Low Buffering Capacity Research Articles

Assessment of lake sensitivity to acidic deposition in national parks of the Rocky Mountains

The sensitivity of high-elevation lakes to acidic deposition was evaluated in five national parks of the Rocky Mountains based on statistical relations between lake acid-neutralizing capacity concentrations and basin characteristics. Acid-neutralizing capacity (ANC) of 151 lakes sampled during synoptic surveys and basin-characteristic information derived from geographic information system (GIS) data sets were used to calibrate the statistical models. The explanatory basin variables that were considered included topographic parameters, bedrock type, and vegetation type. A logistic regression model was developed, and modeling results were cross-validated through lake sampling during fall 2004 at 58 lakes. The model was applied to lake basins greater than 1 ha in area in Glacier National Park (n = 244 lakes), Grand Teton National Park (n = 106 lakes), Great Sand Dunes National Park and Preserve (n = 11 lakes), Rocky Mountain National Park (n = 114 lakes), and Yellowstone National Park (n = 294 lakes). Lakes that had a high probability of having an ANC concentration <100 microeq/L, and therefore sensitive to acidic deposition, are located in basins with elevations >3000 m, with <30% of the catchment having northeast aspect and with >80% of the catchment bedrock having low buffering capacity. The modeling results indicate that the most sensitive lakes are located in Rocky Mountain National Park and Grand Teton National Park. This technique for evaluating the lake sensitivity to acidic deposition is useful for designing long-term monitoring plans and is potentially transferable to other remote mountain areas of the United States and the world.

Fermentation characteristics and transit tolerance of probiotic Lactobacillus casei Zhang in soymilk and bovine milk during storage

Lactobacillus casei Zhang is a novel strain that was screened out of koumiss collected in Inner Mongolia, and our previous research showed that L. casei Zhang has health benefits such as cholesterol-reducing and immunomodulating effects. The fermentation characteristics of L. casei Zhang in soymilk and bovine milk and the transit tolerance of L. casei Zhang in fermented milk products during refrigerated storage for 28 d were assessed. A faster decrease in pH and faster growth of L. casei Zhang during fermentation were observed in soymilk compared with bovine milk at various inoculation rates, probably because of the low pH buffering capacity of soymilk. The fermented bovine milk samples had much higher final titratable acidity (TA) values (between 0.80 and 0.93%) than the soymilk samples (between 0.40 and 0.46%). Dramatic increases in TA values in the fermented soymilk samples during storage were observed, and the TA values of the fermented soymilk samples changed from <0.56% to values between 0.86 and 0.98%. On the other hand, only slight increases in TA were observed in the bovine milk samples during the 28 d of storage. The survival rates of freshly prepared cultures of L. casei Zhang in simulated gastric juice at pH 2.0 and 2.5 were 31 and 69%, respectively, and the delivery of L. casei Zhang through fermented soymilk and bovine milk significantly improved the viability of L. casei Zhang in simulated gastric transit. Lactobacillus casei Zhang showed good tolerance to simulated gastric juice and intestinal juice in the fermented soymilk and bovine milk samples, and maintained high viability (>108 cfu/g) during storage at 4°C for 28 d. Our results indicated that both soymilk and bovine milk could serve as vehicles for delivery of probiotic L. casei Zhang, and further research is needed to elucidate the mechanism of the change in pH and TA of L. casei Zhang in fermented milk samples during fermentation and storage and to understand the difference between soy- and milk-based systems.

In situ dry matter degradability coefficients of whole crop barley silage treated with Lactobacillus plantarum or mixed with Pediococcus pentosaceus plus Propionbacter freudenreichii

Microbial inoculants are applied to forage at the time of ensiling to accelerate the decline of pH during the initial stage of silage fermentation, to preserve plant carbohydrates through homofermentation, and to preserve plant protein by decreasing proteolysis and deamination. Thus, inoculated silages are expected to improve animal performance. Whole crop barley has a low buffering capacity and abundant fermentable carbohydrates and is considered relatively easy to ensile. Results of previous experiments indicated that lactic acid bacteria-based inoculants have the potential to improve the ensilage of whole crop barley (Kung and Ranjit, 2001). The objective of the present study was to determine the chemical composition and in situ dry matter degradability of whole crop barley silage treated with one of two different types of inoculants (Lactobacillus plantarum or mixed with Pediococcus pentosaceus plus propionbacter freudenreichii as provide 1×105 CFU of lactic acid producing bacteria plus 1×104 CFU propionbacterium per g of DM).

The Influence of Fertilization on Greenhouse Tomatoes Cultivated in Peat Bags System

Important factors to be considered for growing tomatoes in order to obtain high and safety yield are variety, system of culture and fertilization. To establish how the fertilization managing can influence both yield and quality of greenhouse tomatoes grown on peat bags system, different doses and types of fertilization (basic and additional) were studied in this experiment. Two Dutch cultivars (Cronos F1 and Menhir F1) with high yield potential were used. Cronos F1 recorded the best early yield (5.87 kg·m -2 ) and Menhir F1 the best total yield (13.06 kg·m -2 ). Foliar fertilization, done with a high K ratio fertilizer (10:5:26), once weekly applied, determined distinct significant efficiencies of early yield and significant efficiencies of total yield. Vitamin C, acidity and total sugar content in the fruit increase with foliar fertilization. None of the nitrate or nitrite values over passed the accepted limits of permission for greenhouse tomatoes. Greenhouse tomatoes grown on peat bags system allows to increase early and total yield in comparison with conventional crop in soil. Because bags contain only a small volume of growth medium, they offer much lower water holding capacity and much lower buffering capacity than most soils regarding both major and minor elements. Therefore it is necessary to monitor continually the nutrient availability in the substrate and to adjust accordingly the composition of feed applied to it. The quantity of nutrients which should be applied also depends on the yield potential of the cultivar and growth conditions. Tomatoes need a continuous and steady supply of nutrients through additional fertilization throughout their life cycle because their vegetative and reproductive stages overlap. Since many experiments have not revealed real differences between the product quality of vegetables grown in soil or hydroponically (Schnitzler and Gruda, 2003) soilless culture in greenhouse may be an alternative to soil culture for high-value vegetable crops including tomatoes. Better tomato fruit quality can be obtained by fertilization measures such as an increase in the concentration of the nutrient solution, or a reduction of nitrate application rates. It is also necessary to adopt appropriate nutrient management practices (use of slow- release fertilizers, split applications, combining of radicular and foliar fertilization) which help to supply nutrients in adequate quantities to just meet crop demand and minimize losses, thus increasing the nutrient use efficiency. The objective of the present study was to evaluate two greenhouse tomato hybrids grown in bags on organic substrate (mostly composed from brown peat) in order to establish how fertilization managing can influence yield and chemical properties of fruit.

Ionic deposition and chemistry of soil solutions in a forested study area in the Chojnów Forest District in the years 2004-2007

The study was carried out in the years 2004-2007 in a permanent observation plot established in a pine tree stand growing in a mixed fresh coniferous forest habitat of the Chojnow Forest District. Analyses pertained to the deposition of mineral compounds delivered to soil with bulk precipitation in the open field and throughfall and to chemical compositions of soil solution at a depth of 25 cm and 50 cm. pH, electrical conductivity and concentrations of Ca, Mg, Cl, NO₃, SO₄, Na, K, Fe, Mn, NH₄, PO₄, Zn, Cd, Cu, and Pb were analysed in precipitation and in soil solution samples.Total load of ions under the canopy of pine trees ranged between 47 and 61 kg·ha⁻¹·year⁻¹. Acidifying ions (N + S + Cl) contributed in 51% to the total ionic load (in molc·ha⁻¹·year⁻¹) while base ions (Ca + Mg + Na + K) in only 36%. Respective percentage contribution in bulk precipitation was 69% and 19%.No relationship was found between the chemical composition of soil solutions (at both depths) and the chemical composition of precipitation waters. Analysed soil solutions were acidic (average pH at the depth of 25 cm and 50 cm was 4.3 and 4.4, respectively) and the molar ratio of the sum of base cations (Ca, Mg, and K) to Al in the majority of examined samples from the upper soil layer, was much lower than 1. This is the evidence of low buffering capacities of analysed soil in relation to acidifying loads and indicates a potential threat for the pine stand stability.

Effect of different agricultural management systems on chemical fertility in cultivated tepetates of the Mexican transvolcanic belt

Volcanic soils in their natural state often require some amelioration to accommodate their use for agriculture. Tepetates are defined as hardened volcanic tuffs derived from geo-pedological processes; they have been partially altered by weathering. Tepetates occupy extensive areas of Mexico's Central Highlands and some of them have been adapted for agricultural use after the mechanical breaking up of this hard material. In their native condition tepetates contain only traces of C, N and available P. So, after their incorporation into agriculture production, the addition of fertilisers becomes necessary to improve soil fertility. In the present work changes in certain chemical and physico-chemical soil properties of cultivated tepetates were studied in the short-term (2002–2005) and medium-term (1986–2005) scales. Experimental plots situated in Tlalpan (State of Tlaxcala) were subjected to the following agricultural management systems: Traditional (Tt), Improved (Ti) and Organic (To). In the short term (4 years), the To management system, in which organic residues and manures were added, led to a decrease in the acidification tendency after cultivation, a recovery of initial exchangeable K + levels, and an increase in soil organic C (SOC), total nitrogen (Nt) and available P (Pa) contents in the Ap horizon. The Ti management, in which crop residues and more chemical fertilisers were added, was especially efficient in increasing the concentration of available P. After 20 years of traditional cultivation, the tepetates showed a decrease in soil pH and exchangeable Mg 2+ and K + values, leading to a decline of the base saturation. These results point to the fragility and low buffer capacity of these systems. In contrast, a tendency of SOC, Nt and Pa accumulation was observed after 20 years of cultivation, influenced by the agricultural management system applied. Tepetates adapted for agricultural use evolved into more fertile substrates over the years of cultivation.

Agroecosystem functioning on different types of soil contaminated with fluorides from aluminum production

The nitrogen cycles and functioning of agroecosystems planted with spring wheat were investigated on different types of soil contaminated with fluorides from aluminum production. The imbalance between the nitrogen fluxes directed toward the external and internal soil cycles was found to be higher in gray forest soil agroecosystems with low buffering capacity to fluoride pollution than in soddy-meadow soil. The stable functioning of agroecosystems on soddy-meadow soil (stress regime) is maintained by intense nitrogen recirculation.

Influence of hydrogeology, microbiology and landscape history on the geochemistry of acid hypersaline waters, N.W. Victoria

Abstract There is now evidence that naturally occurring acid–water is more abundant than previously thought and that it has been important in the geologic past. Understanding the processes leading to the formation of such systems is required to appreciate the role of acid systems in geologic processes and to develop indicators for recognizing the geologic/environmental importance of these systems in the past. This paper characterizes the hydrogeology, hydrogeochemistry, microbial biogeochemistry and landscape attributes of acid–groundwater surface water systems in Australia with an emphasis on a well studied playa-lake system, Lake Tyrrell, Murray Valley. A model for the origin of these acid brines is presented and the importance of acid-brine producing systems is speculated upon. Data include porewater and groundwater geochemical measurements (collected during a 10 day field campaign) and results from geochemical modeling and graphics (e.g., Piper diagrams and x–y plots of seawater evaporation trajectories). Key characteristics of the system are (1) aquifer materials have low acid buffering capacities, (2) saline groundwater flowing onto playa surfaces is an oxic, H2SO4 solution, (3) authigenic minerals include combinations of jarosite [KFe3(SO4)2(OH)6], alunite [KAl3(SO4)2(OH)6] and Fe oxides that can form as evaporite minerals, (4) a source for solutes can be marine aerosols and (5) the formation of ironstones. Groundwater acidification by various processes including sulfide oxidation and ferrolysis, and at many different times, are the unique aspects for evolution of these acid brines and they can be considered another end member of the Eugster–Jones–Hardie model for the evolution of brines in closed basins. Acid–hypersaline groundwater and playa systems such as Lake Tyrrell may be an example of expected changes in the hydrogeochemistry of terrestrial water during late-stage continental denudation under arid conditions. Historically these systems may have been integral to the formation of opal, bauxite, some low temperature ore deposits, of authigenic K-feldspars, and continental redbeds. Natural acid saline systems, such as those in Australia, may also be representative of acid saline systems on Mars.

Abbau von UF-Harzen beim TMP- und CTMP-Aufschluss von mitteldichten Faserplatten (MDF)

Thermo-mechanical (TMP) and chemo-thermo-mechanical pulping (CTMP) of UF-bonded MDF induce considerable degradation of the UF-resin in the board and lead to a conspicuous increase in the content of water extractives of the fibres. Moreover, the water extractives of the fibres have a higher pH-value and a lower buffering capacity as well as higher acetate and formate ions content than the extractives of the original board. However, the lignin content seems rather to increase than to decrease. This is possibly due to reaction between lignin and formaldehyde from the resin.

Application of a fuzzy logic control system for continuous anaerobic digestion of low buffered, acidic energy crops as mono‐substrate

A fuzzy logic control (FLC) system was developed at the Hamburg University of Applied Sciences (HAW Hamburg) for operation of biogas reactors running on energy crops. Three commercially available measuring parameters, namely pH, the methane (CH4) content, and the specific gas production rate (spec. GPR = m(3)/kg VS/day) were included. The objective was to avoid stabilization of pH with use of buffering supplements, like lime or manure. The developed FLC system can cover most of all applications, such as a careful start-up process and a gentle recovery strategy after a severe reactor failure, also enabling a process with a high organic loading rate (OLR) and a low hydraulic retention time (HRT), that is, a high throughput anaerobic digestion process with a stable pH and CH4 content. A precondition for a high load process was the concept of interval feeding, for example, with 8 h of interval. The FLC system was proved to be reliable during the long term fermentation studies over 3 years in one-stage, completely stirred tank reactors (CSTR) with acidic beet silage as mono-input (pH 3.3-3.4). During fermentation of the fodder beet silage (FBS), a stable HRT of 6.0 days with an OLR of up to 15 kg VS/m(3)/day and a volumetric GPR of 9 m(3)/m(3)/day could be reached. The FLC enabled an automatic recovery of the digester after two induced severe reactor failures. In another attempt to prove the feasibility of the FLC, substrate FBS was changed to sugar beet silage (SBS), which had a substantially lower buffering capacity than that of the FBS. With SBS, the FLC accomplished a stable fermentation at a pH level between 6.5 and 6.6, and a volatile fatty acid level (VFA) below 500 mg/L, but the FLC had to interact and to change the substrate dosage permanently. In a further experiment, the reactor temperature was increased from 41 to 50 degrees C. Concomitantly, the specific GPR, pH and CH4 dropped down. Finally, the FLC automatically enabled a complete recovery in 16 days.

The effect of nickel-contamination, nitrogen-supply and liming on the chemical composition of perennial ryegrass (Lolium perenne L.)

Plant-production is determined by many production-factors. Each of these factors became subject of research-works through the years, still we state, that studying their interaction is even more important. For studying these interactions we set up a potexperiment, within that the direct effect and the interactions of four factors was inspected: soil, nitrogen-supply, nickel-loading and liming. Experiments were carried out on two soil types with extremely different characters: one was a chernozem soil with good fertility and buffering capacity, the other was a shifting sand soil with low humus-content and buffering capacity. Nitrogensupply and liming was added on two levels, while nickel on three within 12 combinations on each soil types. Plant production was cut two times within the vegetation period. The amount of production and dry matter was weighted, fractured and their element-content was measured by an ICP-detector.Ca-content on the shifting sand soil was determined by all three factors, however the interaction between nickel-loading and liming was also significant. Nitrogen and liming increased Cauptake, that is due to appropriate nutrient-supply and improvement of a better pH-value. On the chernozem soil nitrogen and CaCO3 also increased the Ca-content. This is caused by a better nutrient supply and a higher amount of available Ca-ions.On the shifting sand soil nickel content was increasing parallel to higher nitrogen-dosages. In presence of higher nickelamount the nickel-content of plants was also increasing, still according to liming, this increment was different. On the chernozem soil nitrogen a nickel increased Ni-uptake. However, liming also had a positive effect on Ni-content, that can be explained by the high amount on colloids in the soil, the adsorption of Ni-ions on them and in presence of liming material the replacement of Ca-and Ni-ions. The potassium-content on the shifting sand soil was different in each liming-combination. In combinations without nickel the potassium-content of limed and not limed combinations was on the same level. In not limed combinations by adding nickel potassiumcontent was increasing, while in limed combinations no change was observed. On the chernozem soil by adding liming material the amount of uptaken potassium was decreasing, that is due to the antagonism between Ca- and K-ions.

Root surface and coronal caries in adults with type 2 diabetes mellitus

– Objectives: To determine the effect of type 2 diabetes mellitus (DM) on coronal and root surface caries and to investigate some factors suspected of being related to or interacting with DM, that may be associated with coronal and root surface caries. Methods: A stratified cross-sectional study was conducted in 105 type 2 diabetic patients and 103 non-diabetic subjects of the same age and gender. Coronal and root surface caries, exposed root surfaces, periodontal status, stimulated salivary functions, oral hygiene status, oral health behaviors, and counts of mutans streptococci and lactobacilli were measured. Results: Type 2 diabetic patients compared with non-diabetic subjects had a higher prevalence of root surface caries (40.0% versus 18.5%; P = 0.001), a higher number of decayed/filled root surfaces (1.2 ± 0.2 versus 0.5 ± 0.1; P < 0.01) and a higher percentage of generalized periodontitis (98.1% versus 87.4%; P < 0.01); but the prevalence and decayed/filled surface of coronal caries was not significantly different (83.8% versus 72.8% and 8.0 ± 9.4 versus 6.3 ± 7.5 respectively). The factors associated with root surface caries included type 2 DM, a low saliva buffer capacity, more missing teeth, and existing coronal caries; whereas wearing removable dentures, more missing teeth, a high number of lactobacilli, and a low saliva buffer capacity were associated with coronal caries. Conclusion: Type 2 DM is a significant risk factor for root surface, but not for coronal caries. Periodontal disease should be treated early in type 2 diabetic subjects to reduce the risk of subsequent root surface caries.

The effect of moisture content and alkalinity on the anaerobic biodegradation of pit latrine sludge

This study investigated the effect of additional moisture and/or alkalinity on the rate of anaerobic digestion in samples of material obtained from pit latrines. In modified serum bottle tests it was shown that poor gas production rates were observed from all experiments with material collected at the lower part of one pit. Using material from the top layer of a second pit it was shown that experimental bottles produced significant amounts of gas for all treatments. Analysis of data indicated that treatment with additional alkalinity had no discernible effect on anaerobic gas production rates, but that there was some correlation between moisture content and gas production rate. These results did not support the hypothesis that low pH buffering capacity was a limiting factor in the rate of digestion of pit latrine sludge, but confirmed that low moisture content could reduce the rate of stabilisation. This implies that increasing the moisture content in a pit latrine has the potential to increase biological stabilisation rates in the pit when the material is not already well-stabilised.

Evaluating of phosphorus quantity/intensity parameters in soil with different systems of organic fertilizing

One of the refinement methods for estimating the parameters of phosphorus dynamics in soil is the construction of sorption isotherms in dependence on changes of exchangeable sorbed phosphorus in soil (&amp;Delta;Q) and changes of phosphorus amount in soil solution (&amp;Delta;I). Regression analysis allows to calculate equilibrium concentration (&lt;I&gt;c&lt;/I&gt;&lt;sub&gt;equ&lt;/sub&gt;) and phosphorus buffering capacity (BC). The mentioned analyses were realised on soils from the long-term field experiments of the Czech University of Life Sciences (CULS) in Prague and Crop Research Institute (CRI) in Ruzyně, Czech Republic. The influence of different organic fertilisers compared to the control (not amended) treatment was tested. For the evaluating of parameters, the root and logarithmic functions were used. The lowest &lt;I&gt;c&lt;/I&gt;&lt;sub&gt;equ&lt;/sub&gt; of the logarithmic function was always found on not amended treatment. Low amounts were found in the treatments amended with barley straw as well. The highest amounts were found in soil after potatoes cropping fertilised with farmyard manure (FYM). In the FYM variant fertilised with 70 kg P/ha, the &lt;I&gt;c&lt;/I&gt;&lt;sub&gt;equ&lt;/sub&gt; value reached 0.45 mg P/l. Both treatments fertilised with sewage sludge (720 kg P/ha and 240 kg P/ha) showed similar values of about 0.25 mg P/l. A different trend was found for the phosphorus buffering capacity (BC); this was the highest at the control treatment and at the treatment fertilised with straw. The lowest BC was observed in both soils after potatoes fertilised with FYM, where it reached 61 mg P/kg and 65 mg P/kg, respectively. Similar trends were found when evaluating root function.

Differential dendritic Ca2+ signalling in young and mature hippocampal granule cells

Neuronal activity is critically important for development and plasticity of dendrites, axons and synaptic connections. Although Ca(2+) is an important signal molecule for these processes, not much is known about the regulation of the dendritic Ca(2+) concentration in developing neurons. Here we used confocal Ca(2+) imaging to investigate dendritic Ca(2+) signalling in young and mature hippocampal granule cells, identified by the expression of the immature neuronal marker polysialated neural cell adhesion molecule (PSA-NCAM). Using the Ca(2+)-sensitive fluorescent dye OGB-5N, we found that both young and mature granule cells showed large action-potential evoked dendritic Ca(2+) transients with similar amplitude of approximately 200 nm, indicating active backpropagation of action potentials. However, the decay of the dendritic Ca(2+) concentration back to baseline values was substantially different with a decay time constant of 550 ms in young versus 130 ms in mature cells, leading to a more efficient temporal summation of Ca(2+) signals during theta-frequency stimulation in the young neurons. Comparison of the peak Ca(2+) concentration and the decay measured with different Ca(2+) indicators (OGB-5N, OGB-1) in the two populations of neurons revealed that the young cells had an approximately 3 times smaller endogenous Ca(2+)-binding ratio ( approximately 75 versus approximately 220) and an approximately 10 times slower Ca(2+) extrusion rate ( approximately 170 s(-1) versus approximately 1800 s(-1)). These data suggest that the large dendritic Ca(2+) signals due to low buffer capacity and slow extrusion rates in young granule cells may contribute to the activity-dependent growth and plasticity of dendrites and new synaptic connections. This will finally support differentiation and integration of young neurons into the hippocampal network.

Microbial Community Dynamics of a Continuous Mesophilic Anaerobic Biogas Digester Fed with Sugar Beet Silage

AbstractThe aim of the study was to investigate the long‐term fermentation of an extremely sour substrate without any addition of manure. In the future, the limitation of manure and therefore the anaerobic digestion of silage with a very low buffering capacity will be an increasing general bottleneck for energy production from renewable biomass. During the mesophilic anaerobic digestion of sugar beet silage (without top and leaves) as the sole substrate (without any addition of manure), which had an extreme low pH of around 3.3, the highest specific gas production rate (spec. GPR) of 0.72 L/g volatile solids (VS) d was achieved at a hydraulic retention time (HRT) of 25 days compared to an organic loading rate (OLR) of 3.97 g VS/L d at a pH of around 6.80. The methane (CH4) content of the digester ranged between 58 and 67 %, with an average of 63 %. The use of a new charge of substrate (a new harvest of the same substrate) with higher phosphate content improved the performance of the biogas digester significantly. The change of the substrate charge also seemed to affect the methanogenic population dynamics positively, thus improving the reactor performance. Using a new substrate charge, a further decrease in the HRT from 25 to 15 days did not influence the digester performance and did not seem to affect the structure of the methanogenic population significantly. However, a decrease in the HRT affected the size of the methanogenic population adversely. The lower spec. GPR of 0.54 L/g VS d attained on day 15 of the HRT could be attributed to a lower size of methanogenic population present in the anaerobic digester during this stage of the process. Furthermore, since sugar beet silage is a relatively poor substrate, in terms of the buffering capacity and the availability of nutrients, an external supply of buffering agents and nutrients is a prerequisite for a safe and stable digester operation.

100 000-Fold Concentration of Anions in Capillary Zone Electrophoresis Using Electroosmotic Flow Controlled Counterflow Isotachophoretic Stacking under Field Amplified Conditions

An electroosmotic flow (EOF) controlled counterflow isotachophoretic stacking boundary (cf-ITPSB) system under field amplified conditions has been examined as a way to improve the sensitivity of anions separated by capillary zone electrophoresis. The system comprised a high concentration of a high-mobility leading ion (100 mM chloride) and a low concentration of low-mobility terminating ion (1-3 mM MES or CHES) added to the sample in an unmodified fused-silica capillary at pH 8.05, buffered with Tris. Computer simulation studies using the software GENTRANS showed an increase in sensitivity of at least 10-fold over the previous cf-ITPSB system for simple inorganic ions, nitrite and nitrate. The simulations also suggested that the cf-ITPSB became stationary within the capillary and that its stationary position was not adversely affected by the concentration of MES. This was in contrast to experimental results that showed a slow and continual movement of the cf-ITPSB. This was more pronounced at lower concentrations of terminator (i.e., <3 mM) and resulted in a loss of resolution due to the cf-ITPSB being closer to the detector upon separation. This discrepancy was attributed to the change in pH across the capillary due to electrolysis and low buffering capacity in the sample, a phenomenon that cannot be simulated by the GENTRANS software. Replacement of MES with CHES as a lower mobility ion with increased buffer capacity failed to reduce the movement of the cf-ITPSB but did provide a further 3-fold improvement in sensitivity. The potential of this approach for sensitivity enhancement was demonstrated for the co-EOF separation of a mixture of six inorganic and small organic ions, with detection limits at the single-figure nanogram per liter level. These detection limits are 100,000 times better than can be achieved by normal hydrodynamic injection (ions prepared in water) and 250 times better than has been achieved by other online preconcentration approaches. The application of the EOF-controlled cf-ITPSB with counter-EOF separation of two pharmaceutical pollutants, naproxen and diflunisal, was also demonstrated with an improvement in sensitivity of 1000 giving detection limits of 350 ng/L in sewage treatment wastewater without any offline pretreatment.

Glasgow Lake: an early-warning sentinel of lake acidification in Cape Breton Highlands National Park (Nova Scotia, Canada)

In contrast to other lakes studied in Cape Breton Highlands National Park (Nova Scotia, Canada), our paleolimnological results indicated that Glasgow Lake has been impacted by acidic deposition starting in the early 1900s. Based on analysis of diatom assemblages, the lake experienced a decrease in diatom-inferred lakewater pH from a pre-industrial pH of ~5.8 to a current pH of 5.3 (2000–2002 measured mean pH = 5.0) as well as a decrease in diatom-inferred Gran-alkalinity. In this study, diatom-based paleolimnological techniques were used in conjunction with a dynamic biogeochemical model (MAGIC) to assess both the timing and extent of the acidification trend, as well as determine a probable explanation as to why this lake, and none of the other 15 Cape Breton Highlands lakes studied for paleolimnology thus far, acidified under a peak non-marine sulphate deposition load of 43.6 mmolc m−2 year−1 in the mid-1970s. Steady-state models estimate that Glasgow Lake had the lowest buffering capacity of six study lakes and estimated critical sulphate loading of <1 mmolc m−2 year−1. MAGIC also estimated a loss of charge balance alkalinity from a pre-1850 value of 38 μmolc l−1 to a low of 12 μmolc l−1. While no evidence of biological recovery has been recorded, MAGIC estimates an increase in charge balance alkalinity to 27 μmolc l−1 in 2002 in response to decreased SO2 emissions. Of the five other lakes that were modelled, all showed trends towards more acidic states and subsequent increases in charge balance alkalinity; however, the empirical paleo-diatom approach applied to these lakes showed no evidence of acidification. Thus, Glasgow Lake has the lowest buffering capacity among the Cape Breton Highland study lakes and serves as a sentinel of potential acidification trends and recovery in this region.

Recovery from groundwater extraction in a small catchment area with crystalline bedrock and thin soil cover in Sweden

An experiment has been in progress since 1997 in a small catchment area (28,000 m 2) with crystalline bedrock and thin soil cover to study the conceivable impact on groundwater conditions of tunneling and the use of groundwater. The impact on hydrology and hydrochemistry from intensive extraction of groundwater at a depth of 50 m in the bedrock has been studied at Lake Gårdsjön in Sweden. The catchment area was first monitored under pristine conditions, followed by four and a half years of extraction and then a recovery phase. The geological conditions result in a low buffer capacity and high sensitivity to acidification. During the period of extraction, the surface runoff decreased by approximately 50% compared to a nearby reference area. The groundwater extraction caused increased fluctuation in groundwater levels in a wetland, which in turn caused oxidation of reduced sulfur to sulfate. The sulfate concentrations increased almost 100-fold in some instances, causing a lowering of the pH by one unit in shallow groundwater. Since extraction of the groundwater was discontinued, the pH has gradually risen and the sulfate concentrations have decreased. However, the concentration of sulfate in groundwater in the wetland has remained stable at approximately double the pre-experiment levels. Magnesium concentrations were lower after the experiment, caused by exhaustion of the magnesium pool in the wetland through acidification. The extraction of water from the bedrock shortened the retention times and increased the recharge of groundwater in the bedrock. After extraction was terminated, the groundwater levels in the boreholes recovered within a month to levels similar to those before extraction. The hydrochemistry of the bedrock groundwater, which was strongly affected by the hydrochemistry of shallow groundwater during the experiment, has also gradually begun to regain its pre-extraction signature. However, the surface runoff has remained low during the first 2 years of recovery, at about 60% of the volume compared to the unaffected catchment area. This could be explained by delayed recovery in resaturation of the shallow rock that was unsaturated during the experiment.

Biohydrogen production by anaerobic co-digestion of municipal food waste and sewage sludges

Food waste (FW), primary sludge (PS) and waste activated sludge (WAS) were characterized and found to be complementary in the concentrations of carbohydrates, total Kjeldahl nitrogen (TKN), PO 4–P and some metal for biological hydrogen production. Moreover, FW was found to have low pH buffering capacity while the values for PS and WAS were relatively higher. An anaerobic toxicity analysis (ATA) derived from a methanogenic ATA protocol showed that these waste materials had no toxicity to hydrogen production. Adding phosphate buffer to the FW significantly improved hydrogen production while initial pH was 7.0. Co-digestion of FW and sewage sludge was studied using a batch respirometric cultivation system. All combinations of the feedstocks (FW+PS, FW+WAS and FW+PS+WAS) showed enhanced hydrogen production potential as compared with the individual wastes. A mixing ratio of 1:1 was found to be the best among the ratios tested for all three co-digestion groups. A hydrogen yield of 112 mL/g volatile solid (VS) added was obtained from a combination of FW, PS and WAS. This yield was equivalent to 250 mL/g VS added if only FW contributed to hydrogen production. The reason for the enhancement of hydrogen production was postulated to be multifold in which the increase in buffer capacity in the co-digestion mixture was verified.