China’s intensive agriculture has led to a broad range of adverse impacts upon ecosystems and thereby caused environmental quality degradation. One of the fundamental problems that face land managers when dealing with agricultural nonpoint source (NPS) pollution is to quantitatively assess the NPS pollution loads from different sources at a national scale. In this study, export scenarios and geo-spatial data were used to calculate the agricultural NPS pollution loads of nutrient, pesticide, plastic film residue, and crop straw burning in China. The results provided the comprehensive and baseline knowledge of agricultural NPS pollution from China’s arable farming system in 2014. First, the nitrogen (N) and phosphorus (P) emission loads to water environment were estimated to be 1.44 Tg N and 0.06 Tg P, respectively. East and south China showed the highest load intensities of nutrient release to aquatic system. Second, the amount of pesticide loss to water of seven pesticides that are widely used in China was estimated to be 30.04 tons (active ingredient (ai)). Acetochlor was the major source of pesticide loss to water, contributing 77.65% to the total loss. The environmental impacts of pesticide usage in east and south China were higher than other parts. Third, 19.75% of the plastic film application resided in arable soils. It contributed a lot to soil phthalate ester (PAE) contamination. Fourth, 14.11% of straw produce were burnt in situ, most occurring in May to July (post-winter wheat harvest) in North China Plain and October to November (post-rice harvest days) in southeast China. All the above agricultural NPS pollution loadings were unevenly distributed across China. The spatial correlations between pollution loads at land unit scale were also estimated. Rising labor cost in rural China might be a possible explanation for the general positive correlations of the NPS pollution loads. It also indicated a co-occurred higher NPS pollution loads and a higher human exposure risk in eastern regions. Results from this research might provide full-scale information on the status and spatial variation of various agricultural NPS pollution loads for policy makers to control the NPS pollution in China.

The phosphorus (P) fractions and adsorption-desorption characteristics in the Wuliangsuhai Lake were investigated through molybdenum blue/ascorbic acid method and indoor simulation experiments, respectively. The results showed that the highest total phosphorus concentration in overlying water (W-TP) was found in S1 which was in the hypereutrophic type. The mean concentration of particulate organic phosphorus (POP) was the most abundant P fraction (31.35% of the W-TP). The results of TP contents in sediments (S-TP) indicated that the most sampling sites were in the mild level of pollution. The contents of calcium-bound P (HCl-P) and residual P (Res-P) fractions together comprised 83.03–98.10% of the S-TP. Pseudo-second-order models fitted well with the adsorption-desorption kinetic of P fractions. The Langmuir and Freundlich models well described the adsorption isotherm of P fractions. The results of adsorption-desorption of P fractions indicated that the adsorption capacity was strong, the chemical adsorption was dominant, and the sediments was a source of P. Accordingly, we concluded that the Wuliangsuhai Lake was in the moderate pollution level, and the sediments as a source could desorb P in natural aquatic environment.

In this study, the canopy drip effect on the exposure of forests to atmospheric deposition of potentially toxic metals and nitrogen (N) and element accumulation was investigated. Thereby, the respective element concentrations of metals and N in moss specimens were investigated by example of North-Western Germany. To this end, on the one hand, the concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Pb, Ni, Sb, V, Zn, and N in mosses sampled under, outside, and at the edge of forest canopies were examined for statistical significant differences. On the other hand, vegetation structures parameterizing the canopy drip effect were quantified by use of information collected, in addition to the element data, at each moss sampling site. The statistical relations between ratios of vegetation parameters and ratios of element concentrations were modeled by regression analysis, and the respective element concentration in moss was geostatistically estimated and mapped for unsampled locations throughout Germany. This article tackles regression models with R² > 0.5 (Cu, Hg, Pb, Sb, and N) to adapt the element concentrations measured at the 400 sites of the European Moss Survey (EMS) to three different features of hypothetical vegetation structures. To this end, the continuum of vegetation structures were represented as follows: open land (meadows) described by a leaf area index (LAI) value of 2.96 and under canopy sites in coniferous forests represented by a LAI value of 11. The arithmetic mean of LAI values at 400 EMS sites throughout Germany amounts to 5.1. The element concentrations for these target LAIs representing three site categories were calculated and mapped. Then, these LAI-dependent element concentration maps were compared with the maps depicting the spatial patterns of “pure” element concentrations. Spatial differences were evaluated and supposed to be of great value for the validation of atmospheric deposition modeling.

Existing studies have analyzed the effects of financial development on economic growth and environmental pollution respectively, but few studies have analyzed the effects of financial development on economic growth and environmental protection from a unified framework. This paper reports on a study which took the 28 provinces of China, for the years 2002–2014, as its research object. It used green efficiency to measure the win-win balance between economic growth and environmental protection. It divided green efficiency into economic efficiency and environmental efficiency and then studied the effects of financial development on economic growth and environmental protection within a unified framework. The primary findings indicate that (1) overall, financial development is conducive to obtaining the win-win balance in China’s economy, with its positive effects on economic growth being more significant than on environmental protection; (2) capital market development promotes both economic growth and environmental protection, while also playing a significant role in the win-win balance of China’s economy.

Anaerobic batch experiments were conducted to study the regulatory role of endogenous iron in greenhouse gas emissions under intensive nitrogen fertilization in subtropical soils of China. Fe²⁺, Fe³⁺, and NO₃⁻-N dynamics and N₂O, CH₄, and CO₂ emissions, as well as the relationships between N fertilizer, endogenous iron, and greenhouse gas emissions were investigated. The emissions of N₂O increased to different extents from all the test soils by N1 (260 mg N kg⁻¹) application compared with N0. After 24 days of anaerobic incubation, the cumulative emissions of N₂O from red soils in De’an (DR) were significantly higher than that from paddy soils in De’an (DP) and Qujialing (QP) under N1. However, N application enhanced CH₄ and CO₂ emissions from the red soils slightly but inhibited the emissions from paddy soils. The maximal CH₄ and CO₂ emission fluxes occurred in DP soil without N input. Pearson’s correlation analysis showed that there were significant correlations (P < 0.01) between Fe²⁺ and Fe³⁺, NO₃⁻-N, (N₂O + N₂)-N concentrations in DP soil, implying that Fe²⁺ oxidation was coupled with nitrate reduction accompanied by (N₂O + N₂)-N emissions and the endogenous iron played a regulatory role in greenhouse gas emissions mainly through the involvement in denitrification. The proportion of the electrons donated by Fe²⁺ used for N₂O production in denitrification in DP soil was approximately 37.53%. Moreover, positive correlations between Fe²⁺ and CH₄, CO₂ were found in both DR and QP soils, suggesting that endogenous iron might regulate the anaerobic decomposition of organic carbon to CH₄ and CO₂ in the two soils. Soil pH was also an important factor controlling greenhouse gas emissions by affecting endogenous iron availability and C and N transformation processes.

Spent magnesia (MgO)-carbon refractory bricks were repurposed as a permeable reactive barrier reactive media to treat a nickel (5 mg l⁻¹)- and cobalt (0.3 mg l⁻¹)-contaminated groundwater. MgO has been used for decades as a heavy metal precipitating agent as it hydrates and buffers the pH in a range of 8.5–10 associated with the minimum solubility of various divalent metals. The contaminated groundwater site’s conditions are typical of contaminated neutral drainage with a pH of 6 as well as high concentrations of iron (220 mg l⁻¹) and sulphates (2500 mg l⁻¹). Using synthetic contaminated water, batch and small-scale column tests were performed to determine the treatment efficiency and longevity. The increase and stabilization of the pH at 10 observed during the tests are associated with the hydration and dissolution of the MgO and promoted the removal not only of a significant proportion of the contaminants but also of iron. During the column test, this accumulation of precipitates over time clogged and passivated the MgO resulting in a loss of chemical performance (pH lowering, metal breakthrough) after 210 pore volumes of filtration. Precipitation also affected the hydraulic conductivity values which dropped from 2.3·10⁻³ to 4.2·10⁻⁴ m s⁻¹ at the end of test. Saturation indices and XRD analyses suggest the precipitates formed are likely composed of goethite as well as iron, cobalt and nickel hydroxides. Recycled MgO-C refractory bricks were demonstrated to be an efficient reactive material for the removal of Co and Ni, but careful considerations should be taken of the potential clogging and passivation phenomena given particular physicochemical conditions.

Si has a beneficial effect on improving plant tolerance to salt stress. Nevertheless, the mechanisms of Si in mediating the stress responses are still poorly understood. Glycyrrhiza uralensis Fisch. (G. uralensis), a well-known medicinal plant, possesses vast therapeutic potentials. In the present study, a pot experiment was conducted to investigate the long-term effects of Si on growth and physiobiochemical characteristics in 2-year-old G. uralensis subjected to different levels of salinity. Si markedly affected G. uralensis growth in a salt concentration-dependent manner and had no effect on G. uralensis growth under 6 g/kg NaCl. However, it partly reversed the reduction effect induced by 9 g/kg NaCl. In addition, Si significantly increased the contents of soluble sugar and protein but deceased proline content and thus increased water relations; Si markedly increased the activities of SOD, peroxidase, and CAT and further resulted in decreased MDA content and membrane permeability. Moreover, Si altered the levels of phytohormones and their balances. With correlation analysis and principal component analysis (PCA), root biomass had a significant negative correlation with MDA and membrane permeability while a positive correlation with indole-3-acetic acid and GA₃. The PCA partitioned the total variance into three PCs contributing maximum (88.234%) to the total diversity among the salt stress with or without Si due to the study of various traits. In conclusion, Si exerts a beneficial property on salt-induced harmful effects in G. uralensis by relieving osmotic stress, improving water relations, and alleviating oxidative stress; thus, altering the levels and balance of phytohormones results in improved growth of salt-stressed G. uralensis.

In this study, particles produced from sericin-alginate blend were used as non-conventional bioadsorbent for removing Cr(III) and Cr(VI) from aqueous solutions. Besides chromium mitigation, the use of sericin-alginate particles as bioadsorbent aims to offer an environmental solution of added value for sericin, which is a by-product from silk industry. Sericin-alginate particles in natura and loaded with Cr(III) and Cr(VI) were characterized using N₂ physical adsorption analysis, optical microcopy, mercury porosimetry, helium pycnometry, scanning electron microscope coupled with energy dispersive X-ray spectrometer, Fourier transform infrared spectrometer, and X-ray diffraction. Kinetic studies on the removal of Cr(III) (at pH = 3.5) and Cr(VI) (at pH = 2) indicate the ion exchange mechanism with Ca(II) and the predominance of external mass transfer resistance. Cr(VI) uptake occurs through an adsorption-coupled reduction process, and bioadsorption equilibrium is reached after ~ 1000 min. Cr(III) bioadsorption occurs faster (~ 210 min). The Cr(VI) bioadsorption is endothermic, as bioadsorption capacity increases with temperature: 0.0783 mmol/g (20 °C), 0.1960 mmol/g (30 °C), 0.4570 mmol/g (40 °C), and 0.7577 mmol/g (55 °C). The three-parameter isotherm model of Tóth best represents the equilibrium data of total chromium. From Langmuir isotherm model, the maximum bioadsorption capacity is higher for total chromium, 0.25 mmol/g (30 °C), than for trivalent chromium, 0.023 mmol/g (30 °C). The comparison of bioadsorption capacities with different biomaterials confirms sericin-alginate particles as potential bioadsorbent of chromium.

Cocoa black pod disease caused by Phytophthora megakarya and reduced soil fertility are major constraints to cocoa production resulting in high yield losses. In the absence of effective control measures and constraints related to the use of chemical fungicides and fertilizers, there is a need to develop additional and sustainable disease and fertilization management strategies. With the lack of studies related to the use of compost in cocoa cultivation, the present study aims to evaluate the potential of cocoa pod husk (CPH)-based compost as a soil amendment to reduce the severity of cocoa black pod disease and enhance plant growth. In vitro antagonism test showed that compost water extracts (CWE) reduced mycelial growth with inhibition rate reaching 100% associated with microorganisms. Disease score of cocoa plantlets grown on compost-amended soils significantly reduced compared to plantlets grown on non-amended soil (control). All compost rates tested significantly increased populations of actinomycetes and fungi and biological activity in the soil. Compost application increased soil pH and majority of the essential elements but decreased Al content, which is toxic to cocoa growth in acidic soils. Soil application of compost at the dose of 20% (v/v) significantly increased stem length and number of leaves compared to the control. This study shows that CPH-based compost can not only improve soil fertility and cocoa growth but also reduce cocoa black pod disease severity by direct effects on inoculums level in the soil and by inducing resistance in the plant.

The effect of seven heavy metals on the motility parameter of zebrafish sperm was tested in order to develop an in vitro toxicological test system as an alternative to live animal testing. In vitro test systems are currently preferred in ecotoxicology due to their practical and ethical advantages and fish sperm can be a suitable model. A number of studies had been carried out previously on this topic, but the described methods had not been standardized in numerous aspects (donor species, measured endpoint, etc.). In this study, heavy metals (mercury, arsenic, chromium, zinc, nickel, copper, cadmium) were used as reference toxicants with known toxicity to develop a standardized fish sperm in vitro assay. The tested concentrations were determined based on preliminary range finding tests. The endpoints were progressive motility (PMOT, %), curvilinear velocity (VCL, μm/s), and linearity (LIN, %) measured by a computer-assisted sperm analysis (CASA) system. According to our results, PMOT was the most sensitive of the three investigated parameters: dose-response curves were observed for each metal at relatively low concentrations. VCL values were less sensitive: higher concentrations were needed to observe changes. Of the three parameters, LIN was the least affected: dose-response relationship was observed only in the case of mercury (e.g., lowest observed effect concentration (LOEC) of Hg at 120 min: 1 mg/L for PMOT, 2.5 mg/L for VCL, 5 mg/L for LIN; LOEC of Cu at 120 min: 1 mg/L for PMOT, 5 mg/L for VCL, any for LIN). The order of toxicity as determined by PMOT was as follows: Hg²⁺ > As³⁺ > Cd²⁺ > Cu²⁺ > Zn²⁺ > Cr³⁺ > Ni²⁺. In conclusion, we found that PMOT of zebrafish sperm was an accurate and fast bioindicator of heavy metal load. Sperm analysis can be adopted to estimate the possible toxic effects of various chemicals in vitro. Future investigations should concentrate on the applicability of this assay to other contaminants (e.g., organic pollutants).