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1.
Zhongsheng Zhang Xianguo Lu Xiaolin Song Yue Guo Zhenshan Xue 《Journal of Soils and Sediments》2012,12(9):1309-1315
Purpose
The theory of ecological stoichiometry has improved understanding of nutrient circulation processes in ecosystems. The purpose of this work was to study ecological stoichiometric characteristics of carbon, nitrogen and phosphorus in wetland soils of Sanjiang Plain, northeast China.Materials and methods
A Deyeuxia angustifolia wetland (swamp meadow) and a Carex lasiocarpa wetland (marsh) were chosen for collection of soil cores (0?C30?cm depth). Soil organic carbon, total nitrogen and phosphorus were analyzed to study patterns of C/N (R CN), C/P (R CP), N/P (R NP), and C/N/P (R CNP) in wetland soils.Results and discussion
Soil carbon, nitrogen and phosphorus stoichiometry differed between the two wetlands. Soil RCN (0?C30?cm depth) in the D. angustifolia wetland was close to that in C. lasiocarpa wetland (12.97 and 12.80, respectively), but R CP and R NP in C. lasiocarpa soils were significantly higher than those in D. angustifolia soils. R CN changed little within soil profile, without obvious trends in both wetlands. Both R CP and R NP decreased with depth from the surface, and both R CP and R NP were higher at every depth interval in C. lasiocarpa soils compared to D. angustifolia soils. R CN in surface soil (0?C10?cm, organic-rich ??Lo?? layer) was not significantly different from R CN in the entire profile (0?C30?cm, ??La layer??) of D. angustifolia wetland, while R CP and R NP were both significantly different between the Lo and La layers. In Carex lasiocarpa wetland, R CN, R CP and R NP in Lo layer were significant higher than those in La layer. R CNP in La layer of D. angustifolia and C. lasiocarpa wetlands were 65:5:1 and 163:13:1, respectively.Conclusions
Soil R CN was relatively consistent, while R CP and R NP reflected P limitation in wetlands of Sanjiang Plain. Further research is needed to determine whether these ratios hold among other wetland ecosystems. 相似文献2.
Purpose
The impacts of land-use change on dynamics of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the subsoil (>?30 cm) are poorly understood. This study aims to investigate whether the effects of land-use change on stocks and stoichiometric ratios (RCN, RCP, and RNP) of SOC, TN, and TP can be different between topsoil (0–30 cm) and subsoil (30–60 cm) in the Ili River Valley, northwest China.Materials and methods
Soil samples (0–10, 10–20, 20–30, 30–40, 40–50, and 50–60 cm) were collected from a pasture (PT), a 27-year-old cropland (CL) converted from PT, and a 13-year-old poplar (Populus tomentosa Carr.) plantation (PP) converted from CL. SOC, TN, and TP concentrations and soil bulk density were determined to calculate stocks and stoichiometric ratios (molar ratios) of SOC, TN, and TP.Results and discussion
Conversion from PT to CL led to substantial losses in SOC, TN, and TP pools in both topsoil and subsoil, and the reduction rates in subsoil (13.8–24.7%) were higher than those in topsoil (8.5–17.3%), indicating that C, N, and P pools in subsoil could also be depleted by cultivation. Similar to topsoil, significant increases in SOC, TN, and TP stocks were detected after afforestation on CL in subsoil, although the increase rates (31.2–56.2%) were lower than those in topsoil (47.8–69.1%). Soil pH and electrical conductivity (EC), which generally increased after conversion from PT to CL while decreased after CL afforestation, showed significant negative correlations with SOC, TN, and TP, suggesting that cultivation might lead to soil degradation, whereas afforestation contributed to soil restoration in this area. Significant changes in C:N:P ratios in topsoil were only detected for RNP after conversion from CL to PP. By contrast, land-use change significantly altered both RCN and RNP in the subsoil, demonstrating that the impacts of land-use change on RCN and RNP were different between topsoil and subsoil. The significant relationship between soil EC and RNP suggested that RNP might be a useful indicator of soil salinization.Conclusions
Stocks of SOC, TN, and TP as well as RCN and RNP in subsoil showed different responses to land-use change compared to those in topsoil in this typical agro-pastoral region. Therefore, it is suggested that the effects of land-use change on dynamics of SOC, TN, and TP in subsoil should also be evaluated to better understand the role of land-use change in global biogeochemical cycles.3.
Purpose
Methanotrophs in wetlands are of great importance because up to 90 % of the methane (CH4) produced in such wetlands could be oxidized by methanotrophs before reaching the atmosphere. The Xianghai wetland of Songnen Plain represents an important ecosystem in northeast China. However, methanotrophic characteristics in this ecosystem have not been studied in detail. The aim of this study is to give an overview of methanotrophic diversity and vertical distribution in the sediments of this important wetland.Materials and methods
Sediment cores were collected from three freshwater marshes, each dominated by a particular vegetation type: Carex alata, Phragmites australis and Typha orientalis. The diversity of methanotrophs was studied by phylogenetic analysis of both the 16S rRNA gene and the particulate methane monooxygenase (pmoA) gene. Methanotroph abundance was determined by quantitative PCR (qPCR) targeting the pmoA gene; group-specific pmoA gene quantification was also used to estimate the abundance of each methanotrophic group.Results and discussion
16S rRNA and pmoA gene homological analysis revealed the presence of type Ia, Ib and II methanotrophs. Novel pmoA sequences distantly affiliated to cultured Methylococcus sp. were detected, implying the existence of novel methanotrophs in the wetland. Most obtained representatives of Methylobacter genus (both 16S rRNA and pmoA genes) were closely clustered in relation to sequences acquired from the Zoige wetland, Tibet and Siberia permafrost soils, therefore suggesting methanotrophs belonging to Methylobacter genus shared characteristics with methanotrophs in cold areas. The dominance of type I methanotrophs (especially the Methylobacter genus) was detected by both clone library analysis and group-specific qPCR assay. The relatively high methanotroph diversity and pmoA copy numbers measured in the T. orientalis marsh sediments indicated that vegetation type played an important role during CH4 oxidation in the wetland.Conclusions
We present the first data set on methanotroph diversity and vertical distribution in the sediments of the Xianghai wetland. DNA sequences information of Methylococcus-like methanotrophs in the wetland will facilitate the isolating of novel methanotrophs from the wetland. In a worldwide context, our study has enriched the database of genotypic diversity of methanotrophs, which will help in the understanding of the geographical distribution of methanotrophic communities. 相似文献4.
Purpose
In summer 2007, biweekly benthic fluxes of the biogenic elements carbon (C), nitrogen (N), silicon (Si), and phosphorus (P) were studied in the Se?ovlje saltern (salt-making facility) in the northern Adriatic Sea, Slovenia in order to determine the impact of stromatolite (??petola??) on the geochemical properties of saltern sediments.Materials and methods
The brine and pore waters were analyzed for salinity, NH 4 + , NO 3 ? , PO 4 3? , SiO 4 4? , total dissolved nitrogen, total dissolved phosphorus, and fluorescent dissolved organic matter. The sediment was analyzed for organic carbon (OC), total nitrogen (TN), total and organic phosphorus (OP), and biogenic Si concentrations, as well as values of ?? 13COC and ?? 15NTN.Results and discussion
Nutrient concentrations in brine water increased along the salinity gradient due to different processes, such as the evaporative concentrations of seawater, bacterial activity, more pronounced transformation and degradation of organic matter, and regeneration of nutrients. The petola from the Se?ovlje saltern, which is predominately composed of cyanobacterial and diatom communities, develops during the early evaporation stage and survives during high salinity and halite crystallization. Nitrogen fixation and P removal were the principal biogeochemical processes controlling dissolved inorganic N and P concentrations. At higher salinities, N limitation was more important. Microbes decomposed at higher salinities, and the remineralized N and P nutrients were released from surface pore waters to the brine. OP remineralization was also an important process influencing the distribution of PO 4 3? concentrations in pore waters deeper in the sediments. The increasing SiO 4 4? concentrations with increasing salinity in the brine waters were due to dissolution of diatom frustules, while the decrease in pore water SiO 4 4? was probably the consequence of microbial uptake.Conclusions
This study provides a better understanding of nutrient cycling and the geochemical processes in the Se?ovlje saltern. 相似文献5.
Immobilization of Cu and Cd in a contaminated soil: one- and four-year field effects 总被引:2,自引:0,他引:2
Hongbiao Cui Jing Zhou Youbin Si Jingdong Mao Qiguo Zhao Guodong Fang Jiani Liang 《Journal of Soils and Sediments》2014,14(8):1397-1406
Purpose
Many amendments have been applied to immobilize heavy metals in soil. However, little information is available on the changes of immobilization efficiencies of heavy metals in contaminated soils over time. This work investigated the immobilization efficiencies of copper (Cu) and cadmium (Cd) in contaminated soils in situ remediated with one-time application of three amendments for 1 year and 4 years.Materials and methods
Apatite, lime, and charcoal were mixed with the topsoil of each plot with the amounts of 22.3, 4.45, and 66.8 t/ha, respectively. Soil chemical properties and fractions of Cu and Cd were examined after in situ remediation for 1 year and 4 years. Soil sorption and retention capacities and desorption proportions for Cu and Cd were investigated by batch experiments.Results and discussion
The addition of amendments significantly increased soil pH, but decreased exchange acid and aluminum (Al). The amendments significantly decreased the CaCl2 extractable Cu and Cd and transformed them from active to inactive fractions. After the application of amendments for 1 year, the maximum sorption capacities ranged from 35.6 to 38.8 mmol/kg for Cu and from 14.4 to 17.0 mmol/kg for Cd, which were markedly higher than those of the application of amendments for 4 years (Cu, 29.6–34.7 mmol/kg; Cd, 10.9–16.4 mmol/kg). Desorption proportions (D) of Cu and Cd using three extractants followed the order of \( {D}_{{\mathrm{NaNO}}_3}<{D}_{{\mathrm{CaCI}}_2}<{D}_{{\mathrm{MgCI}}_2} \) . Moreover, the retention capacities (R) of Cu and Cd both increased and followed the order of R apatite?>?R lime?>?R charcoal, resulting in higher Cu and Cd in the amended soils than the untreated soil.Conclusions
Apatite, lime, and charcoal increased the soil sorption and retention capacities of Cu and Cd and resulted in higher immobilization efficiencies in the amended soils than the untreated soil. However, the immobilization efficiencies of Cu and Cd decreased with the decrease of sorption capacities after 4 years. It was concluded that apatite had the best effect on the long-term stability of immobilized Cu and Cd and can be applied to immobilize heavy metals in contaminated soils. 相似文献6.
Purpose
Nitrous oxide (N2O) production and reduction rates are dependent on the interactions with each other and it is therefore important to evaluate them within the context of simultaneously operating N2O emission and reduction. The objective of this study was to quantify the simultaneously occurring N2O emission and reduction across a range of subtropical soils in China, to gain a mechanistic understanding of potential N2O dynamics under the denitrification condition and their important drivers, and to evaluate the potential role of the subtropical soils as either sources or sinks of N2O through denitrification.Materials and methods
Soils (45, from a range of different land uses and soil parent materials) were collected from the subtropical region of Jiangxi Province, China, and tested for their potential capacity for N2O emission and N2O reduction to N2 during denitrification. N2O emission and reduction were determined in a closed system under N2 headspace after the soils were treated with 200?mg?kg?1 NO 3 ? -N and incubation at 30?°C for 28?days. The soil physical and chemical properties, the temporal variations in headspace N2O concentration, and NO 3 ? -N and NH 4 + -N concentrations in the soil slurry were measured.Results and discussion
Variations in N2O concentration (N) over incubation time (t) were consistent with an equation in which average R 2?=?0.84?±?0.11 (p?<?0.05): $ N = A \times \left( {1 - \exp \left( { - {k_1} \times t} \right)} \right) - B \times \exp \left( {{k_2} \times t} \right) $ , where A is the total N2O emission during the incubation, B is a constant, and k 1 and k 2 are the N2O emission constant and reduction constants, respectively. The results of the simulation showed that k 1 was greater than k 2. The reduced amount of NO 3 ? -N in the first 7?days of incubation and the N2O emission rate (the percentage of A value relative to the amount of NO 3 ? -N reduced during the 28-day incubation, R n) were able to explain 82.9?% (p?<?0.01) of the variation in total N2O emission (A) during the incubation for the soil samples studied, indicating that the total amount of N2O emitted was determined predominately by denitrification capacity. Soil organic carbon content and soil nitrogen mineralization are the key factors that determine differences in the amounts of reduced NO 3 ? -N among the soil samples. The R n value decreased with increasing k 2 (p?<?0.01), indicating that soils with higher N2O reduction capacity under these incubation conditions would emit less N2O per unit of denitrified NO 3 ? -N than the other soils. Results are valuable in the evaluation of net N2O emissions in the subtropical soils and the global N budget.Conclusions
In a closed, anaerobic system, variations in N2O concentration in the headspace over the incubation time were found to be compatible with a nonlinear equation. Soil organic carbon and the amount of NH 4 + -N mineralized from the organic N during the first 7?days of incubation are the key factors that determine differences in the N2O emission constant (k 1), the N2O reduction constant (k 2), the total N2O emission during the incubation (A) and the N2O emission rate (R n). 相似文献7.
Chemical and spectroscopic characteristics of humic acids in marshes from the Iberian Peninsula 总被引:2,自引:2,他引:0
Fernando Perobelli Ferreira Pablo Vidal-Torrado Xose L. Otero Peter Buurman Ladislau Martin-Neto Rafael Boluda Felipe Macias 《Journal of Soils and Sediments》2013,13(2):253-264
Purpose
To characterise soil humic acids (HAs) extracted from Spanish marshes formed under different vegetation types (Spartina maritima (GSp), Juncus maritimus (GJc), Phragmites australis (GPh), and Scirpus maritimus (VSc)), soil depths (0–20, 20–40 and 40–60 cm), physiographic position (low and high marshes), wetland types (salt marshes and lagoons) and environmental conditions (Atlantic and Mediterranean coast).Material and methods
Soil samples were collected in five Spanish marshes, three on the Galicia province and two on the Valencia province. Humic acids were extracted and their elemental composition, semiquinone-type free radical (SFR) content, FTIR and CPMAS 13C NMR spectra determined. Total carbon (TC), total nitrogen (TN), total sulphur (TS), CaCO3 content, and field pH and Eh (mV) in the marsh soils sampled were also measured.Results and discussion
The field pH and Eh values were typical of coastal areas submitted to periodic inundations and the highest TC, TN and TS contents were found in the soil of lagoon marshes as an effect of physiographic position and wetland type. The HAs, in general, were highly aliphatic and exhibited a low SFR content, which suggests a low humification degree of the SOM formed in the studied areas. This is a result of the anaerobic decomposition to which SOM is submitted and the high input of plant-derived organic matter (OM) by vegetation. However, among the studied sites low salt marsh and subsurface layer of the high salt marsh showed higher SFR content, simpler FTIR spectra, higher lignin degradation and lower O-alkyl C/alkyl C ratio than the lagoon marshes, thus suggesting the presence of a more humificated SOM in these sites.Conclusions
From the different factors analysed, only physiographic position (low versus high salt marshes) and wetland type (marshes versus lagoons) caused variations in the HAs characteristics, because as the studied soils are under anaerobic conditions, they control the exportation of plant-derived OM and the allochthonous OM contribution in the studied areas. 相似文献8.
Long-term cultivation impact on the heavy metal behavior in a reclaimed wetland,Northeast China 总被引:1,自引:0,他引:1
Wei Jiao Wei Ouyang Fanghua Hao Fangli Wang Bing Liu 《Journal of Soils and Sediments》2014,14(3):567-576
Purpose
Heavy metal fractionation varies according to land uses. To understand the behavior of heavy metals in wetland soils under long-term agricultural cultivation, we examined the distribution, source, and associated environmental risk of heavy metals in different types of wetland soils.Materials and methods
Soils were collected in cultivated lands, artificial ditches, and riparian zones from a reclaimed wetland in the Sanjiang Plain, Northeast China. They were analyzed for total concentrations and chemical fractions of Pb, Cd, Cu, Zn, Cr, and Ni, as well as pH, soil organic matter, total phosphorus, and particle size distribution.Results and discussion
Heavy metal concentrations were significantly lower in cultivated wetland than in ditch and riparian wetlands. Riparian wetland was found to exhibit the highest metal concentrations. When compared with other two wetland types, the cultivated wetland showed much higher partitioning levels of heavy metals in the acid-soluble fraction and lower partitioning levels in the oxidizable fraction. Although Cr, Cu, and Ni in ditch and riparian wetlands were identified as the metal pollutants of primary concern, they had a low or no risk of further dispersion to other environmental components. Weathering of parent materials was the main source of Cr and Cu, Pb, Cd, and Zn originated mainly from agricultural practices, and Ni emanated from a mixture of sources.Conclusions
Long-term agricultural cultivation can lead to significant heavy metal loss in cultivated wetland but enrich heavy metal concentrations in ditch and riparian wetlands. Periodic ditch dredging is considered an effective measure for decreasing heavy metal input into the fluvial system and thereby reducing the dispersion to the regional water environment. 相似文献9.
Nicolas Reynier Jean-François Blais Guy Mercier Simon Besner 《Journal of Soils and Sediments》2013,13(7):1189-1200
Purpose
In this study, a soil-washing process was investigated for arsenic (As) and pentachlorophenol (PCP) removal from polluted soils. This research first evaluates the use of chemical reagents (HCl, HNO3, H2SO4, lactic acid, NaOH, KOH, Ca(OH)2, and ethanol) for the leaching of As and PCP from polluted soils.Materials and methods
A Box–Behnken experimental design was used to optimize the main operating parameters for soil washing. A laboratory-scale leaching process was applied to treat four soils polluted with both organic ([PCP] i ?=?2.5–30 mg kg?1) and inorganic ([As] i ?=?50–250 mg kg?1, [Cr] i ?=?35–220 mg kg?1, and [Cu] i ?=?80–350 mg kg?1) compounds.Results and discussion
Removals of 72–89, 43–62, 52–68, and 64–98 % were obtained for As, Cr, Cu, and PCP, respectively, using the optimized operating conditions ([NaOH]?=?1 N, [cocamidopropylbetaine] i ?=?2 % w w?1, t?=?2 h, T?=?80 °C, and PD?=?10 %).Conclusions
The use of NaOH, in combination with the surfactant, is efficient in reducing both organic and inorganic pollutants from soils with different levels of contamination. 相似文献10.
Major controlling factors and prediction models for mercury transfer from soil to carrot 总被引:1,自引:0,他引:1
Changfeng Ding Taolin Zhang Xiaogang Li Xingxiang Wang 《Journal of Soils and Sediments》2014,14(6):1136-1146
Purpose
Soil-plant transfer models are needed to predict levels of mercury (Hg) in vegetables when evaluating food chain risks of Hg contamination in agricultural soils.Materials and methods
A total of 21 soils covering a wide range of soil properties were spiked with HgCl2 to investigate the transfer characteristics of Hg from soil to carrot in a greenhouse experiment. The major controlling factors and prediction models were identified and developed using path analysis and stepwise multiple linear regression analysis.Results and discussion
Carrot Hg concentration was positively correlated with soil total Hg concentration (R 2?=?0.54, P?<?0.001), and the log-transformation greatly improved the correlation (R 2?=?0.76, P?<?0.001). Acidic soil exhibited the highest bioconcentration factor (BCF) (ratio of Hg concentration in carrot to that in soil), while calcareous soil showed the lowest BCF among the 21 soil types. The significant direct effects of soil total Hg (Hgsoil), pH, and free Al oxide (AlOX) on the carrot Hg concentration (Hgcarrot) as revealed by path analysis were consistent with the result from stepwise multiple linear regression that yielded a three-term regression model: log [Hgcarrot]?=?0.52log [Hgsoil]???0.06pH???0.64log [AlOX]???1.05 (R 2?=?0.81, P?<?0.001).Conclusions
Soil Hg concentration, pH, and AlOX content were the three most important variables associated with carrot Hg concentration. The extended Freundlich-type function could well describe Hg transfer from soil to carrot. 相似文献11.
Ute Szukics Evelyn Hackl Sophie Zechmeister-Boltenstern Angela Sessitsch 《Biology and Fertility of Soils》2009,45(8):855-863
Denitrification represents one of the main microbial processes producing the primary and secondary greenhouse gases nitrous oxide (N2O) and nitric oxide (NO) in soils. It is well established that abiotic factors like the soil water content and the availability of nitrogen (N) are key parameters determining the activity of denitrifiers in soils. However, soils differing regarding their characteristics such as the content of Corg, the soil texture or the pH value may respond in specific manners to equivalent changes in soil moisture and N input. Thus, short-term incubation experiments were performed to test and compare the capacity of two contrasting Austrian forest soils to respond to mineral N application at increased soil water contents. Soils from the pristine Rothwald forest (rich in Corg) and the more acidic Schottenwald forest (poor in Corg) were amended with either NH 4 + -N or NO 3 ? -N and were incubated at 40% and 70% water-filled pore space for 4 days. Changes in mineral N pools, nitrite reductase activity and NO and N2O emission rates were measured, and the abundance and structural community composition of the functional group involved in nitrite reduction were analysed via quantitative real-time polymerase chain reaction and terminal restriction fragment length polymorphism analysis of the nirK gene. Rapid and distinct activity responses to increased soil moisture and altered mineral nitrogen availability were observed in two contrasting forest soils. In both soils, nitrogen oxide emission rates were stimulated by N inputs and, depending on the soil moisture status, either NO or N2O emission was prevailing. However, different N cycling processes appeared to predominate in either soil under equivalent treatment. Nitrogen oxide emissions peaked following NO 3 ? application in Schottenwald soils but were the highest after NH 4 + application in Rothwald soils. Denitrifying (nirK) communities differed significantly in Rothwald and Schottenwald soils; however, changes in the community structure were marginal during the short-term incubation. Abundances of nirK genes remained unaffected by N application in either soil. The soil water content affected nirK gene abundances only in Rothwald soil, indicating a distinct reaction of nitrite reducing communities in the two soils. 相似文献
12.
Links between vegetation patterns, soil C and N pools and respiration rate under three different land uses in a dry Mediterranean ecosystem 总被引:1,自引:0,他引:1
María Almagro José Ignacio Querejeta Carolina Boix-Fayos María Martínez-Mena 《Journal of Soils and Sediments》2013,13(4):641-653
Purpose
Soil respiration (R s) is controlled by abiotic soil parameters interacting with characteristics of the vegetation and the soil microbial community. Few studies have attempted a comprehensive approach that simultaneously addresses the roles of all the major factors known to influence R s. Our goal was to explore the links between heterogeneity in R s, aboveground plant biomass and belowground properties in three representative land-use types in a dry Mediterranean ecosystem: (1) a 150-year-old mixed Aleppo pine-kermes oak open forest, (2) an abandoned agricultural field, which was cultivated with cereal for several years until abandonment in 1980, when establishment of typical Mediterranean shrubland vegetation started and (3) a rain-fed olive grove, which has been cultivated for 100 years.Materials and methods
We selected two distinctive sampling periods coinciding with annual minimum or near minimum (December) and maximum (April) rates of R s in this dry Mediterranean ecosystem. In each sampling period, R s, temperature and moisture, aboveground plant biomass, carbon (C) and nitrogen (N) contents in both light and heavy soil organic matter fractions, extractable dissolved organic C (EDOC), as well as microbial and fine root biomass were measured within each land-use type.Results and discussion
Across sites, R s rates were significantly higher in April (3.07?±?0.1 μmol?m?2?s?1) than in December (1.30?±?0.1 μmol?m?2?s?1). The labile soil organic matter fractions (light fraction C and N contents, microbial biomass C and EDOC) were consistently and strongly related to one another, and to a lesser extent, to the C and N contents in the heavy fraction across sites and seasons. Linear models adequately explained a large proportion of the within-site variability in R s (R 2 values ranged from 41 to 91 % depending on land use and season) but major controls on R s differed considerably between sites and seasons. Primary controls on spatial patterns in R s were linked to recent plant-derived C inputs in both forest and olive grove sites. However, in the abandoned agricultural field site R s appeared to be mainly driven by microbial activity, which could be sustained by intermediate or recalcitrant C and N pools derived from previous land use.Conclusions
Conversion of native woodland to agricultural land and subsequent land abandonment leads to profound changes in the relationships between R s, aboveground biomass and belowground properties in this dry Mediterranean ecosystem. While above- and belowground vegetation are the primary controls on spatial variability in labile soil C pools and R s in the open forest and olive grove sites, a complete lack of influence of current vegetation patterns on soil C pools and respiration rates in the abandoned agricultural field was observed. 相似文献13.
Sorption isotherms and kinetics of Sb(V) on several Chinese soils with different physicochemical properties 总被引:1,自引:0,他引:1
Jian-Xin Fan Yu-Jun Wang Xiao-Dan Cui Dong-Mei Zhou 《Journal of Soils and Sediments》2013,13(2):344-353
Purpose
Sorption of antimony on soils is the primary factor that influences its immobilization and migration in the environment. In the present study, the sorption of Sb(V) onto seven Chinese soils with different physicochemical properties was investigated for exploring the relationship between the sorption capacity of Sb(V) and the physicochemical properties of the soils.Materials and methods
Sorption isotherms and kinetics experiments were performed to ascertain the sorption capacity and the kinetic rate, respectively. The relationship between the sorption capacity of Sb(V) and the physicochemical properties of the soils was analyzed by multiple linear regressions.Results and discussion
The results showed that the sorption isotherms fitted with both the Langmuir and Freundlich equations very well (R 2?=?0.936–0.997), and the sorption kinetic of Sb(V) onto the seven Chinese soils followed a pseudo-second-order reaction. The maximum sorption capacity of Sb(V) on the soils ranged from 134 to 1,333 mg?kg?1. Nearly 94 % of the variability in maximum sorption of Sb(V) modeled by Freundlich equation could be described by FeDCB (dithionite–citrate–bicarbonicum extractable), and nearly 98 % of the variability could be described by FeDCB and AlDCB.Conclusions
Multiple linear regressions can be successfully applied to analyzing the relationship between sorption capacity and soil properties. FeDCB and AlDCB played important roles in Sb(V) sorption onto soils. It would be useful to understand the environmental behaviors of Sb and for the implementation of risk assessment management and remediation strategies of Sb. 相似文献14.
A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH 4 + ) decreased from 4.6 to 1.7 mg L?1, nitrate (NO 3 ? ) decreased from 6.8 to 5.3 mg L?1, total N (TN) decreased from 14.6 to 10.1 mg L?1, and total P (TP) decreased from 1.6 to 1.1 mg L?1. Average removal efficiencies (loading basis) for NO 3 ? , NH 4 + , TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH 4 + . Results from mesocosm experiments indicated that NH 4 + was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO 3 ? was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2?C4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH 4 + and P can be maximized in the pond while NO 3 ? requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant. 相似文献
15.
Zejiang Cai Boren Wang Minggang Xu Huimin Zhang Lu Zhang Suduan Gao 《Journal of Soils and Sediments》2014,14(9):1526-1536
Purpose
Long-term manure applications can prevent or reverse soil acidification by chemical nitrogen (N) fertilizer. However, the resistance to re-acidification from further chemical fertilization is unknown. The aim of this study was to examine the effect of urea application on nitrification and acidification processes in an acid red soil (Ferralic Cambisol) after long-term different field fertilization treatments.Materials and methods
Soils were collected from six treatments of a 19-year field trial: (1) non-fertilization control, (2) chemical phosphorus and potassium (PK), (3) chemical N only (N), (4) chemical N, P, and K (NPK), (5) pig manure only (M), and (6) NPK plus M (NPKM; 70 % N from M). In a 35-day laboratory incubation experiment, the soils were incubated and examined for changes in pH, NH4 +, and NO3 ?, and their correlations from urea application at 80 mg N kg?1(?80) compared to 0 rate (?0).Results and discussion
From urea addition, manure-treated soils exhibited the highest acidification and nitrification rates due to high soil pH (5.75–6.38) and the lowest in the chemical N treated soils due to low soil pH (3.83–3.90) with no N-treated soils (pH 4.98–5.12) fell between. By day 35, soil pH decreased to 5.21 and 5.81 (0.54 and 0.57 unit decrease) in the NPKM-80 and M-80 treatments, respectively, and to 4.69 and 4.53 (0.43 and 0.45 unit decrease) in the control-80 and PK-80 treatments, respectively, with no changes in the N-80 and NPK-80 treatments. The soil pH decrease was highly correlated with nitrification potential, and the estimated net proton released. The maximum nitrification rates (K max) of NPKM and M soils (14.7 and 21.6 mg N kg?1 day?1, respectively) were significantly higher than other treatments (2.86–3.48 mg N kg?1 day?1). The priming effect on mineralization of organic N was high in manure treated soils.Conclusions
Field data have shown clearly that manure amendment can prevent or reverse the acidification of the red soil. When a chemical fertilizer such as urea is applied to the soil again, however, soil acidification will occur at possibly high rates. Thus, the strategy in soil N management is continuous incorporation of manure to prevent acidification to maintain soil productivity. Further studies under field conditions are needed to provide more accurate assessments on acidification rate from chemical N fertilizer applications. 相似文献16.
Georg Waldner Wolfgang Friesl-Hanl Georg Haberhauer Martin H. Gerzabek 《Journal of Soils and Sediments》2012,12(8):1292-1298
Purpose
The sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) to three different artificial soil mixtures was investigated. Artificial soils serve as model systems for improving understanding of sorption phenomena.Materials and methods
The soils consisted of quartz, ferrihydrite, illite, montmorillonite, and charcoal. In a previous study, several selected mixtures had been inoculated with organic matter, and microbial aging (incubation) had been performed for different periods of time (3, 12, and 18?months) before conducting the sorption experiments. The effect of this pre-incubation time on the sorption behavior was determined. Interaction of MCPA with soil surfaces was monitored by aqueous phase sorption experiments, using high-performance liquid chromatography/ultraviolet and in selected cases Fourier-transformed infrared spectroscopy.Results and discussion
The sorption behavior showed large differences between differently aged soils; Freundlich and linear sorption model fits (with sorption constants K f , 1/n exponents, and K d values, respectively) were given for pH?=?3 and the unbuffered pH of ??7. The largest extent of sorption from diluted solutions was found on the surfaces with a pre-incubation time of 3?months. Sorption increased at acidic pH values.Conclusions
Regarding the influence of aging of artificial soils, the following conclusions were drawn: young artificial soils exhibit stronger sorption at lower concentrations, with a larger K f value than aged soils. A correlation with organic carbon content was not confirmed. Thus, the sorption characteristics of the soils are more influenced by the aging of the organic carbon than by the organic carbon content itself. 相似文献17.
Biochars immobilize soil cadmium, but do not improve growth of emergent wetland species Juncus subsecundus in cadmium-contaminated soil 总被引:1,自引:0,他引:1
Zhenhua Zhang Zakaria M. Solaiman Kathy Meney Daniel V. Murphy Zed Rengel 《Journal of Soils and Sediments》2013,13(1):140-151
Purpose
An addition of biochar mixed into the substrate of constructed wetlands may alleviate toxicity of metals such as cadmium (Cd) to emergent wetland plants, leading to a better performance in terms of pollutant removal from wastewater. The objective of this study was to investigate the impact of biochars on soil Cd immobilization and phytoavailability, growth of plants, and Cd concentration, accumulation, and translocation in plant tissues in Cd-contaminated soils under waterlogged conditions.Materials and methods
A glasshouse experiment was conducted to investigate the effect of biochars derived from different organic sources (pyrolysis of oil mallee plants or wheat chaff at 550 °C) with varied application amounts (0, 0.5, and 5 % w/w) on mitigating Cd (0, 10, and 50 mg kg?1) toxicity to Juncus subsecundus under waterlogged soil condition. Soil pH and CaCl2/EDTA-extractable soil Cd were determined before and after plant growth. Plant shoot number and height were monitored during the experiment. The total root length and dry weight of aboveground and belowground tissues were recorded. The concentration of Cd in plant tissues was determined.Results and discussion
After 3 weeks of soil incubation, pH increased and CaCl2-extractable Cd decreased significantly with biochar additions. After 9 weeks of plant growth, biochar additions significantly increased soil pH and electrical conductivity and reduced CaCl2-extractable Cd. EDTA-extractable soil Cd significantly decreased with biochar additions (except for oil mallee biochar at the low application rate) in the high-Cd treatment, but not in the low-Cd treatment. Growth and biomass significantly decreased with Cd additions, and biochar additions did not significantly improve plant growth regardless of biochar type or application rate. The concentration, accumulation, and translocation of Cd in plants were significantly influenced by the interaction of Cd and biochar treatments. The addition of biochars reduced Cd accumulation, but less so Cd translocation in plants, at least in the low-Cd-contaminated soils.Conclusions
Biochars immobilized soil Cd, but did not improve growth of the emergent wetland plant species at the early growth stage, probably due to the interaction between biochars and waterlogged environment. Further study is needed to elucidate the underlying mechanisms. 相似文献18.
Purpose
Little information is available heretofore on the gradient distribution of persistent organic pollutants in rhizosphere on a field scale. In this field study, we seek to explore the in situ distribution gradient of polycyclic aromatic hydrocarbons (PAHs) in rhizosphere soil proximal to the roots.Materials and methods
Clover (Trifolium pratense L.) and hyssop (Hyssopus officinalis L.) grew in situ in the contaminated field soil near a petrochemical plant and were harvested when about 30 cm tall with mature roots. Rhizosphere soils of the plants were sampled including the rhizoplane, strongly adhering soil, and loosely adhering soil. Eleven EPA-priority PAHs were detected in each layer of rhizosphere soils in proximity to the root surface.Results and discussion
The PAH concentrations followed the descending order of bulk soil, loosely adhering soil, strongly adhering soil, and rhizoplane soil in proximity to the root surface of clover and hyssop. The rhizosphere effect (R, in percent) on PAH distribution clearly decreased with increasing distance from the root, and a more significant decrease was observed for hyssop compared to clover. R values were generally lower for three- and four-ringed PAHs in the rhizosphere, which were more significant in loosely and strongly adhering rhizosphere layers.Conclusions
Our field observations combined with previous potted studies demonstrated that PAH concentrations in rhizosphere soils increased with distance from the root. Results of this work provide new information on the fate of PAHs in rhizosphere. 相似文献19.
Yong-Chun Li Bu-Rong Liu Song-Hao Li Hua Qin Wei-Jun Fu Qiu-Fang Xu 《Journal of Soils and Sediments》2014,14(9):1577-1586
Purpose
Nitrogen (N) is one of the most important elements that can limit plant growth in forest ecosystems. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are considered as the key drivers of global N biogeochemical cycling. Soil ammonia-oxidizing microbial communities associated with subtropical vegetation remain poorly characterized. The aim of this study was to determine how AOA and AOB abundance and community structure shift in response to four typical forest vegetations in subtropical region.Materials and methods
Broad-leaved forest (BF), Chinese fir forest (CF), Pinus massoniana forest (PF), and moso bamboo forest (MB) were widely distributed in the subtropical area of southern China and represented typical vegetation types. Four types of forest stands of more than 30 years grew adjacent to each other on the same soil type, slope, and elevation, were chosen for this experiment. The abundance and community structure of AOA and AOB were characterized by using real-time PCR and denaturing gradient gel electrophoresis (DGGE). The impact of soil properties on communities of AOA and AOB was tested by canonical correspondence analysis (CCA).Results and discussion
The results indicated that AOB dominated in numbers over AOA in both BF and MB soils, while the AOA/AOB ratio shifted with different forest stands. The highest archaeal and bacterial amoA gene copy numbers were detected in CF and BF soils, respectively. The AOA abundance showed a negative correlation with soil pH and organic C but a positive correlation with NO3 ??N concentration. The structures of AOA communities changed with vegetation types, but vegetation types alone would not suffice for shaping AOB community structure among four forest soils. CCA results revealed that NO3 ??N concentration and soil pH were the most important environmental gradients on the distribution of AOA community except vegetation type, while NO3 ??N concentration, soil pH, and organic C significantly affected the distribution of the AOB communities.Conclusions
These results revealed the differences in the abundance and structure of AOA and AOB community associated with different tree species, and AOA was more sensitive to vegetation and soil chemical properties than AOB. N bioavailability could be directly linked to AOA and AOB community, and these results are useful for management activities, including forest tree species selection in areas managed to minimize N export to aquatic systems. 相似文献20.
María Nazaret González-Alcaraz José álvarez-Rogel Antonio María-Cervantes Consuelo Egea Héctor Miguel Conesa 《Journal of Soils and Sediments》2012,12(9):1316-1326