Changes In Cation Exchange Capacity Research Articles

Long-term effects of conventional cultivation on soil cation exchange capacity and base saturation in an arid desert region

Land reclamation and subsequent management affect soil condition, which is critical for sustainable agricultural production. Soil cation exchange capacity (CEC) and base saturation (BS%) play an important role in the assessment of soil fertility and buffering capacity. However, the variation of these indicators in the evolution of oasis farmland in arid desert areas remains unclear. Therefore, this study was carried out aiming to evaluate the effect of desert reclamation and following long-term conventional cultivation on the CEC and BS%. For the study, we investigated the CEC and exchangeable bases (ExBas) content in oasis farmlands along a chronosequence (0–100 years) of cultivation in arid region and identified the key factors affecting CEC and BS%. The results showed that soil CEC and ExBas significantly increased after desert reclamation, whereas the BS% dramatically decreased. However, all these changes were alleviated with the conventional cultivation age. Regression analysis showed that soil CEC, ExBas, and BS% all exponentially changed with cultivation years. Based on our findings, CEC and ExBas were closely related to soil particle size composition, total nitrogen (TN), soil organic matter (SOM) and soil water content (SWC). The multiple stepwise regression further indicated that the changes in CEC and ExBas after reclamation mainly depended on the silt content, SWC, SOM, and TN. Our findings highlight that although desert reclamation increases soil CEC and ExBas in arid area, this effect tends to disappear after about 100 years of conventional cultivation, and meanwhile, the decline in BS% due to increased acids should also be noted.

Comparative analysis and prediction of cation exchange capacity via summation: influence of biochar type and nutrient ratios

IntroductionEnhancing soil cation exchange capacity (CEC) is of paramount importance for sustainable agriculture and ecosystem health. This study investigated the pivotal role of biochar in altering soil CEC and challenges conventional assumptions about universal effects of biochar application.MethodsContrasting biochar types, one with a low ash content of 4.4% (switchgrass-derived biochar, SGB) and the other with a high ash content of 45.9% (poultry litter-derived biochar, PLB) were used. Two experiments treated with increasing biochar application rates were conducted: one without plants and the other grown with ryegrass. Effective CEC (summation method) was determined by two extraction methods: Mehlich-3 (M3) and ammonium acetate (AA).Results and discussionThe SGB decreased CEC by 27% on average (from both experiments) from the lowest to the highest rate of biochar application, while the PLB significantly increased CEC by 91%. This highlights the critical role of biochar properties in influencing CEC dynamics. In the second experiment, ryegrass cultivation revealed the greater importance of the calcium and magnesium/potassium ratio ([Ca+Mg]/K) in the soil CEC than CEC only for plant growth in biochar-amended soils. The ratios for optimum ryegrass production ranged from 82‒86 (M3) and 69‒74 (AA), which was translated to 88:11:1 Ca:Mg:K percent base saturation ratios. Moreover, predictive models for estimation of soil CEC after biochar application were successfully developed based on initial soil and biochar CEC. However, M3 was more reliable than AA for such predictions mainly because it was more successful in predicting nutrient availability from biochar. These models offer a promising tool for informed soil management decisions.ConclusionThis research emphasizes the importance of biochar feedstock, elucidates nutrient ratio effects on plant growth, and provides a practical means to anticipate soil CEC changes post-biochar application.

Influences of coexisting aged polystyrene microplastics on the ecological and health risks of cadmium in soils: A leachability and oral bioaccessibility based study

Whether coexisting microplastics (MPs) affect the ecological and health risks of cadmium (Cd) in soils is a cutting-edge scientific issue. In this study, four typical Chinese soils were prepared as artificially Cd-contaminated soils with/without aged polystyrene (PS). TCLP and in vitro PBET model were used to determine the leachability (ecological risk) and oral bioaccessibility (human health risk) of soil Cd. The mechanisms by which MPs influence soil Cd were discussed from direct and indirect perspectives. Results showed that there was no significant difference in the leachability of soil Cd with/without aged PS. Additionally, aged PS led to a significant decrease in the bioaccessibility of soil Cd in gastric phase, but not in small intestinal phase. The increase in surface roughness and the new characteristic peaks (e.g., Si-O-Si) of aged PS directly accounted for the change in Cd bioaccessibility. The change in organic matter content indirectly accounted for the exceptional increase in Cd bioaccessibility of black soil with aged PS in small intestinal phase. Furthermore, the changes in cation exchange capacity and Cd mobility factor caused by aged PS explained the change in Cd leachability. These results contribute to a deeper understanding about environmental and public health in complicated emerging scenarios.

Seasonal quality and statistical assessment of physicochemical properties and base saturation of Hadejia-Nguru wetland soils, Northwest/Eastern Nigeria

Abstract The evaluation of Hadejia-Nguru wetland soils was carried out for two consecutive dry seasons. Standard analytical techniques were adopted to analyze the samples and statistical models were used to assess the spatial and temporal distribution of the parameters selected. The average pH values of the soil samples were mostly alkaline, and all the measured values were also within the approved standards. Experimental results revealed a significantly positive correlation between Ca and Mg for both seasons as indicated by the p-values and a high coefficient of determination (R2) for both metals with cation exchange capacity (CEC) values as the predictors. The regression analysis showed that the changes in CEC and pH levels in the soil were dependent on changes in Ca and Mg content of the soil. The data obtained showed that the increase in pH is directly proportional to the CEC and base saturation of the soils. A higher percentage of Ca than other cations (Mg, K and Na) was observed from the base saturation of the soils. The pH, base saturation, and CEC levels in the soils are suitable for most crops grown in the area, which has the potential to support a wide range of crops with further exploration.

Soil electrical conductivity as a proxy for enhanced weathering in soils

To effectively monitor and verify carbon dioxide removal through enhanced weathering (EW), this study investigates the use of soil electrical conductivity (EC) and volumetric water content (θ) as proxies for alkalinity and dissolved inorganic carbon (DIC) in soil water. EC-θ sensors offer a cost-effective and straightforward alternative to traditional soil and water sampling methods. In a lab experiment, three different substrates were treated with NaHCO3 solutions to increase the alkalinity of the soil water and analyze the response. The combination of EC and θ to track the increase in carbonate alkalinity due to EW, and therefore CO2 consumption, is applicable for low cation exchange capacity (CEC) soil-substrates like the used quartz sand. However, the presence of organic material and pH-dependent CEC complicates the detection of clear weathering signals in soils. In organic-rich and clay-rich soils, only a high alkalinity addition has created a clear EC signal that could be distinguished from a non-alkaline baseline with purified water. Cation exchange experiments revealed that the used soil buffered alkalinity input and thereby might consume freshly generated alkalinity, initially mitigating CO2 uptake effects from EW application. Effective CEC changes with pH and pH buffering capacity by other pathways need to be considered when quantifying the CO2 sequestration potential by EW in soils. This should be estimated before the application of EW and should be part of the monitoring reporting and verification (MRV) strategy. Once the soil-effective CEC is raised, the weathering process might work differently in the long term.

Temporal changes in soil chemical compositions in acidified mountain forest soils of Czech Republic

The study aimed to investigate the temporal changes of pH, sorption complex, and structure of soil organic matter through the forest soil profile under beech and spruce forests located in Jizera mountains (Czech Republic) and affected by natural and anthropogenic acidification. Soil samples were collected in four different years (2008, 2013, 2015, and 2020) in each horizon: fermented horizons (F), humified horizons (H), organo-mineral horizons (A), and subsurface mineral horizons (B) (cambic or spodic). The cation exchange capacity (CEC), base saturation (BS), exchangeable element contents, pH, and soil organic carbon content (SOC) were determined. The infrared soil spectra were used to calculate indices of potential wettability, aromaticity, and decomposition. Our results showed that most nutrients and aliphatic compounds were retained in the uppermost soil layers. The aromaticity of organic matter increased with depth, while polysaccharides, regarding the decomposition compound, disappeared through the soil horizons. In a long-term observation, SOC content had constantly increased under beech, while spruce remained stable in the organic horizons. Exchangeable element contents increased in each horizon, except for Al and Fe; their content quickly decreased in F horizons and slowly decreased in H horizon under both forest tree species, while the deeper horizons remained constant, but increased in A horizon under spruce. Continuously increasing base cations concentrations in sorption complex of both forest tree species during the study period revealed the effect of forest stand types on acid deposition reduction and mitigation. The temporal changes in CEC, BS, SOC, and soil wettability are more intensive in beech than in spruce forest floor.

Heat–induced changes in soil properties: fires as cause for remobilization of chemical elements

Abstract Exposure of soil constituents to elevated temperatures during wildfire can significantly affect their properties and consequently, increase the mobility of the bound contaminants. To estimate the potential of wildfires to influence metal remobilization from the burned soil due to the changes in cation exchange capacity (CEC) after organic matter combustion and mineral alteration and degradation, changes in soil properties after exposure to different temperatures was investigated. This was accomplished through analysis of geochemical, mineralogical and surface physicochemical properties of a soil sample exposed to different temperatures in a laboratory. Heating the soil sample at 200 °C, 500 °C and 850 °C resulted in an increase in pH (from 5.9 to 12.3), decrease in cation exchange capacity (from 47.2 to 7.3 cmol+kg−1) and changes in the specific surface area (observed only at 500 °C), that are associated with structural modifications of clay minerals and ferromagnetic minerals. Extraction analysis showed the increase in the concentration of almost all analysed elements (Al, Cd, Co, Cr, Fe, Mn and Zn) in soil eluates. The observed increase, following high– temperature heating (500 °C and 850 °C), was as much as 15 times higher (e.g., Al), compared to the native soil sample (25 °C). This strongly indicates that wildfire can act as a trigger for remobilization of heavy metals.

Variations in Soil Physico-Chemical Properties as Influenced by Landuse in a Toposequence

Soil, water and air work interchangeably for optimum growth and productivity. Soil as a resource provides crops with essential nutrients necessary for growth and human consumption. With the insurgence of high population growth leading to pressure on lands, poor land management etc., this tendency of the soil as a nutrient pool is seen to be dwindling. It is therefore prudent to investigate and understand the dynamism of soil properties to inform proper management. Understanding topography effects and assessing soil properties on different slope positions is a first-hand step in ensuring proper soil management practices. This paper considers the assessment of physico-chemical properties of soils located on different slope gradients and land use types on the Wamaso research site in Ghana made principally of cape coast granite. In all, eighteen samples were collected from identified horizons of five distinctive subsections of the slope were delineated as follows, summit (PP1), shoulder (PP2), middle (PP3), foot slope (PP4) and toe slope (PP5) respectively. Remarkable variations were observed within PP1 to PP3 and then PP5. Pearson’s correlation index revealed that the associations between most of the soil physico-chemical were not consistent across the identified slope positions. The biplot of the first two principal components together is 68.3% of the total variation and might be interpreted as change in Cation exchange capacity, sodium, sand and clay. On the first axis highlights the influence of sand and clay on soil fertility, also the relationship between pH and Na. Organic carbon derived from organic matter contributes to the availability of the basic soil cations and therefore enhances ECEC of the soils and hence the relationship obtained from the biplot. In sum, this research achieved the objective which sought to substantiate indeed the impact topography has on soil physico-chemical properties thereby serving as a reference for the classification of the soils identified.

Effects of intensive biomass harvesting on forest soils in the Nordic countries and the UK: A meta-analysis

The use of biomass from forest harvesting residues or stumps for bioenergy has been increasing in the northern European region in the last decade. The present analysis is a regional review from Nordic and UK coniferous forests, focusing on the effects of whole-tree harvesting (WTH) or whole-tree thinning (WTT) and of WTH followed by stump removal (WTH + S) on the forest floor and mineral soil, and includes a wider array of chemistry data than other existing meta-analyses. All intensified treaments led to significant decreases of soil organic carbon (SOC) stock and total N stock in the forest floor (FF), but relative responses compared with stem-only harvesting were less consistent in the topsoil (TS) and no effects were detected in the subsoil (SS). Exchangeable P was reduced in the FF and TS both after WTT and WTH, but significant changes in exchangeable Ca, K, Mg and Zn depended on soil layer and treatment. WTH significantly lowered pH and base saturation (BS) in the FF, but without apparent changes in cation exchange capacity (CEC). The only significant WTH-effects in the SS were reductions in CEC and BS. Spruce- and pine-dominated stands had comparable negative relative responses in the FF for most elements measured except Mg and for pH. Relative responses to intensified harvesting scaled positively with growing season temperature and precipitation for most variables, most strongly in FF, less in the TS, but almost never in the SS, but were negative for P and Al. The greater reduction in FF and TS for soil organic carbon after intensive harvesting decreased with time and meta-regression models predicted an average duration of 20–30 years, while many other chemical parameters generally showed linear effects for 30–45 years after intensified harvesting. Exchangeable acidity (EA), BS and pH all showed the reversed effect with time, i.e. an initial increase and then gradual decrease over 24–45 years. The subsoil never showed a significant temporal effect. Our results generally support greater reductions in nutrient concentrations, SOC and total N in forest soil after WTH compared with SOH in northern temperate and boreal forest ecosystems.

The effect of extraction of labile organic fractions on surface properties of pyrochars

The changes in the properties of pyrochars and the possibility of their use as soil meliorants were evaluated. Pyrochars obtained from linden residues at fixed pyrolysis temperatures of 250°C, 450°C and 650°C and under isothermal conditions in the temperature range from 450°C to 650°C have been studied. Their labile fractions of organic matter extracted with Na4P2O7-NaOH solution and hot water was investigated by UV-VIS spectrometry and after extraction cation exchange capacity of pyrochars was characterized. For the qualitative characteristics of the selected fractions, ratio of the absorption of a colored solution of organic matter at λ = 254 nm to the content of organic carbon was calculated. It was concluded, that the pool of water-soluble and alkaline-soluble organic matter of pyrochars is a mixture of organic compounds of uncertain qualitative composition, whose properties are determined by the pyrolysis temperature. Extraction of this water-soluble and alkaline-soluble organic matter leads to a change in cation exchange capacity of pyrochars.

Legacy effects of prescribed fire season and frequency on soil properties in a Pinus resinosa forest in northern Minnesota

Abstract Prescribed fire is a widely used ecosystem management approach and the vast majority of burns are conducted during the dormant season; however, these burning conditions (and therefore the type and persistence of fire effects) often differ from those of natural or historical fire regimes. Therefore, we leveraged a historical study (conducted 1959–70) with remeasurements in 2015 to evaluate effects of fire season (dormant, summer), frequency (annual, biennial, periodic), and their interaction on soil physical and chemical properties in a red pine (Pinus resinosa Ait.) forest in northern Minnesota, USA. To protect against across-year differences in sampling and analysis, we used a meta-analysis approach to evaluate treatment effects on soil properties. We also used non-metric multidimensional scaling (NMDS) ordination to investigate legacy (>45 years post-fire) treatment effects. The greatest effects of fire occurred in organic horizons, and decreased with depth. In the short-term, fire decreased organic horizon depths and nitrogen (N) and increased base cations (K, Ca, Mg) and pH in the mineral soil, whereas effects on phosphorus (P) were variable. Prescribed fire treatments had legacy effects on organic horizon and mineral soil properties >45 years post-fire. In general, summer burns decreased nutrient stocks, whereas dormant season burns increased nutrient stocks, and the majority of legacy effects occurred in annual burn treatments, in both seasons. Legacy effects of summer burns decreased organic horizon depths, organic matter, nutrient stocks (N, P, K), and pH, as well as lower (0–15 cm) mineral soil N; whereas, the dormant annual burn increased Ca in the total forest floor and N and P in the upper (15–91 cm) mineral soil. In contrast, the summer annual burn increased P, whereas the dormant annual burn decreased pH in the lower mineral soil. Trends in short- and long-term effect sizes appeared to differ by season of burning and further magnified by increased fire frequency within season. Relative to dormant season burns, summer burns resulted in immediate and long-lasting desirable effects for red pine ecosystems (e.g., decreased forest floor depths and nutrient stocks) without persistent undesirable effects (e.g., increased nutrient stocks or changes in cation exchange capacity, soil texture, and bulk density) in the mineral soil. Our results suggest that summer burns may be a valuable approach to increase the variability in burn schedules representative of historical regional fire regimes in red pine forests, and may help promote soil characteristics that support overall ecosystem health.

Influence of physico-chemical properties of soil clay fractions on the retention of dissolved organic carbon.

This study investigated the effects of surface functional groups, cation exchange capacity (CEC), surface charge, sesquioxides and specific surface area (SSA) of three soil clay fractions (SCFs) (kaolinite-illite, smectite and allophane) on the retention of dissolved organic carbon (DOC) in soils. Physico-chemical properties of the SCFs before and after removing native carbon and/or sesquioxides were characterised, and the DOC adsorption-desorption tests were conducted by a batch method. Native organic carbon (OC)/sesquioxide removal treatments led to a small change in the CEC values of kaolinite-illite, but significant changes in those of smectite and allophane. The net negative surface charge increased in all samples with an increase in pH indicating their variable charge characteristics. The removal of native OC resulted in a slight increase in the net positive charge on soil clay surfaces, while sesquioxide removal increased the negative charge. Changes in the functional groups on the SCF surfaces contributed to the changes in CEC and zeta potential values. There was a strong relationship (R 2=0.93, p<0.05) between the Langmuir maximum DOC adsorption capacity (Q max) and SSA. The Q max value also showed a moderately strong relationship (R 2=0.55, p<0.05) with zeta potential (at pH 7). Q max was only poorly correlated with CEC and native OC content. Therefore, along with SSA, the surface charge and functional groups of SCFs played the key role in determining the adsorption affinity and hence retention of DOC in soils.

Response of Vertisols, Andosols, and Alisols to paddy management

Interchanging submergence and drainage in paddy soils induce alternating redox conditions. It is known that this causes changes in organic carbon stocks, in amounts and crystallinity of Fe oxides as well as transformation of clay minerals and subsequent changes in cation exchange capacity (CEC). However, the influence of the initial soil type on the extent of these changes is not yet well understood. Therefore, we studied paddy soils that derived from three different soil types (Vertisols, Andosols, Alisols) on volcanic parent material in Java (Indonesia). To account for the variability in parent materials, we additionally sampled sandstone-derived Alisols in China. Adjacent non-paddy soils were sampled as references. Samples were analyzed for texture, bulk density, clay mineral composition, total element content, pH, CEC, phosphorus retention, organic carbon (OC), and acid oxalate- (Feox) and dithionite–citrate–bicarbonate-extractable Fe (FeDCB).Only the Alisol-derived paddy soil in China showed textural changes, compared to the non-paddy soil. Evidence for paddy management induced ferrolysis was not found. The smaller topsoil clay content in the paddy soil is most probable caused by clay migration. Only minor differences in clay minerals were found; topsoils of Andosol-derived paddy soils, however, tend to be less desilicated, indicating phytolith accumulation. Except for Vertisols, paddy management caused significant depletion in Fe oxides in the topsoils (puddled layer and plow pan) due to redox processes. The extent to which the reduced Fe was leached or re-oxidized as short range-ordered Fe oxides depended on the soil texture. Andosols and sandy Alisols facilitated leaching, clayey Alisols re-oxidation. In either case, the stocks of crystalline Fe oxides diminished, causing increased proportions of short range-ordered Fe oxides. Retention of phosphorus was directly related to changes in the absolute amounts of short range-ordered Fe oxides. An accumulation of Fe oxides in paddy subsoils was not found. Lateral transport with drainage water might be a reason. In highly permeable soils with large vertical water fluxes (e.g., Andosols under paddy management), colloidal transport might also play a role. Despite losses in potential OC storage capacity (i.e., Fe oxides, clay minerals, allophane), paddy soils derived from Andosols and sandy Alisols in China had larger OC concentrations in the puddled topsoil, whereby the other soils showed no increase in OC under paddy management. Therefore, paddy management does not necessarily enhance carbon sequestration. Rather, differences in organic matter input between non-paddy and paddy soils seem to determine whether OC is accumulated under paddy management or not. Effects of paddy management on CEC were little and mainly due to OC accumulation and Fe oxide coating removal from clay minerals.Overall, paddy management-induced changes were partly influenced by the original soil and the parent material. In turn, the main characteristics of the initial soil type were preserved and not overridden by paddy management.

Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production

Biochar is suggested for soil amelioration and carbon sequestration, based on its assumed role as the key factor for the long-term fertility of Terra preta soils. Several studies have shown that certain biochar properties can undergo changes through ageing processes, especially regarding charge characteristics. However, only a few studies determined the changes of different biochars under the same incubation conditions and in different soils. The objective of this study was to characterize the changes of pine chip (PC)- and corn digestate (CD)-derived biochars pyrolyzed at 400 or 600°C during 100days of laboratory incubation in a historical kiln soil and an adjacent control soil. Separation between soil and biochar was ensured by using mesh bags. Especially, changes in charge characteristics depended on initial biochar properties affected by feedstock and pyrolysis temperature and on soil properties affected by historic charcoal production. While the cation exchange capacity (CEC) markedly increased for both CD biochars during incubation, PC biochars showed no or only slight increases in CEC. Corresponding to the changes in CEC, ageing of biochars also increased the amount of acid functional groups with increases being in average about 2-fold higher in CD biochars than in PC biochars. Further and in contrast to other studies, the surface areas of biochars increased during ageing.Changes in CEC and surface acidity of CD biochar were more pronounced after incubation in the control soil, while surface area increase was higher in the kiln soil. Since the two acidic forest soils used in this study did not greatly differ in physical or chemical properties, the main process for inducing these differences in the buried biochar most likely is related to the differences in dissolved organic carbon (DOC). Although the kiln soil contained about 50% more soil organic carbon due to the presence of charcoal particles, extractable DOC was lower and less aromatic than in the adjacent control soil, likely due to strong sorption of dissolved organic matter (DOM) onto charcoal particles. We suggest that higher sorption of DOM onto the surface of biochar in the control soil provided additional acid functional groups and thus increased the surface charge to a greater extent than in the DOC poorer kiln soil. Hence, biochars incubated in the kiln soil showed less changes in CEC and surface acidity. Higher availability of DOM in the control soil could also stimulate microbial activity to a larger extent, resulting in higher oxidation rates of biochars incubated in the control soil.

Influence of Pine Bark Particle Size and pH on Cation Exchange Capacity

Cation exchange capacity (CEC) describes the maximum quantity of cations a soil or substrate can hold while being exchangeable with the soil solution. Although CEC has been studied for peatmoss-based substrates, relatively little work has documented factors that affect CEC of pine bark substrates. The objective of this research was to determine the variability of CEC in different batches of pine bark and determine the influence of particle size, substrate pH, and peat amendment on pine bark CEC. Four batches of nursery-grade pine bark were collected from two nurseries, and a single source of sphagnum moss was obtained, separated in to several particle size classes, and measured for CEC. Pine bark was also amended with varying rates of elemental sulfur and dolomitic limestone to generate varying levels of substrate pH. The CEC varied with pine bark batch. Part of this variation is attributed to differences in particle size of the bark batches. Pine bark and peatmoss CEC increased with decreasing particle size, although the change in CEC from coarse to fine particles was greater with pine bark than peatmoss. Substrate pH from 4.02 to 6.37 had no effect on pine bark CEC. The pine bark batch with the highest CEC had similar CEC to sphagnum peat. Amending this batch of pine bark with sphagnum peat had no effect on composite CEC.

The mechanochemical activation study of Tsagaan-tsav zeolite

Characterisation of mechanochemically activated Tsagaan-tsav zeolite has been performed. Tsagaan-tsav zeolite has been activated with a vibration mill for 2, 3, 5, 10 and 20 minutes. Ball to powder ratios were varied 1:10, 1:20, 1:50 and 1:100. Efficiency of milling determined based on amorphisation rate and cation exchange capacity changes. The highest efficiency was obtained for zeolite milled with ball to powder ratio of 100. Structural characterisation was performed with XRD, SEM, BET and particle size analyzer. Mechanochemical activation improves cation exchange capacity of natural zeolite.DOI: http://dx.doi.org/10.5564/mjc.v12i0.181 Mongolian Journal of Chemistry Vol.12 2011: 98-101

Nutrient removal capacity of wood residues for the Agro-environmental safety of ground and surface waters

Abstract The aim of this study was to determine the effectiveness of wood residues in the removal of nutrients (ammonium-N; NH4-N) from nutrient-rich (NH4-N) waters. The water holding capacity of the wood materials was also determined. Carried out at Rothamsted Research, North Wyke, UK, this controlled laboratory experiment tested two wood residues; in length, one being 1-2cm and the other from 150 µm (microns) to 9.5mm. Although a wide range of studies have shown the effectiveness and performance of various absorbent materials as animal beddings, such as straw (cereal straw), woodchip (sawdust, bark or wood shavings), bracken and rushes, only few have focused on the NH4-N sorption/desorption capacity. The depuration capacity of wood residues from nutrient-rich effluents such as those from cattle bedded on woodchip or straw will be controlled by processes such as sorption (adsorption-absorption) and desorption of nutrients. Studies have reported the nitrogen removal capacity of woodchip materials and biochar from woodchip as well as removal of NH4+-N from domestic and municipal wastewater, farm dirty water, landfill and industry effluents. These studies have observed that the mechanism of removal of nitrogen is by either increasing NO3--N removal form leachate by enhancing N2O losses via denitrification (biochar as carbon source for denitrifiers) or by decreasing NH4+-N in leachate through adsorption to negatively charged sites. Results showed that although the cation exchange capacity (CEC) and surface area (SA) are both fundamental properties of adsorbent materials, no correlation was found with CEC and adsorption or desorption. Nor did changes in pH appear to be sufficiently important to cause changes in CEC. For this reason, osmotic pressure appeared to be a more predominant parameter controlling processes of adsorption and desorption of NH4+-N in both wood residues. Thus, wood residues high in NH4+-N should be avoided, as they could have an opposite effect in the adsorption of nutrients from nutrient-rich effluents. The results also showed that some wood residues (G30) had great capacity to adsorb NH4+-N to levels up to nearly 90% whilst demonstrating low desorption capacity of NH4+-N (less than 1%). These are ideal relevant features for an adsorbent material for the removal of nutrients (or heavy metals) from contaminated waters such us farm o industrial effluents, or for the depuration of eutrophic watercourses. This could help reduce the concentration of farm effluents making them more manageable, subsequently contributing towards the compliance of new environmental regulations. Keywords: nutrients, nitrogen, ground and surface water

The Long-Term Effect of Slowly Dissolved Crushed Basic Rocks Amelioration on Metals Bioavailability in Soil

Concentrations and bioavailability of Al, Fe, Cd, Pb, Cu, Zn, and Mn in mountain forest soil replanted with speckled alder (Alnus incana (L.) Moench) are explored 7 years after soil surface vs. planting hole application of amphibolite and dolomitic limestone mixture. The mechanisms of slow limestone dissolution are explained and discussed from broader systematic view. The aspects of soil pH and oxidable carbon and the cation exchange capacity changes as well as changes of water-soluble, total, and effective concentrations of tested elements in the amended soils are included. The soil amendment invoked the depletion of K (and slightly Zn) effective concentration. The total concentrations of Ca, Mn, Al, and partly Mg in soil were increased owing to the presence of these elements in the amendment; the water-soluble concentrations nor effective concentrations of Al, Mn, Zn, Cu, Cd, and Pb were increased. Moreover, the effective concentration of Al in both amended variants decreased. The usual negative side effects of liming were not observed due to the slow dissolution of the amendment. Further, the surface application of the amendment is cheaper than the planting hole application, but there are some expected losses of the amendment by concurrent uptake by grass and by flushing.

A study of the chemical, mineralogical and physicochemical properties of peloids prepared with two medicinal mineral waters from Lanjarón Spa (Granada, Spain)

We studied the interstitial liquid phase (Liqint), the crystallinity of solid phase minerals (kaolinite and saponite), the cation exchange capacity (CEC) and the exchangeable bases of peloids prepared with two medicinal mineral waters (MMWs) from the springs of Lanjarón Spa (Granada, Spain). The waters employed were: “Salud V” (chloride-, sodium- and calcium-rich, bicarbonated, previously unpublished) and “El Salado” (chloride- and sodium rich, bicarbonate, calcic and ferruginous). The solid phase was a mixture of kaolin and bentonite (9:1, w:w) and maturation times of the peloids were 1, 3 and 6months.The physicochemical properties of the Liqint of the peloid differed from those of the MMW: pH increased (from 6 to 8, approximately), Fe content decreased dramatically (from 12 to 0.03mgl−1), while potassium and bicarbonates also decreased and concentrations of other ions such as carbonates, sodium, chlorides and, especially, sulphates, increased. The effect of maturation time on Liqint properties depended on the MMW employed.Kaolinite crystallinity in the peloid decreased during maturation (Hinckley Index from 0.71 to 0.52), reaching similar values in the peloids from both MMWs after 6months. On the other hand, the crystal perfection of saponite increased, revealing the existence of a process of crystallochemical aggradation towards mica due to the presence of exchangeable ions in Liqint, particularly potassium.There was a change in CEC and the exchangeable bases from the initial mineral material to the solid phase of the peloid. In the initial material the base sequence was Na+>K+~Mg2+>Ca2+ while in the mineral phase of most of the peloids it was Ca2+>Na+>Mg2+>K+. The relationship between the exchangeable bases and the Liqint was demonstrated.We demonstrate that the peloid controls and modifies the properties of the starting materials: MMW and minerals. Therefore a new system of liqint - exchangeable phase - mineral phase interrelationships appears.

Ecological impacts of the N-viro biosolids land-application for wild blueberry (Vaccinium angustifolium. Ait) production in Nova Scotia

Land application of biosolids from processed sewage sludge may deteriorate soil, water, and plants. We investigated the impact of the N-Viro biosolids land-application on the quality of the soil water that moved through Orthic Humo-Ferric Podzols soil of Nova Scotia (NS) at the Wild Blueberry Research Institute, Debert, NS Canada. In addition, the response of major soilproperties and crop yield was also studied. Wild blueberry (Vaccinium angustifolium. Ait) was grown under irrigated and rainfed conditions in 2008 and 2009. Four experimental treatments including (i) NI: N-Viro irrigated, (ii) NR: N-Viro rainfed, (iii) FI: inorganic fertilizer irrigated, and (iv) FR: inorganic fertilizer rainfed (control) were replicated 4 times under randomized complete block design. Soil samples were collected at the end of each year and analyzed for changes in cation exchange capacity (CEC), soil organic matter (SOM), and pH.Soil water samples were collected four times during the study period from the suction cup lysimeters installed within and below crop root zone at 20 and 40 cm depths, respectively. The samples were analyzed for a range of water quality parameters including conductance, hardness, pH, macro- and micronutrients, and the infectious pathogens Escherichia coli (E. coli) and salmonella. Berries were harvested for fruit yield estimates. Irrigation significantly increased CEC during 2008 and the soil pH decreased from 4.93 (2008) to 4.79 (2009). There were significant influences of irrigation, fertilizer, and their interaction, in some cases, on most of the soil water quality parameters except on the infectious bacteria. No presence of E. coli or salmonella were observed in soil and water samples, reflecting the absence of these bacteria in biosolids used in this experiment. Nutrient concentration in the soil water samples collected from the four treatments were higher in the sequence NI > NR > FI > FR. The irrigation treatment had significant effect on the unripe fruit yield. We conclude that the comparable performance of N-Viro biosolids and the increasing prices of inorganic fertilizers would compel farmers to use economically available N-Viro biosolids that, coupled with the supplemental irrigation, did not deteriorate the studied soil properties, soil water quality, and the wild blueberry yield during this experiment.