The objective of the study is to conduct the socio-economic and environmental survey about the feasibility of Saudi Arabia-China-Pakistan Economic Corridor (SCPEC) in five different dimensions, i.e., (i) key strengths of SCPEC project, (ii) prospective weaknesses of SCPEC project, (iii) opportunities attain Pakistan from SCPEC project, (iv) opportunities gain SCPEC from Pakistan, and (v) possible threats from SCPEC to other countries, including India. The larger number of intellects participated in this survey, including armed personnel working in strategic industries, academicians of higher education institutes, colleges, and public/private schools, doctors, civil servants, employees of non-governmental organizations, and others. The survey identified five major key strengths, including tourism promotion, infrastructure development, technology diffusion, energy demand, and mutual trade gains, while the prospective weaknesses are financial constraints, political instability, international dumping, corruption, and lack of good governance. The survey results show that Pakistan economy could attain maximum opportunities from SCPEC project in the form of economic empowerment, mutual trade gains, transportation development, entrepreneurship, and development of Gwadar port, while the SCPEC project gains from Pakistan in the form of economic stabilization, trade gains, and low transportation cost. The possible threats to SCPEC project to the other countries including India are political threats, security issues, Kashmir issue, and economic issues. The survey results conclude that the large number of intellects confirmed the positivity of SCPEC project for both the Pakistan and for the Chinese economy, while few intellects in numbers are incompatible with the SCPEC project due to economic, environmental, and security threats.

Sediments are reservoirs and sources of DDTs to the aquatic ecosystem. However, the role of sediment particulate matter and benthic organisms in transferring DDTs remains unclear. In this study, microcosms were built up with different groups to simulate a freshwater system with DDT-contaminated sediment and organisms. The impacts of different exposure routes (water and sediment) on the changes of DDT and its metabolites (DDD and DDE) in carp (Cyprinus carpio) were investigated. The bioturbation of Tubifex tubifex (Oligochaeta, Tubificidae) was investigated to understand the fate and transfer of DDTs in aquatic environment. For the sediment treatment, the concentrations of o,p’-DDT in carp were significantly higher than those of p,p’-DDT, and the metallothionein (MT) content decreased. The bioaccumulation of DDTs in carp via sediment particulate matter was significantly higher/faster than that via overlying water. T. tubifex and sediment particulate matter accelerate DDT bioaccumulation in carp. Selective enrichment of the (+)-o,p’-DDT and (+)-o,p’-DDD was found in carp. These results help to reduce uncertainty in ecological and health risk assessments and to better understand the risk of DDTs in the environment.

Laccases produced by Leucoagaricus gongylophorus act in lignocellulose degradation and detoxification processes. Therefore, the use of L. gongylophorus laccase (Lac1Lg) was proposed in this work for degradation of anthracene and others polycyclic aromatic hydrocarbons without the use of mediators. Degradation reactions were performed in buffer aqueous solution with 10 ppm of anthracene and other PAHs, Tween-20 in 0.25% v/v and a laccase preparation of 50 U. The optimum condition (pH 6.0 and 30 °C) was determined by response surface methodology with an excellent coefficient of determination (R²) of 0.97 and an adjusted coefficient of determination (R²ₐdⱼ) of 0.93. In addition, the employment of the mediator ABTS decreased the anthracene biodegradation from 44 ± 1% to 30 ± 1%. This optimum pH of 6.0 suggests that the reaction occurs by a hydrogen atom transfer mechanism. Additionally, in 24 h Lac1Lg biodegraded 72 ± 1% anthracene, 40 ± 3% fluorene and 25 ± 3% phenanthrene. The yellow laccase from L. gongylophorus biodegraded anthracene and produced anthrone and anthraquinone, which are interesting compounds for industrial applications. Moreover, this enzyme also biodegraded the PAHs phenanthrene and fluorene justifying the study of Lac1Lg for bioremediation of these compounds in the environment.

Natural steroid estrogens (NSEs), including free estrogens (FEs) and conjugated estrogens (CEs), are of emerging concern globally among public and scientific community due to their recognized adverse effects on human and wildlife endocrine systems in recent years. In this review, the properties, occurrence, sorption process, and transformation pathways of NSEs are clarified in the environment. The work comprehensively summarizes the occurrence of both free and conjugated estrogens in different natural and built environments (e.g., river, WWTPs, CAFOs, soil, and sediment). The sorption process of NSEs can be impacted by organic compounds, colloids, composition of clay minerals, specific surface area (SSA), cation exchange capacity (CEC), and pH value. The degradation and transformation of free and conjugated estrogens in the environment primarily involves oxidation, reduction, deconjugation, and esterification reactions. Elaboration about the major, subordinate, and minor transformation pathways of both biotic and abiotic processes among NSEs is highlighted. The moiety types and binding sites also would affect deconjugation degree and preferential transformation pathways of CEs. Notably, some intermediate products of NSEs still remain estrogenic potency during transformation process; the elimination of total estrogenic activity needs to be addressed in further studies. The in-depth researches regarding the behavior of both free and conjugated estrogens are further required to tackle their contamination problem in the ecosystem. Graphical abstract ᅟ

Today, environmental pollution, especially heavy metal pollution, is known as a new and possibly more dangerous pollutant than other environmental ones. For this purpose, the uptake of four aquatic plants in different environments was chosen. In this experiment, four macrophytes, i.e., umbrella palm (Cyperus alternifolius), duckweed (Lemna minor), water hyacinth (Eichhornia crassipes), and canna (Canna × generalis), were studied in five contaminated aquatic environments, i.e., Gohar Rood river, Zarjoob river, Eynak lagoon, Anzali lagoon, and control solution (containing Cd, Cr, Pb, and Zn). The results showed that the highest uptake rates of cadmium, cobalt, vanadium, chromium, zinc, nickel, and lead were observed for duckweed fronds. The highest bioconcentration factor (BCF) of nickel was related to duckweed stem and water hyacinth root, and the highest BCF of cadmium belonged to duckweed fronds and canna root. The highest rate of uptake of cadmium, chromium, zinc, and lead was related to control. The least amount of uptake of several metals by plants was obtained from the water of Gohar Rood and Zarjoob. Generally, based on the results of this study, it can be stated that duckweed is suitable for the uptake of most heavy metals.

This study mainly focuses on the preparation, characterization, and sorption performance for Cu(II) and Zn(II) by using nano-alumina material (NA) synthesized through the sol-gel method. The SEM, EDS, FT-IR, and XRD analysis methods were implemented to identify the micromorphology and crystal structure of the synthesized NA absorbent and its structure after the adsorbing procedure. The effect of effective variables including various absorbent dose, contact time, initial ion concentration, and temperature on the removal of Cu(II) and Zn(II) from aqueous solution by using NA was investigated through a single factor experiment. Kinetic studies indicated that adsorption of copper and zinc ions by NA was chemical adsorption. The adsorption isotherm data were fitted by Langmuir (R²: 0.919, 0.914), Freundlich (R²: 0.983, 0.993), and Temkin (R²: 0.876, 0.863) isotherms, indicating that copper and zinc ions were easily adsorbed by NA with maximum adsorption capacities of 87.7 and 77.5 mg/g for Cu²⁺ and Zn²⁺, respectively. Thermodynamic parameters indicated that the adsorption of Cu²⁺ was spontaneous(G<0) and the adsorption of Zn²⁺ might not be spontaneous (G > 0) by NA. Graphical abstract ᅟ

Poly(L-lactic acid) (PLLA) can be used as an external electron donor in denitrification reactors to treat drinking water, aquaculture water, and industrial wastewater with an imbalanced carbon/nitrogen ratio. However, for PLLA to function in these applications, its chemical hydrolyzability requires improvement. Although the adjustment of the crystallinity (Xc) is effective in improving the hydrolyzability of PLLA, the condition for the Xc of PLLA, in which a sufficient amount of lactic acid is released for denitrification, must be clarified. Therefore, this study investigated the effective Xc range and optimal PLLA content as an electron donor for continuous nitrate removal in denitrification reactors. This study also explored the abundance, succession, and diversity of active denitrifying bacteria in denitrification reactors. The nitrate removal activity of activated sludge using the highly crystalline PLLA (Xc = 39.4%) was 1.8 mg NO₃⁻ -N g MLSS⁻¹ h⁻¹, which is 2.4 times higher than that using the nearly amorphous PLLA (Xc = 0.9%). During the 57 days of operation, the denitrification reactor with 3% (w/v) highly crystalline PLLA continued to completely remove nitrate, with a maximum nitrate removal activity of 22.8 mg NO₃⁻ -N g MLSS⁻¹ h⁻¹. The 16S rRNA amplicon sequencing and clone library analyses are using transcripts of two nitrite reductase genes, encoding cytochrome cd₁ nitrite reductase, and copper-containing nitrite reductase revealed that bacteria belonging to the families Comamonadaceae, Rhodocyclaceae, and Alcaligenaceae were active denitrifying bacteria in the denitrification reactor using PLLA.

Based on the compartment and exponential models, the distribution of Fukushima-derived ¹³⁷Cs was evaluated at four sampling dates in undisturbed coniferous forest soil. The compartment model was employed to evaluate the dynamic of ¹³⁷Cs in the three sub-sections of the forest floor (FF), namely undergrowth (UG), litter layer (OL), and fragmented litter layer (OF), while the exponential model was administrated to describe its distribution below the FF. According to the compartment model, the derived ecological half-life of ¹³⁷Cs in the UG, OL, and OF layers was 0.97, 1.1, and 4.9 years, respectively, indicating ¹³⁷Cs resides much longer in the OF layer. Hence, this soil section remains a potential source of radiation dose mainly due to its high ¹³⁷Cs content associated with low attenuation effect. Below the OF layer, the ¹³⁷Cs distribution was well described by exponential model and its derived relaxation lengths were in the range of 0.8–1.4 cm, implying the migration of ¹³⁷Cs in mineral soil is very slow and almost intact during the observation time. Collectively, our results highlighted that the compartment model for the FF and the exponential model for the soil below the FF are adequate enough to generate essential information. Thus, the potential decontamination measures should have to be chosen on their effect on the FF’s ¹³⁷Cs. Graphical abstract

The novel nano-flocculants were synthesized through a conjugation of dodecylamine with partly oxidized sodium alginate. The structures of the flocculants were characterized by FTIR, ¹HNMR, TGA, and EA. The flocculants possessed amphiphilic structures and formed nano-micelles through self-assembly in water. The nano-micelles showed rod-like shapes about 100 nm. Removal rates of the flocculants for Pb²⁺ and bisphenol A were determined under different conditions, showing the removal rates as high as 97.20% and 88.66% for Pb²⁺ and bisphenol A, respectively. The flocculation mechanisms were revealed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM), respectively. Isotherm adsorption studies indicated that the flocculation for Pb²⁺ accorded with the Langmuir single-layer adsorption model, and for bisphenol A accorded with the Freundlich multi-layer adsorption model. The quasi-second-order kinetic model was suitable for describing the adsorption kinetics. The new nano-flocculant was a promising agent for removing both heavy metal ions and organic pollutants of wastewater.

Nitrate pollution in water is a common environmental problem worldwide. The Qinhe Basin (QHB) faces with the risk of eutrophication. To clarify nitrate pollution of river water, water chemical data, water isotope values (δD and δ¹⁸O–H₂O), and dual nitrate isotope values (δ¹⁵N–NO₃⁻ and δ¹⁸O–NO₃⁻) were used to discern sources and transformation mechanisms of nitrogen in the QHB. The nitrate concentrations of river water ranged from 0.71 to 20.81 mg L⁻¹. The δD and δ¹⁸O–H₂O values of river water varied from − 74 to −52‰ and from − 10.8 to − 7.2‰, with an average value of − 60‰ and − 8.2‰, respectively. The δ¹⁵N–NO₃⁻ and δ¹⁸O–NO₃⁻ values of nitrate ranged from − 6.7 to + 14.8‰ and from − 6.0 to + 5.6‰, with a mean value of + 4.6‰ and − 0.6‰, respectively. Assimilation by algae and the mixing of soil nitrogen, chemical fertilizer, sewage, and industrial wastewater could account for increasing δ¹⁵N–NO₃⁻ values. There was neither significantly positive nor negative correlation between δ¹⁵N–NO₃⁻ and δ¹⁸O–NO₃⁻ in river water, indicating that no obvious denitrification shifted isotopic values of nitrate in the QHB. Based on the dual isotopic values of nitrate and land use change in the watershed, it could be concluded that intensive nitrification dominated in the QHB, and dissolved nitrate was mainly derived from nitrification of ammonium in fertilizer, soil nitrogen, and domestic sewage. As the primary nitrate sources identified in the QHB, effective fertilization and afforestation can be taken to protect water resource from nitrate pollution.