Excessive fertilization leads to high nitrogen (N) leaching under intensive plastic-shed vegetable production systems, and thereby results in the contaminations of ground or surface water. Therefore, it is urgent to develop cost-effective strategies of nitrogen management to overcome these obstacles. A 15-year experiment in annual double-cropping systems was conducted to explore impacts of N application rate and straw amendment on mineral N leaching loss in plastic-shed greenhouse. The results showed that seasonal mineral N leaching was up to 103.4–603.4 kg N ha⁻¹, accounting for 12%–41% of total N input under conventional N fertilization management. However, optimized N application rates by 47% and straw addition obviously decreased mineral N leaching by 4%–86%, while had no negative impacts on N uptake and tomato yields. These large decreases of N leaching loss were mainly due to the reduced leachate amount and followed by N concentration in leachate, which was supported by improved soil water holding capacity after optimizing N application rates and straw addition. On average, 52% of water leachate and 55% of mineral N leaching simultaneously occurred within 40 days after planting, further indicating the dominant role of water leakage in regulating mineral N leaching loss. Moreover, decreasing mineral N leaching was beneficial for reducing leaching loss of base cations. Therefore, optimized N application rates and straw amendment effectively alleviates mineral N leaching losses mainly by controlling the water leakage without yield loss in plastic-shed greenhouse, making this strategy promising and interesting from environmental and economical viewpoints.

Many naturally seleniferous soils are faced with Cd contamination problem, which severely limits crop cultivation in these areas. Straw returning has been widely applied in agricultural production due to its various benefits to soil physicochemical properties, soil fertility, and crops yield. However, effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils remain largely unclear. Therefore, the effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils were investigated in this study. The results showed that iron reduction driven by Clostridium and Anaeromyxbacter was responsible for the variations in Se and Cd fates in soil. Straw application respectively increased the gene copy numbers of Clostridium and Anaeromyxbacter by 19.5–56.3% and 33.6–39.8%, thus promoting iron reductive dissolution, eventually resulting in a high release amount of Se and Cd from Fe(III) (oxyhydr) oxides. Under reducing conditions, the released Cd was adsorbed by the newly formed metal sulfides or reacted with sulfides to generate CdS precipitates. Straw application decreased the soil exchangeable Se and soil exchangeable Cd concentration during flooding phase. However, straw application significantly increased Se/Cd in soil solution which had the highest bioavailability during flooding. In addition, straw application increased soil exchangeable Se concentration, but it had no significant effects on soil exchangeable Cd concentration after soil drainage. Taken together, straw application increased Se bioavailability and Cd mobility. Therefore, straw application is an effective method for improving Se bioavailability, but it is not suitable for the application to Cd-contaminated paddy soils. In the actual agricultural production, straw could be applied in seleniferous soils to improve Se bioavailability. At the same time, straw application should be cautious to avoid the release of Cd from Cd-contaminated soil.

The active use of solid fossil fuels (coal) in the production of heat and electricity has led to significant pollution, climate change, environmental degradation, and an increase in morbidity and mortality. Many countries (in particular, European ones, China, Japan, the USA, Canada, etc.) have launched programs for using plant and agricultural raw materials to produce heat and electricity by burning them instead of or together with traditional fuels. It is a promising solution to produce slurry fuels, based on a mixture of coal processing, oil refining and agricultural waste. This paper presents the results of experimental research into the formation and assessment of the most hazardous emissions (sulfur and nitrogen oxides) from the combustion of promising coal slurry fuels with straw, sunflower and algae additives, i.e. the most common agricultural waste. A comparative analysis has been carried out to identify the differences in the concentrations of sulfur and nitrogen oxides from the combustion of typical coal, coal processing waste, as well as fuel slurries with and without plant additives. It has been shown that the concentration of sulfur and nitrogen oxides can be reduced by 62–87% and 12–57%, respectively, when using small masses of plant additives (no more than 10 wt%) and maintaining high combustion heat of the slurry fuel. However, the use of algae and straw in the slurry composition can increase the HCl emissions, which requires extra measures to fight corrosion. A generalizing criterion of slurry fuel vs. coal efficiency has been formulated to illustrate significant benefits of adding plant solid waste to coal-water slurries containing petrochemicals. Straw and sunflower waste (10 wt%) were found to be the best additives to reduce the air pollutant emissions.

Pollution by antimony (Sb) and arsenic (As) in soil can pose a great threat to human health. Straw-returning is widely applied to paddy fields for improving and remediating soil. A pot experiment was conducted to investigate the effect of straw-returning on Sb and As transformation and translocation in a soil–rice system. In this study, Sb and As co-contaminated soil was thoroughly mixed with different proportions (0, 0.5, 1, and 2%) of straw and used for growing rice plants through the entire growing stage in a pot experiment and 4 weeks in a microcosm experiment. The straw application significantly increased Sb and As mobility. The concentrations of total Sb and As in soil-pore water increased after the application of straw in most growing stages. The Sb volatilization in the pot and microcosm experiments was also stimulated by straw application. With the high dose of straw application (2%), the concentration of Sb in brown grain was reduced by 72% compared with the control, but As concentrations increased by around 77%. These findings provide a new perspective in that straw-returning could affect the behavior of both Sb and As in soil and reduce the Sb accumulation in brown grain and some guidance in the use of straw-returning in Sb-contaminated paddy soil.

Occurrence, behavior, and fate of 11 OPEs in multiple environmental matrices, which include air, rainwater, dustfall, paddy soil, irrigation water, and rice plants from nine subtropical paddy fields of South China, were investigated. The total concentrations of 11 OPEs (∑₁₁OPEs) in all matrices are generally higher in the urban areas than in rural areas, and they are higher in summer than in fall. However, both urban and rural areas showed a similar composition profile of OPEs, indicating that the OPEs come from similar sources in the two areas. Except for irrigation water, significant positive correlations of ∑₁₁OPEs were observed between air and the other five matrices. The exchange and partition of OPEs among air, soil, and water demonstrate that most of OPEs were transferred from air into water and soil, and from water into soil. Thus, the air may be an important source of OPEs in the paddy fields, and the soil may act as a principal environmental reservoir of OPEs. The contribution of air-soil exchange, atmospheric deposition (rainwater plus dustfall), and irrigation water to the total input fluxes of OPEs (2100 ± 980 ng/m²/day) reached an average of 19%, 38% (37% + 1%), and 43%, respectively. The water (rainwater plus irrigation water) is the primary medium transferring the OPEs into the paddy fields and contributed to the input flux by 80%. Output flux of OPEs via mature rice plants was about 220 μg/m², 2% of which were presented in rice, and the remaining 98% may be re-released into the environment through the pathway of straw turnover or burning. Dietary exposure via rice was much higher than inhalation exposure, dust ingestion, and dermal absorption via dust. However, no data shows that all of the intakes via the four exposure pathways could cause the risks to human health at present.

Cadmium (Cd) uptake and accumulation in crop plants, especially in wheat (Triticum aestivum) and rice (Oryza sativa) is one of the main concerns for food security worldwide. A field experiment was done to investigate the effects of limestone, lignite, and biochar on growth, physiology and Cd uptake in wheat and rice under rotation irrigated with raw effluents. Initially, each treatment was applied alone at 0.1% and combined at 0.05% each and wheat was grown in the field and then, after wheat harvesting, rice was grown in the same field without additional application of amendments. Results showed that the amendments applied increased the grain and straw yields as well as gas exchange attributes compared to the control. In both crops, highest Cd concentrations in straw and grains and total uptake were observed in control treatments while lowest Cd concentrations was observed in limestone + biochar treatment. No Cd concentrations were detected in wheat grains with the application of amendments except limestone (0.1%). The lowest Cd harvest index was observed in limestone + biochar and lignite + biochar treatments for wheat and rice respectively. Application of amendments decreased the AB-DTPA extractable Cd in the soil while increasing the Cd immobilization index after each crop harvest. The benefit-cost ratio and Cd contents in plants revealed that limestone + biochar treatment might be an effective amendment for increasing plant growth with lower Cd concentrations.

The practice of incorporating post-harvest crop waste is widely used because it maintains soil fertility and avoids environmental pollution from straw burning. However, the practice of straw incorporation may also retain the pesticides that are applied to crop plants, which may pose a potential long term risk to local and regional environments if the applied pesticide is a Persistent, Bioaccumulative, and Toxic (PBT) substance or a Persistent Organic Pollutant (POP). Here we investigate the influence of the “receiving-retention-release” route on the distribution of a POP pesticide (endosulfan) and the associated environmental risk among different environmental compartments. Our study indicates that most endosulfan enters the atmosphere (φatmosphere = 64.5–72.5%), which is dominated by the indirect route of volatilization from crop plants (φatmosphere, indirect = 54.7–70.3%). In contrast, soil releases are minor (φsoil = 10.8–20.5%), and are dominated by direct release during application (φsoil, direct = 8.0–18.0%). Under the practice of straw incorporation, the use of endosulfan posed an environmental risk to agricultural soil. In addition, the atmospheric deposition of endosulfan also posed an environmental risk to sediment. The study highlights the significance of the “receiving-retention-release” route by crop plants in determining the fate of POP pesticides associated with straw incorporation; hence complementing the current methodology for assessing the environmental risk of these compounds.

Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising.

Coronene is a high molecular weight polycyclic aromatic hydrocarbon with seven aromatic rings. It, more specifically a lower ratio of Benzo[a]pyrene to Coronone (BaP/COR), is suggested as a marker for vehicle emission. In the present study, emissions of Coronene were measured from residential combustions of wood, crop straw, and pellets. The detection of COR in non-vehicle emission sources, and comparable BaP/COR ratios between the solid fuel combustion and vehicle emissions indicated that the generality of COR or the BaP/COR ratio as markers for the vehicle emission would be questionable, especially for the area where solid fuel combustion dominated the PAHs emission.