Recently, China is named among the most carbon dioxide (CO₂)-emitting countries in the world after the United State of America (USA). A major part of Chinese carbon dioxide emissions is as a result of offshore industrial activities which come into the economy as foreign direct investment (FDI). Following this, the present study seeks to investigate the nexus between CO₂ emissions, FDI, energy use, and tourism arrivals, and possibly to advise on who will bear the responsibility of offshore CO₂ emissions. Utilizing ARDL-bound testing and Granger causality approaches for both short- and long-run effects the author found that economic growth (GDP) has a positive relationship with both tourism arrivals, energy use, FDI, and CO₂.This contributes to heavy CO₂ emissions which the author classified as the outsourced/offshore CO₂emissions in China’s FDI. Tourism arrivals have a bi-directional (feedback) causal relationship with energy use and a uni-directional causal relationship with CO₂(transmitting from tourism to CO₂). Both FDI and energy use have a bi-directional (feedback) causal relationship; CO₂, energy use, and tourism arrivals have a unidirectional relationship with GDP which established the triangular nexus causality among the variables and the impact on GDP. Hence, the policy implication should be geared towards implementing the policies and regulations that will checkmate and reduce the excesses of foreign firms to the environment quality of China and promote environmentally friendly economic activities.

Acid mine drainage is one of the main environmental hazards to ecosystems worldwide and it is directly related to mining activities. In Ecuador, such acidic-metallic waters are drained to rivers without treatment. In this research, we tested a laboratory combined (Ca-Mg) Dispersed Alkaline Substrate (DAS) system as an alternative to remediate acid drainage from the Zaruma-Portovelo gold mining site, at El Oro, Ecuador. The system worked at low and high flow hydraulic rates during a period of 8 months, without signs of saturation.. Analysis of physico-chemical parameters and water composition (ICP-OES, ICP-MS) demonstrated that treatment effectively increased water pH and promoted the retention of about 80% of Fe, Al, Mn and Cu. Under acid conditions As, Cr and Pb concentrations decreased with Fe and possible precipitation of jarosite and schwertmannite. However, the homogeneous depletion of Cr at pH above 6 could be related to ferrihydrite or directly with Cr (OH)₃ precipitation. After DAS-Ca, sulphate, phosphate and rare earth elements (REE) concentrations decreased to 1912, 0.85 and 0.07 mg/L respectively, while DAS-Mg contributed to form a complex model of minor carbonate and phosphate phases as main sink of REE. DAS-Mg also promoted the retention of most divalent metals at pH values over seven. Thus, this low cost treatment could avoid environmental pollution and international conflicts. Anyway, further investigations are needed to obtain higher Zn retention values. Graphical abstract

During the evolution of the human, agriculture and land utilization was inevitably connected with survival in nature. Human activity was not only restricted to the production of agricultural products but also extended into many other sectors, such as the production of several industrial-made products, mining, and usage of fossil fuels as a standard method of generating electricity. However, the intense urbanization phenomenon ultimately caused, during the last few decades, the degradation of our natural environment. As a result, the quality (and quantity) of produced food we consume has significantly decreased. The need for the evolution of alternative methods of cultivation is constant and always a hot topic, especially in order to confront the multiple problems that conventional agriculture has. Hydroponics, an innovative cultivation method, comes to solve many of these problems.

As an active substance, dissolved organic matter (DOM) acts a pivotal part in heavy metals (HMs) transportation from urban forestland soil to aquatic ecosystem. In this study, the soil samples from 35 individual subareas were scientifically collected with the aid of geographical information system (GIS) technology. UV-visible (UV-vis) and excitation-emission matrix (EEM)–related parameters suggested that the DOM in urban forestland soil mainly originated from terrestrial and microbial sources. Fluorescence quenching titration associated with parallel factor (PARAFAC) modeling was applied to quantify the complexation ability of four HMs (Cu, Cd, Pb, and Ni) and DOM in urban forestland soil. One fulvic-like (C1), two humic-like (C2 and C3), and one protein-like fluorophores (C4) were identified by EEM-PARAFAC modeling. Considerable differences in fluorescence quenching curves were observed between individual organic constituents and target HMs. Among the four HMs, addition of Cu(II) ions resulted in EEM spectra quenching of each PARAFAC-decomposed organic constituent. However, relatively strong fluorescence quenching phenomena were only detected in humic-like constituents (C2 and C3) with the titration of Pb(II) and Ni(II), which revealed that these types of organic constituent were predominantly responsible for Pb(II) and Ni(II) binding in urban forestland soil–derived DOM. Furthermore, considering the resistant nature of C2 and C3 constituents along with their significant quenching effects for the four target HMs, the concentrations of humic-like constituents in urban forestland soil may be a useful parameter to evaluate the potential risk of HMs immobilization and transformation.

3-Phenoxybenzoic acid (3-PBA) is a shared metabolite of several synthetic pyrethroid pesticides (SPs) resulting from environmental degradation of parent compounds and thus occurs frequently as a residue in samples. Hence, the importance of 3-PBA evaluation after pyrethroid application. There is a gap of analytical methods to determine 3-PBA in soil samples. Therefore, an analytical method that combines the solid-phase extraction (SPE) and gas chromatography–mass spectrometry (GC/MS) detection has been developed for the determination of 3-PBA in soil samples. The analytical method was validated in terms of linearity, sensitivity, intra- and inter-day batch precisions, recoveries, and quantification limits. An SPE method using a Strata X cartridge allows obtaining limits of detection and quantification equal to 4.0 and 13.3 ng g⁻¹, respectively. Under optimized conditions, the method average recovery levels ranged from 70.3 to 93.5% with a relative standard deviation below 3.4%. Method intra- and inter-day precision was under 5.0 and 4.8%, respectively. The developed method was applied to 11 agricultural soil samples in the north of Portugal. The developed methodology allowed for the determination of the pyrethroid metabolite, 3-PBA, in agricultural soil samples at levels of few ng g⁻¹. Graphical abstract ᅟ

The aim of our study was to investigate the concentrations of toxic metals in the feathers of predatory birds in the Hortobágyi Madárpark (Bird Hospital Foundation). Samples were collected from different predatory birds originated from the eastern and north-eastern region of Hungary. Inductively coupled plasma optical emission spectrometry was used to determine the concentration of toxic metals. The mean values varied between bird species groups, their concentrations were between 0.29 ± 0.24 and 0.40 ± 0.30 mg/kg for arsenic (As), 0.09 ± 0.03 and 0.20 ± 0.18 mg/kg for cadmium (Cd), 1.15 ± 1.40 to 2.30 ± 1.52 mg/kg for lead (Pb) and 0.58 ± 0.31 to 2.19 ± 1.25 mg/kg for mercury (Hg), respectively. The measured values are not over the considered threshold values for these toxic metals and in accordance with similar concentrations of them recorded in similar species within Europe. No significant differences were found in their concentration between genders or age in the species. According to the detected concentrations of these metals, their levels accumulated in the feather of the investigated birds do not indicate the possibility of poisoning.

Indoor air quality (IAQ) is one of important issues in indoor environment due to exposure to inhalable aerosol which is affected by indoor and outdoor factors. To demonstrate the effect of indoor and outdoor to the IAQ, this study presents three fractions of particulate matter (PM) (PM₂.₅, PM₄, PM₁₀), characterization of I/O ratios for PM under potential indoor (average occupancy) and outdoor factors (Asian dust, rain, wind, and snow days) and evaluation of chemical components in aerosols. In the chemical characteristics of PM, organic carbon (OC), elemental carbon (EC), and trace elements were analyzed in indoors and outdoors. There was no significant difference of respirable aerosol (PM₂.₅ and PM₄) concentration in different indoor environments. The concentration of OC in PM₁₀ was lower in indoor than outdoor in summer and winter seasons, while the concentration of OC in PM₂.₅ was higher in indoor than outdoor. Also, the OC/EC ratios in PM₂.₅ were higher than those in PM₁₀. Further, the ratios of trace elements in PM₂.₅ and PM₁₀ were different at various locations within the building. This study demonstrated that the exposure to PM₂.₅ is greatly affected by outdoor environment. Although there was no difference in inhalable and respirable aerosol concentration at different locations within the building, the impact of outdoor factors is strongly supported by OC/EC ratios and PM₂.₅/PM₁₀ ratios of trace elements. This study shows that chemical components through the HVAC system affected the exposure to the indoor respirable aerosol, which could lead to adverse effect on the indoor air quality.

Energy affects the economic growth and development of a country. Renewable energy has become an important part of the world’s energy consumption. The use of fossil fuel energy contributes to global warming and carbon dioxide emissions, and has a detrimental effect on the environment. The long-run and short-run causality relationships between electric power consumption, renewable electricity output, renewable energy consumption, fossil fuel energy consumption, energy use, carbon dioxide emissions, and gross domestic product per capita for Pakistan over the period of 1990–2017 were investigated in this paper using the autoregressive distributed lag bounds testing approach to cointegration. The augmented Dickey–Fuller unit root test and the Phillips–Perron unit root test were used to check the stationarity of the variables, while the Johansen cointegration test was applied to check the robustness of the long-run relationships. The Granger causality test under the vector error correction model extracted during the short-run estimation showed a unidirectional relationship among all variables except for the relationship between gross domestic product per capita and carbon dioxide emission, which was bidirectional (feedback hypothesis). The evidence showed that in the long run, carbon dioxide emissions, electric power consumption, and renewable electricity output had a positive and significant relationship with the gross domestic product per capita, while the relationship of renewable energy consumption, energy use, and fossil fuel energy consumption with the gross domestic product per capita had a negative effect. Overall, the long-run effects of the variables were found to have a stronger effect on the gross domestic product per capita than the short-run dynamics, which indicated that the findings were heterogeneous. The evidence suggests that the government of Pakistan should take steps to enhance the use of renewable energy resources to resolve the energy crisis in the country and introduce new policies to reduce carbon dioxide emissions.

As one kind of cheap, environmentally-friendly and efficient treatment materials for direct control of cyanobacterial blooms, modified clays have been widely concerned. The present study evaluated cyanobaterial removal by a red soil-based flocculant (RSBF) with a large enclosure experiment in a tropical mesotrophic reservoir, in which phytoplankton community was dominated by Microcystis spp. and Anabaena spp. The flocculant was composed of red soil, chitosan and FeCl₃. Twelve enclosures were used in the experiment: three replicates for each of one control and three treatments RSBF₁₅ (15 mg FeCl₃ l⁻¹), RSBF₂₅ (25 mg FeCl₃ l⁻¹), and RSBF₃₅ (35 mg FeCl₃ l⁻¹). The results showed that the red soil-based flocculant can significantly remove cyanobacterial biomass and reduce concentrations of nutrients including total nitrogen, nitrate, ammonia, total phosphorus, and orthophosphate. Biomass of Microcystis spp. and Anabaena spp. was reduced more efficiently (95%) than other filamentous cyanobacteria (50%). In the RSBF₁₅ treatment, phytoplankton biomass recovered to the level of the control group after 12 days and cyanobacteria quickly dominated. Phytoplankton biomass in the RSBF₂₅ treatment also recovered after 12 days, but green algae co-dominated with cyanobacteria. A much later recovery of phytoplankton until the day of 28 was observed under RSBF₃₅ treatment, and cyanobacteria did no longer dominate the phytoplankton community. The application of red soil-based flocculant greatly reduces zooplankton, especially rotifers, however, Copepods and Cladocera recovered fast. Generally, the red soil-based flocculant can be effective for urgent treatments at local scales in cyanobacteria dominating systems.

In this study, we effectively suppressed arsenic and cadmium uptake into a plant using magnetic nanoparticle powder (MNP) and fermented bark amendment (FBA) in agar medium. The MNP (which consists of FeO·Fe₂O₃) quantitatively adsorbed arsenite (As(III)) and the FBA (which mainly consists of bark waste) adsorbed cadmium, regardless of the pH. The properties of MNP and FBA in agar medium were compared based on the amounts of arsenic and cadmium in cultivated radish sprouts. While adding FBA selectively suppressed cadmium uptake by radishes, adding MNP suppressed the uptake of both arsenic and cadmium. Considering that the uptake of analytes was slightly reduced even in agar without any additives, the agar itself might also have contributed to the suppression of analyte uptake into plants. In addition, even when radish sprouts were cultivated in agar containing arsenic and cadmium (100 μg/L each) mixed with 25 g MNP and 1.25 g FBA per 25 mL agar, arsenic and cadmium absorption decreased by 90% and 82%, respectively, versus agar without additives. Furthermore, adding the mixed amendment to agar accelerated the growth of radishes, whereas MNP significantly inhibited radish growth even though it reduced analyte uptake. Our results indicated that mixing inorganic and organic adsorbents could simultaneously inhibit cadmium and arsenic uptake by plants and accelerate plant growth in the cadmium and arsenic-contaminated agar medium.