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The present study was carried out to ascertain the level of various metals in wheat variety (Chagi–4) irrigated with diverse doses of wastewater. The concentration of metals in soil, water and wheat grain samples was examined through an atomic absorption spectrophotometer. In wheat grains, the mean values of metals (mg/kg) varied from 0.06 to 0.2 for Pb, 1.2 to 1.6 for Cd, 0.6 to 0.9 for Ni, 0.8 to 1.6 for Fe, 0.4 to 1.0 for Mn, 0.7 to 1.4 for Cu, 0.3 to 0.5 for Cr, 0.1 to 0.9 for Zn and 0.03 to 0.2 for Co, correspondingly. Measured concentrations were found within the permissible limit given by FAO/WHO except for cadmium whose concentration exceeded an acceptable limit 0.2 mg/kg suggested by FAO/WHO. It might be due to high soil pH, which hinders the efficient transfer of metals between different mediums. Wastewater irrigated soil, wheat and water had high metal values, but the low rate of transfer was noticed from soil to grains. Higher bioconcentration factor was obtained for manganese and cadmium; cadmium had even higher pollution load index, which could indicate the contamination status of soil. Therefore, regular monitoring of wastewater is necessary to prevent the excessive build-up of metals.

Climate change predictions derived from coupled carbon-climate models are highly dependent on assumptions about feedbacks between the biosphere and atmosphere. One critical feedback occurs if C uptake by the biosphere increases in response to the fossil-fuel driven increase in atmospheric CO2 (\"CO2 fertilization\"), thereby slowing the rate of increase in atmospheric CO2. Carbon exchanges between the terrestrial biosphere and atmosphere are often first represented in models as net primary productivity (NPP). However, the contribution of CO2 fertilization to the future global C cycle has been uncertain, especially in forest ecosystems that dominate global NPP, and models that include a feedback between terrestrial biosphere metabolism and atmospheric CO2 are poorly constrained by experimental evidence. We analyzed the response of NPP to elevated CO2 (approximately equal to 550 ppm) in four free-air CO2 enrichment experiments in forest stands. We show that the response of forest NPP to elevated CO2 is highly conserved across a broad range of productivity, with a stimulation at the median of 23 +/- 2%. At low leaf area indices, a large portion of the response was attributable to increased light absorption, but as leaf area indices increased, the response to elevated CO2 was wholly caused by increased light-use efficiency. The surprising consistency of response across diverse sites provides a benchmark to evaluate predictions of ecosystem and global models and allows us now to focus on unresolved questions about carbon partitioning and retention, and spatial variation in NPP response caused by availability of other growth limiting resources.

Nowadays rare earth elements (REEs) are widely applied in high-technology and clean energy products, but their environmental risks are still largely unknown. To estimate the ecological risk of REEs, soil samples were collected from REE mine tailings with and without phytoremediation. The results showed that the tailings had rather low organic matter and high total REE concentrations, up to 808.5 mg/kg. The 10% effective concentration (EC10) of neodymium (Nd) and yttrium (Y) were calculated based on the toxicity tests of seed germination and root growth. For both wheat and mung bean, the EC10 of Nd and Y in soils were in the range of 1053.1–1300.1 mg/kg. The average hazard quotient of mine tailing soil without phytoremediation was higher than that with phytoremediation. All the hazard quotient of Nd and Y were less than 1, indicating that Nd or Y alone was unlikely to cause adverse ecological effects. Given to the coexistence of REEs on mine sites, the ecological risk of REE mixture could be potentially high towards local soil environments, even for soils with phytoremdiation.

Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.

Silver nanoparticles (AgNPs) is widely used as an antibacterial agent, but the specific antibacterial mechanism is still conflicting. This study aimed to investigate the size dependent inhibition of AgNPs and the relationship between inhibition and reactive oxygen species (ROS). Azotobactervinelandii and Nitrosomonaseuropaea were exposed to AgNPs with different particles size (10 nm and 50 nm). The ROS production was measured and the results showed that the generation of ROS related to the particle size and concentrations of AgNPs. At 10 mg/L of 10 nm Ag particles, the apoptosis rate of A. vinelandii and N. europaea were 20.23% and 1.87% respectively. Additionally, the necrosis rate of A. vinelandii and N. europaea reached to 15.20% and 42.20% respectively. Furthermore, transmission electron microscopy images also indicated that AgNPs caused severely bacterial cell membrane damage. Together these data suggested that the toxicity of AgNPs depends on its particle size and overproduction of ROS.

The aim of the present research was to determine the trace metal accumulations in Trigonella foenum-graecum irrigated with three different water regimes (ground water, canal water and sugar mill water). Also, transfer factors, pollution load indices, and health risk indices were assessed to evaluate metal transport and accumulation through the food chain. The analysis was conducted by Atomic Absorption Spectrophotometer (Shimadzu model AA-6300) to evaluate the concentration of metals in water, soil and vegetables. Trace metal concentrations in water samples ranged from 0.84 to 1.67, 0.42 to 0.72, 0.45 to 0.85, 2.51 to 9.99, 1.21 to 1.92, 1.82 to 9.98 and 0.64 to 0.91 mg/kg for Cd, Cr, Cu, Fe, Ni, Zn and Mn, respectively. The mean metal concentrations in soil samples were determined as 0.25, 0.86, 0.96, 3.37, 0.4, 0.44 and 2.31 mg/kg for Cd, Cr, Cu, Fe, Ni, Zn and Mn, respectively. Trace metal accumulations in T. foenum-graecum samples gathered from where soil samples were taken are as follows: The contents of Cd, Cr, Cu, Fe, Ni, Zn and Mn ranged from 0.48 to 1.06, 0.11 to 0.35, 0.15 to 0.29, 1.43 to 8.39, 0.39 to 0.54, 2.1 to 3.05 and 0.42 to 0.47 mg/kg, respectively. Statistical analyses showed that the treatments have non-significant effect (p > 0.05) on concentrations of metals in T. foenum-graecum samples collected from three sites for Ni, Cr, Cu, Zn and Mn and significant effect on Fe and Cd.

Extended spectrum beta lactamase (ESBL) are emerging beta-lactamases in Gram-negative pathogens, causing serious problems in hospitalized patients worldwide. Biofilm mode of virulence has decreased the efficiency of antibiotics used for treatment against ESBL pathogens. Therefore, there is an urgent need for alternative agents such as nanoparticles that can prevent and inhibit the biofilm formation. The aim of the present study was to inhibit the biofilm formed by ESBL-producing Escherichia coli using silver nanoparticles (AgNPs) synthesized with fresh water diatom ( Nitzschia palea ). AgNPs were characterized using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), and XRD. AgNPs at their biofilm inhibitory concentration (BIC) of 300 ng ml −1 significantly reduced the biofilm formed by E. coli . Interestingly, Congo red assay revealed the reduction of curli, essential for biofilm formation in the presence of AgNPs. Light and CLSM examination of the biofilm images also validated that in the presence of AgNPs, the biofilm architecture was disintegrated and the thickness was significantly reduced. Overall, the present study exemplifies the use of AgNPs as a plausible alternative for conventional coating agents on implant devices to prevent and control biofilm-associated urinary tract infections.

Previous studies show mercury (Hg) can be effectively removed from solution by biochar, but limited attention was paid on the complexation between Hg and components released from biochars, e.g. dissolved organic matter (DOM). Here, aqueous data from batch-style experiments were modeled using PHREEQC, incorporating thermodynamic constants between Hg and DOM, which was assumed to be composed of thiol, carboxylic, and phenolic functional groups. Modelling results suggest that > 99% Hg complexed with thiol groups in DOM. The modelled concentrations of Hg–DOM complexes from low-T (low-temperature, 300°C) biochars were greater than from high-T (600°C) biochars. The concentrations of Hg–DOM complexes were lower in wood-based than in agricultural residue- and manure-based biochars. Hg–DOM complexes may affect Hg speciation, bioavailability, transport, and methylation processes. This research describes a method to evaluate Hg–DOM interactions, and the results indicate extra caution regarding Hg–DOM complex formation is required in the selection of biochar for Hg remediation.

Sardinia was known as an important mine pole in Europe during his history. Still after decades from mine closure, 75.000.000 m3 of mine waste, rich in heavy metals, were left abandoned causing a huge environmental legacy on the mine district area. Consequently, cost effective remediation is required. In this frame, phytoremediation is considered a feasible candidate. This research was focused on Helichrysum microphyllum subsp. tyrrhenicum, which is pioneer in xeric soils with low-functions, like mine tailings. The aim of this study was to evaluate its ability to extract heavy metals from mine soils and accumulate them in plant tissues and its suitability for phytostabilization. Sundry samples of soil, roots and epigean organ were collected through field sampling and analysed in order to obtain metals concentration and mineralogical characteristics. Our results indicate that this species tolerates high concentration of zinc, lead and cadmium, behaving as a species suitable for phytostabilization.

Poly(imide-ether)s (PIEs), which is porous in nature, was synthesized using aromatic diamines and dianhydrides via the solution polycondenzation reaction. In the process, PIEs was used as an adsorbent for the removal of basic dye [Methylene blue (MB)] from the aqueous solution. The structure and the thermal stability of PIEs were characterized by FT-IR, 1H-NMR, XRD and TG analysis, and the adsorption behaviour of the PIEs was confirmed using UV/Visible, FT-IR and SEM with EDX analysis. Batch adsorption experiments were carried out and their parameters (pH 6.95), initial MB concentration (200 mg/L), adsorbent dosage (50 mg), contact time (120 min) and temperature (28 °C) were optimized. The batch adsorption experimental data of the effect of contact time, initial MB concentration and temperature were evaluated using the adsorption kinetics (Pseudo-first order, Pseudo-second order, Elovich and Intra-particle diffusion kinetic), isotherm (Langmuir, Freundlich, Redlich–Peterson and Sips isotherms) and thermodynamic models respectively. In the study, adsorption of MB onto PIEs followed Pseudo-second kinetics and found to be the best fitting model based on the obtained experimental data. The homogeneity and heterogeneity surface nature of PIEs were elucidated with two and three isotherm parameters respectively. The adsorption thermodynamic study indicates that the adsorption of MB onto PIEs was endothermic and spontaneous in nature. The adsorbed PIEs solid waste was utilized to prepare the polymer composite, and its property was characterized.Graphical Abstract