Effect of different biochars amendment on soil biological indicators in a calcareous soil

Environmental Science and Pollution Research - Previous studies suggest that biochar has potential to benefit soil when used as an amendment, but only few studies have investigated how the...     

The effects of simultaneous large acidic and alkaline airborne pollutants on forest soil

The effects of air pollutants on soil were studied in Scots pine (Pinus sylvestris L.) forests near the boundary of Russia and Estonia. The study area is characterized by large amounts of acidic and basic pollutants, mainly sulphur dioxide (SO(2)) and calcium (Ca). Several variables were measured in different horizons of the podzolic soil polluted by emissions from local sources in areas of several thousands of square kilometers. Alkalinization dominates the processes in the soil, since sulphur is absorbed only in small quantities and Ca is much better absorbed. Ca content in humus horizon may rise even to 100 000 mg kg(-1) and the pH of originally very acidic soil may rise to 8.3. Total aluminum (Al) content was high in the heavily polluted plots, since emissions contain much Al. On the other hand, the exchangeable Al was very low in these alkaline sites. A larger quantity of exchangeable Al occurred farther from the pollutant sources, even though total Al in these plots was low. These plots had acidic soils in which Al is in exchangeable form. Due to the neutralizing effect of acidic and basic pollutants, forest damage in the study area was not as serious as might be supposed. Complicated pollutant situations must be taken into consideration when pollution-caused environmental protection measures are planned. It is not reasonable to reduce only SO(2) emissions, but necessary to lower the basic emissions at the same time.     

The effects of acidic irrigation on soil microorganisms at Kevo, Northern Finland

Effects of simulated acid rain (a mixture of H(2)SO(4) and HNO(3); pH(3)) on soil microbiology were studied in a field experiment in northern Finland. Irrigated control plots received the same amount of spring water (pH 6) as the acid treated plots. Fungal lengths and total bacterial numbers were studied after the treatments had continued for three growing seasons. The numbers of bacteria in five physiological groups (those utilizing starch, protein, pectin, xylan, or cellulose) were measured by MPN (most probable number) techniques. The lengths of total and FDA active fungal hyphae were not significantly different between the acid treated and the control plots. The counts of total bacteria were not significantly different between treatments, but the MPNs of all five physiological groups of bacteria were approximately 60% lower in the acid treated plots than in the controls.     

新制备生物炭的特性表征及其对石油烃污染土壤的吸附效果

生物炭作为一种绿色环保的功能材料因其在污水处理和污染土壤修复方面具有显著效果而受到极大关注。采用红外光谱、元素分析仪及微孔分析对不同温度(200、300、400、500和600℃)条件下制备的木屑和麦秆生物炭进行特性表征,并采用制备的生物炭净化石油污染土壤,分别考察了污染物性质、生物质原料和热解温度对其净化效果的影响。结果表明,随着热解温度的增高,生物炭芳香化程度增加,极性降低,微孔结构逐渐发育,表面积增大。加入生物炭33 d后,污染土壤中总石油烃及其组分烷烃的浓度比对照略有降低,而PAHs浓度下降显著。随着热解温度升高,2种生物炭对PAHs的吸附强度均逐渐增大,芳香度增高、表面积增大是强吸附的主要原因。2种生物炭在400℃及以下温度制备时对PAHs的吸附强度为:木屑生物炭 > 麦秆生物炭;而400℃以上温度制备的生物炭吸附强度则相反,即麦秆生物炭 > 木屑生物炭,说明生物炭原料对其吸附强度也具有显著影响。     

Effect of Pinus radiata derived biochars on soil sorption and desorption of phenanthrene

Biochars are anthropogenic carbonaceous sorbent and their influences on the sorption of environmental contaminants need to be characterized. Here we evaluated the effect of Pinus radiata derived biochars on soil sorption and desorption of phenanthrene. Two biochars separately produced at 350 °C and 700 °C and three soils were tested. Biochar amendment generally enhanced the soil sorption of phenanthrene. The biochar produced at 700 °C generally showed a greater ability at enhancing a soil’s sorption ability than that prepared at 350 °C. The single-step desorption measurement showed an apparent hysteresis in biochar-amended soils. After 28 d equilibration, the sorptive capacity of biochar-amended soil (with an organic carbon content of 0.16%) significantly decreased. This study clearly suggested that biochar application enhanced soil sorption of hydrophobic organic compounds, but the magnitude of enhancement depended on the preparation of biochars, the indigenous soil organic carbon levels, and the contact time between soil and biochar.     

Effect of wheat and rice straw biochars on pyrazosulfuron-ethyl sorption and persistence in a sandy loam soil

The objective of this research was to investigate the effect of wheat and rice biochars on pyrazosulfuron-ethyl sorption in a sandy loam soil. Pyrazosulfuron-ethyl was poorly sorbed in the soil (3.5–8.6%) but biochar amendment increased the herbicide adsorption, and the effect varied with the nature of the feedstock and pyrolysis temperature. Biochars prepared at 600°C were more effective in adsorbing pyrazosulfuron-ethyl than biochars prepared at 400°C. Rice biochars were better than wheat biochars, and higher herbicide adsorption was attributed to the biochar surface area/porosity. The Freundlich constant 1/n suggested nonlinear isotherms, and nonlinearlity increased with increase in the level of biochar amendment. Desorption results suggested sorption of pyrazosulfuron-ethyl was partially irreversible, and the irreversibility increased with increase in the level of biochar. Both sorption and desorption of pyrazosulfuron-ethyl correlated well with the content of biochars. The free energy change (ΔG) indicated that the pyrazosulfuron-ethyl sorption process was exothermic, spontaneous and physical in nature. Persistence studies indicated that biochar (0.5%) amendment did not have significant effect on herbicide degradation, and its half-life values in the control, 0.5% WBC600- and RBC600-amended rice planted soils were 7, 8.6, and 10.4 days, respectively.     

Aging and temperature effects on DOC and elemental release from a metal contaminated soil

The combined effect of time and temperature on elemental release and speciation from a metal contaminated soil (Master Old Site, MOS) was investigated. The soil was equilibrated at 10, 28, 45, 70 and 90 degrees C for 2 days, 2 weeks, and 2 months in the laboratory. Dissolved organic carbon (DOC), total soluble elements (by ICP), and labile metals (by DPASV) were determined in the filtered (0.22 microm) supernatants. For the samples equilibrated at 90 degrees C, DOC fractions were size fractionated by filtration and centrifugation; a subsample was only centrifuged while another was also filtered through a 0.45 microm filter. Analyses of the supernatants (ICP, DPASV, DOC) were performed on all size fraction subsamples. Dissolved organic carbon (DOC) increased both with temperature and incubation time; however, metal behavior was not as uniform. In general, total soluble metal release (ICP) paralleled the behavior of DOC, increasing with both time and temperature, and confirming the importance of soil organic matter (SOM) in metal retention. Voltammetric analysis (dpasv) of Cu and Zn showed that very little of these metals remains labile in solution due, presumably, to complexation with dissolved organic matter. Labile concentrations of Cd, on the other hand, constituted a significant portion (50%) of total soluble Cd. Copper and Al increased in solution with time (up to 2 months) and temperature up to 70 degrees C; however, at 90 degrees C the soluble concentration declined sharply. The same behavior was observed after equilibration for longer periods of time (550 days) at lower temperatures (23 and 70 degrees C). While concentrations of labile Cu and total soluble Cu and Al increased in the unfiltered samples, the trend remained the same. DPASV analysis showing shifts in labile Cu complexes with temperature and time, together with the results from the unfiltered samples, lead to the hypothesis that Cu was complexing with large polymers that could form at the elevated temperature, and thus be removed from the analyzed solution. It is possible that Cu and Al released by SOM oxidation has re-sorbed or complexed to more recalcitrant organic matter or to mineral phases. Variations in the relative molecular size fractions present within the DOC pool produced by increased time and temperature may influence the element-DOC complexes present in solution and their behavior in soil environments.     

Amelioration of acidic soil using various renewable waste resources

In this study, improvement of acidic soil with respect to soil pH and exchangeable cations was attempted for sample with an initial pH of approximately 5. Acidic soil was amended with various waste resources in the range of 1 to 5 wt.% including waste oyster shells (WOS), calcined oyster shells (COS), Class C fly ash (FA), and cement kiln dust (CKD) to improve soil pH and exchangeable cations. Upon treatment, the soil pH was monitored for periods up to 3 months. The exchangeable cations were measured after 1 month of curing. After a curing period of 1 month, a maize growth experiment was conducted with selected-treated samples to evaluate the effectiveness of treatment. The treatment results indicate that in order to increase the soil pH to a value of 7, 1 wt.% of WOS, 3 wt.% of FA, and 1 wt.% of CKD are required. In the case of COS, 1 wt.% was more than enough to increase the soil pH value to 7 because of COS's strong alkalinity. Moreover, the soil pH increases after a curing period of 7 days and remains virtually unchanged thereafter up to 1 month of curing. Upon treatment, the summation of cations (Ca, Mg, K, and Na) significantly increased. The growth of maize is superior in the treated samples rather than the untreated one, indicating that the amelioration of acidic soil is beneficial to plant growth, since soil pH was improved and nutrients were replenished.     

Mitigation effects of silicon rich amendments on heavy metal accumulation in rice (Oryza sativa L.) planted on multi-metal contaminated acidic soil

The mechanisms of stabilization by silicon-rich amendments of cadmium, zinc, copper and lead in a multi-metal contaminated acidic soil and the mitigation of metal accumulation in rice were investigated in this study. The results from a pot experiment indicated that the application of fly ash (20 and 40 g kg⁻¹) and steel slag (3 and 6 g kg⁻¹) increased soil pH from 4.0 to 5.0-6.4, decreased the phytoavailability of heavy metals by at least 60%, and further suppressed metal uptake by rice. Diffusion gradient in thin-film measurement showed the heavy metal diffusion fluxes from soil to solution decreased by greater than 84% after remediation. X-ray diffraction analysis indicated the mobile metals were mainly deposited as their silicates, phosphates and hydroxides in amended treatments. Moreover, it was found metal translocation from stem to leaf was dramatically restrained by adding amendments, which might be due to the increase of silicon concentration and co-precipitation with heavy metals in stem. Finally, a field experiment showed the trace element concentrations in polished rice treated with amendments complied with the food safety standards of China. These results demonstrated fly ash and steel slag could be effective in mitigating heavy metal accumulation in rice grown on multi-metal contaminated acidic soils.     

Long-term effects of soil heterogeneity on cadmium behaviour in soil

A deterministic model for long-term behaviour of contaminants in the rootzone is developed that includes sorption, leaching, and plant uptake. The model is applied to cadmium accumulation in a sandy soil and uptake of cadmium by barley. Sensitivity analysis showed that the sensitivity of the leaching rate to changes in soil chemical and soil physical parameters decreases as a function of time, and becomes zero when steady state is reached. In contrast, accumulation of cadmium in soil and the plant uptake rate of barley are increasingly sensitive to soil chemical and soil physical parameters as time preceeds. To analyse cadmium behaviour in a field that is heterogeneous with respect to soil physical properties, the interstitial flow velocity was assumed to be a random, lognormally distributed variate. Using Monte Carlo simulation, the average plant uptake rate appeared to be much higher in the stochastic analysis than in the deterministic approach. Steady state is reached after a very long period of time. For a lognormally distributed proton activity, causing heterogeneity with respect to the sorption capacity of the soil, the model predicted similar deviations from the deterministic approach. It is concluded that reference values for groundwater and crop quality are exceeded earlier in a heterogeneous field than in a homogenous soil profile. Moreover, when average values suggest an acceptable situation, variability of the leaching rate and the plant uptake rate can still cause exceedance of reference values in part of the field. Therefore, it is reasoned that environmental quality standards should take soil heterogeneity into account.     

Properties of biochars from conventional and alternative feedstocks and their suitability for metal immobilization in industrial soil

In contaminated soils, excessive concentrations of metals and their high mobility pose a serious environmental risk. A suitable soil amendment can minimize the negative effect of metals in soil. This study investigated the effect of different biochars on metal (Cu, Pb, Zn) immobilization in industrial soil. Biochars produced at 300 and 600 °C from conventional (MS, maize silage; WP, wooden pellets) and alternative (SC, sewage sludge compost; DR, digestate residue) feedstocks were used as soil amendments at a dosage of 10 % (w/w). The type of feedstock and pyrolysis temperature affected the properties of the biochars and their ability to immobilize metal in soil. Compared to production at 300 °C, all biochars produced at 600 °C had higher pH (6.2–10.7), content of ash (7.2–69.0 %) and fixed carbon (21.1–56.7 %), but lower content of volatile matter (9.7–37.2 %). All biochars except DR biochar had lower dissolved organic carbon (DOC) content (1.4–2.3 g C/L) when made at 600 °C. Only MS and SC biochars had higher cation exchange capacity (25.2 and 44.7 cmol/kg, respectively) after charring at 600 °C. All biochars contained low concentrations of Cd, Cu, Ni, Pb and Zn; Cd was volatilized to the greatest extent during pyrolysis. Based on FTIR analysis and molar ratios of H/C and O/C, biochars had a greater degree of carbonization and aromaticity after charring at 600 °C. The efficiency of the biochars in metal immobilization depended mainly on their pH, ash content, and concentration of DOC. SC and DR biochars were more effective for Cu and Zn immobilization than MS and WP biochars, which makes them attractive options for large-scale soil amendment.     

温度和表面活性剂对菲在土壤中吸附的影响

通过静态吸附实验,研究了北京地区土壤对菲的吸附行为,考察了温度和表面活性剂对菲吸附的影响.结果表明,6种土样对菲的吸附等温线均较好地符合Freundlich吸附模式,其吸附能力的大小顺序为:轻壤土>轻粘土>砂壤土>中壤土>重壤土>紧砂土;温度升高不利于菲在土壤中的吸附;十二烷基苯磺酸钠(LAS)和十六烷基三甲基澳化铵(CTAB)均利于菲在土壤表面的解吸,LAS和CTAB对菲的解吸率最高可达66.2%和31.8%,且LAS的解吸效果更好.     

Evaluation of accelerated dechlorination of p,p'-DDT in acidic paddy soil

The reductive dechlorination and behavior of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) was investigated in a paddy soil. Treatment with 5% (w/w) metallic iron (Fe(0)) resulted in sharp decrease of p,p'-DDT, whereas there was no extra effect when 2% (w/w) aluminum sulfate (Al(2)(SO(4))(3)) was added to the Fe(0) treatment. These results suggest that Fe(0) could effectively promote the reductive dechlorination of p,p'-DDT and its metabolites while Al(2)(SO(4))(3) did not show any effect on those processes. Furthermore, p,p'-DDT and its daughter compounds inhibited holistic soil respiration greatly at first but could be metabolized by certain species of indigenous microorganisms after a period of adaptation time in the soil. When treated with Fe(0), the polluted soil produced much less CO(2) while the addition of Al(2)(SO(4))(3) counteracted its negative effect to much extent.     

Assessment of natural and calcined starfish for the amelioration of acidic soil

Quality improvement of acidic soil (with an initial pH of approximately 4.5) with respect to soil pH, exchangeable cations, organic matter content, and maize growth was attempted using natural (NSF) and calcined starfish (CSF). Acidic soil was amended with NSF and CSF in the range of 1 to 10 wt.% to improve soil pH, organic matter content, and exchangeable cations. Following the treatment, the soil pH was monitored for periods up to 3 months. The exchangeable cations were measured after 1 month of curing. After a curing period of 1 month, the maize growth experiment was performed with selected treated samples to evaluate the effectiveness of the treatment. The results show that 1 wt.% of NSF and CSF (700 and 900 °C) were required to increase the soil pH to a value higher than 7. In the case of CSF (900 °C), 1 wt.% was sufficient to increase the soil pH value to 9 due to the strong alkalinity in the treatment. No significant changes in soil pHs were observed after 7 days of curing and up to 3 months of curing. Upon treatment, the cation exchange capacity values significantly increased as compared to the untreated samples. The organic content of the samples increased upon NSF treatment, but it remains virtually unchanged upon CSF treatment. Maize growth was greater in the treated samples rather than the untreated samples, except for the samples treated with 1 and 3 wt.% CSF (900 °C), where maize growth was limited due to strong alkalinity. This indicates that the amelioration of acidic soil using natural and calcined starfish is beneficial for plant growth as long as the application rate does not produce alkaline conditions outside the optimal pH range for maize growth.     

蛋白多肽对强酸化土壤的改良效应

以强酸化土壤(pH为4.30)为研究对象,以蛋白多肽为新型土壤改良剂,将传统施加生石灰的酸化土壤治理技术和施加复混肥的常规种植技术为对照,研究蛋白多肽对强酸化土壤的改良效应。结果表明：土培实验中的蛋白多肽与生石灰对强酸化土壤均有碱化效应,将土壤pH分别提高了0.23和0.30 (120 d稳定值),而复混肥碱化程度较低(提高0.02);同时,蛋白多肽组与生石灰组土壤交换性酸含量比复混肥组(35.93 mmol·kg⁻¹)分别降低了12.56 mmol·kg⁻¹和18.68 mmol·kg⁻¹,盐基饱和度分别比复混肥组(67.30%)高7.01%和9.85%;蛋白多肽组土壤有机质含量(19.96 g·kg⁻¹)变化尤为明显,并且,显著高于复混肥组(8.58 g·kg⁻¹)和生石灰组(12.23 g·kg⁻¹)。蛋白多肽与生石灰均能提高强酸化土壤pH,但未能一次性达到6.5以上的中性程度。基于此,以结球甘蓝为供试植物,研究此背景下的种植情况。结果显示,蛋白多肽可在偏低pH条件下种植出高产的结球甘蓝,比其他组合效果明显,其平均生物量(371.78 g)比复混肥组和生石灰组分别高9.54倍和1.90倍。蛋白多肽具有改良强酸化土壤的潜力,并能达到改良与种植同步化(蛋白多肽施加后直接种植作物幼苗)。研究结果可为强酸化土壤的改良与种植提供参考。     

多因素影响下SUFR系统除磷效果研究

在进水COD浓度控制在300～400 mg/L范围内,针对SRT、C/N和C/P 3个因素对TP的影响设计了正交实验,并在此基础上进行回归正交实验。实验结果显示：SRT、C/N、C/P 3个因素中SRT对厌氧释磷和好氧吸磷速率的影响最大,随着SRT的增大,系统除磷效率逐渐下降。C/N和C/P的增长使系统进水TN、TP浓...     

Deltamethrin degradation and effects on soil microbial activity

Deltamethrin [(S)-cyano-3-phenoxybenzyl-cis-(1R,3R)-2,2-dimethyl) cyclo–propane carboxylate),1] labelled at gem-dimethyl groups of the cyclopropane ring was applied on two Egyptian soils at a level of 10 mg/kg soil for a laboratory incubation experiment under aerobic and anaerobic conditions. A steady decrease of soil extractable¹⁴C-residues, accompanied by a corresponding increase of non- extractable bound ¹⁴C-residues was observed over a 90-day incubation period. The percentage of evolved ¹⁴CO₂ increased with time under aerobic and anaerobic conditions in both soils. The effect of deltamethrin on soil microorganisms as well as the counter effect of microorganisms on the insecticide was also investigated. As the incubation period increased, the inhibitory effect of the insecticide on the microorganisms decreased and the evolution of carbon dioxide depended on the applied dose. The nature of soil methanol soluble residues was determined by chromatographic analysis which revealed the presence of the parent insecticide as the main product in addition to four metabolites: 3-(2′,2′-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (II); 3-phenoxybenzaldehyde (III); 3-phenoxybenzoic acid (IV); 3-phenoxybenzyl alcohol (V).     

Assessment of natural sepiolite on cadmium stabilization, microbial communities, and enzyme activities in acidic soil

A pot trial was conducted to assess the efficiency of sepiolite-induced cadmium (Cd) immobilization in ultisoils. Under Cd concentrations of 1.25, 2.5, and 5 mg?kg^?1, the available Cd in the soil after the application of 1–10 % sepiolite decreased by a maximum of 44.4, 23.0, and 17.0 %, respectively, compared with no sepiolite treatments. The increase in the values of soil enzyme activities and microbial number proved that a certain metabolic recovery occurred after sepiolite treatment. The dry biomass of spinach (Spinacia oleracea) increased with increasing sepiolite concentration in the soil. However, the concentration (dry weight) of Cd in the spinach shoots decreased with the increase in sepiolite dose, with maximum reduction of 92.2, 90.0, and 84.9 %, respectively, compared with that of unamended soils. Under a Cd level of 1.25 mg?kg^?1, the Cd concentration in the edible parts of spinach at 1 % sepiolite amendment was lower than 0.2 mg?kg^?1 fresh weight, the maximum permissible concentration (MPC) of Cd in vegetable. Even at higher Cd concentrations (2.5 and 5 mg?kg^?1), safe spinach was produced when the sepiolite treatment was up to 5 %. The results showed that sepiolite-assisted remediation could potentially succeed on a field scale by decreasing Cd entry into the food chain.     

Effects of photovoltaic panels on soil temperature and moisture in desert areas

Environmental Science and Pollution Research - Photovoltaic power generation is an important clean energy alternative to fossil fuels. To reduce CO2 emissions, the Chinese government has ordered...