Total Base Cations Research Articles

The potential feasibility for soil improvement, based on the properties of biochars pyrolyzed from different feedstocks

Biochars have been considered as useful soil amendments due to their beneficial properties in improving soil fertility, carbon (C) sequestration, and soil decontamination. In our study, a series of biochars produced from different types of feedstocks at two pyrolysis temperatures (300 and 500 °C) were characterized to evaluate their different potentials as soil amendments. Ten types of feedstocks were used to prepare biochars at the pyrolysis temperatures of 300 and 500 °C, for 2 h. Chemical and physical analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier Transform Infrared (FTIR) analyses were conducted to determine differences in biochar properties. Then, soil incubation studies were used to investigate the relationships between these biochar properties and their different ameliorant values in soil. The pH, ash, total C, total potassium, total phosphorus, total base cation concentrations, surface areas, and total pore volumes of biochars produced at 500 °C were higher than at 300 °C, while the reverse applied for yields, total oxygen and total hydrogen, and average pore widths and particle sizes. Cluster analysis suggested that biochars derived from similar feedstock types belonged in the same category. The SEM, XRD, and FTIR analyses of typical biochars from the different categories suggested both variations and similarities in their characteristics. In addition, the results from soil incubation experiments were consistent with the conclusions made from biochar characteristics analysis. Biochars derived from swine manures, fruit peels, and leaves with high pH and macro-nutrients appeared appropriate to increase soil pH and soil nutrient availability; whereas, biochars from wetland plant residues with high C concentrations and Brunauer–Emmett–Teller were better for soil C sequestration and contaminant adsorption.

A decade of monitoring at Swiss Long-Term Forest Ecosystem Research (LWF) sites: can we observe trends in atmospheric acid deposition and in soil solution acidity?

Trends in atmospheric acid deposition and in soil solution acidity from 1995 or later until 2007 were investigated at several forest sites throughout Switzerland to assess the effects of air pollution abatements on deposition and the response of the soil solution chemistry. Deposition of the major elements was estimated from throughfall and bulk deposition measurements at nine sites of the Swiss Long-Term Forest Ecosystem Research network (LWF) since 1995 or later. Soil solution was measured at seven plots at four soil depths since 1998 or later. Trends in the molar ratio of base cations to aluminum (BC/Al) in soil solutions and in concentrations and fluxes of inorganic N (NO(3)-N + NH(4)-N), sulfate (SO(4)-S), and base cations (BC) were used to detect changes in soil solution chemistry. Acid deposition significantly decreased at three out of the nine study sites due to a decrease in total N deposition. Total SO(4)-S deposition decreased at the nine sites, but due to the relatively low amount of SO(4)-S load compared to N deposition, it did not contribute to decrease acid deposition significantly. No trend in total BC deposition was detected. In the soil solution, no trend in concentrations and fluxes of BC, SO(4)-S, and inorganic N were found at most soil depths at five out of the seven sites. This suggests that the soil solution reacted very little to the changes in atmospheric deposition. A stronger reduction in base cations compared to aluminum was detected at two sites, which might indicate that acidification of the soil solution was proceeding faster at these sites.

Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils

Abstract A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn 2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn 2+/Ca 2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn 2+/Ca 2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn 2+ and consequently stronger effects on E. coli viability.

Estimating base cation weathering rates in Canadian forest soils using a simple texture-based model

Mineral weathering is the primary source of long-term buffering capacity in soils and is important for forest nutrient sustainability. Regional assessments of weathering rates in Canada and the U.S. have employed an empirical clay-based Soil Texture Approximation (STA) owing to limited data availability, although the STA is rarely calibrated before application to a study area. Soil weathering rates estimated with the STA at 75 sites in Canadian forests (6–367 eq ha−1 year−1) were on average seven times lower than estimates obtained using the PROFILE model and when mineralogy was not available, the Analysis to Mineralogy model and parameter estimation (143–2,119 eq ha−1 year−1). Comparison with a catchment mass balance at a subset of sites in Ontario (n = 19) demonstrated the reliability of PROFILE weathering estimates. A revised (generalized) STA model for total base cation weathering was developed at the 75 study sites to incorporate soil silt content (%) and loss-on-ignition (LOI, %) (BCw = (1.73 + 0.03 · silt − 0.06 · LOI) · 1,000 · depth). The model performance (Radj2 = 73%) and relative bias (−1%) suggested that the revised STA may have broad application to forest soils in Canada but may not necessarily be suited to all soil texture classes.

Coupled modeling of biospheric and chemical weathering processes at the continental scale

In this contribution, a reactive‐transport model describing weathering in soil profiles and at the watershed scale is coupled to a dynamic global vegetation model to calculate the dissolved load of continental waters on a 0.5° latitude × 0.5° longitude grid. The so‐called Biosphere‐Weathering at the Catchment Scale (B‐WITCH) model is applied to the Orinoco watershed (South America). We show that B‐WITCH is able to reproduce the main cation composition of the surface waters over the watershed. Sensitivity tests demonstrate that clay mineral reactivities are key factors controlling the calculated discharge of dissolved species. More specifically, our simulations show that the dissolution and precipitation rates of clay minerals in the weathering profiles are strongly intertwined, and that this coupling must be accurately described when modeling the weathering fluxes at the continental scale. A second set of sensitivity tests show that, for the tropical environment, land plants control the total base cation discharge through their impact on the soil hydrology, rather than through enhanced soil CO2 pressures. Indeed, the complete removal of the continental vegetation leads to an increase in the dissolved fluxes to the ocean by 80% because of the collapse in the evapotranspiration, resulting in a more efficient drainage of the weathering profiles. On the other hand, neglecting the root respiration and setting the soil CO2 pressure to the atmospheric level forces the total base cation discharge to decrease by only 20%.

Increased belowground biomass and soil CO2 fluxes after a decade of carbon dioxide enrichment in a warm‐temperate forest

Atmospheric CO2 concentrations have risen 40% since the start of the industrial revolution. Beginning in 1996, the Duke Free-Air CO2 Enrichment experiment has exposed plots in a loblolly pine forest to an additional 200 microL/L CO2 compared to trees growing in ambient CO2. This paper presents new belowground data and a synthesis of results through 2008, including root biomass and nutrient concentrations, soil respiration rates, soil pore-space CO2 concentrations, and soil-solution chemistry to 2 m depth. On average in elevated CO2, fine-root biomass in the top 15 cm of soil increased by 24%, or 59 g/m2 (26 g/m2 C). Coarse-root biomass sampled in 2008 was twice as great in elevated CO2 and suggests a storage of approximately 20 g C x m(-2) x yr(-1). Root C and N concentrations were unchanged, suggesting greater belowground plant demand for N in high CO2. Soil respiration was significantly higher by 23% on average as assessed by instantaneous infrared gas analysis and 24-h integrated estimates. N fertilization decreased soil respiration and fine-root biomass by approximately 10-20% in both ambient and elevated CO2. In recent years, increases in root biomass and soil respiration grew stronger, averaging approximately 30% at high CO2. Peak changes for root biomass, soil respiration, and other variables typically occurred in midsummer and diminished in winter. Soil CO2 concentrations between 15 and 100 cm depths increased 36-60% in elevated CO2. Differences from 30 cm depth and below were still increasing after 10 years' exposure to elevated CO2, with soil CO2 concentrations >10000 microL/L higher at 70- and 100-cm depths, potentially influencing soil acidity and rates of weathering. Soil solution Ca2+ and total base cation concentrations were 140% and 176% greater, respectively, in elevated CO2 at 200 cm depth. Similar increases were observed for soil-solution conductivity and alkalinity at 200 cm in elevated CO2. Overall, the effect of elevated CO2 belowground shows no sign of diminishing after more than a decade of CO2 enrichment.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Base Cation Fluxes in Mountain Landscapes of Lake Baikal Southern Shore

Assessing base cation [calcium (Ca2+), magnesium (Mg2+), potassium (K+)] fluxes is necessary for determining ecosystem stability. This study was conducted in the Osinovka River catchment located on the Khamar‐Daban Ridge, South Baikal, which is characterized by high precipitation (more than 1700 mm per annum). The contributions of different ecosystem components such as atmospheric deposition, soil exchange pool, minerals, vegetation, surface water, and groundwater into the total base cations flux were evaluated, combining the strontium isotope approach and budget study. Results show the leading role of atmosphere in ecosystem supply with base cations. The atmosphere contributes 48% of total base cations flux, and its contributions to plant‐available nutrition pools of both organic and mineral horizons are equal to 50%. This makes the vitality of vegetation, to a great extent, dependent on the stability of atmospheric chemistry.

Deposition patterns in bulk precipitation and throughfall in a subtropical mixed forest in central-south China

The chemistry and deposition pattern in bulk precipitation and throughfall (TF) were examined and evaluated based on the 3-year observations in Shaoshan subtropical deciduous-conifer mixed forest in central-south China. The TF chemistry was notably changed when passing through canopies, which probably was attributed to the dry deposition (DD) on leaf surface and the canopy exchanges. Base cations' (Ca 2+ , Mg 2+ and K + ) fluxes were significantly enriched in TF, in particular for K + . The annual K + canopy exchange was ∼12 times larger than DD, and canopy exchange of Ca 2+ , Mg 2+ and K + was four times as high as the DD. The canopy exchange of base cations in association with weak acid accounted for 28.4 per cent of total leached base cations, which was one of the important factors to modify the TF chemistry.

Effects of Weak Acids on Canopy Leaching and Uptake Processes in a Coniferous-Deciduous Mixed Evergreen Forest in Central-South China

The effects of Weak acids (WA) on the canopy leaching and uptake processes are evaluated by comparing the leached base cations or the absorbed protons while including and excluding WA, e.g. the WA-included method and the WA-excluded method. The seasonal WA throughfall flux is even larger than twice the bulk precipitation flux except summer, which not only partly agrees with the conclusion that the total deposition of WA equals twice the bulk or dry deposition flux in European Intensive Monitoring plots (level II), but also indicates the significant canopy leaching of WA in Shaoshan forest. The seasonal canopy leaching of base cations in association with WA accounts for 6–30% of the total base cations in throughfall, with an annual mean of 23%, which is slightly higher than the 15% at the Speulder forest in The Netherlands. The canopy exchange capacity of H+ to NH4+ is closed to 6.0 while neglecting the WA exchange, which probably supports the assumption that the exchange capacity of H+ is six times that of NH4+. Simultaneously, we suggest that the WA is competitive to a certain extent with protons to leach base cations of plant tissues during the canopy exchange processes.

Cation and anion exchange properties of Andisols from the Azores, Portugal, as determined by the compulsive exchange and the ammonium acetate methods

The cation exchange capacity (CEC) and the anion exchange capacity (AEC) of 31 soil horizons from a representative range of Andisols and related soils from the Azores, Portugal, were measured using the 1 M NH 4OAc standard method (SM) and the compulsive exchange method (CE). The effective cation exchange capacity (ECEC) was also measured by these two methods and by a 1 M NH 4OAc simplified method (sm). The amount of base cations extracted by sm, SM and CE, as well as Al extracted by 1 M KCl and 0.1 M NH 4Cl/BaCl 2 reagents, were compared. The amounts of Ca, Mg, K and Na determined by SM, sm and CE were highly correlated. A high correlation for values of total base cations obtained by the three methods was also observed. Soils with high allophane and/or organic C content showed higher values of Ca and of sum of basic cations by CE than by SM. The inverse was observed in the other soils. The sm extracted higher amounts of Na than SM. Generally, the amounts of Al extracted by 1 M KCl and 0.1 M NH 4Cl/BaCl 2 reagents were not significantly different, and were highly correlated. Values of effective cation exchange capacity by SM, sm and CE were also strongly correlated. The CEC values measured by CE were much lower than those measured by SM. The CEC values obtained by SM were positively correlated with organic C and Al o contents. CEC CE values were negatively correlated with Al o and allophane contents. These values were highly correlated with the amount of basic cations determined by SM, sm and CE. Values of AEC showed a wide variation and were correlated with both allophane and Al o contents. In the presence of high amounts of allophanic materials and low content of organic matter, the AEC becomes more important than the CEC whereby soils have a very low capacity to retain cations.

Weathering and atmospheric deposition signatures of base cations in upland soils of NE Scotland: their application to critical load assessment

Although the importance of atmospheric base cation deposition to soils is increasingly acknowledged, field data demonstrating the signatures of atmospheric and weathering-derived cations are seldom presented. This paper explores how combined atmospheric and internal base cation inputs are reflected in exchangeable and soil solution base cation compositions of upland soils, ranging from acidic to basic parent materials. Although total atmospheric base cation deposition exceeded weathering inputs for most soils, relative proportions of exchangeable base cations were controlled by parent materials. Calcium and magnesium concentrations were most closely related to geology, but were likely affected by the affinity of humic material for divalent cations, which resulted in elevated concentrations in surface horizons. In contrast, soil solution compositions deviated little from those of precipitation, showing minimal geochemical influence. A soil-based weathering rate index utilizing the dominance of the base cation Na was explored with the goal of enhancing spatial resolution in critical load assessment. However, the calibration of the relative proportions of exchange site Na against weathering rates, determined by three conventional critical load calculation methods, was inconclusive. Although power relationships were suggested, these were poor and largely insignificant, with a considerable range of %Na values at low weathering rates. It was not resolved whether the data available was insufficient to obtain accurate weathering rates, or that the base cation chemistry was affected by factors other than weathering alone.

Inter- and intra-annual chemical variability during the ice-free season in lakes with different flushing rates and acid deposition histories.

Quantifying chemical variability in different lake types is important for the assessment of both chemical and biological responses to environmental change. For monitoring programs that emphasize a large number of lakes at the expense of frequent samples, high variability may influence how representative single samples are of the average conditions of individual lakes. Intensive temporal data from long-term research sites provide a unique opportunity to assess chemical variability in lakes with different characteristics. We compared the intra- and inter-annual variability of four acidification related variables (Gran alkalinity, pH, sulphate concentration, and total base cation concentration) in four lakes with different flushing rates and acid deposition histories. Variability was highest in lakes with high flushing rates and was not influenced by historic acid deposition in our study lakes. This has implications for the amount of effort required in monitoring programs. Lakes with high flushing rates will require more frequent sampling intervals than lakes with low flushing rates. Consideration of specific lake types should be included in the design of monitoring programs.

Mapping of Base Cation Deposition in South Korea

Deposition of non-seasalt base cations (Ca2+ + Mg2++ K+) in South Korea was mapped for 1994 to 1997 on a 11 × 14 km grid using the so-called inferential modeling technique. It is found that the annual mean wet deposition of non-seasalt base cations is about 290 eq ha-1 yr-1 with a maximum of 470 eq ha-1 yr-1 and a minimum of 120 eq ha-1 yr-1 while the annual mean dry deposition is about 130 eq ha-1 yr-1 with a maximum of 240 eq ha-1 yr-1 and a minimum 70 eq ha-1 yr-1. Theannual mean total deposition of non-seasalt Ca2+ + Mg2+ + K+ is found to be about 420 eq ha-1 yr-1 with the predominant range of 400 eq ha-1 yr-1 to 550 eq ha-1 yr-1 thatoccupies more than 45% of total deposition of non-seasalt base cations and dry deposition constitutes on average30% of the total base cation deposition. About 30% of the annualtotal deposition of sulfur is found counteracted by depositionof non-seasalt base cations over South Korea.

Measurement of the acid neutralizing capacity of agroforestry tree prunings added to tropical soils

Laboratory incubation in the UK of an Oxisol from Burundi and an Ultisol from Cameroon with 3·1% by weight of prunings of young shoots of Calliandra calothyrsus, Cassia siamea, Flemingia congesta, Grevillea robusta, Gliricidia sepium, Leucaena diversifolia and Leucaena leucocephala resulted in increased soil pH and decreased exchangeable aluminium content. The greatest increase in pH and corresponding decrease in exchangeable aluminium occurred during the first 14 days of incubation and the decrease continued at a slower rate until 42 days incubation. The acid neutralizing effect decreased after 42 days but was still important at the last sampling time at 98 days. Polyphenol to nitrogen ratio was not well correlated with observed change in soil pH whereas the total base cation (calcium, magnesium and potassium) content proved to be a good predictor of these changes in the Ultisol, but not in the Oxisol. The proposed mechanism giving rise to acid neutralization is complexation of protons and aluminium by organic anions. The total base cation content of the prunings ranged from 0·94 to 2·25 molc/kg and the buffer capacity of the Oxisol was 48 mmol OH−/pH/kg.

Base cation deposition in europe—part I. Model description, results and uncertainties

Deposition of base cations (Na +, Mg 2+, Ca 2+, K +) in Europe was mapped for 1989 with a spatial resolution of 10 x 20 km using the so-called inferential modeling technique. Deposition fields resembled the geographic variability of sources, land-use and climate. Dry deposition constituted on average 45% of the total base cation deposition in Europe. Modeled deposition estimates compared reasonably well with deposition estimates derived from throughfall and bulk-precipitation measurements made at 174 sites scattered over Europe. Using error propagation, the random and systematic error in total deposition for an average grid cell of 10 x 20 km was estimated to equal 35–50% and 25–40%, respectively. Within individual grids a relatively large variability in deposition is expected.

Estimating the total deposition of base cations from throughfall measurements

The relationships between the deposition of ions in bulk precipitation and throughfall have been examined in order to assess the validity of the simple ratio technique proposed by Sverdrup et al. (1990) for determining total base cation deposition to forest canopies. The results of the analysis are consistent with the hypothesis that there is negligible canopy leaching of sodium and chloride, at least for Sitka spruce. The enrichment in throughfall compared to precipitation for sodium is very similar to that for chloride but differs from that of the other base cations. The relationship between the deposition of sodium and chloride in throughfall and bulk precipitation can be described using a simple linear regression model which could provide a basic tool for estimating total base cation deposition to UK Sitka spruce forests at a regional scale. Independent verification of the model is required to ascertain whether it is appropriate for base cations such as calcium, which have a significant non-seasalt deposition component.

Assessment of critical loads in liuzhou, China using static and dynamic models

The project Comprehensive Control and Demonstration for Acid Deposition in Liuzbou area is a national key project in the 8th Five-year-plan, and the study on critical loads will provide scientific and quantitative accordance for formulating control strategy. In this paper, critical loads of acid deposition to soil in Lirzhou area, China, were calculated using the Steady State Mass Balance method (SMB and PROFILE) and dynamic modeling methods(MAGIC), based on data obtained from field investigations and physiochemical properties measured through experiments such as the organic content, cation exchange capacity, base saturation, sulfate adsorption capacity, gibbsite coefficient, biomass base cation uptake and selectivity coefficient for cations. Weathering rates necessary to calculate soil chemistry in applying SMB and MAGIC model were determined by computation with PROFILE using independent geophysical properties such as soil texture and mineralogy as the input data, or by the total soil base cation content correlation. The results have shown that the critical loads of acidity in this area are in the range of 0.7–6.0 keq ha−1 yr−1, indicating sulfur deposition should be cut down by 50–90 percent of the present level. The upper soil layer is the most sensitive. The maximum allowable deposition loading of this area is also presented in the paper.

Seasonal variation in water chemistry over a bog-rich fen gradient in Continental Western Canada

Surface and subsurface (0.5, 1.0, and 1.5 m depths) water was sampled weekly in 1989 and biweekly in 1990 during the ice-free season along a bog-rich fen gradient in central Alberta. Acidity–alkalinity were most closely related to peatland type and were the most useful parameters for characterizing peatlands. Potassium, nitrogen, and phosphorus concentrations were more related to season, year, or peatland–year interactions and cannot be used to categorize the bog–fen gradient. Hydrogen ion, ammonium, alkalinity, and corrected conductivity were relatively constant throughout the ice-free season, while total metal ions (Al, Fe, Mn, and Zn), base cations (Ca2+, Mg2+, Na+, K+), nitrate, and components of phosphorus fluctuated seasonally. Nitrate remained constant with depth in all peatland types, whereas ammonium increased with depth. Relationships of surface water chemistry to pH for all sites showed three patterns: a positive and highly significant correlation with little seasonal variation within peatland types (base cations, alkalinity, and corrected conductivity); less significant correlation with strong seasonal variation within peatland types (N and P); and a general negative and highly significant correlation with some seasonal variation in peatland types (metals and S). Water temperatures increased along the bog-rich fen gradient.

Acid rain and soils of the Adirondacks. III. Rates of soil acidification in a montane spruce–fir forest at Whiteface Mountain, New York

To assess the impact of atmospheric deposition on soil acidification and base cation supplies in montane spruce–fir forest soils at Whiteface Mountain, New York, base cation and proton fluxes were determined for organic and mineral horizons from measurements made at four stands (1020–1090 m above sea level) over a 4-year period. Our best estimates indicate an annual accumulation of H+ and a net loss of base cations from the forest floor of about 0.71 kmolc/ha, a 2.8% per year loss of the total forest floor base cation pool. This high rate of acidification is attributable to base cation leaching by sulfate and organic anions, and uptake by living biomass. From 1986 to 1990, the annual net loss rate of forest floor Ca, the most abundant base cation, was several times greater than historical loss rates as determined by 50-year comparisons of forest floor Ca in nearly identical forests of the Adirondack High Peaks region. Published data on long-term trends in Ca deposition in the U.S. Northeast suggest that the difference between historical and current net loss rates of forest floor Ca may be due to sharply reduced atmospheric inputs of Ca after about 1970, exacerbated by sulfate leaching. In mineral horizons where the total base cation pool (mostly mineral bound) is very large, the net losses of base cations were substantially lower and in the range where losses due to leaching and uptake can be countered by mineral weathering.