The effects of pyrolysis temperature (350, 450, and 550 °C) on the properties of biochar prepared from chicken manure (CM), dairy manure (DM), and their digestates (CMD and DMD) were investigated in this study. The physicochemical properties and the transformation of phosphorous and heavy metal forms in various types of biochar were analyzed, and the bioavailability was assessed to optimize the pyrolysis condition towards biochar land application. The larger specific surface area was found in CM and CMD derived biochars (14.90–22.45 m²/g), as compared to DM and DMD derived biochars (1.17–7.36 m²/g). The highest contents of total phosphorous (TP) and bioavailable non-apatite inorganic phosphorus (NAIP) were obtained in DMD biochar, i.e., 49.31 and 27.03 mg/g TS, respectively. Cu and Zn are identified as the harmful heavy metal elements in manure derived biochars due to its high level of total concentration. When increasing pyrolysis temperature, the fractions of Zn and Cu in exchangeable-, carbonate-, and the organic-bonded state decreased and the fractions of manganese oxidized and residual state increased. Finally, the citric acid leaching treatment was proposed to decrease the Zn and Cu contents in biochar before land application. The overall leaching rates for Cu and Zn were 37–45% and 27–32%, respectively.

Leaching of phosphorus fertilizer from loose-structured subtropical soils is a major course of agricultural water pollution in southeastern USA. Soil amendments play a major role in the phosphorus retention in soil through different mechanisms. In the present study we tested the effect of two soil amendments; biochar and coal fly ash in immobilizing the soluble phosphorus fertilizer added to sandy Ultisol soils from subtropical USA. Column leaching tests were conducted with Ultisol soil added with biochar (from avocado branch cut biomass) and coal fly ash at 5 tons/ha rate, under simulated rainfall, to collect the leachate over five pore volumes. The leachate was analyzed for the phosphate phosphorus content. In the end, the soil columns were carefully extracted, sectioned and analyzed for the total phosphorus, after acid digestion. Results showed 50% and 6% drop of soluble phosphorus leaching loss in biochar and coal fly ash added soil respectively. Soil amendments have shifted the loosely bound phosphorus into the Ca/Mg bound and Al/Fe/Mn bound pools which are not readily water extractable. Addition of biochar and coal fly ash together showed a synergistic interaction effect in reducing the leaching loss of phosphorus which needs further investigation to understand the exact mechanism.

Acetochlor is one of the most widely used pesticides worldwide and widely distributed in the water environment. However, studies on the reproductive influence of acetochlor are still limited. To investigate the impact and potential mechanism of acetochlor on fish ovarian development, zebrafish were utilized as experiment models. The ovarian histology, ovarian development-related genes, and plasma oxidative stress-related indexes were investigated following acetochlor (at nominal concentration 1, 10, and 100 μg/L) exposure for 7 and 21 days. Results showed that low-dose acetochlor had estrogen effect and induced zebrafish estradiol (E₂) and ovarian vitellogenin (Vtg) synthesis and promoted ovarian development, while long-term exposure to higher doses of acetochlor reduced the ability of ovarian resistance to oxidative stress and destroyed the development of the ovary. Moreover, bone morphogenetic protein 15 (bmp15) and growth differentiation factor 9 (gdf9) were also involved in the influence of acetochlor on the ovarian development of zebrafish.

In this study, the forest landscape in the Beijing mountain area is assessed using the Integrated Valuation of Ecosystem Services and Tradeoffs model. The results showed the natural forests have higher functional capital than the planted forests and different species contribute to different ecological functions. Specifically, Larix gmelinii forests have the highest water resources and soil conservation function which are about 334.14 m³ hm⁻² year⁻¹ and 115.92 t hm⁻² year⁻¹; Betula allegansis forests have the highest carbon storage and biodiversity function which are about 128.46 t hm⁻² year⁻¹ and 0.76. Besides soil, water is conserved more within coniferous forests than within broadleaf forests. Carbon sequestration and the functional capacity for biodiversity within a unit area of coniferous forests are much smaller than those within a unit area of a broadleaf forest. Previous studies highlight the forest management strategies will influence the ecosystem functions while in the current studies we also found the species option during the afforestation is equally important and protecting of the natural forests is more important than afforestation for maintaining the ecological functional capitals.

Offshore oil spills are a critical form of marine pollution, requiring researchers to mitigate their impacts. In this sense, this paper contributes to a better understanding of oil behavior after spillage and the improvement of contingency measures. Using Bacia de Campos as the study area, which accounts for approximately 32% of daily oil and gas production in Brazil, information regarding the properties of light, medium, and heavy oils, seawater, wind and wave weather conditions, and oil spill characteristics was used to perform simulations to identify the percentage of oil remaining after the offshore spill and the effectiveness of the chemical dispersant in dispersing this oil. The results show that after the weathering simulation, on average, 55% of the spilled oil remains at sea in dispersed and remaining form and that the use of chemical dispersant under the conditions defined in this study did not result in significant oil removal.

The asymmetrical impacts of globalization and tourism on pollution emissions of 5 South Asian countries for the period from 1980 to 2018 are examined through a non-linear autoregressive distributed lag (NARDL) technique, which shows that both short and long-run coefficients are asymmetric. The findings suggest that positive and negative shocks in globalization affect carbon emissions differently in the case of Bangladesh, India, and Pakistan, while similar results are found in the case of Nepal and Sri Lanka in the long run. Furthermore, positive tourism shock, in the long run, ameliorates the environmental quality by reducing carbon emissions in Nepal and Sri Lanka, however, increases the carbon emissions in Bangladesh, India, and Pakistan. While negative tourism shock has an adverse effect on positive shock on carbon emissions in South Asia. The phenomena of globalization and tourism can exert a severe impact in aggravating the pollution emissions that policymakers should forecast and oppose. Based on these findings, some policy suggestions are proposed for South Asian economies.

Freshwater ecosystems are recognized as one of the important natural methane (CH₄) sources, but little is known about the emission hotspots and the effects of algal blooms on CH₄ production in deep lakes. In this study, carried out from the littoral (S1), pelagic (S2-S4), and the deepest site (S5), water samples from different depths and sediment cores were collected along the transect of Lake Fuxian, a deep monomictic lake to investigate the spatial–temporal variations of CH₄. Dissolved methane concentration observed at the oxic metalimnion was 37.5% and 19.5% higher than that those observed at the epilimnion and at the layer between 80 and 100 m depth, respectively. During the overturn period, the vertical distribution of CH₄ in the water column was uniform, with an average concentration of 0.031 ± 0.007 μM in S2–S5. Statistical analysis indicated that the CH₄ concentration in the water column was significantly higher in S1 than other sites along the transect during both sampling periods. Sediment CH₄ concentration and methane production potential (MPP) were also significantly higher in S1 than in other sites. Along the sediment depth, the maximum MPP was observed at 6–8 cm in S1, but it moved up to the surface layer in S2–S5 in both sampling periods. In addition, stable carbon isotope analysis indicated that the surface sediments in the pelagic zone (S2–S5) mainly comprised autochthonous organic matters. In this zone, MPP had a significantly positive correlation with sediment total organic carbon (TOC) (R² = 0.401, p < 0.01). In summary, we described the spatial and temporal distributions of CH₄ in deep Lake Fuxian, littoral zones are CH₄ emission hotspots that can contribute to the CH₄ accumulation in the oxic metalimnion layer during the stratification period. In the pelagic zone, autochthonous organic matter was transported into the surface sediment after a massive algal bloom, representing another hotspot for CH₄ production.

Although numerous linear regressions have been conducted to identify driving forces of farmland investment, this study uses panel threshold techniques to explore the nonlinear effects of resource endowment, labor cost, and other potential influencing factors on China’s investment in farmland in 40 foreign countries during the period 2008–2016. Results show that increased resource endowment promotes China’s investment in overseas farmland, but the correlation gradually weakens in magnitude as levels increase. A lower labor cost attracts greater Chinese investment in farmland, but the degree of influence declines with the continued increase in labor cost. Further, host country corruption, infrastructure level, and urbanization ratio have significant negative impacts on investment, whereas an increase in China’s overall economic power significantly increases overseas farmland investment. Policy implications are proposed with respect to implementing environmental responsibility in host countries, creating comprehensive risk assessments, and optimizing the structure of overseas investment portfolios.

Three different synthesis methods were applied to obtain TiO₂ nanoparticles: microwave-assisted hydrothermal (TiO₂-MW), sonochemical (TiO₂-US), and polymeric precursor (TiO₂-PP). The nanoparticles thus obtained presented 93% (TiO₂-MW) and 92% (TiO₂-US) anatase phase, and TiO₂-PP 93% rutile phase. The TiO₂-US sample performed best during the Prozac® photodegradation assays because of its lipophilic surface, attributable to the C-H groups therein. Additionally, adsorption rate and photodegradation were optimized by adjusting Prozac® solution to pH ~ 8. Following Prozac® photodegradation, quantitative monitoring of its by-products (PPMA, MAEB, and TFMP) was done using HPLC. This quantitative approach led us to conclude that semiconductor photoactivity cannot be discussed solely in terms of the main compound. Lastly, it was seen that these by-products compete with each other in the degradation mechanisms and are influenced by different materials. Graphical abstract

The main problem in the reduction of river bottom sediments is to solve the dewatering of the sludge. The commonly used natural air drying method requires a large amount of time and economic cost. In this paper, different treatments were developed for the needs of the project, and related tests were carried out on the reduction of the sludge. Firstly, two or more flocculants were compounded according to the nature of the sludge. The 6 different treatments were determined according to the sedimentation and the turbidity value of the supernatant. Secondly, the dewatering test was carried out on river sediments after flocculation-vacuum preloading. The dewatering effect of different flocculants, water quality, dissipation of pore water pressure, vane shear strength, compression coefficient, and coefficient of consolidation have been analyzed after flocculation-vacuum preloading. The polysilicate aluminium ferric (PSAF) can greatly increase the dewatering efficiency of the filter press membrane, and the final dewatering amount could reach 310 g. The effect of purifying water quality was PSAF>PAM (polyacrylamide, PAM-1(18 million): PAM-2(23 million) = 3:7)>PAC (polyaluminium chloride). The PSAF and PAC could increase the pH of the water during the vacuum preloading test. The PAM has the best the vane shear strength. Lime could improve the vacuum preloading and the vane shear strength when it was added to other flocculants. The incorporation of PSAF could accelerate the dissipation and increase the final dissipation value of pores water pressure. Compared with PAM+PAC+lime, PAM+lime, PAM+PSAF+lime, PAM+PSAF, and PAM+PAC, the overall effect and price of the PAM is optimal.