Sulfur (S) is one of the most redox-sensitive elements and has a marked impact on the geochemical cycling of biogenic elements in freshwater sediments. Current understanding of the speciation of sedimentary S, and of the processes regulating it, is insufficient. In this study, the speciation and spatial variations of S and iron (Fe) in sediments (soils) from Lake Hongfeng, one of the largest freshwater lakes in Southwest China, were investigated using X-ray absorption near-edge structure (XANES) spectroscopy and diffusive gradient in thin film technique (DGT). The results show that S in sediments and soils was composed of seven fractions in different electronic oxidation states (EOSs), including (i) reduced S (R-S, G1, EOS = − 1), (ii) lowly oxidized S (LO-S, including G2-G5; EOS = 0, 0.5, 2, and 3.7), and (iii) highly oxidized S (HO-S, including G6 and G7; EOS = 5 and 6). Proportional differences of S speciation in sediments and soils indicated that HO-S is largely reduced to LO-S and R-S during depositional processes. The HO-S fraction decreased in the top surface sediments and then increased in the deeper layers, whereas the R-S fraction showed the opposite trend, suggesting that sulfate reduction and re-oxidation processes occurred in the sediments. High ratios of soluble Fe/S provided a favorable foundation for the reduction and burial of sedimentary S. The speciation and spatial variations of S in freshwater sediments are controlled by complex environmental factors, including terrigenous material discharges, water redox conditions, and porewater chemistry (such as for pH, Eh, and reactive Fe). Our study will help to deepen the understanding of the geochemical dynamics of S in the sediments of freshwater ecosystems.

Although phosphorus (P) enrichment alone or in combination with other nutrients such as nitrogen (N) and potassium (K) due to anthropogenic activities may modify the nutrient pools and nutrient elemental ratios of terrestrial ecosystems, few studies have revealed the global effects of P alone or in combination with N and K enrichment on terrestrial ecosystems. In this study, we conducted a meta-analysis of the impacts of P addition alone or in combination with N and K on the C, N, and P pools and C/N/P ratios of plants, soils, and microbial biomass in terrestrial ecosystems. The results suggest that the following changes occurred: (1) P addition resulted in a significantly larger plant C pool, which was further enhanced when extra N and K were added. (2) The soil and microbial biomass C pools and the plant, soil, and microbial biomass N pools were minimally affected by P addition at the global scale but were noticeably affected when N and K were simultaneously added. (3) The P pools of the plants, soil, and microbial biomass were significantly and consistently enhanced by the addition of P, NP, and NPK. (4) The plant C/N, N/P, and C/P ratios were significantly reduced when P was added, while the C/N/P ratios in the soil and microbial biomass were minimally affected. These results, which show the inconsistent responses of plant, soil, and microbial biomass nutrient pools and elemental ratios to P, NP, and NPK addition, improve our understanding of terrestrial ecosystem functions under global change scenarios.

Copper is a common aqueous pollutant that is known to cause oxidative stress and disrupt the thyroid axis in amphibians. In the present study, tadpoles of the Chinese toad (Bufo gargarizans) were exposed to 1, 6.4, 32, and 64 μg L⁻¹ of copper from Gosner stages 26 to 42. We aimed to examine the influence of copper on thyroid hormone-responsive and stress-associated gene expression in the hind-limb, tail, and liver of B. gargarizans tadpoles. Exposure to 64 μg L⁻¹ copper decreased percent metamorphosis and increased length of both hind-limb and tail of B. gargarizans tadpoles at Gs 42. In addition, according to real-time PCR results, exposure to 64 μg L⁻¹ copper induced downregulation of Dio2, Dio3, TRα, and TRβ mRNA levels in all tissues examined. We inferred that copper might induce a considerable reduction of TH levels through downregulation of Dio2 and Dio3 mRNA levels in peripheral tissues. Decreased TH levels may then decrease the expressions of TRα and TRβ. Also, HSP, SOD, and PHGPx transcript levels were measured to assess cellular stress which might affect TH signaling and metamorphosis. We found that copper significantly downregulated the level of HSP, SOD, and PHGPx transcripts in the hind-limb and tail. This demonstrates that high concentrations of copper could disrupt the antioxidant system of B. gargarizans tadpoles and increase oxidative damage. Therefore, we conclude that copper could disrupt the antioxidant system and cause thyroid hormone disruption in B. gargarizans tadpoles.

The soil saltiness in the Brazilian semiarid environment is a common problem caused by incorrect agricultural practices, allied to the local weather and soil condition. The use of phosphogypsum (PG) to recover these soils still is a concern since this material has in its composition natural radionuclides. An experiment was conducted to study the use of phosphogypsum to reduce the salinity and evaluate the bioavailability of radionuclides on the Brazilian semiarid region soils. The radionuclide content of phosphogypsum samples were previously analyzed by gamma spectrometry. Three differents doses of phosphogypsum were mixed with samples of surface soil in the greenhouse, and after a reaction time and irrigation, controlled soil samples + phosphogypsum underwent simple extractions based on the sequential extraction method by Tessier et al. Ra isotopes and ²¹⁰Pb in the extracted fractions were analyzed by counting alpha and beta. The higher concentration of Ra isotopes and ²¹⁰Pb were associated to residual fraction, followed by exchangeable fraction due to the low levels of carbonates, organic matter, and manganese and iron oxides. The use of phosphogypsum studied did not contribute to increase the ²²⁶Ra activity on the analyzed soils. ²²⁶Ra levels in phosphogypsum were lower than those recommended by the USEPA to allow the use of phosphogypsum in agricultural soils, but can contribute to the accumulation of ²²⁸Ra and ²¹⁰Pb. The phosphogypsum Imbituba promoted a satisfactory reduction of electrical conductivity in the soils, which indicates the possibility of recovery of these soils.

Land application of organic manure, crop residue, and biosolid, an important means for the disposal and recycling of wastes, has been shown to significantly increase the amount of dissolved organic matter (DOM) in soil. However, limited information is available on the dynamics of DOM, the concentration is usually expressed by dissolved organic carbon (DOC), and its influence on Cd behaviors in paddy soil amended with and without organic materials during rice (kinmaze) growing season. In this study, in situ field experiments were conducted to investigate the dynamics of DOC in paddy soil amended with green manure (GM), pig manure (PM), and chemical fertilizer (F) and its effect on Cd mobility and bioavailability. The results showed that DOC concentrations in soil solutions extracted from different depths were higher in GM and PM plots than those in F plot, and DOC concentrations all declined with time and rice growth. DOC concentrations in the root zone soil for all treatments were higher than those in the non-root zone due to root exudation and the higher pH value. The temporal dynamics of DOC in the root zone were found to be correlated to rice growth stage, as DOC concentrations decreased in the initial stage (week 1 to 6) of rice seedling and then gradually increased and reached the highest levels with 30.42 mg DOC L⁻¹ for GM, 28.88 mg DOC L⁻¹ for PM, and 19.19 mg DOC L⁻¹ for F at rice heading and flowering stage (week 10), hereafter decreased again until when the rice was harvested. However, soil DOC in the non-root zone exhibited a continuous decrease trend and remained at a relatively low level after week 10 with 15.36 mg DOC L⁻¹ for GM, 15.31 mg DOC L⁻¹ for PM, and 8.43 mg DOC L⁻¹ for F. The dynamics of water soluble Cd displayed statistically significant positive relationship with DOC (r ₀.₀₁ = 0.765, n = 9) regardless of soil depth and root presence/absence, suggesting that DOC enhanced the mobility and transport of through the formation of Cd-DOC complexes. As a result, DOC could increase the potential uptake of Cd by rice as well as the downward Cd migration to deeper soil. In these experiments, the uptake of Cd by rice grown in the GM and PM plots reached 5.55 and 3.71 mg plot⁻¹, respectively, which were much higher than that in the F plot with 1.88 mg plot⁻¹. The amounts of Cd downward migration were 17.0 mg plot⁻¹ for GM plot, 14.74 mg plot⁻¹ for PM plot, and 4.13 mg plot⁻¹ for F plot, respectively. It could be concluded that the application of green manure and pig manure to Cd-contaminated paddy soil will increase the risk of Cd uptake by rice and Cd downward migration into groundwater. For this reason, care should be taken when organic manures was applied to contaminated soil to remediate or alleviate soil pollution and maintain soil fertility as well as provide nutrients for plant growth.

In recent years, the ecology, security, and sustainable development of modern mines have become the theme of coal mine development worldwide. However, spontaneous combustion of coal under conditions of oxygen supply and automatic exothermic heating during coal mining lead to coalfield fires. Coal spontaneous combustion (CSC) causes huge economic losses and casualties, with the toxic and harmful gases produced during coal combustion not only polluting the working environment, but also causing great damage to the ecological environment. China is the world’s largest coal producer and consumer; however, coal production in Chinese mines is seriously threatened by the CSC risk. Because deep underground mining methods are commonly adopted in Chinese coal mines, coupling disasters are frequent in these mines with the coalfield fires becoming increasingly serious. Therefore, in this study, we analyzed the development mechanism of CSC. The CSC risk assessment was performed from the aspects of prediction, detection, and determination of the “dangerous area” in a coal mine (i.e., the area most susceptible to fire hazards). A new geophysical method for CSC determination is proposed and analyzed. Furthermore, the main methods for CSC fire prevention and control and their advantages and disadvantages are analyzed. To eventually construct CSC prevention and control integration system, future developmental direction of CSC was given from five aspects. Our results can present a reference for the development of CSC fire prevention and control technology and promote the protection of ecological environment in China.

The losses of total solids, moisture, nitrogen (N), phosphorus (P), potassium (K), carbon (C), and sulfur (S) were determined in two storage events of laying-hen manure immediately removed from three different housing systems in Iowa, USA. The three laying-hen houses were conventional cage (CC), enriched colony (EC), and aviary (AV). The houses held a nominal number of 200,000, 46,700, and 50,000 Lohmann LSL lite layers, respectively. The manure collected on belts in each house was cleaned out twice a week. A fraction of the cleaned out manure was transferred to designated storage rooms wherein losses of different components were determined in two storage events. Manure was loaded into the storage rooms over 171 days during the first storage event and over 185 days during the second storage event. The total storage periods were 202 and 245 days, respectively, for the first and second storage events. Manure was weighed, sampled, and analyzed before it was loaded into the storage rooms and at the end of each storage event. Mass balance calculations were used to determine the losses of different components. Statistical analyses show that the nutrient contents, on a wet basis, of manure loaded in CC, AV, and EC storage rooms were significantly different due to the differences in manure moisture contents. However, on a dry basis, they had no significant differences. The fresh manure cleaned out from the EC layer house was drier than that from the other two houses. Loaded-in nitrogen losses in the CC, AV, and EC storage rooms were 24.6, 12.9, and 20.8%, respectively. Nitrogen losses depended on house temperature, manure moisture, and pH. The average losses of loaded-in manure mass, moisture, and total solids during the two storage events were 27.6 ± 1.9, 33.8 ± 8.3, and 20.8 ± 7.0%, respectively. The losses of N, P, K, C, and S were 19.4 ± 13.4, 11.7 ± 5.6, 10.2 ± 6.8, 27.0 ± 6.5, and 8.3 ± 8.5% of their loaded-in amounts, respectively. The total loss of N, P, K, C, and S was 56% of the total loaded-in solids loss; thereof, the loss of N, P, and K was 7%, and C loss was 48%. The laying-hen-specific losses of N, P, K, C, and S were 0.34, 0.05, 0.08, 3.2 and 0.019 g day⁻¹ hen⁻¹, respectively. The results of this research are important for assessing impacts of stored manure on environment and nutrient losses. They can also be used to develop methodologies for the mitigation of the emissions from egg production facilities.

While some countries disaggregate N₂O emission factors for urine and dung deposited onto pastures, in Canada, distinct N₂O emission factors for beef cattle urine and dung have not been defined. To help address this knowledge gap, we conducted a 1-year study to quantify N₂O fluxes from beef cattle urine and dung patches on a semiarid tame pasture in western Canada, as well as to quantify the N₂O emission factors (EF3) for urine and dung as the percentage of applied N emitted as N₂O-N. Urine and dung were deposited when soil water-filled pore space was nearly 60%, a wet soil condition for the grazing season in the semiarid study region, which led to a burst of N₂O from urine in the first 14 days of the study (42% of total N emitted). Urine emitted more cumulative N₂O (P < 0.001) and had a greater N₂O emission factor (P = 0.002) than dung. The urine patch emitted 1.30 ± 0.47 g N₂O-N m⁻² year⁻¹, while the dung patch emitted 0.083 ± 0.020 g N₂O-N m⁻² year⁻¹ (mean values ± SD). The N₂O emission factor for urine was 1.32 ± 0.49%, while for dung it was 0.03 ± 0.02%. We conclude that more study is needed to determine if distinct N₂O emission factors are required for urine and dung deposited onto pasture in western Canada to more accurately estimate national N₂O inventories.

Research was conducted on the most polluted river system in Poland, impacted by active and historical mining. Bottom sediment, suspended particulate matter and river water were collected in 2014 from Przemsza river and its tributaries. Sampling points remained the same as those chosen in a 1995 study. This allowed the comparison of heavy metal accumulation in bottom sediment over a span of almost two decades. It was concluded that Przemsza river water and its tributaries are heavily contaminated with the following (in μg/dm³): Pb (0.99–145.7), Zn (48–5020), and Cd 0.12–12.72). Concentrations of metals in bottom sediment exceeded the background values by a factor of several hundred (100 times for Zn, 150 times for Pb, and 240 times for Cd). The arithmetic mean for metal concentration in fractions <63 μm sampled in 2014 has remained comparable to the level found in 1995 (in mg/kg): Zn 16,918 and 13,505, Pb 4177 and 4758, and Cd 92 and 134. It was determined that 20–50% more metals have accumulated in suspended matter, rather than in bottom sediment (in mg/kg): 20,498 Zn, Pb 5170, and 164 Cd. This exceeds the limits of the most polluted LAWA Class IV classification. Since the concentrations of Zn, Pb, and Cd increase drastically after the outlet of the Przemsza into the Vistula, it was concluded that river Przemsza is the cause of significant degradation of Vistula’s bottom sediment and suspended matter. A two-decade legacy of extremely high contamination of the Przemsza river sediments has persisted despite decreasing mining and smelting activity in the vicinity.

Nowadays, the increasing pollution of natural water effluents with surfactant, wetting, dispersing, and emulsifying agents which contain nonylphenol ethoxylate (NP₇EO) is an emerging problem that has not received the enough attention. Currently, it is known that degrading this type of highly stable compounds is possible through advanced electrochemical oxidation (AEO), but the degradation of NP₇EO has not been tested yet. Thus, this work carries out a study of the degradation of the NP₇EO (500 mg L⁻¹) through advanced electrochemical oxidation, using a DiaClean® cell, equipped with boron-doped diamond electrodes (BDD, 70 cm²). The cell operated in a recirculation system with a peristaltic pump, which allowed to control the electrolyte flow. The buffer media for degradation was NH₄OH 0.1 M/HCl 0.05 M (pH 9.25). The effect of the current density (j = 20, 30, 40 mA cm⁻²) was studied, and the cell efficiency for each condition was evaluated. The degradation was followed by total organic carbon (TOC), chemical oxygen demand (COD), and absorbance. The cell potential was monitored to determine the operating costs. The best conditions for the mineralization of NP₇EO (initial concentration = 500 mg L⁻¹) were applying 40 mA cm⁻² and at a flow rate of 12.6 L min⁻¹ during 8 h of electrolysis, achieving a 90% of TOC removal. Therefore, this technology appears as a promising alternative for degrading surfactants like NP₇EO in aqueous media.