Stable isotope analysis of human hair and nail samples: the effects of storage on samples

When submitting samples for analysis, maintaining sample integrity is essential. Appropriate packaging must be used to prevent damage, contamination or loss of sample. This is particularly important for stable isotope analysis by isotope ratio mass spectrometry as this technique is capable of detecting subtle differences in isotopic composition with great precision. In a novel study, scalp hair and fingernail samples were placed in five different types of packaging, routinely used in forensic laboratories and stored for 6 weeks and 6 months. Samples were subsequently cleaned and submitted for 13C/12C, 15N/14N, 2H/1H and 18O/16O analysis. Results from 13C analysis indicate that type of packaging can cause slight changes in 13C abundance over time. Differences were noted in the 15N isotope signatures of both hair and nail samples after 6-week storage, but not after 6 months. This apparent discrepancy could be a result of the packaging not being properly sealed in the 6 weeks study. Fewer differences were noted when analyzing samples for 2H and 18O abundance

Do CEOs Ever Lose? Fairness Perspective on the Allocation of Residuals Between CEOs and Shareholders

In this study we introduce a justice perspective to examining the result of bargaining between CEOs and boards over the allocation of firm residuals that ultimately determines CEO compensation. Framing CEO pay as the result of bargaining between CEOs and boards focuses attention on the power of CEOs to increase their share of firm residuals in the form of increased compensation, and the diligence of boards of directors to constrain CEO opportunism. Framing this negotiation through a theory of justice offers an alternative perspective to the search for pay-performance sensitivity. We predict and find that as board diligence in controlling opportunism declines and CEO power increases, CEOs are increasingly able to capture a larger portion of firm residuals relative to shareholders. This finding supports critics who charge that CEO pay violates norms of distributive and procedural justice

Getting the message across: an experiment in radio-based water resources management education in Malawi

Recent studies have recommended leveraging on the potency of media advocacy in attaining the goals of sustainable safe water as key to healthy and prosperous communities. This paper describes the experience of trialling a 6-week radio pilot focussed on water resources management and tracking its effectiveness using SMS technology and field interviews with radio listener groups. Despite a short broadcast period, the radio pilot registered measurable traction with audiences due to a 56% response rate to the SMS tracking system, evidence of behaviour change at village-level and cases of unsolicited queries from the general public demanding for more information. Though effective, any radio-based intervention, at-scale, has to be complemented with field support to receptive communities that could act as model villages. This could be achieved through close collaboration with local government extension networks and the establishment of a community of practise to act as a referral system for queries

Simplifying and improving the extraction of nitrate from freshwater for stable isotope analyses

Determining the isotopic composition of nitrate (NO3_) in water can prove useful to identify NO3_ sources and to understand its dynamics in aquatic systems. Among the procedures available, the ‘ionexchange resin method’ involves extracting NO3_ from freshwater and converting it into solid silver nitrate (AgNO3), which is then analysed for 15N/14N and 18O/16O ratios. This study describes a simplified methodology where water was not pre-treated to remove dissolved organic carbon (DOC) or barium cations (added to precipitate O-bearing contaminants), which suited samples with high NO3_ ($400 mM or 25 mg L_1 NO3_) and low DOC (typically <417 mM of C or 5 mg L_1 C) levels. % N analysis revealed that a few AgNO3 samples were of low purity (compared with expected % N of 8.2), highlighting the necessity to introduce quality control/quality assurance procedures for silver nitrate prepared from field water samples. Recommendations are then made to monitor % N together with % O (expected at 28.6, i.e. 3.5 fold % N) in AgNO3 in order to better assess the type and gravity of the contamination as well as to identify potentially unreliable data

Predicted and Back-calculated Coefficients of Permeability of Randomly Fractured Rock Mass: A Case Study

This paper presents the discrepancy between the coefficients of permeability measured for randomly fractured limestone using field falling-head tests and that back-calculated for the same rock mass based on the actual discharge yielded from a dewatering system designed for a typical construction site in Doha, Qatar. The study results showed that the back-calculated coefficient of permeability is outside the range of the values measured from the falling-head tests and almost seven times higher in magnitude than the fallinghead tests average. The need of having a reliable correlation that can be used to predict the actual permeability of randomly fractured rock in terms of its rock quality indices and the results of the commonly conducted field falling-head test is highlighted.The funding provided by the Qatar National Research Fund (QNRF), Qatar, under Project No: NPRP12S-0314-190366, for this research work is deeply appreciated

A national scale assessment of temporal variations in groundwater discharge to rivers : Malawi

This study presents the first national-scale assessment of temporal variations in the Base Flow Index (BFI) for watercourses in Malawi. A proxy indicator of groundwater discharge to rivers, the BFI is a measure of the ratio of long term baseflow to total river flow and is a key parameter for sustainable water resources management. The smoothed minima technique was applied to river flow data from 68 river gauges across Malawi (data records ranging from 11-64 years). The long-term average annual BFI for each gauged site was determined, as well as seasonal values of BFI. The Mann Kendal (MK) statistical test was used to identify trends in the BFI. Average annual BFI was 0.57, average wet season BFI was 0.52 and average dry season BFI was 0.97. This indicates that 57%, 52% and 97% of the total river flow is derived from groundwater and other stored sources in the annual, wet and dry season periods respectively. These results show that baseflow in Malawi follows a seasonal pattern with minimal differences between the average annual and average wet season BFI; however, significant increases are generally seen in the dry season BFI. The results also found long-term behavioural changes in BFI across all periods. Annually, 74% showed no trend, 10% showed an increasing trend and 16% showed a decreasing trend. The wet season trends showed similar values with 66% showing no trend, 16% showing an increasing trend and 18% showing a decreasing trend. In contrast, for the dry season, 93% showed no trend, 1% showed an increasing trend and 6% showed a decreasing trend. The dataset determined in this study can support sustainable water resources management in Malawi and contribute to measuring its progress towards Sustainable Development Goal 6

Barriers to handpump serviceability in Malawi : life-cycle costing for sustainable service delivery

The implementation of handpumps has contributed to increased improved water access. However, 'universal access' as the metric for success within Sustainable Development Goal (SDG) 6, potentially conceals fundamental barriers for sustainable services and hinders SDG 6 target success. Tariffs, in the form of household contributions, are the most common form of financial provision for the maintenance of rural water supplies. However, the annualised financial resources significantly vary across local contexts. Four tariff scenarios (collected per month, when required for repairs, per year and no tariff) were investigated across the life-cycle of 21 997 Afridev handpumps in Malawi. Known local costs for Afridev components from suppliers in Malawi were used to determine the potential shortfall in financial resources over the handpumps' 15 year design life. Domains that influence functionality, such as the operations, maintenance and quality of infrastructure, were also investigated to identify significant factors impacting the sustainability of the handpumps. Logistic regression indicates sub-standard installations (i.e. seasonality and poor water quality), structural damage to civil works, no preventative maintenance, lack of spare parts on site and a shortfall in potential financial resources were significantly associated with the poor status of infrastructure (broken or worn components) over the life-cycle of the Afridev. The findings highlight the burden placed on rural communities of maintaining inherently unsustainable assets that inevitably hinders lasting service delivery and benefits for rural communities in the SDG period and beyond. This journal i

A national border-based assessment of Malawi's transboundary aquifer units : towards achieving sustainable development goal 6.5.2

Study region: Malawi. Study focus: The adoption of the United Nations Sustainable Development Goal 6 in 2016 has triggered countries across the globe to assess and improve management and use of water resources. Monitoring of these resources is becoming increasingly important, and the management of transboundary water resources, in particular groundwater aquifers, required to meet SDG target 6.5.2, is lagging behind. It is vital to assess and manage these resources in a sustainable manner within an integrated water resource management approach. Transboundary aquifer assessments have largely focused on the regional scale which is not sufficient for countries to manage their transboundary aquifers effectively. This paper focuses on results of a national transboundary aquifer unit assessment in Malawi as a case study to support the countries plans for achieving Sustainable Development Goal 6.5.2. New hydrological insights for the region: We have identified 38 new transboundary aquifer units shared between Malawi and its neighbours. These results can form the basis for future transboundary aquifer management between Malawi and its neighbouring countries. We also highlight the current limitations of transboundary aquifer assessments and management that should be addressed to achieve SDG 6.5.2. These include institutional mechanisms, limited cross-border data sharing, limited groundwater monitoring, and a need to revisit the wording of the transboundary-focused SDG target and its indicators

Hydrostratigraphic characterisation of shallow coastal aquifers of Eastern Dahomey Basin, S/W Nigeria using integrated hydrogeophysics; implication for saltwater intrusion

This study employed electrical resistivity tomography (ERT) in characterising the shallow groundwater aquifers of Eastern Dahomey basin in southwestern Nigeria to assess the possible occurrence and distribution of saltwater within the aquifers. Electrical resistivity tomography (ERT), induced polarization (IP) and borehole logging were carried in locations with relatively enhanced electrical conductivity (EC) within the coastal zone of the basin through 97 groundwater samples from shallow wells and boreholes; 500 m-length ERT and IP sections were carried out along three traverses A–B, C–D and E–F in directions perpendicular and parallel to the coastline. Three geoelectrical layers were identified along traverse line A–B which comprises cross-sections 1, 2, 3 and 4 located around Ugbonla, Aboto and Igbokoda with layers’ resistivity and chargeability values ranging from (1–1000, 33–200 and 1–1700 Ωm), and (−50–200 Ωm, −30–200 Ωm and −50–120 Ωm, respectively, from the top to the bottom layer. These values indicated unconsolidated sand/lateritic silty clay, underlain by a sandy/silty clay layer with underlying fine-grained sand with disseminated clay lenses. The average thickness of the first two layers was 16 and 53 m while that of the third layer was undetermined. Resistivity and chargeability results from ERT and IP cross-sections along profile C–D exhibited characteristics similar to that of profile A–B with unconsolidated sands which were underlain by intercalation of sandy/silty clay and fine-grained sands with suspected clay lenses saturated with saline water. Profile E–F revealed a geoelectrical layer with low resistivity which ranged from 1–30 Ωm with the corresponding chargeability between −150–400 ms. This indicated a saline water-saturated layer of fine-grained sand and silty clay which is overlaid by the unconsolidated unconfined freshwater aquifer. Correlation of selected ERT results with borehole logs further affirmed the suspected lithology from the sections. Two scenarios of saltwater intrusions into coastal freshwater aquifer were suggested which include the presence of trapped salt-saturated clay lenses within aquifer lithology and seawater incursion induced by over-drafting of groundwater in this basin.Therefore, it identified the need for further investigation which will involve a combination of hydrochemical and isotopes to further understand the paleowater hypothesis

Assessing the impact of climate change on groundwater quality of shallow coastal aquifer of eastern Dahomey basin, southwestern Nigeria

Despite the increasing interest in climate change and water security, research linking climate change and groundwater quality is still at an early stage. This study explores the seasonal effect of the change in biogeochemical process for the redox-sensitive ions and metals Fe 2+, Mn 2+, SO 4 2-, and NO 3 - to assess the groundwater quality of the shallow coastal aquifer of Eastern Dahomey Basin in southwestern Nigeria. Field physicochemical measurement of EC, pH TDS, Eh, salinity, temperature, and the static water level (SWL) was carried out on 250 shallow wells; 230 water samples were collected for analysis between June 2017 and April 2018. A spatial distribution map of these ions and metals showed an increasing concentration in the dry season water samples compared to those of the wet season. This higher concentration could be attributed to change in the intensity of hydrochemical processes such as evaporation, redox, and mineral precipitation. Results of linear regression modelling established significant relationships between SWL, SO 4 2-, NO 3 -, Fe, and Eh for both wet and dry seasons with the p-value falling between 75% and 95%, which can also be seen in the plots of Eh/ORP against Fe 2+, Mn 2+, SO 4 2-, and NO 3 -. These results revealed the influence of the redox process for both seasons, while also having a higher impact in the dry season while variation of concentration revealed decrease with increase in depth, which could be attributed to a decrease in well hydraulic properties and aeration. An Eh-pH geochemical diagram revealed NO 3 - as the controlling biogeochemical process over Fe in most of the sample wells. Concentrations of NO 3 -, Fe, and Mn are above the World Health Organization's (WHO) standard for drinking water in most water samples. This study has established the link between climate change and groundwater quality in shallow coastal aquifers and suggested the need for strategic groundwater management policy and planning to ameliorate groundwater quality deterioration