Sulfur mineralization in sphagnum peat

Abstract

Open and closed incubation systems were studied as means of quantifying sulfate fractions in sphagnum peat moss. Sulfate was extracted in the closed system with a 0.15% CaCl₂‐H₂O or a 500 mg P/L extractant. Sulfate was extracted in the open system with 10 mM KC1, 0.15% , CaCl₂‐H₂O, or 500 mg P/L extractant. Extractants were quantified by ion chromatography. Phosphate extractant released more sulfate than CaCl₂, in the closed system. There was a significant increase over time of sulfate released by the CaCl₂ extractant. In the open system, there was no significant difference in release and total amounts leached of sulfate‐S between extractants. The closed system released more sulfate‐S than the open system. Phosphate extractants in both systems mineralized 43% of initial sulfur content     

A method for extracting sulfate from sphagnum peat

Abstract

The efficacy of five solutions for extracting sulfate from a peat‐based medium was investigated. Extracting solutions used were 10 mM LiCl, 10 mM KC1, 100 mg/L P, 500 mg/L P, 0.15% CaCl₂, or distilled water. Equilibration time affected the amount of sulfate extracted with the use of 100 mg/L P or distilled water extractants. Differences in the amount of sulfate extracted were observed at 0.5‐, 4‐, and 12‐hour equilibration times. Extraction effectiveness increased with the increase of equilibration time, up to a maximum of 4 hours. The concentration of sulfate extracted with all extractants levelled off at the 2‐hour equilibration time. CaCl₂ was the most effective solution for the extraction of water‐soluble sulfate. Water‐soluble sulfate plus absorbed sulfate was most efficiently extracted with 500 mg/L P. No relationship was observed between measured sulfate and the pH levels of the extracted solutions.     

The effect of pH on sulfate availability in sphagnum peat

Abstract

The influence of pH upon the availability of sulfate‐sulfur in sphagnum peat moss was studied. Samples of sphagnum peat moss amended with 0, 1.41, 2.82, 3.81 and 5.64 g/L Ca(OH)₂, had pH values of 2.8, 3.7, 4.7, 5.8 and 7.0, respectively. Sulfate was extracted from peat samples with a 0.15% CaCl₂.H₂O or a 500 mg P/L (as Ca(H₂PO₄)₂.H₂O) extractant and quantified with a Dionex QIC ion Chromatograph. Sulfate availability from the CaCl₂‐extracted solutions was greatest at pH 4.7 and 5.8, but highest at pH 4.7 only for the P‐extracted solutions, in which no measurable extracted sulfur was found at pH levels greater than 4.7.     

Response to micronutrient on carrots grown on a virgin sphagnum peat

Field studies were conducted over a period of years on a virgin sphagnum peat bog in St. Charles, New Brunswick to determine the effect of trace elements on carrot (Daucus carota L.) root yield and nutrient concentration. Addition of the trace elements, boron (B), molybdenum (Mo), copper (Cu), and zinc (Zn), did not affect the marketable carrot root yields, although yields differed significantly from year to year. Addition of B at 10 kg/ha resulted in leaf tissue B concentrations as high as 75 mg/kg. Addition of foliar Mo at 0.14 kg/ha and soil Mo at 0.56 kg/ha raised the leaf tissue Mo concentrations to 3 to 4 mg/kg. Copper applications at 30 kg/ha raised the leaf tissue Cu concentration to 12 mg/kg. Zinc addition at 10 kg/ha did not increase the leaf Zn levels which ranged from 44 to 58 mg/kg. The leaf tissue B, Mo, Cu, and Zn levels as low as 29, 0.17, 4, and 44 mg/kg, respectively, were not related to deficiency of these elements. Such leaf tissue concentrations of B, Mo, and Cu are marginal for optimum crop production on this bog and should be monitored periodically to detect any significant trends through continuous use of this bog in crop production.     

Effect of carbon source and nitrogen on urease activity in a sphagnum peat medium

Abstract

Sphagnum peat moss was supplemented with 0, 0.01, 0.1, or 1.0 mg as C/cm³ of medium using glucose, galactose, succinate, or acetate as a carbon source. These treatments were factorially combined with 0, 30, or 60 μg N/cm³ using ammonium sulfate as the nitrogen source. Medium treatments were then incubated at 20°C and 40% water holding capacity. Urease activity was determined immediately prior to treatment (day = 0), and 7, 14, and 21 days following treatment. In another study, sphagnum peat was treated with 1.0 mg C/cm³ of medium using galactose as a carbon source. These treatments were factorially combined with 0 or 60 μg N cm³ medium using either ammonium sulfate or urea as a nitrogen source. Treatments were incubated and assayed for urease activity as described for the previous experiment. In the first experiment, the addition of carbon stimulated urease activity with activity being greatest for the highest rate of carbon. Treatments receiving the two monosaccharides, glucose and galactose, showed greater urease activity levels with treatments receiving galactose having the greatest urease activity. The addition of ammonium retarded the increase in urease activity from the addition of carbon. In the second experiment, in the absence of galactose, urease activity increased in samples supplemented with urea as compared to when ammonium was added. When galactose was present, the addition of urea had no effect on urease activity as compared to treatments receiving ammonium.     

Influence of organic matter on the sorption of aromatic hydrocarbons by peat and chernozem

The interaction of water-soluble monoaromatic hydrocarbons with an organic matrix of chernozem and peat was studied. As a result of high levels of soil pollution by monoaromatic hydrocarbons, soil organic matter with the high sorption capacity actively adsorbs aromatic hydrocarbons. The hydrophobic properties of aromatic compounds determine the strength of the interactions between themselves and the soil organic matrix. The presence of lipids in the organic matter of chernozem decreases the sorption of aromatic hydrocarbons because of the blocking of hydrophobic centers of the soil humic substances.     

Effect of nitrogen,phosphorus and potassium on yields and nutrient levels in cabbage grown on sphagnum peat

Abstract

Fertilizer treatments for cabbage, grown on sphagnum peat, consisted of an N, a P and a K series. Each nutrient was applied at four rates in combination with constant rates of the other two.

Results indicated that 270 kg N/ha, the highest rate used, may not have been adequate whereas P and K at 80 and 150 kg/ha respectively were. In the N, the P, and the K series, highest head weights coincided with midribs containing 2.06% N, 0.48% P and 4.18% K respectively.     

Competitive sorption of copper,nickel, and zinc by an Oxisol

Abstract

The competitive sorption of copper (Cu), nickel (Ni), and zinc (Zn) in an Oxisol suspension was investigated using the Sheindrof‐Rebhun‐Sheituch (SRS) equation. Experimental data were obtained for a system containing these cations as single components, binary, and ternary mixtures. The associated competitive coefficients a_ij can be viewed as a way to quantify competitive interaction. The competition coefficients obtained for the cations indicated that the sorption of Ni and Zn by the soil was significantly inhibited by the presence of Cu, while the inhibition exerted in the reverse situation was milder. After a _ij ‐values were substituted in the SRS equation, the sorption values predicated by this equation for the ternary solute mixture Cu‐Ni‐Zn, were compared to values determined experimentally. The SRS equation modeled sorption successfully for the range of solute concentrations used.     

Effect of nitrogen,phosphorus and potassium on yields and nutrient levels in onions grown on a sphagnum peat soil

Abstract

Onions were grown on two areas of sphagnum peat. One (old area) had been fertilized and cropped for a 5‐year period and the other (new area) had not. Fertilizer treatments on both areas consisted of an N, a P and a K series. Each nutrient was applied at four rates in combination with constant rates of the other two.

In practically all instances comparable treatments resulted in lower N, P and K levels in plant tissue samples from the new area than from the old where residual effects from previous cropping and fertilization were evident. Yield data indicate that initially, previously unfertilized sphagnum peat should receive N, P and K at 275–300, 40–50 and 70–80 kg/ha respectively.     

The influence of the bog water level on the transformation of sphagnum mosses in peat soils of oligotrophic bogs

Quantitative estimates of the rate of transformation of moss residues of two species (Sphagnum angustifolium and Sphagnum fuscum) in the peat soils (Histosols) were obtained for two oligotrophic bogs with different hydrological conditions in the southern taiga of Western Siberia. The coefficients of decomposition rate (k) significantly differed for the studied species; the decomposition of Sphagnum fuscum proceeded much slower. The most intense decomposition was observed in the first year of transformation (k = 0.06 and 0.16–0.66 for Sph. fuscum and Sph. angustifolium, respectively); then, the rate of moss decomposition decreased. Despite the great amount of fungal mass in the moss residues (exceeding the bacterial biomass by 3–10 times), the rate of the initial decomposition was very low. The hydrological conditions affected the intensity of this process—in the peat of the Kirsanovskoe bog with the low level of bog water, losses of the mass of sphagnum moss were 1.1–1.6 times greater as compared to those in the Bakcharskoe bog. For Sph. angustifolium, the level of bog water was more important than for Sphagnum fuscum, whereas for Sphagnum fuscum, the composition of organic matter played a decisive role in the rate of decomposition of moss residues. The activity of the microflora also depended on the level of bog water, which was manifested in a greater abundance of bacteria in the peat of the Kirsanovskoe bog.     

Effect of nitrogen,phosphorus and potassium on yields and nutrient levels in carrots grown on sphagnum peat and mineral soils.

Abstract

Carrots, Daucus carota L., were grown on both sphagnum peat and mineral soils from 1969 to 1972 inclusive. Fertilizer treatments consisted of three rates of N, of P and of K applied in all possible combinations.

In practically every instance rates of N, P and K applied to sphagnum peat were reflected in the levels of these nutrients found in carrot leaves. This was not the case with mineral soils. On sphagnum peat there were eight opportunities, and on mineral soils seven, for each of the three applied nutrients to influence yields. On peat N increased yields in three instances, P in one and K in five. On mineral soils N decreased yields in two instances, P decreased them in one and increased them in one while K had no effect.

The results suggest that on sphagnum peat carrots may require N, P and K up to 250, 50 and 150 kg/ha respectively whereas on mineral soils maximum rates would be 25, 25 and 50 kg/ha.     

中甸泥炭中胡敏酸的分离及其吸附特征

The Zhongdian swamp meadow in Zhongdian, China is well known as “Shangri-la”, where the peat has never been studied for its potential to interact with pollutants. Humic acid (HA) was extracted from Zhongdian peat using two methods, namely sodium pyrophosphate extraction (SPE) and dilute base extraction (DBE), and characterized for its functional groups and sorption property. The HAs extracted by both methods contained several active functional groups and had large external specific surface areas. The adsorption mechanism of methylene blue onto HAs was interpreted as Langmuir sorption. SPE-HA showed higher sorption capacity because of its larger specific surface area, whereas the extraction yield of DBE-HA was twice that of SPE-HA. Kinetics modeling indicated that the sorption of methylene blue was a two-component first order reaction. The component with the higher rate constant also showed higher sorption capacity. No pH effect was observed for methylene blue sorption on HA in our experimental design, and the sorption decreased as the temperature increased.     

The specific sorption of trace amounts of Cu,Pb, and Cd by inorganic particulates

Thin film A.S.V. was used to study the specific sorption of Cd, Pb and Cu by hydrous oxides (Mn, Fe, and Al) or clay mineral suspensions from acetate buffer solutions containing 10 to 100 μg L^?1 of each metal ion. The amount sorbed varied with system pH (range 3 to 9), substrate crystal form, the ratio of adsorbent to absorbate present, and the metal ion involved. Uptake by hydrous Mn(IV) oxide was near total over the whole pH range. With other particulates the pH required for onset of sorption varied with solid phase composition, with uptake subsequently increasing steadily with increasing pH. In general, affinity and relative uptake values followed the sequences Pb > Cu > Cd and Mn(IV) oxides > Fe(III) oxides > A1(OH)₃ > clays > iron ores. The solid phases loaded with sorbed metal were equilibrated with a range of extractant solutions used in soil/sediment studies, and the results confirmed that chemi-sorption was the main retention process. Significant release was achieved using extractants that attacked the substrate or formed stable complexes with the metal ion.     

Historical rates of atmospheric Pb deposition using210Pb dated peat cores: Corroboration,computation, and interpretation

Lead-210 dating of peat cores is one approach that has been used to arrive at historical rates of heavy metal deposition. Despite concerns regarding the validity of²¹⁰Pb dating due to Pb mobility,²¹⁰Pb dating can be used if the dates are corroborated with some other independent dating technique. In this study, based on analyses of²¹⁰Pb dated, pollen corroborated peat cores from two sites in the Czech Republic (Jezerní sla and Bo?í Dar Bog), we illustrate a previously unexplored problem concerning the computation of metal deposition, using Pb as an example. When peat cores are collected, sectioned into depth intervals,²¹⁰Pb dated and analyzed for metal contents, the²¹⁰Pb dates most appropriately correspond to the midpoint depth for each interval, whereas the metal contents correspond to the interval between the top and bottom of each section. Thus the²¹⁰Pb dates and metal content values throughout the core are offset by half the distance of each depth interval. In calculating historical rates of heavy metal deposition two approaches are available for correcting for the depth interval offsets, the traditional approach of date interpolation and our newly proposed metal content interpolation. We see noa priori reason for choosing one approach over the other, and suggest simultaneous use of both date and metal content interpolation. Additionally, acid-insoluble ash (AIA), which has been proposed as a dating technique in and of itself, may be more useful as an interpretive tool which may provide insights into the nature or sources of atmospherically deposited Pb. For example, plots of Pb content per core section versus AIA content per core section for Jezerní slat, located in a relatively pristine area, reveal increased Pb content without increased AIA contents in depths shallower than 6 cm, indicating deposition of gasoline-derived Pb after its introduction in 1922. Similar plots for Bo?í Dar Bog, located in a polluted industrialized region, indicate greater inputs of Pb than would be predicted from AIA, based on the Jezerní sla analyses. We interpret the apparent excess Pb deposition at Bo?í Dar Bog as being contributed by soil-derived dust from local metal mining. Elevated rates in Pb deposition at Bo?í Dar Bog are consistent with the history of local mining known to have occurred in the vicinity. Finally, magnetic susceptibility measurements identify combustion of fossil fuels as a source of atmospheric Pb deposition at Bo?í Dar Bog, but not at Jezerní sla      

Saturation of raised bog peat exchange sites by Pb and Al stimulates CH4 production

We examined the effect of cation treatments on methanogenic activity and nutrient release from exchange sites in raised bog and fen peats. Treatments consisted of cation chloride solutions (MgCl₂, AlCl₃ and PbCl₂) applied individually. In raised bog peat Al³⁺ and Pb²⁺ increased CH₄ production. A correlation was found between CH₄ production and the amount of micro- and macronutrient cations released by the treatments. In calcareous fen peat, such a stimulation was also found, but there was no correlation between CH₄ production and micro and macronutrient release. Direct nutrient and pH effects could not account for these observations. Thus the results support the hypothesis that the methanogenic community in the raised bog is limited by the availability of mineral nutrients and/or inactivity of exo-enzymes, both of which are bound onto exchange sites.     

Competitive sorption of cadmium and lead in acid soils of Central Spain

The bioavailability and ultimate fate of heavy metals in the environment are controlled by chemical sorption. To assess competitive sorption of Pb and Cd, batch equilibrium experiments (generating sorption isotherms) and kinetics sorption studies were performed using single and binary metal solutions in surface samples of four soils from central Spain. For comparisons between soils, as well as, single and binary metal solutions, soil chemical processes were characterized using the Langmuir equation, ionic strength, and an empirical power function for kinetic sorption. In addition, soil pH and clay mineralogy were used to explain observed sorption processes. Sorption isotherms were well described by the Langmuir equation and the sorption kinetics were well described by an empirical power function within the reaction times in this study. Soils with higher pH and clay content (characterized by having smectite) had the greatest sorption capacity as estimated by the maximum sorption parameter (Q) of the Langmuir equation. All soils exhibited greater sorption capacity for Pb than Cd and the presence of both metals reduced the tendency for either to be sorbed although Cd sorption was affected to a greater extent than that of Pb. The Langmuir binding strength parameter (k) was always greater for Pb than for Cd. However, these k values tended to increase as a result of the simultaneous presence of both metals that may indicate competition for sorption sites promoting the retention of both metals on more specific sorption sites. The kinetic experiments showed that Pb sorption is initially faster than Cd sorption from both single and binary solutions although the simultaneous presence of both metals affected the sorption of Cd at short times while only a minor effect was observed on Pb. The estimated exponents of the kinetic function were in all cases smaller for Pb than for Cd, likely due to diffusion processes into micropores or interlayer space of the clay minerals which occurs more readily for Cd than Pb. Finally, the overall sorption processes of Pb and Cd in the smectitic soil with the highest sorption capacity of the studied soils are slower than in the rest of the soils with a clay mineralogy dominated by kaolinite and illite, exhibiting these soils similar sorption rates. These results demonstrate a significant interaction between Pb and Cd sorption when both metals are present that depends on important soil properties such as the clay mineralogy.     

Competitive sorption of microbial metabolites on an iron oxide mineral

A large fraction of soil organic matter (SOM) is composed of small molecules of microbial origin. However, the biotic and abiotic cycling of these nutrients is poorly understood and is a critical component of the global carbon cycle. Although there are many factors controlling the accessibility of SOM to microbes, sorption to mineral surfaces is among the most significant. Here, we investigated the competitive sorption of a complex pool of microbial metabolites on ferrihydrite, an iron oxide mineral, using a lysate prepared from a soil bacterium, Pseudomonas stutzeri RCH2. After a 24-h incubation with a range of mineral concentrations, more than half of the metabolites showed significant decreases in solution concentration. Phosphate-containing metabolites showed the greatest degree of sorption followed by dicarboxylates and metabolites containing both nitrogen and an aromatic moiety. Similar trends were observed when comparing sorption of metabolites with an equimolar metabolite mixture rather than a bacterial lysate. Interestingly, ectoine, lysine, two disaccharides and uracil were found not to sorb and may be more bioavailable in iron oxide-rich soils. Additionally, the highest-sorbing metabolites were examined for their ability to mobilize mineral-sorbed phosphate. All phosphate-containing metabolites tested and glutathione released phosphate from the mineral surface within 30 min of metabolite addition. These findings of preferential sorption behavior within a complex pool of microbial metabolites may provide insight into the cycling of SOM and specific nutrient availability. Finally, the release of highly-sorptive metabolites may be an underexplored mechanism utilized by microbial communities to gain access to limited environmental nutrients.     

Fe(III)-EDDHA and -EDDHMA sorption on Ca-montmorillonite, ferrihydrite, and peat.

The effectiveness of Fe chelates as Fe sources and carriers in soil can be severely limited by the adsorption of Fe chelates or chelating agents in the solid phase. To study this phenomenon, well-characterized peat, Ca-montmorillonite, and ferrihydrite were used as model compounds, and the adsorption of Fe-EDDHA and Fe-EDDHMA chelates were studied. Sorption isotherms for the meso and racemic isomers of these chelates on the soil materials are described. The variability of sorption with pH in peat and ferrihydrite was also determined because both have variable surface charge at different pH values. In montmorillonite, at low concentrations, the retention of Fe from the Fe-EDDHMA chelate is greater than the one of the Fe-EDDHA chelate. As well as the concentration increased, the inverse situation occurs. The behavior of both meso and racemic isomers of chelates in contact with Ca-montmorillonite is similar. The Fe-meso-EDDHA isomer was highly adsorbed on ferrihydrite, but the racemic isomer is not significantly retained by this oxide. For Fe-EDDHMA isomers, the racemic isomer was more retained by the oxide, but a small sorption of the racemic isomer was also observed. Results suggest that Fe-EDDHA chelates were more retained in peat than Fe-EDDHMA chelates. The most retained isomer of Fe-EDDHA was the meso isomer. For Fe-EDDHMA, the adsorption was very low for both racemic and meso isomers.     

Phosphate fixation by bentonite

Introduction

The relative ability of soils, clay minerals, and hydrous oxides to fix phosphorus has been determined by a variety of methods. In order to study phosphate fixation, it is necessary to rigidly control such factors as concentration of phosphorus added, time of reaction, temperature, and pH.     

Competitive sorption between imidacloprid and imidacloprid-urea on soil clay minerals and humic acids

Soil organic matter and clay minerals are responsible for the adsorption of many pesticides. Adsorption and competitive sorption of imidacloprid on clay minerals and humic acids (HA) were determined using the batch equilibration method. The sorption coefficient of imidacloprid on humic acids was significantly higher than that on Ca-clay minerals, indicating that soil organic matter content was a more important property in influencing the adsorption of imidacloprid. Competitive sorption was investigated between imidacloprid and its main metabolite imidacloprid-urea on HA and Ca-clay minerals. The results showed that the sorption capacity of imidacloprid on clay minerals and HA was reduced in the presence of the metabolite, implying that imidacloprid-urea could occupy or block adsorption sites of imidacloprid on soil, potentially affecting the fate, transport, and bioavailability of imidacloprid in the environment. The interactions between a Ca-clay or HA-clay mixture and adsorption of imidacloprid and imidacloprid-urea were studied using IR differential spectra on thin films made of the adsorbent. The possible mechanisms were discussed from the shift of characteristic IR absorption bands of imidacloprid and imidacloprid-urea after sorption.