Foundry sands from the iron foundry industry were employed as a support source for photocatalysts. TiCl₄ was used as the titanium precursor in the preparation of the supported photocatalysts. The solids were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, diffuse reflectance spectroscopy in the ultraviolet range, small-angle X-ray scattering, nitrogen porosimetry, and zeta potential measurements. The prepared catalyst systems contained Ti, Al, Fe, K, Na, or Cu. All systems were also found to contain carbon. The systems were evaluated in the photodegradation of rhodamine B. For comparative reasons, P25 (Degussa) was also employed as a catalyst. Among the tested systems, the greatest percent dye degradation occurred with ultraviolet (65 %) and visible (38 %) radiation, whereas under the same conditions, the commercial P25 catalyst achieved 93 and 14 % degradation, respectively, for the ultraviolet and visible radiation.

The study of fluvial bed sediments is essential for deciphering the impact of anthropogenic activities on water quality and drainage basin integrity. In this study, a systematic sampling design was employed to characterize the spatial variation of lead (Pb) concentrations in bed sediment of urban streams in the Palolo drainage basin, southeastern Oahu, Hawaii. Potentially bioavailable Pb was assessed with a dilute 0.5 N HCl extraction of the <63 μm grain-size fraction from the upper bed sediment layer of 169 samples from Palolo, Pukele, and Waiomao streams. Contamination of bed sediments was associated with the direct transport of legacy Pb from the leaded gasoline era to stream channels via a dense network of storm drains linked to road surfaces throughout the basin. The Palolo Stream had the highest median Pb concentration (134 mg/kg), and the greatest road and storm drain densities, the greatest population, and the most vehicle numbers. Lower median Pb concentrations were associated with the less impacted Pukele Stream (24 mg/kg), and Waiomao Stream (7 mg/kg). The median Pb enrichment ratio values followed the sequence of Palolo (68) > Pukele (19) > Waiomao (8). Comparisons to sediment quality guidelines and potential toxicity estimates using a logistic regression model (LRM) indicated a significant potential risk of Palolo Stream bed sediments to bottom-dwelling organisms.

The use of synthetic dyes is commonplace in many industries, and the effluent is often dumped into the environment with no prior treatment. The aim of the present study was to analyze the use of an industrial strain of Saccharomyces cerevisiae (Meyen) for the removal of the textile dye Acid Blue 161 from an aqueous solution. Kinetic, isotherm, and thermodynamic models were created to evaluate the biosorption mechanisms. Fourier transfer infrared (FT-IR) spectroscopy was used to characterize and identify possible binding sites. A toxicity test was also performed using Artemia salina to analyze the degree of toxicity of the dye following treatment. The kinetic results demonstrated the occurrence of intraparticle diffusion in the yeast cells as the controlling mechanism of the sorption process. Biosorption followed the Langmuir model, except at pH 8.50, when it fit the Freundlich model. The thermodynamic results demonstrate that the biosorption process is spontaneous and endothermic. The FT-IR analyses confirmed the occurrence of a chemical reaction in acid pH, but physical adsorption only occurred at pH 8.50. The toxicity test showed that the use of the yeast biomass led to the complete removal of toxicity from the dye solution, demonstrating the effectiveness of the biosorption process in the treatment of effluents contaminated with these compounds.

We investigated the effects of exposure to molluscicidal metaldehyde (MET) on golden apple snail (GAS) Pomacea canaliculata and Rhinella arenarum tadpoles by assessing mortality and/or other effects via: acute toxicity assays; B-esterase activities (acetilcholinesterase (AChE) and carboxilesterase (CbE)) and oxidative responses (glutathione-S-transferase (GST) and catalase (CAT)). The effect of sublethal concentrations of MET was also analysed by assessing biochemical changes and swimming parameters in tadpoles. The LC₅₀ value in P. canaliculata was as 0.50 mg L⁻¹ and in R. arenarun tadpoles, 229.7 mg L⁻¹ at 48 h. The intestine of MET-exposed P. canaliculata exhibited a significant reduction in CbE and CAT activities, but not in AChE activity; hepatopancreas of GAS showed a decreased GST activity decreased with respect to control individuals. In addition, a significant reduction of CbE activities was detected in R. arenarum tadpoles exposed to MET, and AChE presented lower values than the control but without statistical differences. Antioxidant enzymes (GST and CAT) were significantly reduced in tadpoles exposed to MET compared with the control group. In addition, MET had a significant effect on the swimming behaviour of R. arenarum. Finally, since amphibian tadpoles and P. canaliculata often co-occur, other native amphibian species should be studied to elucidate the ecological risk of MET to amphibian populations.

Silicon (Si) is one of beneficial elements for rice and is considered to enhance plant resistance to toxic metals. Nanofertilizers generally have a smaller particle size and specific characters and behaviors in soil and plants. Thus, nano-Si fertilizers may putatively have an advantage over traditional fertilizers in reducing heavy metal accumulation in rice straws and grains, but their effects still require investigation. Here, using a greenhouse pot culture experiment, we studied the effects of foliar application with organic or inorganic nano-Si on growth and yields, and heavy metal accumulation in six rice cultivars grown in soil artificially polluted with Cd, Pb, Cu, and Zn. Generally, hybrid cultivars had higher biomass and yields than conventional cultivars (P < 0.001), and nano-Si showed positive effects on at least four cultivars (P < 0.001). The average spike weight of six cultivars increased to 25.3 and 24.8 %, respectively, by inorganic and organic nano-Si. Hybrid cultivars generally had higher Cd concentrations in roots, shoots, and grains than conventional cultivars. In most cases, both organic and inorganic nano-Si reduced concentrations (P < 0.01) and bio-concentration factor (BCF) of the heavy metals in grains and decreased the translocation factor (TF) of heavy metals from roots to shoots and/or from shoots to grains, and the most pronounced effects were found on Cd. The average grain Cd concentration decreased to 27.1 and 23.8 %, respectively, by inorganic and organic nano-Si. In general, inorganic nano-Si had more pronounced effect than organic nano-Si on both rice growth and heavy metal accumulation. This present study firstly showed that nano-Si had positive effects on the growth and yields of rice grown in multi-metal-polluted soil and potentially reduced heavy metal accumulation in rice, especially the toxic Cd in grains. However, both rice cultivar and chemical form of Si fertilizers should be taken into account to develop efficient nano-Si fertilizers for preventing heavy metal-contaminated rice grains.

Phytotoxic effects of a single heavy metal on different crops are widely reported; however, consequences of combined metal toxicity on maize are rarely investigated. In this study, a pot experiment was conducted to assess the phytotoxic effects both Al and Cr on morphophysiological and biochemical traits, photosynthetic gas exchange capacities, metal uptake, and translocation in different plant parts. Plants were exposed to Al³⁺ (100 μM), Cr⁶⁺ (100 μM), and Al³⁺ + Cr⁶⁺ (100 + 100 μM), and data were collected at pre- and post-silking stages while uncontaminated pots were served as control (Ck). Results depicted that both Al and Cr impaired maize growth and yield response and inhibited photosynthesis and gas exchange attributes i.e., transpiration, stomatal conductance, inter-cellular CO₂, as well as water use efficiency (WUE) and intrinsic water use efficiency (WUEi). Moreover, Al and Cr toxicities caused lipid peroxidation and membrane damage while activated antioxidative defense system in terms of superoxide dismutase (SOD), peroxidaes (POD), and catalase (CAT) and mediated reduced glutathione contents (GSH). Increased proline and reduced protein contents were also observed with a combined metal toxicity. Interestingly, Cr proved to be more toxic than Al whereas affects were more apparent where both Al and Cr were applied simultaneously. Plant exposure to both Al and Cr increased metal contents in different plant parts, while maximum metal contents were recorded in roots followed by stem, leaves, corn ear, and grains. Overall severity in phytotoxic effects was observed as Al+Cr > Cr > Al > Ck. Additionally, values of combined application of both Al + Cr were higher than those of the linear sum of Al and Cr alone, suggesting that synergistic effects of Al + Cr were more toxic than their individual effects. Hence, combined metal toxicity proved more damaging for maize than individual metal stress.

Indoor dust samples were collected from 40 homes in Kocaeli, Turkey and were analyzed simultaneously for 14 polybrominated diphenyl ethers (PBDEs) and 16 poly aromatic hydrocarbons (PAHs) isomers. The total concentrations of PBDEs (Σ₁₄PBDEs) ranged from 29.32 to 4790 ng g⁻¹, with a median of 316.1 ng g⁻¹, while the total indoor dust concentrations of 16 PAHs (Σ₁₆PAHs) extending over three to four orders of magnitude ranged from 85.91 to 40,359 ng g⁻¹ with a median value of 2489 ng g⁻¹. Although deca-PBDE products (BDE-209) were the principal source of PBDEs contamination in the homes (median, 138.3 ng g⁻¹), the correlation in the homes was indicative of similar sources for both the commercial penta and deca-PBDE formulas. The PAHs diagnostic ratios indicated that the main sources of PAHs measured in the indoor samples could be coal/biomass combustion, smoking, and cooking emissions. For children and adults, the contributions to ∑₁₄PBDEs exposure were approximately 93 and 25 % for the ingestion of indoor dust, and 7 and 75 % for dermal contact. Exposure to ∑₁₆PAHs through dermal contact was the dominant route for both children (90.6 %) and adults (99.7 %). For both groups, exposure by way of inhalation of indoor dust contaminated with PBDEs and PAHs was negligible. The hazard index (HI) values for BDE-47, BDE-99, BDE-153, and BDE-209 were lower than the safe limit of 1, and this result suggested that none of the population groups would be likely to experience potential health risk due to exposure to PBDEs from indoor dust in the study area. Considering only ingestion + dermal contact, the carcinogenic risk levels of both B2 PAHs and BDE-209 for adults were 6.2 × 10⁻⁵ in the US EPA safe limit range while those for children were 5.6 × 10⁻⁴ and slightly higher than the US EPA safe limit range (1 × 10⁻⁶ and 1 × 10⁻⁴). Certain precautions should be considered for children.

Acid rain caused a severe loss on agricultural productivity, aggravating the challenge for achieving sustainable food production to feed the increasing globe population. To clarify the mechanism on adaptation of rice root to acid rain, we studied the root morphology and growth regulated by nutrient absorption under hydroponic conditions. Our results show that acid rain (pH 5.0 or 3.5) increased the density of root hair and root volume by increasing concentrations of K⁺, Na⁺, and Ca²⁺ in rice roots, and the root dry weight was increased. However, strong acid rain (pH 2.5) decreased the root length, surface area, volume, and number of root tips by decreasing the concentrations of K⁺, Na⁺, and Mg²⁺ in rice root, and fresh and dry weight were both decreased. After a 5-day recovery, the root morphology of rice seedlings treated with acid rain (pH 5.0 or 3.5) was recovered to the control levels, and the concentrations of K⁺, Na⁺, Ca²⁺, and Mg²⁺ also had no difference from the control (p < 0.05). However, the root growth treated with strong acid rain (pH 2.5) was still lower than the control because the inhibition on root activity and hydrolytic activity of plasma membrane H⁺-ATPase might have exceeded the self-regulating capacity of rice seedlings, and the absorption of mineral nutrient could not sustain the growth. Hence, we concluded that the adaption of root morphology of rice seedlings to acid rain was related to regulation of mineral nutrient absorption in rice root.

The aim of this 2-year study was to examine the temporal changes in the concentration of microbiological indicators of water contamination and selected physicochemical parameters within the Białka river and its selected tributaries in the vicinity of the largest ski station in Białka Tatrzańska. The study involved 24 series of sampling in eight sites throughout the Białka river and on its selected tributaries. Temperature, pH, and electrical conductivity (EC₂₅ °C) were measured onsite. The microbiological assays included the numbers of mesophilic and psychrophilic bacteria, Staphylococcus spp. and Salmonella spp., as well as coliforms, thermotolerant (fecal) coliforms, Escherichia coli, Enterococcus faecalis, and sulfate-reducing Clostridium. The chemical analyses were conducted to determine the concentration of NH₄ ⁺, NO₂ ⁻, NO₃ ⁻, and PO₄ ³⁻. The analyses showed that contrary to common opinion, waters of the Białka river are strongly polluted in some sections. Seasonal variation in the prevalence of microbial indicators of fecal pollution was found, and the largest numbers of microorganisms were observed in winter ski season, followed by summer holidays. Similar seasonal pattern was observed in the examined chemical parameters. There was also very strong spatial variation within the tested microbial and chemical parameters, indicating the presence of pollution hotspots in the course of the Białka river. The employed principal component analysis revealed the presence of two main pollution sources, mainly affecting the quality of river water, i.e., fecal contamination of human origin and the natural source in the form of surface runoff and soil leaching. These factors, depending on the location of the sampling site, occurred in different configurations.

Cr(VI) adsorption onto a novel fibrous ethylenediamine-functionalized polyethylene/polypropylene (PE/PP-g-PGMA-EDA) nonwoven fabric was investigated in aqueous solutions. The ethylenediamine functionalities were immobilized on the PE/PP nonwoven fabric through the epoxy groups of poly(glycidyl methacrylate) (PGMA) grafted to the fibers via radiation-induced emulsion graft polymerization in aqueous solution. Optimum conditions for grafting and subsequent modification steps were determined. The adsorbents were characterized by FTIR, XPS, and SEM techniques. Cr(VI) adsorption was studied in batch mode as a function of pH, feed concentration, contact time, ionic strength, and coexisting anions. The nonwoven adsorbent exhibited efficient, rapid Cr(VI) removal; high adsorption capacity; and insignificant interference from coexisting ions. Adsorbed Cr(VI) ions were desorbed using 2 M HNO₃ solution, and the adsorption capacity of the nonwoven fabric was retained for four adsorption–desorption cycles. The data for Cr(VI) adsorption on the nonwoven fabric fitted to the Langmuir isotherm model well. The maximum adsorption capacity for the Langmuir isotherm was 178.9 mg Cr(VI)/g polymer at pH 3.00. Graphical Abstract ᅟ