Organic Matter Removal on Oxide Determination in Oxisols Via Portable X-ray Fluorescence

Many factors can influence the results obtained by portable X-ray fluorescence analysis (pXRF). The effect of soil organic matter on pXRF results is not satisfactory understood. Thus, we conducted this study to verify the effect of organic matter removal on oxide determination by pXRF in Oxisols. To obtain soil material with different organic matter contents and maintaining the same elemental composition from soil minerals, six contrasting Oxisols were heated in a muffle furnace for 30 min at the following temperatures (°C): 100; 200; 300; 400; 500 and 600. After heating, the soil samples were scanned using a pXRF Bruker® S1 Titan LE model (Dual Soil mode) for 60 s and the contents of SiO₂, Al₂O₃, Fe₂O₃, TiO₂, P₂O₅, and MnO were recorded. The soil organic matter presence underestimated the pXRF results for lightest oxides (Si and Al) compared to heaviest oxides (Fe, Ti, and Mn). These oxides are important for tropical soils classification and for many soil-related studies and pXRF technology has been a useful tool for soil chemical characterization. Our findings contribute to more suitable use of pXRF highlighting the possible effect of organic matter.     

Effect of Organic Matter and Salinity on Ethylenediaminetetraacetic Acid–Extractable and Solution Species of Cadmium and Lead in Three Agricultural Soils

Abstract

A study was conducted to investigate the chemical speciation of added cadmium (Cd) and lead (Pb) and their availability as influenced by fresh organic matter (OM) and sodium chloride (NaCl) in three agricultural soils. The soils were treated with 20 mg Cd/kg as cadmium nitrate [Cd(NO₃)₂ · 4H₂O], 150 mg Pb/kg as lead nitrate [Pb(NO₃)₂], 20 g/kg alfalfa powder, and 50 mmol/kg of NaCl and then incubated for 3 months at 60% water‐holding capacity (WHC) and constant temperature (25 °C). Subsamples were taken after 1, 3, 6, and 12 weeks of incubation, and electrical conductivity (EC), pH, dissolved organic carbon (DOC), and concentrations of cations and anions were determined in the 1:2.5 soil/water extract. Available Cd and Pb were determined in 0.05 M ethylenediaminetetraacetic acid (EDTA) extract. Concentrations of organic and inorganic species of Cd and Pb in soil solution were also predicted using Visual Minteq speciation program. The most prevalent species of dissolved Pb and Cd in the soils were Pb‐DOC and Cd²⁺ species, respectively. Salinity application increased the available and soluble Cd significantly in the acid and calcareous soils. It, however, had little effect on soluble Pb and no effect on available Pb. Organic‐matter application decreased availability of added Pb significantly in all soils. In contrast, it raised soluble Pb in all soils except for the acid one and approximated gradually to the added Pb with time. Impact of OM on available Cd was somewhat similar to that of Pb. Soluble Cd increased by OM application in the calcareous soil, whereas it decreased initially and then increased with time in the other soils.     

Modification of Soil Quality Near a Pulp and Paper Mill

The Nagaon Pulp and Paper Mill (Assam, India) produces 100,000 tonnes of paper annually from bamboo. The mill is surrounded by a vast spread of agricultural land on all sides excepting the southern side, which is covered with hills and deep forests. The present study was undertaken with a view to assess the impact of the paper mill operations on the quality of the surrounding soil. Surface soil samples (0–15 cm depth) were collected in both dry and wet seasons over a four-year period from 19 points at different distances from the mill. The soil quality was determined with respect to a large number of representative physico-chemical properties. Estimation of the major oxides, e.g., SiO₂, Al₂O₃, Fe₂O₃, MnO, and TiO₂ showed a preferential accumulation of Al₂O₃, Fe₂O₃, and MnO in soil near the mill due to the dumping of fly ash and other solid wastes in the surrounding low lying land. Definite directional trends were observed not only with respect to these oxides, but also with the metals Ca, Mg, Na, and Pb, which decreased away from the mill. The soil pH had a tendency to turn alkaline near the mill owing to the discharge of highly alkaline effluent by the mill. The physical characteristics of the soil, viz., water holding capacity and bulk density increased with distance from the mill while the hydraulic conductivity had an opposite trend. N, P, K, B, Cl^-, and organic C contents of the soil had shown a rapid decreasing trend away from the mill indicating that the dumping of solid waste and discharge of nutrient-rich treated effluent had contributed to raised levels of these constituents near the mill.     

华中黄棕壤和黄褐土粘粒胶膜的微量元素地球化学特征

The relationships between the basic properties and trace elementsin soil argillans and corresponding matrix soils were studied by sampling from the B horizons of 26 Alfisols in croplands of the subtropical area in Central China. The soil elements (K, Na, Ca, Mg, Mn, Co, Cu, Cr, Cd, Li, Mo, Ni, Pb, Ti, V, and Zn) were extracted by acid digestion and their contents were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean contents of clay and organic matter in the argillans were approximately 1.1 and 1.3 times greater than those in the matrix soils, respectively. The pH values and the contents of P₂O₅ and bases (K₂O, Na₂O, CaO, and MgO) in the argillans were higher than those in the corresponding matrix soils. Cu, Cd, Ti, and V were enriched in the argillans. Correlation coefficients and factor analyses showed that Co, Cu, Li, and Zn were bound with phyllosilicates and manganese oxides (Mn-oxides) in the argillans. Cr and Pb were mainly associated with iron oxides (Fe-oxides), while Ni was bound with Mn-oxides. Cd, Ti, and V were chiefly associated with phyllosilicates, but Cr and Mo were rarely enriched in the argillans. In contrast, in the matrix soils, Co and Zn were associated with organic matter and Fe-oxides, Cr existed in phyllosilicates, and Mo was bound to Fe-oxides. Cd, Ti, and V were associated with organic matter. The results of this study suggest that clays, organic matter, and minerals in the argillans dominate the illuviation of trace elements in Alfisols. Argillans might be the active interfaces of elemental exchange and nutrient supply in cropland soils in Central China.     

Podzol development with time in sandy beach deposits in southern Norway

The coastal areas of SE Norway provide suitable conditions for studying soil development with time, because unweathered land surfaces have continuously been raised above sea level by glacio‐isostatic uplift since the termination of the last ice age. We investigated Podzol development in a chronosequence of six soils on sandy beach deposits with ages ranging from 2,300 to 9,650 y at the W coast of the Oslofjord. The climate in this area is rather mild with a mean annual temperature of 6°C and an annual precipitation of 975 mm (Sandefjord). The youngest soil showed no evidence of podzolization, while slight lightening of the A horizon of the second soil (3,800 years) indicated initial leaching of organic matter (OM). In the 4,300 y–old soil also Fe and humus accumulation in the B horizon were perceptible, but only the 6,600 y–old and older soils exhibited spodic horizons. Accumulation of OM in the A horizons reached a steady state in <2,300 y, while in the B horizons OM accumulated at increasing rates. pH dropped from 6.6 (H₂O)/5.9 (KCl) in the recent beach sand to 4.5 (H₂O)/3.8 (KCl) within approx. 4,500 y (pH_H2O)/2,500 y (pH_KCl) and stayed constant thereafter, which was attributed to sesquioxide buffering. Base saturation showed an exponential decrease with time. Progressive weathering was reflected by increasing Fe_d and Al_d contents, and proceeding podzolization by increasing amounts of pyrophophate‐ and oxalate‐soluble Fe and Al with soil age. These increases could be best described for most Fe and Al fractions by exponential models. Only the increasing amounts of Fe_p could be better described by a power function and those of Fe_o by a linear model.     

Effects of Paper Mill Effluent Irrigation on Agronomical Characteristics of Vigna radiata (L.) in Two Different Seasons

Seven rates of paper mill effluent (viz., 0%, 5%, 10%, 25%, 50%, 75%, and 100%) were used for irrigation of V. radiata (mung bean) along with a control (bore well water). The effluent had significant (P < 0.001) effects on electrical conductivity (EC), pH, chlorides (Cl^?), organic carbon (OC), bicarbonates (HCO₃ ^?), carbonates (CO₃ ^2?), sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺), total Kjeldahl nitrogen (TKN), nitrate (NO₃ ^2?), phosphate (PO₄ ^3?), sulfate (SO₄ ^2?), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), and lead (Pb) and insignificant (P > 0.05) effects on moisture content, water-holding capacity (WHC), and bulk density (BD) in both the cultivated seasons: rainy (Kharif) and summer (Zaid) season. The agronomical performance of V. radiata was increased from 5% to 50% in the rainy season and 5% to 25% in the summer season as compared to the control. The enrichment factor (Ef) of various heavy metals were ordered for soil as Pb > Cd, Cr > Zn > Cu in rainy season and Pb > Cd > Zn > Cr > Cu in summer season and for V. radiata plants as Cu > Zn > Cr > Pb > Cd in rainy season and Cu > Zn > Cr > Pb > Cd in summer season after irrigation with paper mill effluent.     

Soil and plants nutrient status and wheat growth after mycorrhiza inoculation with and without vermicompost

Two vermicompost treatments providing 45 (V1) and 90 (V2) kg P ha^?1 and mycorrhizae (M) inoculation were evaluated alone and in combinations for wheat (Triticum aestivum L.) growth and soil fertility status. The treatments included; the Control, nitrogen (N): dipotassium oxide (K₂O) as basal dose (BD; 120:60 kg ha^?1), N: phosphorus pentoxide (P₂O₅): K₂O as recommended dose (RD; 120:90:60 kg ha^?1), BD+Myccorhiza (BDM), BD+V1 (BDV1), BDM+V1 (BDMV1), BD+V2 (BDV2), and BDM+V2 (BDMV2). Combination of mycorrhizae and vermicompost (BDMV1 and BDMV2) significantly and maximally improved the growth, plant N, phosphorus (P), and micronutrient concentrations over the control, reduced the soil pH by 5 and 6%, increased OM by 25 and 112%, total N by 41%, and extractable P up to 200% while the extent of improvement was directly related to the content of added vermicompost. Results indicated that vermicompost at either level synergistically affected the mycorrhizae in plant nutrition as well as improved soil fertility status and soil chemical properties.     

Trace elements in tropical Asian paddy soils

Attempts were made to evaluate correlations of total trace elements with various soil characters in the hope that such correlations would allow prediction of the trace element status of paddy soils in Tropical Asia.

Among the 11 trace elements studied, Ni and Cr showed by far the highest correlation, followed by the pairs of V and Zn, Ni and Zn, and Cr and Zn.

High positive correlations of trace elements with soil characters were found for the following pairs: total Fe₂O³, and V and Zn, total K₂0 and Rb, total CaO and Sr, total TiO₂, and V, total Al₂0³ and Zn, 10 Å clay content and Rb, clay and V, and sand and Zr. Among the negative correlations, the highest was between total SiO₂ and V, followed by those between total SiO₂ and Zn and sand and Zn.

Soil material classes and inherent potentiality ratings previously established were found to have some value for the prediction of the status of certain trace elements in soil.     

Redistribution of cadmium,copper, lead,nickel, and zinc among soil fractions in a contaminated calcareous soil after application of nitrogen fertilizers

This study was conducted to evaluate the redistribution of the heavy metals Cd, Cu, Pb, Ni, and Zn among different soil fractions by N fertilizers. In a lab experiment, soil columns were leached with distilled water, KNO₃, NaNO₃, NH₄NO₃, or Ca(NO₃)₂ · 4H₂O. After leaching, soil samples were sequentially extracted for exchangeable (EXCH), carbonate (CARB), organic‐matter (OM), Mn oxide (MNO), Fe oxide (FEO), and residual (RES) fractions. Distilled water significantly increased the concentrations of Cd and Ni in EXCH fraction, while concentration of Cu and Zn did not change significantly. Application of KNO₃, NaNO₃, NH₄NO₃, or Ca(NO₃)₂ · 4H₂O significantly increased the concentrations of Cd and Zn in EXCH fraction, while concentration of Pb and Ni was decreased. Application of all fertilizers caused an increase of Cu in the OM fraction. Moreover, leaching with these solutions significantly increased Cd [except in Ca(NO₃)₂ · 4H₂O], Cu, and Zn concentrations in the CARB fraction, while Pb and Ni concentrations were decreased. With application of all leaching solutions, Zn in the EXCH, CARB, FEO, and MNO fractions was significantly increased, while Zn in the OM fraction did not change. The mobility index indicated that Ca(NO₃)₂ · 4H₂O increased the mobility of Cd, Cu, and Zn in the soil, whereas NaNO₃ decreased the mobility of Pb and Ni in the soil. The mobility index of Pb decreased by all leaching solutions. Thus, these results suggest that applying N fertilizers may change heavy‐metal fractions in contaminated calcareous soil and possibly enhance metal mobility and that N‐fertilization management therefore may need modification.     

Multivariate geostatistical analysis of heavy metals in topsoils from Beijing,China

Background  Regional soil environmental quality is a hotspot and difficulty in the environmental sciences for the spatial variability of pollutants and the relationship between them. Beijing, the capital of China, has been undergoing a rapid economical development during the past three decades, and thus might encounter the same issues as the developed countries. However, there is little information about the soil environmental quality of Beijing, especially at the regional scale. The real soil environmental situation of heavy metals remains unknown, even less the sources of possible pollutants. Objectives  The main objectives were to identify the spatial variability and main sources of heavy metals in Beijing soils by conducting multivariate statistical analyses, including geostatistical analysis assisted with GIS tools. These results will contribute to the establishment of the soil quality baseline and the management of regional environment. Materials and Methods  Seven hundred and seventy-three samples of topsoils (0–20 cm) were collected from all over Beijing, China. The samples were digested with HNO₃ and H₂O₂. The concentrations of Cr, Cu, Ni, Pb and Zn were analyzed with a FL-AAS and those of Cd with a GF-AAS. The concentrations of As were determined with AFS-2202. Principal component analysis (PCA) and partial correlation analysis (CA) were used and geostatistics was conducted for the data processing. Results  Concentrations of topsoil As, Cd, Cr, Cu, Ni, Pb and Zn in the Beijing area were measured and contour maps were constructed to describe the metals’ spatial distribution. Except for the background effect of the soils, anthropogenic factors made the soil heavy metal concentrations increase, especially in the center of the city. Combined with the PCA results, it was found that vehicle exhaust and smelters were the main sources of soil heavy metals. Pedogenic factors were also controlling the spatial features of metals. Discussion  Combined with the results of PCA, 7 heavy metals could be divided into 4 factors. F1 was the metals, i.e., Cu, Pb, Zn, mainly controlled by the human activities. Cr and Ni was in F2, Cd in F3 and As in F4. These 3 factors might be controlled by the soil parent materials. Concentrations of 7 heavy metals were comparable with the first level of environmental quality standard for soils of China and much lower than the second level of national standard for soils. Conclusion  The heavy metal concentrations in the topsoil of Beijing are mostly comparable with the background values, especially for As, Cr and Ni. In the city center of Beijing, Cu, Pb and Zn had a high concentration of distribution. The spatial features of As, Cr and Ni are mainly controlled by pedogenic factors, whereas Cd, Cu, Pb and Zn are controlled by anthropogenic and parent factors. Traffic and smelting contribute greatly to the increase of Pb, Zn and Cu in the soil, especially in the center of the city. Landfill may have also affected the soil quality around it. Recommendation  Different factors were controlled by parent materials, which might be related to the different soil minerals. Further research should be conducted in Beijing to elucidate the relationship between heavy metals and soil minerals. ESS-Submission Editor: Chengron Chen, PhD (c.chen@griffith.edu.au)     

土壤对镉的吸附与解吸——Ⅰ.土壤组份对镉的吸附和解吸的影响

采用选择溶解法研究了有机质、游离铁、无定型硅、铝等土壤组份对青黑土、黄棕壤、红壤和砖红壤胶体吸附和解吸Cd的影响。结果表明,去除有机质后胶体吸附Cd减少,这可能是由于交换吸附的减少所致;游离铁的去除使得黄棕壤、红壤和砖红壤的吸附量显著减少,显示了在这些土壤中游离氧化铁专性吸附的重要性;随着无定形铝含量的上升,吸附量下降,这是因为铝离子占据了高能量的吸附位。经不同处理后的土壤胶体,其Cd的解吸顺序(解吸%)大致为:去无定型硅、铝者>去游离铁者>去有机质者>原胶体,但在不同土壤和不同pH条件下该顺序略有差别。研究结果为控制和改造土壤Cd污染提供了理论依据。     

Relationship between mineral composition or soil texture and available silicon in alluvial paddy soils on the Shounai Plain,Japan

Abstract

To evaluate the relationship between the amount of available Silicon (Si) in paddy soils and their mineral properties on the Shounai Plain in Japan, which is formed from several parent materials, we evaluated the amount of available Si, the particle size distribution, the oxide composition of crystalline minerals and the amount of oxalate-extractable Si (Si_o), iron (Fe_o) and aluminum (Al_o) in the soil. The amount of available Si in the soil and the oxide content of the crystalline minerals differed among four soil groups that were distinguished by their clay mineral composition. There was no difference in the particle size distribution among the soil groups. The amount of available Si was positively related to the SiO₂/Al₂O₃ ratio of clay, the CaO concentration of silt and fine sand, and the amounts of Si_o, Fe_o and Al_o in the soil. The amount of available Si in the soils was negative correlated with the Na₂O and K₂O concentrations of silt, the K₂O concentration of fine sand, and the coarse sand content. These results suggest that the amount of available Si in soils is affected by the weathering resistivity of their minerals and that the particle size distribution and mineral composition are related to the available Si of the soils. Mineralogical properties, including the particle size distribution and mineral composition such as the SiO₂/Al₂O₃ ratio × clay fraction content and the amounts of CaO and MgO in silt-sized particles, were positively correlated with the amount of available Si in the soil, but these correlations were not found for fine sand-sized particles. The Si_o, Fe_o and SiO₂/Al₂O₃ ratio × clay fraction contents contributed approximately 50% to the amount of available Si in the soils. The amount of available Si in the soil was divided into two groups according to the location of the paddy field. The amount of soil-available Si in the alluvial plain was affected by the geology upstream through the mineral composition.     

Effect of flooding on physico-chemical changes in sodic soils

Laboratory experiments were conducted with sodic soils of varying exchangeable sodium percentage (ESP) (82, 65, 40, and 22) and a normal soil (ESP 4) to study the changes with time in soil pH, pCO₂, Fe²⁺ and Mn²⁺ under submerged conditions with and without 1.0 per cent rice husk. In all the soils pCO₂, Fe²⁺ and Mn²⁺ increased after flooding, reached the maximum value and then either maintained or declined slightly. The release of Fe²⁺ and Mn²⁺ was maximum in normal soil and decreased with increase of ESP in sodic soils. Addition of rice husk brought about a conspicuous increase in Fe²⁺ and Mn²⁺, the maximum increase being in lowest ESP soil. Flooding reduced the pH of all soils. The effect was more pronounced in the presence of rice husk. The kinetics of pCO₂ indicated that accumulation of CO₂ was higher in normal soil and least in highest ESP soil. The addition of rice husk showed an average increase of 0.0074 atm pCO₂ in comparison to rice husk untreated soils.     

Nitrous oxide production of heavy metal contaminated soil

Arsenic (As), lead (Pb), copper (Cu) and zinc (Zn) can be found in large concentrations in mine spills of central and northern Mexico. Interest in these heavy metals has increased recently as they contaminate drinking water and aquifers in large parts of the world and severely affect human health, but little is known about how they affect biological functioning of soil. Soils were sampled in seven locations along a gradient of heavy metal contamination with distance from a mine in San Luis Potosí (Mexico), active since about 1800 AD. C mineralization and N₂O production were monitored in an aerobic incubation experiment. Concentrations of As in the top 0-10 cm soil layer ranged from 8 to 22,992 mg kg⁻¹, from 31 to 1845 mg kg⁻¹ for Pb, from 27 to 1620 mg kg⁻¹ for Cu and from 81 to 4218 mg kg⁻¹ for Zn. There was a significant negative correlation between production rates of CO₂ and concentrations of As, Pb, Cu and Zn, and there was a significant positive correlation with pH, water holding capacity (WHC), total N and soil organic C. There was a significant negative correlation (P<0.05) between production rate of nitrous oxide (N₂O) attributed to nitrification by the inhibition method in soil incubated at 50% WHC and total concentrations of Pb and Zn, and there was a significant positive correlation (P<0.05) with pH and total N content. There was a significant negative correlation (P<0.05) between the production rate of N₂O attributed to denitrification by the inhibition method in soil incubated at 100% WHC and total concentrations of Pb, Cu and Zn, and a significant positive correlation (P<0.01) with pH; there was a significant positive correlation (P<0.05) between the production of N₂O attributed to other processes by the inhibition method and WHC, inorganic C and clay content. A negative value for production rate of N₂O attributed to nitrifier denitrification by the inhibition method was obtained at 100% WHC. The large concentrations of heavy metals in soil inhibited microbial activity and the production rate of N₂O attributed to nitrification by the inhibition method when soil was incubated at 50% WHC and denitrification when soil was incubated at 100% WHC. The inhibitor/suppression technique used appeared to be flawed, as negative values for nitrifier denitrification were obtained and as the production rate of N₂O through denitrification increased when soil was incubated with C₂H₂.     

Calcium accumulation alleviates soil acidification in Japanese cedar (Cryptomeria japonica) stands

Based on chemical and mechanical compositions and quartz content of red and/or yellow colored soil materials in the southwestern part of Japan, lithology index (LI) and weathering index (WI) were derived using a multivariate statistical method (factor analysis). The variables used for factor analysis are Fe₂O₃/Al₂O₃, TiO₂/Al₂O₃, Fe₂O₃+Al₂O₃+Quartz, Si(non-quartz)/(Fe₂O₃ + Al₂O₃), CaO + MgO + K₂O₃, MgO/K₂O₃ and Quartz/Sand, all of which represent certain different aspects of weathering and/or Iithological characteristics. Since LI and WI are mutually independent, it is possible to evaluate the effect of the degree of weathering on the characteristics of red and/or yellow colored soil materials independently from that of lithology.     

Influence of Increasing Soil Copper Concentration on the Susceptibility of Phosphomonoesterase and Urease to Heat Disturbance

The sorption of chromium (Cr) species to soil has become the focus of research as it dictates the bioavailability and also the magnitude of toxicity of Cr. The sorption of two environmentally important Cr species [Cr(III) and Cr(VI)] was examined using batch sorption, and the data were fitted to Langmuir and Freundlich adsorption isotherms. The effects of soil properties such as pH, CEC, organic matter (OM), clay, water-extractable SO₄ ^2– and PO₄ ^3–, surface charge, and different iron (Fe) fractions of 12 different Australian representative soils on the sorption, and mobility of Cr(III) and Cr(VI) were examined. The amount of sorption as shown by K _f was higher for Cr(III) than Cr(VI) in all tested soils. Further, the amount of Cr(III) sorbed increased with an increase in pH, CEC, clay, and OM of soils. Conversely, the chemical properties of soil such as positive charge and Fe (crystalline) had a noticeable influence on the sorption of Cr(VI). Desorption of Cr(VI) occurred rapidly and was greater than desorption of Cr(III) in soils. The mobility of Cr species as estimated by the retardation factor was higher for Cr(VI) than for Cr(III) in all tested soils. These results concurred with the results from leaching experiments which showed higher leaching of Cr(VI) than Cr(III) in both acidic and alkaline soils indicating the higher mobility of Cr(VI) in a wide range of soils. This study demonstrated that Cr(VI) is more mobile and will be bioavailable in soils regardless of soil properties and if not remediated may eventually pose a severe threat to biota.     

Assessment of Changes in Soil Infiltration,Water-Holding Capacity,Bulk Density and Fertility Parameters under Different Tree- and Crop-Based Systems in Semiarid Alfisols

Field experiments were conducted to assess changes in soil infiltration, water-holding capacity (WHC), bulk density and soil fertility with 15 custard apple (CA)-based systems of T1:CA+Fingermillet; T2:CA+Fodder Maize; T3:CA+Fieldbean; T4:CA+Niger; T5:CA+Chilli; T6:CA+Cowpea; T7:CA+Foxtailmillet; T8:Fingermillet; T9:Fodder Maize; T10:Fieldbean; T11:Niger; T12:Chilli; T13:Cowpea; T14:Foxtailmillet and T15:CA in 2012 and 2013 under semiarid Alfisols at Bangalore. T2 gave the maximum CA equivalent yield (1333 kgha^?1), rainwater-use efficiency (4.90 kgha^?1mm^?1), net returns of Rs. 52690 ha^?1 and a benefit-cost ratio of 2.92. T6 gave the maximum WHC of 41.0%; an infiltration rate of 33.1 cmhr^?1; a cumulative infiltration of 66.2 cm; and a minimum bulk density of 1.40 gcc^?1. T6 maintained maximum soil nitrogen (N) of 259 kgha^?1; phosphorus pentoxide (P₂O₅) of 67.9 kgha^?1; and potassium oxide (K₂O) of 141.5 kgha ^?1; while T9 gave uptake N of 102.7 kgha^?1; P₂O₅ of 24.6 kgha^?1; and K₂O of 103.7 kgha^?1. T6 was efficient for improving the soil physical, chemical, and biological parameters based on the study.     

滨湖城市典型公园化河口岸带土壤理化性状研究

为摸清五里湖公园化河口岸带土壤理化性质,探明土壤质量状况,本研究于2017年10月对五里湖3个典型公园化河口区域(陆典桥浜L、梁塘河C、圩田里河W)的24个点位进行岸带土壤采集,分析土壤颗粒组成、容重(BD)和孔隙度(Pt)等物理性状和pH、有机质(OM)、全氮(TN)、碱解氮(AN)、全磷(TP)和有效磷(AP)等化学性状,并利用与植物生长相关的土壤指标(石砾、砂粒、黏粒、BD、pH、OM、TN、AN、TP、AP)进行土壤质量指数(SQI)评价。结果表明:①3个河口岸带土壤均存在结构退化的情况,土壤主要以石块和石砾为主(700g/kg),砂粒、粉粒和黏粒含量较低,土壤容重偏大(1.35 g/cm3),孔隙度偏低(50%);②3个河口岸带土壤pH均呈碱性(平均8.30),且陆典桥浜河口圩田里河河口梁塘河河口,AP含量趋势相反;除梁塘河河口TP含量差异不大外,陆典桥浜和梁塘河河口的OM、TN、AN、AP、TP均呈现近岸大于远岸的趋势。③3个河口岸带土壤质量状况均较差(SQI0.5),AN、BD、OM、AP和pH是影响研究区域岸带土壤质量的5个主因子。     

我国几种土壤中铁锰结核的元素组成和地球化学特点

The objective of this research was to isolate a dichlorvos （2,2-dichlorovinyl dimethyl phosphate）-degrading strain of Ochrobactrum sp., and determine its effectiveness in remediation of a dichlorvos-contaminated soil. A dichlorvos-degrading bacterium （strain DDV-1） was successfully isolated and identified as an Ochrobactrum sp. based on its 16S rDNA sequence analysis. Strain DDV-1 was able to utilize dichlorvos as a sole carbon source, and the optimal pH and temperature for its cell growth and degradation were 7.0 and 30 ℃, respectively. Also, the growth and degradation of strain DDV-1 showed the same response to dissolved oxygen. In addition, the soil degradation test indicated that in soil spiked with 100 mg L^-1 or 500 mg L^-1 dichlorvos and inoculated with 0.5% or 1.0% （v/v） strain DDV-1, complete degradation of dichlorvos could be achieved in 24 h. The present study showed that strain DDV-1 was a fast dichlorvos-degrading bacterium in soil. However, further research will be needed to clarify the degradation pathway and the properties of the key enzymes involved in its biodegradation.