ABSTRACTThe yak manure based biochar was produced at different temperatures of 300, 500 and 700 ℃ held for 3 h, which was characterized by BET surface area, X-ray diffraction, Fourier transform infrared spectroscopy, pH measurement, analysis, scanning electron microscopy and ultimate analysis. The resultant biochar had characteristics of high surface area, high pH, porous structure and rich nutrients such as N, P, Ca, Mg, and K, inferring that the yak manure-derived biochar could be used as a soil conditioner. The field experiment was conducted to study the effect of yak manure derived biochar amendment on the yield and biological traits of highland barley, revealing that adding biochar to soil could increase the yield and growth of highland barley in short-term although the long-term benefits remain to be quantified. The present results can be useful to fill the knowledge gap regarding the potential of yak manure derived biochar to soil improvement.

ABSTRACTRisk assessment indices such as risk assessment code (RAC), potential ecological risk index (PERI), geoaccumulation index (Igeo), contamination factor (CF) and enrichment factor (EF) provide a good measure of environmental risk posed by Pb accumulated in shooting range soils as opposed to total Pb concentration. For this reason, the S/P Pistol shooting range, even though accumulated lower concentration of Pb (685±218 mg/kg), exhibited ‘very high risk’ to the environment with RAC value of 77 exceeding the 51 set guideline value for ‘very high risk’ with a significant margin compared to MAT R2 (20888±5419 mg/kg) at RAC value of 48 and highest total Pb concentration. This implies that mobility and bioavailability of Pb at S/P Pistol shooting range will be higher posing a greater risk to biota even though contamination from Pb is low. Best shooting range management practices and low cost remedial actions such as phytoremediation and chemical immobilization should be carried out as soon as possible to minimize the bioavailability and mobility of Pb in the studied shooting ranges.

ABSTRACTThis study aims to determine the sediment changes and the trends in TOC, BC and TN before and after restoration of the mangrove wetland in the Jinjiang Estuary and to determine the effect of the wetland restoration process on the biogeochemical cycle of carbon and nitrogen. The results suggest that the sediments were mainly silt-sized. Among different sites with different types of plants and vegetation densities, the adsorptive ability of N in the plots in plantations of Kandelia obovata, Avicennia marina and Acanthus ilicifolius was the highest. The TOC content differed (p < 0.05) with the density of the plot and significantly differed (p < 0.01) with the mangrove species at the densities of 0.5 × 1 m and 0.5 × 0.5 m. There was a positive relationship between the TOC and TN and the TOC and carbon-nitrogen ratio (C/N) (P < 0.05).

The effects of adding larch (Larix kaempferi) leaf litter and nitrogen (N) on microbial activity and phosphorus (P) fractions in forest soil were examined in a short-term (28-d) laboratory incubation study. The soil was analyzed using a modified Hedley sequential extraction procedure and an acid phosphatase assay. The addition of larch litter and N increased the acid phosphatase activity and decreased the labile P (H2O-P + NaHCO3-P) concentration. Compared with addition of larch litter only, addition of both inputs decreased the proportion of inorganic P (Pi) and increased that of organic P (Po) in the NaOH fraction, bound to aluminum and iron oxides. The results of nutrient (carbon, N, or P) addition indicated that acid phosphatase was synthesized to acquire P. This study suggests that, in this forest soil, P in the H2O-P + NaHCO3-P and in the NaOH-Pi fractions was available for soil microorganisms to decompose leaf litter and that increase in microbial activity eventually translated in an increase in the proportion of Po found in the NaOH fraction in this forest soil.

ABSTRACTAdsorption of levofloxacin (LEV) onto four types of magnesium (Mg)-impregnated biochars, fabricated via thermal pyrolysis of wood chips pretreated with MgSO4 was investigated. The Mg-impregnated biochars were characterized with various tools and techniques. Batch sorption experiments were conducted to determine the sorption kinetics and isotherms of LEV onto the Mg-impregnated biochars. The pseudo-second order kinetic model described the adsorption kinetic data better than the pseudo-first order kinetic model and the Elovich equation. Due to multi-mechanisms, the Freundlich model described the experimental isotherms better than the Langmuir model. The Langmuir maximum adsorption capacities of the Mg-impregnated biochars to LEV ranged from 7.38 to 25.2 mg g−1. In the fixed-bed column experiment, higher bed height and lower flow rate led to greater LEV removal. Findings from this work indicate that Mg-impregnated biochars can be used as an alternative adsorbent to effectively remove LEV from aqueous solutions.

The investigations of nanotechnology with the application on agricultural products also have been few reported, especially the plant regeneration. The effects of activated charcoal and nanocarbon on the callus induction and plant regeneration of aromatic rice were studied. Activated charcoal was added into the callus induction and regeneration medium. The presence of activated charcoal in the callus induction medium (100–500 mg L−1), activated charcoal significantly reduced the percentage of the callus induction and biomass accumulation (fresh weight, dry weight and size). Whereas, the regeneration medium supplemented with 100 mg L−1 of activated charcoal showed the highest percentage of plant regeneration (61.90%) and the ratio of the number of seedlings to the number of regenerated calli (RSR; 3.06) that derived from the callus induction medium (without activated charcoal). Moreover, the induced calli derived from the callus induction medium supplemented with nanocarbon at 5 mg L−1 showed the highest percentage of callus induction (94.70%), the percentage of green spots (95.83%), the percentage of plant regeneration (60.42%) and the RSR (3.12) when transferred the calli into the regeneration medium (without nanocarbon). After that, nanocarbon was also added into the regeneration medium. The percentage of green spots (96.08%), the percentage of plant regeneration (62.75%) and the RSR (3.16) obtained from the regeneration medium supplemented with 20 mg L−1 of nanocarbon showed the highest values. This experiment showed that the optimum concentration of activated charcoal and nanocarbon had potential to enhance the callus induction and plant regeneration frequencies in tissue culture medium of aromatic rice.

Columnar sediment samples were collected from five representative river inflow areas of Dianchi Lake, China. The vertical distribution of each form of P were tested. Results showed that the concentration of TP in the sediments from areas A, B, C, D and E in the order of D > B > A > C > E, and the average concentration of D, B, A, C and E were 2991, 2064, 1308, 879, and 759 mg•kg−1, respectively. The concentration of Ex-P, Fe/Al-P, Ca-P and Org-P all decreased with increasing depth. The release of Ex-P was significantly related to TP whereas the Fe/Al-P was not significantly related to TP in the samples from areas polluted by domestic sewage. However, the release of Ex-P and Fe/Al-P were both significantly related to TP in the samples from areas polluted by phosphate mining and phosphate fertilizer application. The results of equilibrium P concentration (EPC0) analysis showed that P in the sediments of areas A, D and E were the source of P in Dianchi Lake, and the P in the sediments of areas B and C were in relative equilibrium with the overlying water.

Soil humus degradation strengthens nutrient mining, especially phosphorus. This study was carried out on the Ukrainian Forest-Steppe Zone (UFSZ). A total of 21 soil profiles have been investigated: 11 Phaeozems, 6 Luvisols, and 4 Chernozems. Soils were tested for particle size distribution, calcium carbonate (CC), pH, and organic carbon (Corg). The evaluation of humus degradation as a reason of P depletion was performed based on indicators such as Humus Stock Gap (HSG), Humus Stability Index (S), and Yield Gap/Gain (YG/G). In order to evaluate the degree of P depletion, total phosphorus (Ptot) and its five fractions: water soluble – PH2O, exchangeable – PEX, bound to Fe and Al – PFe/Al, bound to Ca – PCa, and residual P – Pres, have been determined.Data revealed that in 14 of 21 investigated soils, S indices were below the threshold its value of nine, considered as the balanced content of humus with respect to soil texture. Next, in 11 of 21 cases, the negative humus balance indicates the yield gap in Phaeozems and Chernozems. The first three P pools (PH2O, P­EX and PAl/Fe) in Phaeozems were exhausted, constituting less than 10% of the Ptot. In Phaeozems, PAl/Fe, in Luvisols, PEX, and in Chernozems, PH2O fractions were basic indicators of available P status. Their pools were directly or indirectly controlled by PCa. Humus content in Phaeozems and Chernozems revealed as the key factor impacting both total P and/or its available resources. Amelioration of P depletion requires efforts oriented on restoration of soil humus stock, concomitant with P fertilization.

ABSTRACTThe interactive effects of straw-derived biochar and bio-based polymer-coated urea (BPCU) was examined with a pot experiment conducted in 2014 and 2015. Using a split-plot design, the main plot factor was the form of straw use and the sub-plot factor was the type of N fertilizer. The soil inorganic nitrogen (N), organic carbon and lint yield of biochar treatments were significantly higher than for straw treatments. Meanwhile, the BPCU treatments enhanced nitrogen use efficiency (NUE) and yield over urea treatments. Biochar combined with BPCU resulted in the highest lint yield, 14.3–108.2% increasing over the other treatments, with NUE 27.1–63.5% increased. We attributed this superior performance to the interactive effects between BPCU’s controlled supply of N according to cotton’s N requirements and biochar’s functionalities in enhancing soil quality. Thus, the application of biochar and BPCU is a sustainable strategy to improve soil quality and increase cotton yield.

ABSTRACTThe transport of Pb(II) or Cd(II) in subsurface has been studied in the literature; however; their co-transport in porous media in presence of colloids has not been clearly understood. In this work, a series of column experiments were conducted to study Pb(II) and Cd(II) co-transport in saturated porous media under various experimental conditions with different combination of colloidal solution (montmorillonite colloid, manual loessial soil colloid and humic acid), flow rate (0.1, 0.5 and 1.0 ml min−1) and sand grain size (0.4–0.8mm and 0.8–2.0mm). The results showed that increase of flow rate and grain size promoted the mobility of Pb(II) and Cd(II), furthermore, the presences of mobile colloids also enhanced the mobility of the two heavy metals, meanwhile, Cd(II) showed higher mobility than Pb(II) in the columns. Findings from this work enhanced current understanding of the competitive transport and colloid-facilitated transport of heavy metals in saturated porous media.