The purpose of this study was to use zero‐valent iron nanoparticles (nZVI) and cellulosic wastes to reduce bioavailability of lead (Pb) and cadmium (Cd), and to establish Persian maple seedlings (Acer velutinum Bioss.) in contaminated soil. One‐year‐old seedlings were planted in pots filled with unpolluted soil. Lead [Pb(NO3)2] and Cd [Cd(NO3)2] were added with concentrations of 0 (Control), 100 (Pb100), 200 (Pb200), and 300 (Pb300) mg kg−1 and 10 (Cd10), 20 (Cd20), and 30 (Cd30) mg kg−1. Cellulosic wastes were mixed with soil at the same time of planting [four levels: 0, 10 (W1), 20 (W2), 30 (W3) g 100 g−1 soil]. The nZVI was prepared by reducing Fe3+ to Fe0 and injected to pots [four levels: 0, 1 (N1), 2 (N2), and 3 (N3) mg kg−1]. Height, diameter, biomass, tolerance index of seedlings, bioavailability of heavy metals in soil, and removal efficiency of amendments were measured. The highest values of seedling characteristics were observed in N3. The highest removal efficiency of Pb (Pb100: 81.95%, Pb200: 75.5%, Pb300: 69.9%) and Cd (Cd10: 92%, Cd20: 73.7%, Cd30: 68.5%) was also observed in N3. The use of nZVI and cellulosic waste could be a proper approach for seedling establishment in forests contaminated with heavy metals.

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Biogeosciences and Forestry Biogeosciences and ForestryUsing nano-scale Fe 0 particles and organic waste to improve the nutritional status of tree seedlings growing in heavy metalcontaminated soil Mahya Tafazoli (1) , Seyed Mohammad Hojjati (1) , Pourya Biparva (2) , Yahya Kooch (3) , Norbert Lamersdorf (4) The rehabilitation of heavy metal-contaminated lands is a challenging issue worldwide. The application of effective eco-friendly techniques and materials is necessary for amending the contaminated soils, and the in-situ results should be examined. The present study investigated the effect of zero-valent iron-nanoparticles (Fe 0 -NPs) and cellulosic wastes (CW) on the lead (Pb) and cadmium (Cd) uptake and nutrients' (N, P, K) concentration of maple seedlings in contaminated soil. First, one-year-old seedlings were planted in pots containing unpolluted soil (volume = 3 Kg), and then the soil was contaminated by adding Pb (0, Pb100, Pb200, and Pb300 mg kg -1 ) and Cd (0, Cd10, Cd20, and Cd30 mg kg -1 ) solutions. The CW (0, 10, 20, 30 g/100g soil) and Fe 0 -NPs (0, 1, 2, 3 mg kg -1 ) treatments were applied to the soil before and after Pb and Cd addition, respectively. The biomass of seedlings and the concentration of nitrogen, potassium, and phosphorus in leaves were measured. Leaves, stems, and roots were digested to measure the Pb and Cd concentrations. Results showed that CW and Fe 0 -NPs improved N, P, and K concentrations in leaves at all levels of contamination. The lowest concentration of Pb and Cd in all organs and treatments was observed in the highest level of Fe 0 -NPs. The cellulosic waste and Fe 0 -NPs (the highest level only) significantly increased the soil pH at all levels of contamination. Our findings suggested that the use of Fe 0 -NPs (3 mg kg -1 ) and CW (30g/100g soil) could be appropriate for reducing the bioavailability of Pb and Cd in contaminated soil and improving the growth of maple seedlings.

Key message Nitrogen (N) addition (10 and 15 g N m −2 year −1 as dissolved 4 3 ) significantly increased the CO 2 efflux from the forest soil and the fine root biomass in a maple (Acer velutinum Bioss.) plantation. Following a seasonal pattern, soil CO 2 efflux showed an exponential relationship with the fine root biomass and soil temperature.• Context The effect of increased atmospheric Nitrogen (N) deposition on forest soil CO 2 efflux is still unclear in the Hyrcanian forests and has received considerable attention in the context of global climate change.• Aims Aims of this study were to determine how soil CO 2 efflux and fine root biomass change after N addition in a maple (Acer velutinum Bioss.) plantation.• Methods Since the wet N deposition in these areas is 3-5 g N m −2 year −1 , four treatments including N1 (5 g N m −2 year −1 ), N2 (10 g N m −2 year −1 ), N3 (15 g N m −2 year −1 ), and N0 (control) were selected. Twelve plots (10 × 20 m) were established, and a NH 4 NO 3 solution was sprayed monthly below the trees' canopy for 1 year. Soil temperature, moisture, and soil CO 2 efflux were measured monthly with static dark closed chambers. Fine root biomass was seasonally measured by soil sampling at the same depth.• Results Soil temperature, moisture, and soil CO 2 efflux were affected by different levels of N addition. Soil CO 2 efflux significantly increased with N addition, and N3 displayed the highest rate (174 ± 16.1 mg CO 2-C m −2 h −1 ). Fine root biomass increased significantly in N3. • ConclusionThe predicted levels of N deposition in such plantations will probably lead to enhanced CO2 efflux from soils in reforested areas close to industrial sites in the Hyrcanian forest.

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