The shortage of fresh water is a major problem throughout the world, but the situation is worst in the arid and semiarid regions. Therefore, reuse of nonconventional water resources such as treated wastewater (TWW) is a common practice to irrigate field crops, vegetables, and forestry sectors. The present study was conducted to evaluate the significant impact of different heavy metals such as copper (Cu), iron (Fe), chromium (Cr), and zinc (Zn) on the soil and leafy, root, and fruit vegetables following irrigation with TWW through subsurface drip irrigation. Our results indicate that iron (Fe) was highest in lettuce followed by spinach, and Zn and Cr were second and third most abundant element in the different vegetables. Eggplant and radish showed the lowest concentrations of various heavy metals. A significant difference was observed in transfer factor (TF) among vegetables, and highest TFₛₒᵢₗ₋ᵥₑg was observed for Fe in lettuce and the lowest for Cr in eggplant. Estimated daily intake (EDI) was the lowest in adults and highest in children. Target hazard quotient (THQ) of Cu, Zn, and Fe being < 1.0 appears relatively safe in all the tested vegetables. Risk index (RI) values showed that heavy metals were lower than 1.0 and hence lower risk for human. The combined HI values for Cu, Zn, Cd, Cr, and Pb were substaintionaly higher 12.8 and 9.21 after consumption of lettuce and carrot. So, consumption of these vegetables should be avoided after irrigation with TWW. Spinach exhibited maximum total coliform loading, while ecological risk was negligible due to sandy nature of soil type. Health risks to human could be reduced through proper selection of suitable vegetables, time of maturity, and consumed organs (leaf, fruit, or root part). Appropriate should be followed to decontaminate the microbial load in order to avoid any risks to human health (both adults and children).

The 4-nitrophenol (4-NP) is one of the carcinogenic pollutants listed by US EPA and has been detected in industrial wastewater. This study investigates the photocatalytic degradation of 4-NP with TiO₂ and boron (B)-doped TiO₂ nanostructures. The degradation on undoped and B-doped TiO₂ with various boron loadings (1–7%) was studied to establish a relationship between structure, interface, and photo-catalytic properties. The results of XRD, micro Raman, FTIR, and HRTEM show that the B doping has improved the crystallinity and induces rutile phase along with anatase (major phase). The N₂ adsorption-desorption, SEM-EDX, and XPS indicated that the B induced the formation of mesoporous nanostructures in TiO₂ and occupies interstitial sites by forming Ti-O-B type linkage. The surface area of pure TiO₂ was decreased from 235.4 to 63.3 m²/g in B-TiO₂. The photo-physical properties were characterized by UV-Vis DRS, which showed decrease in the optical band-gap of pure TiO₂ (2.98 eV) to B-TiO₂ (2.95 eV). The degradation results demonstrated that the B doping improved the photocatalytic activity of TiO₂; however, this improvement depends on the B concentration in doped TiO₂. B-doped TiO₂ (> 5% B) showed 90 % degradation of 4-NP, whereas the undoped TiO₂ can degrade only 79 % of 4-NP. The degradation followed pseudo-first-order kinetics with rate constant values of 0.006 min⁻¹ and 0.0322 min⁻¹ for pure TiO₂ and B-TiO₂ respectively. The existence of a reduced form of Ti³⁺ on the surface of TiO₂ (as evidence from XPS) was found responsible for enhancement in photocatalytic activity.

“Swimming across the Pearl River” is an annual large-scale sporting event with great popularity in Guangzhou. To reduce the risk of swimmers’ exposure to various contaminants in the Pearl River during swimming activities, the local government limits direct sewage and effluent discharge from urban channels during the event. However, the impact of discharge reduction on some contaminants of emerging concern (CECs), such as organophosphorus flame retardants (OPFRs), bisphenol analogues (BPs), and triclosan remains unknown. In the present study, the concentrations of CECs, as well as ammonia-nitrogen (NH₃-N), dissolved organic carbon, and chemical oxygen demand, were measured in aqueous and suspended particulate matter (SPM) from the Guangzhou reaches of the Pearl River. The concentration ranges of sixteen OPFRs, eight BPs, and triclosan were 21.2–91.0, 8.46–37.3, and 1.47–5.62 ng/L, respectively, in aqueous samples, and 25.2–492, 14.0–86.3, and 0.69–17.5 ng/g, respectively, in SPM samples. Hydrophobic and π-π interactions could be contributing to the distribution of CECs. Principal component analysis indicated that consumer materials, manufacturing, and domestic sewage might be the main sources of the CECs. In addition, our study showed that the concentrations of CECs did not change considerably before or after discharge reduction activities, although NH₃-N showed a substantial decrease following pollution control measure. The results demonstrated that temporary reductions of contaminant discharges to the Pearl River had only limited effect on the levels of CECs. Further research is needed to investigate the distributions and potential health risks of CECs in the Pearl River.

The coupled carbonate weathering represents a significant carbon sink and can be controlled by the riverine hydrochemical variations. However, magnitudes, variations, and mechanisms responsible for the carbon sink produced by coupled carbonate weathering are unclear. In view of this, temperature, pH, dissolved oxygen, turbidity, electrical conductivity, and discharge of the Xijiang River at Wuzhou Hydrologic Gauging Station was recorded during October 2013 to September 2015 to elucidate the temporal variations in riverine hydrochemistry and their controlling mechanisms. To obtain the complete carbon sink flux (CSF) produced by coupled carbonate weathering with terrestrial aquatic photosynthesis in the river basin, the fluxes of dissolved inorganic carbon (DIC), autochthonous organic carbon (AOC, sourced from the transformation of DIC via aquatic photosynthesis), and sedimentary AOC were all considered. The results show that seasonal hydrochemical variations in the Xijiang River were related not only to dilution effects but also aquatic primary production. These results demonstrate that the variations in discharge caused by rainfall played a dominant role in controlling the variations in the CSF due to the chemostatic behavior of DIC and dissolved organic carbon (DOC). The CSF of the Xijiang River produced by coupled carbonate weathering was calculated as 11.06 t C km⁻² a⁻¹, including DIC carbon sink flux of 6.56 t C km⁻² a⁻¹, AOC flux (FAOC) of 2.25 t C km⁻² a⁻¹, and sedimentary AOC flux (FSAOC) of 2.25 t C km⁻² a⁻¹. The FAOC and FSAOC together accounted for approximately 69% of DIC carbon sink flux, or approximately 41% of the CSF, indicating that the riverine AOC flux may be high and must be considered in the estimation of rock weathering-related carbon sinks.

In recent years, EU countries have recognized national policies to authorize dispersant use to mitigate the petroleum hydrocarbon contamination in case of unintentional oil spills at sea. A harmonization of dispersant approval procedures is needed because the application of different methodologies agrees on dissimilar toxic responses for the same dispersant in different European countries. Actually, different dispersant approval procedures are applied in France and Italy with one French mandatory toxicity test and three Italian bioassays accompanied with different criteria of toxicity classification. In this paper, a harmonized tiered approach is proposed to address the dispersant ecotoxicological assessment in these two nations. Our approach, applicable at the European level, introduces two mandatory tests (algal growth inhibition test and mortality test with crustaceans) and one discretionary test (fish mortality test), by reducing use of vertebrates as much as possible in accordance with humane principles and animal welfare.

Nitrogen (N) cycle in forest soils is altered by water, salt, or acid solutions, and its internal transfers to and from each existing inorganic pools are not known comprehensively. To evaluate the soluble and exchangeable N pools, bulk soil (B soil), water-extracted soil (W soil), and the 0.5 mol L⁻¹ K₂SO₄–treated soil (K soil) were incubated for up to 48 days to comprehend the dynamics of inorganic (NH₄⁺ and NO₃⁻) and soluble organic N (SON) in water-soluble, exchangeable, 2.5 mol L⁻¹ H₂SO₄ (labile pool I, LPI) and 13 mol L⁻¹ H₂SO₄ (labile pool II, LPII) pools. To test the N deposition effects, additional NH₄NO₃ solution was added to B, W, and K soils at amount of 40 mg N kg⁻¹ soil. The results showed that though there was more NO₃⁻ removed when W soil was prepared, the similar net nitrification rate in W soil to B soil and more than 20 mg N kg⁻¹ water-soluble NO₃⁻ were observed in W soil, which indicated that the loss of NO₃⁻ would be enhanced. In contrast, there was more water-soluble and exchangeable NH₄⁺ for K soil compared with B soil. The different dynamic of NO₃⁻ between W and K soil suggested that nitrifiers might dominate in the soil matrix rather than the soil solution. After incubation, each N form in the LPI decreased, which can be attributed to the allocation of remaining N into the recalcitrant pool, except the increase of NH₄⁺ for B soil and NO₃⁻ for K soil, and NO₃⁻ in LPII for B soil. Compared with control, N addition increased mineralization of exchangeable SON to promote nitrification regardless of soils, but weakened the immobilization of NO₃⁻. In addition, N in LPI and LPII pools have increased, which might be related to decomposition of recalcitrant organic matter induced by N addition to transform when the water-soluble and exchangeable N was removed. Therefore, the changes of soluble and exchangeable nitrogen pools impact the N cycling. Our findings can give some explanation for whole soil N transformation responses to N deposition.

A high-performance mesoporous biochar (MBCX) was fabricated from chicken bone via a facile and low-energy consumption pyrolysis process without any additional activators and templates. The physicochemical properties of biochar were carried out by elemental compositions, N₂ adsorption-desorption isotherms, FTIR, and TG. The results illustrated that lower carbonization temperature leaded to a lower specific surface area and more polar functional groups. And the meso-structure of biochar was obtained at 350 °C. Combined with the result of batch experiment, Cr(VI) adsorption capacity was decreased with the increasing in pyrolysis temperature, which suggested that the removal performance was depended on the functional groups of mesoporous biochar rather than the surface area. Kinetic analysis showed that the Cr(VI) adsorption process on MBCX was suitable for Elovich kinetic. The experimental data was well explained by Langmuir isotherm models. And the maximum adsorption capacity was 58.195 mg/g, which was higher than that of most report pristine biochars. This work not only paved a way for subsequent mesoporous biochar preparation but also demonstrated the application potentials of MBCX as an environment benign Cr(VI) adsorbent.

Fixed-asset investment directly affects energy consumption through purchasing and upgrading energy-saving equipment on the one hand, and indirectly affects energy consumption by expanding output scale on the other hand. This paper analyzes the multiple effects of fixed-asset investment on energy consumption by three strata of industry in China during 1991–2017. The econometric methods based on VAR model such as Johansen co-integration test and Granger causality test (linear Granger causality test and non-linear Granger causality test) are utilized to explore the long-run stable equilibrium relationships and causal interactions between fixed-asset investment and energy consumption. And the mediation test is performed by employing the bias-corrected non-parametric percentile bootstrap method combined with causal steps approach to obtain the direct and indirect effects of fixed-asset investment on energy consumption. Our study indicates that there are long-run stable equilibrium relationships between fixed-asset investment and energy consumption by three strata of industry. Bidirectional causalities exist in secondary and tertiary industries between fixed-asset investment and their respective energy consumption, and a unidirectional causality exists in primary industry from fixed-asset investment to energy consumption. The fixed-asset investment in primary industry directly suppresses its energy consumption, while indirectly promotes its energy consumption through its value added. And the fixed-asset investment in secondary industry not only directly promotes its energy consumption but also indirectly promotes its energy consumption through its value added.

Previous research has reported avian plastic ingestion in marine bird species. Yet, while research attention on plastic pollution is shifting from marine to freshwater ecosystems, very few information on plastic ingestion is available for freshwater birds. Here, we examined the presence of microplastic in regurgitated pellets of the common kingfisher (Alcedo atthis) collected along the Ticino River (North Italy). In total, 133 kingfisher’s pellets were examined between March and October 2019 from 54 transects along the river. Plastic elements were detected and identified by visual inspection followed by μ-FTIR and SEM-EDS. Overall, we found 12 (micro)plastics from at least three different polymers in 7.5% of the pellets. This study provides the first report of plastic uptake of this bird species. It highlights the importance of spectroscopic techniques in plastic monitoring studies in order to avoid misidentification of items found. Documenting the presence of plastic ingestion by top carnivores such as fish-eating birds is necessary to understand the pervasiveness and impact of (micro)plastic pollution in food webs of freshwater ecosystems.

A comprehensive understanding of the relationships between greenhouse gas (GHG) emissions and industrial structure and economic growth holds great significance for China to realize the development of a green economy. This paper calculates GHG emissions based on China’s energy consumption, divides the industrial structure in detail, and uses the extended Stochastic Impacts by Regression on Population, Affluence, and Technology model that is realized by PLS method and Tapio decoupling model to study the relationship of GHG emissions to industrial structure and economic growth. The results show that (1) China’s total GHG emissions showed a year-on-year growth trend from 2000 to 2017. For CO₂, CH₄, and N₂O, only N₂O emission showed a significant downward trend, while CO₂ and CH₄ emissions showed a slow growth trend. (2) The proportions of added value of industry and construction are positively correlated with GHG emissions, while those of farming, forestry, animal husbandry, and fishery; wholesale and retail trade; transport; and accommodation and catering are negatively correlated with GHG emissions. (3) China’s GHG emissions and overall economic growth are in a decoupling state, but in the energy field, N₂O emission reduction control has the best effect. Additionally, the overall economic growth of China’s industrial sector and GHG emissions have experienced the process of decoupling-link-negative decoupling-link-decoupling. Graphical abstract