Low Buffering Capacity Research Articles

Microbial population dynamics in temperature‐phased anaerobic digestion of municipal wastewater sludge

AbstractBACKGROUNDThe present study compared the performance and capability of thermophilic–mesophilic, temperature‐phased anaerobic digestion (TPAD) of wastewater sludge at 45 and 55 °C in terms of rate of hydrolysis and methanogenesis at two point interval times – December and January – with operational conditions kept constant (total solid content 6.5%, solids retention time 12.5 days).RESULTSThe reduction of volatile solids (VS) was 77% at 45 °C TPAD‐1 and 72% at 55 °C TPAD‐II. The accumulation of ammonia and volatile fatty acids (VFAs; propionic acid) were observed to be below the inhibitory range (>3000 mg L−1), whereas the methane (CH4) production (45 °C, 3.55 ± 0.47 L CH4 L−1 day−1; 35 °C, 1.44 ± 0.12 L CH4 L−1 day−1) remained considerably higher in TPAD‐I than TPAD‐II. Furthermore, the TPAD‐II system suffered from certain degree of instability due to high level of total VFAs (6087 ± 1578 mg L−1), low buffering capacity, increased level of total NH3 (2982 ± 219 mg L−1) and free NH3 (246 ± 25 mg L−1), and relatively reduced CH4 production (1.69 ± 0.1 L L−1 day). The bacterial and archaeal population of the TPADs investigated by 454 pyrosequencing and Illumina sequencing showed, in both TPAD systems, a bacterial community dominated by Firmicutes, followed by Bacteriodetes, Proteobacteria, Synergistetes and Actiniobacteria. The archaeal community was dominated by Methanimicrobia (74–84% Methanosarcina) and Methanobacteria (15–27% Methanobacterium). A progression from genus Clostridium to Coprothermobacter and Tepidanaerobacter, and Methanocarcina to Methanothermobacter and Methanobacterium was observed in TPAD‐II.CONCLUSIONSThis study proved the processes driving the dynamics of key microbial population and its correlation with hydrolytic functionality of TPAD systems. © 2019 Society of Chemical Industry

Influence of black tea on Streptococcus mutans and Lactobacillus levels in saliva in a Saudi cohort.

ObjectivesDental caries are associated with high counts of Streptococcus mutans (SM) and Lactobacillus (LB) and low saliva buffering capacity (BC). This study aimed to evaluate the antimicrobial activity of black tea on salivary cariogenic microflora, SM and LB species in an adult population. Antimicrobial activity was measured from the number of colony forming units (CFUs) of SM and LB, and BC of saliva.MethodsIn this prospective experimental study, unstimulated saliva samples were acquired from the participants before, immediately after, and 1 h after drinking tea by collecting saliva in sterilised containers. Samples were taken to the laboratory for incubation and subsequent counting. SM and LB counts and BC of saliva were calculated using the caries risk test (CRT).ResultsA total of 21 participants, 13 males and 8 females, with a mean age of 32.6 ± 8.02, were recruited in this study. Black tea had no significant effect on reducing the cariogenic bacterial counts (p > 0.05).ConclusionBased on this study, it can be deduced that black tea exhibits an insignificant antimicrobial effect against Streptococcus mutans and Lactobacillus bacteria.

The influence of simulated global ocean acidification on the toxic effects of carbon nanoparticles on polychaetes

Ocean acidification events are recognized as important drivers of change in biological systems. Particularly, the impacts of acidification are more severe in estuarine systems than in surface ocean due to their shallowness, low buffering capacity, low salinity and high organic matter from land drainage. Moreover, because they are transitional areas, estuaries can be seriously impacted by a vast number of anthropogenic activities and in the last decades, carbon nanomaterials (CNMs) are considered as emerging contaminants in these ecosystems. Considering all these evidences, chronic experiment was carried out, trying to understand the possible alteration on the chemical behaviour of two different CNMs (functionalized and pristine) in predicted climate change scenarios and consequently, how these alterations could modify the sensitivity of one the most common marine and estuarine organisms (the polychaeta Hediste diversicolor) assessing a set of biomarkers related to polychaetes oxidative status as well as the metabolic performance and neurotoxicity. Our results demonstrated that all enzymes worked together to counteract seawater acidification and CNMs, however oxidative stress in the exposed polychaetes to both CNMs, especially under ocean acidification conditions, was enhanced. In fact, although the antioxidant enzymes tried to cope as compensatory response of cellular defense systems against oxidative stress, the synergistic interactive effects of pH and functionalized CNMs indicated that acidified pH significantly increased the oxidative damage (in terms of lipid peroxidation) in the cotaminated organisms. Different responses were observed in organisms submitted to pristine CNMs under pH control, where the lipid peroxidation did not increase along with the increasing exposure concentrations. The present results further demonstrated neurotoxicity caused by both CNMs, especially noticeable at acidified conditions. The mechanism of enhanced toxicity could be attributed to slighter aggregation and more suspended NMs in acidified seawater (as demonstrated by the DLS analysis). Therefore, ocean acidification may cause a higher risk of CNMs to marine ecosystems.

Paper-Based Disk-Type Self-Powered Glucose Biosensor Based on Screen-Printed Biofuel Cell Array

There is an increasing need for wearable diagnostic sensor devices and for enzymatic biofuel cells (EBFCs) as efficient power sources. In this study, a six-glucose/O2 biofuel cell array connected in series was fabricated by screen printing as a self-powered glucose sensor exhibiting an electromotive force of 3.2 V. Porous carbon electrodes were formed by screen printing of MgO-templated carbon on water-repellent paper to improve the performance of the cathode and thus prevent it from being the limiting step. The bioanode contained glucose oxidase as a catalyst and tetrathiafulvalene as a mediator, and the cathode contained bilirubin oxidase as an oxygen reduction catalyst. A good linear relationship was obtained between the output of EBFCs and glucose concentration (1–25 mM), which contains the range of urine glucose levels. The artificial urine components did not interfere with the output of the EBFC, but it was limited by low ion conductivity and low buffer capacity.

Macrohabitat studies in large Brazilian floodplains to support sustainable development in the face of climate change

Large floodplains are complex ecosystems at the land–water boundary. Because of rainy and dry seasons, most tropical floodplains are subjected to annual water-level fluctuations. During typical low-water periods, extensive areas of the floodplains are dry. However, relatively small geomorphological differences within the boundaries of the floodplains result in comparatively large differences in the length and depth of inundation and, in turn, the establishment of distinct plant communities, called macrohabitats. The specific ecological conditions of these macrohabitats have to be taken into consideration in the development of sustainable management methods and protection measures. Extreme floods and droughts have very strong effects on flora and fauna. The low hydrological buffer capacity of floodplains makes them vulnerable to anthropogenic changes in hydrology and to the impacts of global climate change. This study presents a macrohabitat classification system that has been applied to three large Brazilian floodplains: the forested Amazonian várzeas and igapós, and the savanna floodplains of the upper Paraguai River (Pantanal of Mato Grosso). Examples are provided to demonstrate the applicability of this system in comparative inter- and intra-wetland studies and therefore its utility in assessing environmental changes, including those arising from global climate change. Our approach can also be used to guide the implementation of sustainable management methods and as a focal point for the development of environmental legislation.

Influence of soil characteristics on yield response to lime in sugar beet

Sugar beet is an economically important crop grown on around 30,000 ha in the province of Skåne in the south of Sweden. This project examined the effects of lime on soil factors and yield response in sugar beet in 52 soils in Skåne. Previous research in sugar beet in this area has postulated the importance of appropriate calcium concentrations in the soil to avoid yield losses caused by the root pathogen Aphanomyces cochlioides. Field trials on liming in Sweden have, however shown contrasting results on yield and subsequent economic benefits. The practice of liming has therefore been neglected and resulted in suboptimal pH for plant growth and development in many soils. The aim of the present investigation was to identify and evaluate soil factors of importance for a positive yield response in sugar beet after application of two different lime products: factory lime and limestone meal in rates with similar neutralizing effect (4 tons CaO/ha). Data on soil texture, cation exchange capacity (CEC) and clay mineralogy were available for each site. After liming, nutritional status and Aphanomyces root rot potential in the soil were analysed in each treatment and finally the yield was measured. In total, 52 soils were treated with the two lime products. In addition, 12 of these were also treated with increasing doses of limestone meal.In average for all 52 soils, the yield increased significantly after treatment with either of the lime products. Similarly, the root rot potential of A. cochlioides decreased significantly with no difference between the products. In 12 field trials with 4, 8, 16 and 32 ton/ha limestone meal, 8 ton/ha gave the highest yield. In classifying the soils according to pH and prevailing recommendations, soils with an initial pH >7.0 and with no liming requirement responded positively with significant increases in sugar yield. Soils with initial pH 6.5–7.0 and with a liming requirement, showed less response, with no significant increase in sugar yield. However, the concentration of calcium increased above the suggested threshold of 250 mg/100 g soil and the root rot potential of A. cochlioides decreased significantly in this group. For soils with an initial pH <6.5, the calcium content remained unchanged after liming. Also, Aphanomyces root rot, which was most prevalent in these soils, was not affected by liming. These soils have a low buffering capacity due to the combined effects of clay mineralogy with a low proportion swelling clay minerals and a low clay content. Sugar beets have been shown to acidify the rhizosphere and a high buffering capacity and a high base saturation maintain an optimal pH for nutrient uptake. The results suggest that for crop rotations including sugar beet, liming should be done on a regular basis, also for soils with a pH >7.0. It is of special importance in soils with low pH and CEC to maintain or increase calcium concentrations to a level >250 mg/100 g, which reduce the propagation of A. cochlioides.

Technical note: An anomaly in pH data in South Africa’s national water quality monitoring database – implications for future use

The South African national water quality database (Water Management System) houses data records from several environmental monitoring programmes, including the National Chemical Monitoring Programme (NCMP). The NCMP comprises an extensive surface water quality monitoring programme, managed by the Department of Water and Sanitation (DWS). The purpose of this technical note is to alert users to a systematic anomaly recently observed in the pH dataset of the NCMP, reflected in an abrupt increase between pre- and post-1990 data records. Although the cause of the anomaly in pH could not be confirmed with high confidence, an inappropriate acid rinse procedure in pre-1990 analytical methods was identified as the most likely cause, based on available evidence. This was supported by the variation in relative sensitivity when comparing the effect on waters with different buffering capacities, i.e., water with low buffering capacity (represented by total alkalinity &lt; 10 mg/L, as CaCO3) showing the largest anomaly, compared with waters of higher buffering capacity (represented by total alkalinity &gt; 30 mg/L, as CaCO3) showing the smallest anomaly. Historical pH data records in the NCMP (i.e. pre-1990), therefore should be used with caution, especially in more weakly buffered systems. The possibility of reconstructing data using a correction factor derived from detailed statistical analyses of the post-1990 pH characteristics at selected sites is a possible solution that could be investigated in future. A key lesson learnt is the need to be diligent in capturing detailed meta-data on sampling procedures and analytical methods in datasets spanning several generations. Availability of such information is critical in order to provide users with a means of evaluating the suitability and comparability of data records in long-term datasets. The DWS includes such meta-data in the current version of the database, dating from about 1995 onwards.

Association between sickle cell disease and the oral health condition of children and adolescents

BackgroundSickle cell disease (SCD) is the most prevalent monogenic hereditary pathology associated with the presence of hemoglobin SS in the world. It can affect individuals, leading to changes in the face and body, causing a deficiency in dental and bone tissue formation that can ultimately result in a higher level of predisposition to developing dental caries. This study aimed to evaluate the oral condition of children and adolescents with SCD in comparison with the condition of healthy controls.MethodsThis was a cross-sectional study of children and adolescents aged 5 to 18 of both sexes from a hematology center in Bahia, Brazil, and subjects without hemoglobinopathies from a public school of the same state (comparison group). There were 124 individuals, 63 in the comparison group and 61 in the disease group. Interviews, dental and periodontal exams using the DMFT and Periodontal Community Index, respectively, were performed, and the salivary buffer capacity and salivary flow rates of the entire sample population were evaluated. The categorical variables were compared using a chi-square test or Fisher’s exact test. For comparison of means, the Student’s-t test was used for independent samples that presented symmetrical distribution.ResultsThe study showed that the DMFT was 2.08 (2.71) for the SCD group and 1.05 (1.67) for the comparison group (p = 0.013). For dmft, the values were 2.3 (2.6) and 0.88 (1.2), respectively, (p = 0.018). Exams of the periodontium showed the presence of gingival bleeding and dental calculus, with no statistical significance between groups (p = 0.984). When evaluating salivary flow and buffer capacity, no significant differences were observed for the flow rates (p = 0.485), but the SCD group presented a lower buffer capacity compared with the comparison group (p = 0.006). Individuals who used hydroxyurea had a dmft (2.50) higher than that of the comparison group (2.00), and salivary flow was lower than the normal rate in 70% of the children who did not use this medication.ConclusionChildren and teenagers with SCD had deficient oral health when compared with the comparison group, presenting a higher level of dental caries and lower buffer capacity.

Low buffering capacity and slow recovery of anthropogenic phosphorus pollution in watersheds

Excess anthropogenic phosphorus in watersheds, transported with runoff, can result in aquatic eutrophication, a serious global water quality concern. Watersheds can retain phosphorus, especially in their soils, which can serve as a buffer against the effect of excessive use of phosphorus. However, whether there is a quantifiable threshold at which a watershed exceeds its optimal phosphorus buffering capacity (beyond which riverine loads would dramatically increase) remains unknown. Here we quantified a watershed phosphorus buffering capacity threshold based on accumulation data over 110 years in 23 watersheds of a large North American river basin with globally representative agricultural soils. We found a surprisingly low threshold of just 2.1 t P km−2 (0.03–8.7 t P km−2). Beyond this, further P inputs to watersheds cause a significant acceleration of P loss in runoff. Using a simple exponential decay model, the time estimated to eliminate legacy P via runoff in our watersheds ranges from ~ 100 to over 2,000 years. The rapidity with which the watershed buffering threshold can be surpassed during accumulation, particularly given current anthropogenic phosphorus input rates, versus the long return to baseline suggests that new strategies to reconcile watershed activities and water quality are urgently needed. Watersheds have a low buffering capacity for phosphorus inputs, and their recovery from phosphorus pollution can take over 2,000 years, according to an analysis of phosphorus data from a large North American river.

Operationalizing food system resilience: An indicator-based assessment in agroindustrial, smallholder farming, and agroecological contexts in Bolivia and Kenya

Resilience is often considered a precondition for sustainable social-ecological systems. But how can this understanding of resilience be applied to food systems? We operationalized the concept by subdividing it into different resilience dimensions, namely: buffer capacity, self-organization, and capacity for learning and adaptation. Specific indicators were defined for each dimension: (1) agrobiodiversity and livelihood assets for buffer capacity; (2) decentralization and independence, local consumption of production, interest groups, ecological self-regulation, and connectivity for self-organization; and (3) knowledge of threats and opportunities, reflective and shared learning, feedback mechanisms, existence and use of local-traditional knowledge, and a shared food system vision for capacity for learning and adaptation. Next, we applied the resilience indicators to different food systems (agroindustrial, local, and agroecological) in Kenya and Bolivia, including assessment of the interaction and coexistence of food systems. While the contexts in the two countries differ greatly, we identified several common trends that appear to be undermining food system resilience in both settings. These trends include low ecological buffer capacity and self-regulation in agroindustrial food systems; strong disparities in income and access to productive resources; competition for water, land, and labor; exclusion from markets; and low human capital and feedback mechanisms in locally based, traditional food systems. Taken together, these trends cast doubt on food system coexistence narratives. Finally, the results enable us to identify leverage points in the food systems – e.g., regarding learning and feedback mechanisms – that could be used to foster food system transformations linked to goals of sustainability and justice.

Dolomitic limestone as an alkalizing agent for treating cassava starch wastewater in an anaerobic reactor

ABSTRACT Cassava processing wastewater has a low Volatile Acidity/Total Alkalinity ratio, low buffering capacity and became quickly acidified. In this trial, dolomitic limestone was used as an alkalizing agent in an anaerobic reactor to treat cassava starch wastewater. The dolomitic limestone contained 27% CaO and 23% MgO and granulometry between 24.5 and 38.1 mm. The average Chemical Oxygen Demand of the wastewater was 13331.30 mgO2 L-1, the organic loading rates (OLR) ranged from 1.23 to 16.43 gCOD L-1 d-1 and the hydraulic retention times ranged from 10.00 to 0.80 days. The results showed that the calcium concentrations increased in the reactor effluent and the magnesium concentrations decreased as the organic loading rates increased. Ca2+ and Mg2+ concentrations were approximately 5,000 and 5.05 times greater in the sludge than in the inoculum, respectively. The average pH, Total alcalinity, Volatile Acidity and Volatile Acidity/ Total alcalinity values were 6.69, 882.54 mgCaCO3 L-1, 221.55 mgCH3COOH L-1 and 0.22, respectively. The loss of limestone mass corresponded to only 2.51% of the initial mass, after 134 days of anaerobic reactor operation. Finally, it was concluded that the limestone effectively controlled acidification through the alkalinity increased in the system.

Electrodeposition of Copper on Mild Steel: Peculiarities of the Process

The process of electrodeposition of copper coatings on a mild steel substrate was analyzed. The reasons for poor adhesion of the coatings from acid and alkaline cyanideless electrolytes were determined. It was shown that the problem of the direct copper coatings’ electrochemical plating on a steel substrate from cyanideless electrolytes results from the presence of the adjoint process of contact exchange in a copper ions–iron system. Good adhesion coatings can be developed only on termination of the contact exchange at the initial stage until the steel substrate under the sediment pores is not subjected to significant etching. In acid electrolytes, the adhesion is poor because of a large value of the contact exchange current. In alkaline cyanideless electrolytes iron is passivated, and adhesion of the coating is insufficient because of the presence of a separating passive film at the substrate–coating interface. In neutral electrolytes, it is possible to obtain a coating with a good adhesion to the substrate, but the results are not stable due to a low buffer capacity of the solution. During the deposition of a copper coating from acid electrolytes using a prenickel-plating, a thin nickel sublayer has pores through which the process of the contact exchange occurs. It is shown that, in order to develop coatings with a good adhesion, the minimum thickness of the nickel sublayer must be 3–5 μm.

Coupling of Nanofiltration and Thermal Fenton Reaction for the Abatement of Carbamazepine in Wastewater.

The complete removal of biorecalcitrant xenobiotics, including most notably the pharmaceutical pollutants, by advanced oxidation processes is often difficult to be reached in urban or industrial wastewater because of the high concentration of organic and inorganic scavengers that compete with the xenobiotics for the oxidizing species. This work investigates a coupled treatment train in which wastewater effluents are pretreated with a negatively charged loose nanofiltration (NF) membrane (HydraCoRe70, made up of sulfonated polyethersulfone) to enhance the removal of xenobiotics with the thermal Fenton process. Carbamazepine (CBZ), a drug prescribed mainly for epilepsy treatment, is used here as a model xenobiotic. After optimizing the conditions for separation and degradation, the NF–Fenton approach was applied to both synthetic wastewater and real samples to assess the overall efficiency of CBZ removal. The Fenton degradation of CBZ was drastically enhanced in nanofiltered samples, thanks to the removal by the membrane of nearly all organic matter that would otherwise consume the reactive oxidizing species (e.g., the hydroxyl radical). On the basis of a preliminary treatment cost analysis, it can be concluded that the combined process is potentially applicable to the treatment of several kinds of wastewaters (e.g., industrial ones) to favor the removal of biorecalcitrant contaminants. Key cost savings of NF–Fenton concern the lower amounts of Fenton reagents needed to degrade CBZ and (even more importantly) the decreased levels of acids and bases for pH adjustment before and after the oxidative process because of the lower buffer capacity of the NF permeate compared to feed wastewater, after the removal by the NF of many inorganic ions and most organic carbon.

Escherichia coli wild type and hydrogenase mutant cells growth and hydrogen production upon xylose and glycerol co-fermentation in media with different buffer capacities

In this study, the new strategy for long term bio-hydrogen (H2) production using different substrates and waste materials is presented. Growth characteristics and H2 production were investigated upon consumption of 0.4% xylose and 1% glycerol alone (which were optimal) or their mixture by Escherichia coli BW25113 wild type parental strain (PS) and ΔhyaB, ΔhybC, ΔhycE, ΔhyfG mutants with genes deletions for key subunits of hydrogenase (Hyd)-1 to Hyd-4, respectively, in high and low buffer capacity peptone (HPM, LPM) mediums, pH 5.5 and 7.5. Overall, pH 5.5 negatively affected bacterial growth and H2 production. At pH 7.5, apart from Hyd-3 and Hyd-4 mutants, upon growth of PS, Hyd-1 and Hyd-2 mutants drop of Pt redox electrode readings from positive (∼+150 mV) to negative (of −400 to −550 mV) values was detected during log growth phase mentioning H2 formation. Xylose and glycerol co-utilization did not affect PS and Hyd-1 and Hyd-2 mutant's biomass and H2 formation during log growth phase in LPM, but ∼1.5 fold stimulated these parameters, especially in HPM, pH 7.5, during prolonged 96 h bacterial growth. Roles of Hyd-3 and Hyd-4 in H2 production; and Hyd-1 and Hyd-2 in H2 oxidation during bacterial log growth phase were stated under xylose and glycerol co-fermenting conditions. The results obtained might be valuable for industrial long term H2 production by bacteria using mixture of carbon sources and combining various organic waste materials.

Influence of soil properties and feedstocks on biochar potential for carbon mineralization and improvement of infertile soils

The impact of biochar (BC) application on soil varies with BC feedstock and soil type. The objective of this study was to investigate the linkage between the properties and surface functionality of various BCs and their role in the rehabilitation of two infertile soils. Sandy loam (SL) and sandy (S) soils were collected from agricultural areas in Korea and Vietnam, respectively. The BCs of amur silvergrass residue (AB), paddy straw (PB), and umbrella tree (UB) were applied to the soils at a rate of 30 t ha−1 and incubated at 25 °C for 90 d. Soil carbon (C) mineralization was investigated by a periodic measurement of CO2 efflux. Soil texture strongly influenced the CO2 efflux more than the BC type as indicated by 2–4 folds increase in cumulative CO2-C efflux from the SL soil compared to that from the S soil. For the PB-, AB-, and UB-treated S soils, the values of cation exchange capacity (CEC) were increased by 906%, 180%, and 130%, respectively, compared to that of the control; however, for the PB-treated SL soil, only a 13% increase in CEC was found. The pH in the PB-treated S soil sharply increased by 4.5 units compared to that in the control, due to a high concentration of readily soluble compounds in the PB and the low buffering capacity of the S soil. The S soil was more sensitive to the addition of BCs than the SL soil. A more prominent improvement in soil fertility can be achieved by BC application to the sandy soil having low clay, nutrient, and organic matter contents.

Impacts of hydrogeochemical processes and anthropogenic activities on groundwater quality in the Upper Precambrian sedimentary aquifer of northwestern Burkina Faso

This study investigates the hydrogeochemical and anthropogenic factors that control groundwater quality in an Upper Precambrian sedimentary aquifer in the northwestern Burkina Faso. The raw data and statistical and geochemical modeling results were used to identify the sources of major ions in dug well, private borewell and tap water samples. Tap waters were classified as Ca–HCO3 and Ca–Mg–HCO3 types, reflecting the weathering of the local dolomitic limestones and silicate minerals. Dug well waters, with a direct contact with various sources of contamination, were classified as Ca–Na–K–HCO3 type. Two factors that explain 94% of the total variance suggested that water–rock interaction was the most important factor controlling the groundwater chemistry. Factor 1 had high loadings on pH, Ca2+, Mg2+, HCO3−, SO42− and TDS. These variables were also strongly correlated indicating their common geogenic sources. Based on the HCO3−/(HCO3− + SO42−) ratios (0.8–0.99), carbonic acid weathering appeared to control Ca2+, Mg2+, HCO3− and SO42− acquisition in the groundwater. With relatively lower Ca2+ and Mg2+ concentrations, the majority of dug well and borewell waters were soft to moderately hard, whereas tap waters were considered very hard. Thus, the dug well and, to a lesser extent, borewell waters are likely to have a low buffering capacity. Factor 2 had high loadings on Na+, NO3− and Cl−. The strong correlation between Na+ and NO3− and Cl− implied that factor 2 represented the anthropogenic contribution to the groundwater chemistry. In contrast, K+ had moderate loadings on factors 1 and 2, consistent with its geogenic and anthropogenic sources. The study demonstrated that waters from dug wells and borewells were bacteriologically unsafe for human consumption, and their low buffering capacity may favor mobility of potentially toxic heavy metals in the aquifer. Not only very hard tap waters have aesthetic inconvenient, but their consumption may also pose health problems.

Evaluation of changing surface water abstraction reliability for supplemental irrigation under climate change

In many temperate parts of the world, supplemental irrigation is crucial to assure both crop yield and quality. Climate change could increase the risks of irrigation being restricted by increasing crop water requirements and/or decreasing water availability. In England, water abstraction for irrigation is limited by maximum annual volumetric limits, as specified in the abstraction licences, and surface water abstraction restrictions imposed by the regulator during drought. This paper assesses how climate change might impact future irrigation abstraction reliability from surface water in England. Firstly, the probability of annual abstraction being close to the maximum licence limit was estimated for the baseline (1961–1990) and future (2071–2098) periods in each catchment based on observed relationships between annual weather and irrigation abstraction in three licence usage groups. Secondly, the current river discharge triggers for mandatory drought restrictions were used to assess the annual probability of surface water abstraction restrictions being imposed by the regulator in each period. Results indicate significant future increases in irrigated abstraction licence use due to an increase in aridity, particularly in the most productive agricultural areas located in eastern and southern England, assuming no adaptation. The annual probability of having less than 20% licence headroom in the highest usage group is projected to exceed 0.7 in 45% of the management units, mostly in the south and east. In contrast, irrigators in central and western England face an increased risk of drought restrictions due to the lower buffering capacity of groundwater on river flows, with the annual probability of mandatory drought restrictions reaching up to 0.3 in the future. Our results highlight the increasing abstraction reliability risks for irrigators due to climate change, and the need for the farming community and the regulator to adapt and collaborate to mitigate the associated impacts.

Application of an In Vitro Dissolution/Permeation System to Early Screening of Oral Formulations of Poorly Soluble, Weakly Basic Drugs Containing an Acidic pH-Modifier

This study aimed to evaluate the usefulness of the dissolution/permeation system (D/P system) as an in vitro tool for early screening of oral formulations of weakly basic drugs containing an acidic pH-modifier. Dipyridamole, having a prominent pH-dependent solubility, was used as a model drug, and various granules containing different amounts of fumaric acid were prepared. Prepared granules were administered orally to hypochlorhydria model rats. It was confirmed that fumaric acid improved the absorption of dipyridamole depending on its amount in the granules. Separately, dissolution and permeation of dipyridamole were observed in vitro in the D/P system. When using a medium with a low buffer capacity which mimicked the human intestinal fluid, rank order of the permeated amount of dipyridamole from various granules in the D/P system did not correlate with its absorption in hypochlorhydric rats. In contrast, when applying a medium with high buffer capacity, the permeated amount in the D/P system well reflected the effects of fumaric acid on the in vivo absorption of dipyridamole. In conclusion, by setting appropriate experimental protocols according to the properties of test compounds and formulations, D/P system can be a potent in vitro tool to predict in vivo performance of oral formulations.

Effects of Complexes and pH Buffer Solution in Electrokinetic Oxidation Treatment on Sediments Chromium Removal

Three electrokinetic (EK) experiments were designed to study the remediation efficiency of Cr(III) by EK-oxidation method and to investigate the influence of complexes and pH buffer solution in EK-oxidation process. Sediments Cr (III) can be oxidized into Cr(VI) effectively by KMnO4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The pH control and KMnO4 improved the removal of Cr(VI) and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr(III) in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the pH of cathode and anode pond solution on EK-oxidation processes.

A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.