Studies on replacement of inorganic fertilizer with organic residues to improve crop productivity and their impact on greenhouse gas emission from agricultural soil merit more attention. Two-year field experiments were conducted to study the impact of different organic residues with varied carbon (C)/nitrogen (N) ratios as substitutes of chemical fertilizer on emission reduction of nitrous oxide (N₂O) and crop yield from a tropical summer rice paddy of India. Five treatments comprising of conventional N fertilizer (NPK), cow manure (CD), rice straw (RS), poultry manure (PM), and sugarcane bagasse (SCB) were applied in a rice field to estimate N₂O emission. Application of CD (at 10 t ha⁻¹) resulted in maximum reduction of seasonal N₂O emissions (15 %) over NPK, RS, PM, and SCB. Application of CD and RS enhanced leaf photosynthetic rate and caused maximum utilization of photosynthates towards developing grains as evident from grain filling ability and higher grain yield. Substitution of NPK with organic residues enhanced soil nutrient availability in terms of C and N resulting in improved soil fertility and to some extent influenced soil nitrogen processes which in turn reduced N₂O emissions. We conclude that suitable management of soil in agricultural ecosystem can reduce the emission of N₂O and protect and preserve the soil health without compromising the agronomic productivity reducing the use of chemical fertilizer and maintaining the sustainability of rice ecosystem as evident from lower carbon equivalent emissions (CEE) and higher carbon efficiency ratio (CER) at CD in rice paddies in the present study.

Most of the chemicals containing non-biodegradable metal pollutants from anthropogenic sources are highly mobile in nature. The only way to contain or limit their movement is through sorption and entrapment in the soil matrices. In this study, the sorptive response of the three most commonly found divalent metal contaminants, copper (Cu⁺²), lead (Pb⁺²), and zinc (Zn⁺²), are studied using two locally available semi-arid soils from Saudi Arabia. To enhance their retention capacity, these soils are amended with lime. The response to sorption at varying initial contaminant concentrations, pH conditions, temperature levels, and dilution ratios are investigated. Relying on empirical models (Langmuir and Freundlich), the nature of sorption (monolayer or heterogeneous) is ascertained. Further, kinetic models are employed to validate the type and nature of sorption that occurs (whether pseudo first-order or second-order). It is found that the experimental results correlate well with these empirical models for both the Al-Ghat and Al-Qatif soils when amended with lime and attenuate Cu, Pb, and Zn to satisfactory levels. The R ² values are close to 1 for all the tested models. The order of sorption was Pb > Cu > Zn for these heavy metals, and also for soils and soil mixtures that were considered: Al-Qatif soil amended with 6 % lime > Al-Ghat soil with 6 % lime > Al-Qatif > Al-Ghat. Lime-treated soils sorbed 73, 65, and 60 % more than the untreated soils for Pb, Cu, and Zn, respectively.

Industrial production of poultry meat is associated with indirect environmental impacts such as contributing to climate change and deforestation and other direct impacts such as the deterioration of the quality of surface waters. Poultry industry effluents are rich in organic matter, nitrogen, and phosphorus; nutrients can be removed from wastewater through the use of macrophytes and periphyton. An essay in mesocosms with poultry industry wastewater recirculation was developed in the presence and absence of a native macrophyte Spirodela intermedia and periphyton from a lowland stream (La Choza stream, Buenos Aires) where the effluent is poured. The diffusion of O₂, increased by water recirculation, had the effect of increasing the concentration of dissolved oxygen in wastewater. The presence of S. intermedia and algae periphyton significantly contributed to the removal rates (%) of solids (69.7 ± 3.9), ammonium nitrogen (84.0 ± 3.4), and total phosphorus (38.1 ± 1.8) from residual water and favored nitrification. The dominance of Bacillariophyceae on other groups of algae of periphyton and the low representation of Euglenophyceae indicated an advanced stage of the effluent treatment process at the end of the assay.

This study investigates the effectiveness and mechanism of decreasing the bioavailability of Pb in bacterial culture and in pot experiments of Pb-contaminated paddy soil by Alishewanella sp. WH16-1. The WH16-1 strain was isolated from mine soil and exhibited high resistances to many heavy metals, especially to Pb²⁺ (2070 mg/L) and Cr (VI) (2340 mg/L). During cultivation of the WH16-1 strain with the addition of 100 mg/L Pb²⁺, Pb²⁺ was precipitated, and 84.13 % of Pb²⁺ was removed in 72 h. The precipitant was observed by transmission electron microscopy (TEM) and further confirmed to be PbS by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The WH16-1 strain was incubated in Pb²⁺-added paddy soil pot experiments for 60 days and compared with the uninoculated Pb²⁺-added paddy soil. Comparison showed that the exchangeable and carbonate-bound Pb in the paddy soil decreased by 14.04 and 10.69 % (P < 0.05), respectively. The Fe-Mn oxide-bound Pb, organic matter-bound Pb and the residual Pb increased by 4.47, 19.40, and 22.78 % (P < 0.05), respectively. Compared with the uninoculated Pb²⁺-added paddy soil, the dry weight of rice significantly increased by 28.59 %, and the Pb concentrations in rice, husk, leaves, and culms in Pb²⁺-added paddy soil pot experiment incubated with the WH16-1 strain significantly decreased by 26.18, 26.94, 26.61, and 25.56 % (P < 0.05), respectively. These results suggest that Alishewanella sp. WH16-1 can reduce the bioavailability of Pb in soil. This bacterium may be applicable for the biological stabilization of Pb in Pb-contaminated paddy soil.

The elimination of herbicides in aquatic environment is influenced by various biotic or abiotic factors. Thus, efficient, more applicable, and flexible methods are in demand. Photodegradation has been applied to remove three main types of herbicides, phenylurea, triazine, and chloroacetanilide, from water, based on a series of TiO₂–reduced graphene oxide nanocomposites. Experimental results showed that the three types of herbicides could be mostly removed under simulated sunlight irradiation for 5 h with the as-prepared photocatalyst. Compared with pure TiO₂ or P25, the photodegradation efficiency has been markedly increased. Thus, the present work could promote a new strategy dealing with the pollution of herbicides in aquatic ecosystems.

Both ultrafine particles (UFP) and polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment, thus increasing their chances of exposure to human in the daily life. However, the study on the combined toxicity of UFP and PAHs on respiratory system is still limited. In this study, we examined the potential interactive effects of silica nanoparticles (SiNPs) and benzo[a]pyrene (B[a]P) in bronchial epithelial cells (BEAS-2B). Cells were exposed to SiNPs and B[a]P alone or in combination for 24 h. Co-exposure to SiNPs and B[a]P enhanced the malondialdehyde (MDA) contents and reduced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities significantly, while the reactive oxygen species (ROS) generation had a slight increase in the exposed groups compared to the control but not statistically significant. Cell cycle arrest induced by the co-exposure showed a significant percentage increase in G2/M phase cells and a decrease in G0/G1 phase cells. In addition, there was a significant increase in BEAS-2B cells multinucleation as well as DNA damage. Cellular apoptosis was markedly increased even at the low-level co-exposure. Our results suggest that co-exposure to SiNPs and B[a]P exerts synergistic and additive cytotoxic and genotoxic effects.

The current experiment was conducted to evaluate the effects of feeding dried sweet orange peel (SOP) and lemon grass leaves (LGL) as feed additives on broiler growth performance, serum metabolites, and antioxidant status. A total of 192-day-old (Ross 308) broiler chickens were distributed randomly into 4 dietary treatments with 4 replicates per each treatment. The dietary treatments included a control diet without any feed additive (T1), a diet containing 0.8 % SOP (T2), a diet containing 0.8 % LGL (T3), and a diet containing combination of 0.4 % SOP + 0.4 % LGL (T4) was fed during the growth period from 22 to 42 days. Feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), carcass traits, serum components, and antioxidant status were measured. At the end of the experimental period, the results indicated that supplementation of SOP and LGL alone or in combination did not significantly (P > 0.05) affect BWG, FI, FCR, and carcass characteristics in broiler chickens. Serum total protein was increased significantly (P < 0.05) in T3 and T4 compared to the other treatments. Also, serum globulin increased significantly (P < 0.05) in the treated groups. Serum glucose, low density lipoprotein, triglyceride, and very low density lipoprotein decreased significantly (P < 0.05) in the treatment groups, while cholesterol and high-density lipoprotein decreased in T2 compared to the other groups. Significantly (P < 0.05) higher total antioxidant status was observed in T2 compared to the other treatments. In conclusion, these results indicate that SOP, LGL, and their combination may positively modify some serum components and the antioxidant status without any beneficial effect on growth performance and carcass traits in broiler chickens.

In early April 2011, radiostrontium was accidentally released from the Fukushima Daiichi Nuclear Power Plant to the Pacific coast of eastern Japan. We developed a simple procedure to analyze radiostrontium levels in marine mussels (Septifer virgatus) and seawater using crown ether (Sr Resin; Eichrom). Then, we used our method to describe the spatial and temporal distribution of radiostrontium in mussels and seawater on the Pacific coast of eastern Japan from 2011 to 2013 and for 2015. Activity of ⁹⁰Sr in mussels and seawater decreased with distance from the Fukushima Daiichi Nuclear Power Plant and between 2011 and 2013 tended to be higher in areas south of the Fukushima Daiichi Nuclear Power Plant than to the north of it. Activity in mussels and seawater also tended to decrease from 2011 to 2013 and by 2015 had reached levels experienced prior to the Fukushima accident. Our results suggest that radiostrontium discharged from the Fukushima Daiichi Nuclear Power Plant was dispersed by coastal currents in a southerly direction along the Pacific coast of eastern Japan from 2011 to 2013, following which its activity decreased to background levels by 2015.

Metals are significant environmental pollutants, and their toxicity is a problem for all living organisms. Indeed, aquatic plants are particularly sensitive to the excess of metal ions. Several researches report that aquatic plants exposed to metal-induced toxicity showed similar responses (e.g. inhibition of growth and induction of oxidative stress). Meanwhile, many studies were involved to counter these toxicities. This paper provides a brief review of the role of the exogenous supply of some compounds in the alleviation or reduction of toxicity in aquatic plants generated by metals. Particular attention is given to the role of polyamine, proline, nitric oxide, glutathione and phytochelatin.

Since the industrial revolution, the impact of effluents produced by human activities on ecosystems has been a major international environmental concern. This study was aimed at observing the changes in water and sediment qualities at a watershed level of two different river systems facing the same land use practices, but impacted to different degrees. Samples were collected at strategically selected sites within the mainstream of both rivers, the major tributaries draining into them, as well as a major impoundment in each system. A distinct difference between the two different rivers was observed. It was established that certain variables, for example pH, contributed to the differential water and sediment quality signatures in the upper Olifants and Mokolo rivers, having important considerations for the future management of both river ecosystems. Other abiotic factors, such as alkalinity and sulphate levels, were also found to be important. The tributaries were found to play an important role in the purification and/or pollution of the mainstream rivers. On the other hand, the present impoundments in the Mokolo River were observed to affect the water and sediment qualities downstream. Overall, through the use of comparative models, it was observed that the upper Olifants River was in a different state than the Mokolo River and the information from this study may aid in the future management of the Mokolo River to prevent a shift to an undesirable state.