experiment 2 evaluated triticale and oats planted in two soils differing in pH, and fertilized with either struvite or MAP at 0, 56, 112, and 224 kg P₂O₅ ha⁻¹. When oats were grown in acidic soil, struvite provided greater P uptake (P < 0.0001) and concentration of P (P < 0.0001) in the plant compared to MAP. When triticale was grown in acidic soil, struvite provided the greatest DM yield (P < 0.005), P uptake (P < 0.0001), and concentration of P (P < 0.0001) compared to MAP. When triticale and oats were grown in alkaline soil, struvite produced the greatest concentration of P (P < 0.003) compared to MAP for oats. Experiment 3 evaluated corn and alfalfa over a 3-year period planted in alkaline soil and fertilized with either struvite or MAP at 0, 140, and 280 kg P₂O₅ ha⁻¹. In 2006 and 2007, struvite and MAP were comparable for DM yield (P < 0.05) and concentration of P (P < 0.05) in alfalfa. Using MAP resulted in greater P uptake (P < 0.05) all 3 years for alfalfa, and greater DM yields (P < 0.05) and concentrations of P (P < 0.05) in 2008. For corn, MAP produced the greatest DM yield (P < 0.001), P uptake (P < 0.003), and concentration of P (P < 0.001) all 3 years. Struvite was a comparable or superior P fertilizer compared to MAP in acidic soils and inferior to MAP in alkaline soils.

Inorganic arsenic occurs mainly in As(III) and As(V) states in water environment, but arsenite is more toxic and difficult to remove than arsenate by usual adsorption processes. To achieve the in situ oxidation of As(III) and simultaneous removal of both As(III) and As(V) in water, a novel-layered double hydroxide (Mg–Fe–S₂O₈–LDH) with the intercalation of persulfate has been designed and synthesized by a calcination-reconstruction method. The arsenic adsorption performances and removal mechanism with the Mg–Fe–S₂O₈–LDH material were studied. The experimental result showed that, since the strong oxidation ability of the exchangeable persulfate ions from the LDH, the As(III) species in water were almost completely oxidized to the As(V) state and simultaneously adsorbed onto the Mg–Fe–S₂O₈–LDH. It was found that the maximum adsorption capacity for As(III) and As(V) in single-pollutant system was 75.00 and 75.63 mg·g⁻¹, respectively. When the adsorbent dosage was 0.5 g·L⁻¹ for a mixed As(III) and As(V) solution, the batch experiment showed that the residual arsenic concentration can be reduced from 1 mg·L⁻¹ to lower than the limit value of drinking water standard recommended by WHO. It indicated that the synthesized Mg–Fe–S₂O₈–LDH is a potential attractive adsorbent for simultaneous removal of As(III) and As(V) in water.

This study evaluated the possibility of improving the macronutrient status of Cd-stressed white mustard ‘Rota’ using intensive S nutrition. Three S-SO₄ (2, 6, 9 mM S) and four CdCl₂ doses (0, 0.0002, 0.02, 0.04 mM Cd) in the Hoagland’s nutrient solution were conducted for 14 days. High S supply (6 or 9 mM) appears, to some extent, to affect positively the macronutrient status of Cd-stressed mustard. It increased roots and shoots contents of K and S, without significant changes in P content. Simultaneously, Mg content in shoots and roots remained stable, but Mg bioaccumulation was elevated. Shoot Ca content at the lowest and medium Cd dose decreased, whilst was unaffected at the highest Cd treatment. Intensive S nutrition of Cd-stressed mustard increased root N content and accumulation at the highest Cd concentration, but the N content dropped in above-ground parts. The bioaccumulation of remained macronutrients in general was substantially elevated together with enhanced Cd accumulation. Thus, the intensive S nutrition can enhance mustard tolerance to Cd stress by improvement macronutrients relations in plants, and S supplementation may be recommended for mustard cultivation on the Cd-contaminated areas.

Freshwater lakes are an important natural and cultural resource in national parks across the USA. At Cape Cod National Seashore, in southeastern Massachusetts, the water quality of these water bodies (known as kettle ponds), along with local precipitation chemistry, has been measured since the 1980s. These datasets, along with air temperature obtained from a local weather station, were analyzed to assess temporal trends in the air temperature, precipitation acidity, pond temperature, and pond pH, and are interpreted within the context of regional air quality improvements and increasing temperatures from regional climate warming. The results suggest that all parameters have increased significantly during the last several decades. As temperature and pH regulate a wide variety of physical, chemical, and biological processes, these changes may be influencing the overall ecology of the kettle ponds. This analysis provides an opportunity to gauge the future trajectory of this important resource and may ultimately guide management strategies for their continued protection against a backdrop of climate change and atmospheric emission controls.

The contribution of atmospheric deposition to the metal load at the outlet of a small urban catchment (Pin Sec, France) was studied. A new method, which takes into account the type of urban surfaces (glass, tile, bitumen, zinc sheet, grass, facade coating, and slate) as well as turbulence and local micrometeorology, was developed to measure atmospheric dry deposition. Dry deposition, wet deposition, and stormwater runoff load were all measured from September 2010 to August 2011. At the annual scale, atmospheric deposition was not a major contributor to the metal load at the outlet of this small catchment. Wet deposition however ranged from <1 to 29 %. The contribution of dry deposition (generally less than 5 %) was especially low and appeared to be smaller than that reported in previous studies. On this catchment, the majority of the metal load could be attributed to stormwater runoff (64–99 %). This methodology looks promising and should be taken into consideration when conducting new research on the contribution of atmospheric deposition to the pollutant load in urban catchments.

Drought stress is one of the major environmental factors responsible for reduction in crop productivity. In the present study, responses of two maize cultivars (Rung Nong 35 and Dong Dan 80) were examined to explicate the growth, yield, leaf gas exchange, leaf water contents, osmolyte accumulation, membrane lipid peroxidation, and antioxidant activity under progressive drought stress. Maize cultivars were subjected to varying field capacities (FC) viz., well-watered (80 % FC) and drought-stressed (35 % FC) at 45 days after sowing. The effects of drought stress were analyzed at 5, 10, 15, 20, ad 25 days after drought stress (DAS) imposition. Under prolonged drought stress, Rung Nong 35 exhibited higher reduction in growth and yield as compared to Dong Dan 80. Maize cultivar Dong Dan 80 showed higher leaf relative water content (RWC), free proline, and total carbohydrate accumulation than Run Nong 35. Malondialdehyde (MDA) and superoxide anion were increased with prolongation of drought stress, with higher rates in cultivar Run Nong 35 than cultivar Dong Dan 80. Higher production of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and glutathione reductase (GR) resulted in improved growth and yield in Dong Dan 80. Overall, the cultivar Dong Dan 80 was better able to resist the detrimental effects of progressive drought stress as indicated by better growth and yield due to higher antioxidant enzymes, reduced lipid peroxidation, better accumulation of osmolytes, and maintenance of tissue water contents.

The fate of emerging organic micropollutants (EOMs) in wastewater treatment plants (WWTPs) is still not fully determined, and further studies are still needed to assess whether the existing treatment units can be further exploited (e.g., by modifying the operating parameters) or new and different techniques have to be implemented for their removal. The present study investigates the fate of a class of EOMs, i.e., the endocrine disrupting chemicals (EDCs), in batch-activated sludge tests under mixed and aerated conditions, as those usually adopted in full-scale WWTPs. Among the EDCs, the research focused on: bisphenol A, 17α-ethinylestradiol (EE2), and two natural EDCs—estrone (E1) and 17β-estradiol (E2). By applying different operating conditions to the tests, it was possible to distinguish between contributions due to volatilization, adsorption onto the sludge flocs, and biodegradation to the overall removal of each EDC. It was found that all the investigated EDCs were removed mainly by adsorption and biodegradation. Starting from a relatively high concentration (1000 ng/L), the removal process was capable of reducing the influent load to very low values within the duration of the test (i.e., 48 h). Kinetics of the removal process were found to be best fitted by the pseudo-second-order model for all the investigated EDCs; the values of the relative constants were always found to be equal to about 0.0023 1/h. Furthermore, the values of the coefficients K D and K OM were determined and found to be comparable with the data reported by the specialized literature.