Sorption of sulfamethoxazole, sulfachloropyridazine and sulfamethazine onto six New Zealand dairy farm soils

We have investigated the sorption potential of three sulfonamides (SAs) in six New Zealand dairy farming soils using a modified batch equilibrium method employing 0.005 M CaCl₂ as background solution. Both liquid and solid phases were extracted to analyse for the antibiotic concentrations in order to avoid underestimation that may arise a result of photolysis or biotic degradation. The experimental data were later used to construct Freundlich isotherms to determine the effective distribution coefficients. Low log Koc value for all SAs suggests considerable leaching potential for SAs under conditions that are conducive for leaching. The sorption affinity for all soils followed the trend SCP>SMZ>SMO

Evaluating mechanism and inconsistencies in hydraulic conductivity of unsaturated soil using newly proposed biochar conductivity factor

In the past few decades, numerous studies have been conducted to promote the use of biochar as a soil amendment and most recently, for compacted geo-engineered soils. In general, the definite trends of biochar effects on water retention and fertility of soils have been confirmed. However, the biochar effects on hydraulic conductivity, particularly unsaturated hydraulic conductivity of soil-biochar mix remain unclear, making it difficult to understand water seepage in both agricultural and geo-engineered infrastructures in semi-arid regions. This study examines the unsaturated hydraulic conductivity function derived based on the measurements of soil water characteristic curves of soil with biochar contents of 0%, 5% and 10%. A new parameter “biochar conductivity factor (BCF)” is proposed to evaluate the inconsistency in reported biochar effects on soil hydraulic conductivity and to interpret it from various mechanisms (inter- and intra- pore space filling, cracking, aggregation, bio-film formation and piping/internal erosion). The impact of biochar content on unsaturated hydraulic conductivity appears to reduce as the soil becomes drier with minimal effect in residual zone. Qualitative comparison of near-saturated hydraulic conductivity with test results in the literature showed that the BCF is generally higher for smaller ratio of sand to fine content (clay and silt). Moreover, the particle size of biochar may have significant influence on soil permeability. Future scope of research has been highlighted with respect to biochar production for its applications in agriculture and geo-environmental engineering. Long term effects such as root decay and growth, aggregation and nutrient supply need to be considered. Graphical Abstract

A geotechnical perspective on soil-termite interaction: Role of termites in unsaturated soil properties

The soil-insect interaction has gathered significant attention in the recent years due to its contribution to bio-cementation. Termites, as a group of cellulose-eating insects, alter physical (texture) and chemical (chemical composition) properties of soil. Conversely, physico-chemical properties of soil also influence termite activities. It is vital to understand the soil-termite interaction and their influence on hydraulic properties and shear strength of soil, which are related to a series of geotechnical engineering problems such as ground water recharge, runoff, erosion and stability of slopes. In this study, an attempt has been made to review the latest developments and research gaps in our understanding of soil-termite interaction within the context of geo-environmental engineering. The hydraulic properties and shear strength of termite modified soil were discussed with respect to soil texture, density and physico-chemical composition. The incorporation of hysteresis effect of soil water characteristic curve, and spatio-temporal variations of hydraulic conductivity and shear strength of termite modified soil is proposed to be considered in geotechnical engineering design and construction. Finally, the challenges and future trends in this research area are presented. The expertise from both geotechnical engineering and entomology is needed to plan future research with an aim to promote use of termites as maintenance engineers in geotechnical infrastructure

Interactions between microplastics, pharmaceuticals and personal care products: implications for vector transport

Microplastics are well known for vector transport of hydrophobic organic contaminants, and there are growing concerns regarding their potential adverse effects on ecosystems and human health. However, recent studies focussing on hydrophilic compounds, such as pharmaceuticals and personal care products (PPCPs), have shown that the compounds ability to be adsorbed onto plastic surfaces. The extensive use of PPCPs has led to their ubiquitous presence in the environment resulting in their cooccurrence with microplastics. The partitioning between plastics and PPCPs and their fate through vector transport are determined by various physicochemical characteristics and environmental conditions of specific matrices. Although the sorption capacities of microplastics for different PPCP compounds have been investigated extensively, these findings have not yet been synthesized and analyzed critically. The specific objectives of this review were to synthesize and critically assess the various factors that affect the adsorption of hydrophilic compounds such as PPCPs on microplastic surfaces and their fate and transport in the environment. The review also focuses on environmental factors such as pH, salinity, and dissolved organics, and properties of polymers and PPCP compounds, and the relationships with sorption dynamics and mechanisms. Furthermore, the ecotoxicological effects of PPCP-sorbed microplastics on biota and human health are also discussed

Novel Fe-Mn binary oxide-biochar as an adsorbent for removing Cd(II) from aqueous solutions

In this study, a pristine biochar (BC) and Fe-Mn binary oxide-biochar (FMBC) were prepared using Pennisetum sp. straw as the feedstock for Cd(II) removal from aqueous solutions. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and specific surface area (SSA) analyses revealed the physico-chemical characteristics of the pristine and designer adsorbents, suggesting that an ultrasonic treatment during synthesis enhanced the SSA and pore volume of the BC, and assisted successful loading of Fe-Mn binary oxide particles on the BC surface. The Cd(II) adsorption data of the adsorbents were fitted to the Langmuir isothermal and pseudo-second-order kinetic models. At a system temperature of 25 °C and pH 5, the maximum Cd(II) adsorption capacities of BC (30.58 mg/g) and FMBC (95.23 mg/g) were obtained. Multiple Cd(II) adsorption mechanisms by FMBC were identified, including precipitation with minerals, complexation with surface functional groups, Cd(II)-π interactions, and cation exchange. As the most dominant adsorption mechanism, Cd-O bonds were formed on the FMBC surfaces precipitating Cd(OH)2 (63.9 wt%) and CdO (36.1 wt%). The FMBC thus could be potentially used as an effective adsorbent for Cd(II) removal from aqueous solutions

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

Persistence and mobility of triasulfuron, metsulfuronmethyl, and chlorsulfuron in alkaline soils / Ajit K. Sarmah.

Bibliography: leaves 157-174.xx, 192 leaves : ill. (some col.) ; 30 cm.This study examined the fate of three common sulfonylurea herbicides in highly alkaline soils through a series of laboratory and field experiments to determine if existing leaching models could be used to describe their field behaviour under Australian climatic conditions. A liquid chromatographic method was developed to simultaneously determine levels of triasulfuron, metsulfuronmethyl, and chlorsulfuron in soil and water. The investigation of base hydrolysis for the herbicides in aqueous buffer and soil solutions determined that it was unlikely to be a major loss pathway for sulfonylureas in alkaline soils. The herbicides were found to have low sorption, very little retardation and high mobility, moving at a marginally slower rate than water. Degradation did not follow first-order kinetics, but rather a two-stage process appeared to be involved. Both VARLEACH and LEACHM models predicted the measured concentration of the herbicides reasonably well in profile under low rainfall conditions but were less adequate under high rainfall. Forecasts with the LEACHP model predicted levels of the herbicides for a dominant soil type of the cereal belt of southern Australia with median rainfall after a year.Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 199

Co-contaminants and factors affecting the sorption behaviour of two sulfonamides in pasture soils

We investigated the effect of soil pH, organic carbon, ionic strength and steroid hormones on the sorption of sulfamethoxazole (SMO) and sulfachloropyridazine (SCP) in three pastoral soils of New Zealand. A model linking sorbate speciation with species-specific sorption coefficients describing the pH dependence of the apparent sorption coefficients was used to derive the fraction of each species of SMO. All soils displayed a decrease in sorption when pH was increased, with SMO exhibiting the highest sorption at pH 2. The cationic form of SMO appeared to sorb more close to pH ≥ pKa1 and, when pH ≥ pKa2 (6.5, 7.5 and 8.5) the anionic species seems to dominate, however, its sorption affinity to all soils was low. SMO sorption was affected by ionic strengths and organic carbon content, while the presence of hormones showed only a subtle decrease in SCP sorption in a selected model pasture soil