Fertilization plays an essential role in forest management on the site being under air pollution load in last years. The soil acidity due to the acid fall-out is markedly worse and at the same time the concentration of calcium, phosphorous, potassium and magnesium are decreasing. The fertilization besides positive influence on height increment could help in adaptation process of plants establishment after transplanting and it can eliminate negative ifluence of anthropogenic conditions of the environmnet

Identifying the bioavailability and release-desorption mechanism of heavy metals (HMs) in soil is critical to understand the release risk of HMs. Simultaneously, the mechanistic investigation of affecting the bioavailability of HMs in soil is necessary, such as the grain-size distribution and soil mineralogy. Herein, the bioavailability of HMs (Cu, Cd, Ni, Pb, and Zn) in different area soils near a typical copper-smelter was evaluated by the sequential extraction technique (BCR), diffusive gradients in thin-films (DGT), and DGT-induced fluxes in sediments (DIFS) model. Results showed that the HMs proportion of the residual fraction in all soils was the highest. The average bioavailability concentration (CDGT) of Cu and Cd in industrial soil was the highest, with 45.12 μg· L⁻¹ and 9.06 μg· L⁻¹. The result of DIFS model revealed that the decreased order of the mean value of desorption rate constant (K₋₁) was Cd > Zn > Ni > Cu > Pb, 5.91 × 10⁻⁵, 4.96 × 10⁻⁵, 2.89 × 10⁻⁵, 9.64 × 10⁻⁶, and 8.69 × 10⁻⁶, respectively. According to the spatial distribution of release potential (R-value), the release potential of labile-Cu in agricultural soil was the highest, which was mainly attributed to fertilizer application in farmland. Simultaneously, the reduced hydroxyl was also related to the agricultural activities, resulting in the weakened adsorption capacity of HMs by soil. Redundancy analysis (RDA) results showed that the bioavailability of Cd, Ni, and Zn was mainly driven by soil pH, while the bioavailability of Cu and Pb was primarily driven by dissolved organic carbon (DOC). Meanwhile, carbonate minerals had a positive correlation with the bioavailability of Cd, Ni, and Zn, which could promote the release of HMs in mining soil as chemical weathering progresses. In conclusion, this study provides a structured method which can be used as a standard approach for similar scenarios to determine the geochemical fractionation, bioavailability, and release kinetics of heavy metals in soils.

Both inorganic and organic fertilizers are widely used to increase rice yield. However, these fertilizers are also found to aggravate mercury methylation and methylmercury (MeHg) accumulation in paddy fields. The aim of this study was to reveal the mechanisms of inorganic and organic fertilizers on MeHg accumulation in rice grains, which are not yet well understood. Potting cultures were conducted in which different fertilizers were applied to a paddy soil. The results showed that both inorganic and organic fertilizers increased MeHg concentrations rather than biological accumulation factors (BAFs) of MeHg in mature rice grains. Inorganic fertilizers, especially nitrogen fertilizer, enhanced the bioavailability of mercury and the relative amount Hg-methylating microbes and therefore intensified mercury methylation in paddy soil and MeHg accumulation in rice grains. Unlike inorganic fertilizers, organic matter (OM) in organic fertilizers was the main reason for the increase of MeHg concentrations in rice grains, and it also could immobilize Hg in soil when it was deeply degraded. The enhancement of MeHg concentrations in rice grains induced by inorganic fertilizers (5.18–41.69%) was significantly (p < 0.05) lower than that induced by organic fertilizers (80.49–106.86%). Inorganic fertilizers led to a larger increase (50.39–99.28%) in thousand-kernel weight than MeHg concentrations (5.18–41.69%), resulting in a dilution of MeHg concentrations in mature rice grains. Given the improvement of soil properties by organic fertilizer, increasing the proportion of inorganic fertilizer application may be a better option to alleviate MeHg accumulation in rice grains and guarantee the rice yield in the agricultural production.

Overuse of phosphorus (P) fertilizer and the resulting soil P accumulation in vegetable production increases the risk of P runoff and leaching. However, P transformations under continuous fertilization and their effects on environmental risk are unclear. The current study examined the effects of long-term P fertilizer application on P fractions in different soil layers, and assessed the correlations between P fractions and environmental risks in intensive vegetable production in a subtropical region. A total of 32 fields were studied, including 8 uncultivated fields and 24 fields continuously used for vegetable production for 1–3, 4–9, or 10–15 years. The results showed that excessive P fertilizer input caused soil P surpluses ranging from 204.6 to 252.4 kg ha⁻¹ yr⁻¹. Compared to uncultivated fields, vegetable fields contained higher levels of labile P, moderately labile P, sparingly labile P, and non-labile P. The combined percentage of labile P and moderately labile P increased from 55.2% in fields cultivated for 0–3 year to 65.5% in fields cultivated for 10–15 years. The concentrations of soil P fractions were higher at 0–20 cm soil depth than at 20–40 and 40–60 cm soil depth. Soil available P was positively correlated with all soil P fractions except diluted HCl-Pᵢ or concentrated HCl-Pₒ. Long-term vegetable production increased CaCl₂–P downward movement, which was positively correlated with levels of labile and moderately labile P. The P index indicated a high risk of P losses from the vegetable fields. The P index was on average 3.27-fold higher in the vegetable fields than in uncultivated fields, and was significantly correlated with soil available P and organic and inorganic P fertilizer input. The environmental risk caused by P in vegetable production should be reduced by reducing P fertilizer input so as to maintain soil available P within an optimal range for vegetable production.

Insight in the phosphorus (P) flows and P balances in the food chain is largely unknown at county scale in China, being the most appropriate spatial unit for nutrient management advice. Here, we examined changes in P flows in the food chain in a typical agricultural county (Quzhou) during 1980–2017, using substance flow analyses. Our results show that external P inputs to the county by feed import and fertilizer were 7 times greater in 2017 than in 1980, resulting in a 7-fold increase in P losses to the environment in the last 3 decades, with the biggest source being animal production. Phosphorus use efficiency decreased from 51% to 30% in crop production (PUEc) and from 32% to 11% in the whole food chain (PUEf), but increased from 4% to 7% in animal production (PUEa). A strong reduction in P inputs and thus increase in PUE can be achieved by balanced P fertilization, which is appropriate for Quzhou considering a current average adequate soil P status. Fertilizer P use can be reduced from 7276 tons yr⁻¹ to 1765 tons yr⁻¹ to equal P removal by crops. This change would increase P use efficiency for crops from 30% to 86% but it has a negligible effect on P losses to landfills and water bodies. Increasing the recycling of manure P from the current 43%–95% would reduce fertilizer P use by 17% and reduce P losses by 47%. A combination of reduced fertilizer P use and increased recycling of manure P would save fertilizer P by 93%, reduce P accumulation by 100% and P loss by 49%. The results indicate that increasing manure-recycling and decreasing fertilizer-application are key to achieving sustainable P use in the food chain, which can be achieved through coupling crop-livestock systems and crop-based nutrient management.

This study focused on the seasonal variation and source identification of heavy metals (HMs) while considering effects of municipal wastewater (MWW) in peri-urban farms of Hue city, central Vietnam. Moreover, associated non-carcinogenic and carcinogenic health risks from consuming vegetables containing HMs were also assessed considering the hazard quotient and cancer risk, respectively. Therefore, concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb, and As were determined in irrigation water, soil, and lettuce samples collected during dry and wet seasons from one upstream site where irrigation water has no impact on MWW as well as from two downstream sites in farms on the outskirt of the city. Although irrigation water and soil in the same farms were not polluted as strongly, lettuce samples were polluted with Cd, Zn, and Pb. Furthermore, levels of soil Cu and As and HMs (except for Cu) in lettuce in the wet season were significantly higher (p < 0.05) than those in the dry season, indicating the impact of MWW with seasonal change. The health risk assessment via lettuce consumption demonstrated an unacceptable carcinogenic risk owing to Cd and a cumulative non-carcinogenic risk owing to selected HMs in the lettuce, while all other risks were negligible. Correlation and principal component analyses were performed to identify HM sources, indicating that Cu, Zn, Cd, Pb, Cr, and As in irrigation water and soil could have anthropogenic sources (e.g., untreated MWW, fertilizer use); meanwhile, irrigation-water and soil Fe, Mn, As, and Cr could originate from non-anthropogenic sources (e.g., parent materials weathering). This study revealed that rapid urbanization together with high precipitation leading to urban floods in Hue city was a significant factor spreading HMs in agricultural farms, suggesting the importance of wastewater treatment system, which can reduce the HM load in the city to protect the local food production.