Occurrence, Geochemistry and Speciation of Elevated Arsenic Concentrations in a Fractured Bedrock Aquifer System

The presence of elevated arsenic concentrations (≥ 10 µg L−1) in groundwaters has been widely reported in areas of South-East Asia with recent studies showing its detection in fractured bedrock aquifers is occurring mainly in regions of north-eastern USA. However, data within Europe remain limited; therefore, the objective of this work was to understand the geochemical mobilisation mechanism of arsenic in this geologic setting using a study site in Ireland as a case study. Physicochemical (pH, Eh, d-O2), trace metals, major ion and arsenic speciation samples were collected and analysed using a variety of field and laboratory-based techniques and evaluated using statistical analysis. Groundwaters containing elevated dissolved arsenic concentrations (up to 73.95 µg L−1) were characterised as oxic-alkali groundwaters with the co-occurrence of other oxyanions (including Mo, Se, Sb and U), low dissolved concentrations of Fe and Mn, and low Na/Ca ratios indicated that arsenic was mobilised through alkali desorption of Fe oxyhydroxides. Arsenic speciation using a solid-phase extraction methodology (n = 20) showed that the dominant species of arsenic was arsenate, with pH being a major controlling factor. The expected source of arsenic is sulphide minerals within fractures of the bedrock aquifer with transportation of arsenic and other oxyanion forming elements facilitated by secondary Fe mineral phases. However, the presence of methylarsenical compounds detected in groundwaters illustrates that microbially mediated mobilisation processes may also be (co)-occurring. This study gives insight into the geochemistry of arsenic mobilisation that can be used to further guide research needs in this area for the protection of groundwater resources.

The Effect of Exercise Intensity and Duration on Oxidative Stress and Antioxidant Enzymes Activity among Sedentary Healthy Adults: A Repeated Measures Study

Background Aerobic exercise can increase oxidative stress, but it can produce the necessary stimulus for physiological adaptation of exercise. However, the effects of intensity and duration of exercise on oxidative stress status are unclear. This study aimed to compare the effects of exercise intensity (I) and duration (D) on the oxidative stress [malondialdehyde (MDA)], and the responses of the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), antioxidant enzymes ratio (AE)] among sedentary adults. Methods In a randomized crossover design, 25 sedentary adults, performed nine cycling exercise sessions with a constant load of 50%, 60% and 70% VO2peak for 10-, 20- and 30- minutes duration. Plasma MDA, CAT, GPx and SOD activity were measured before exercise (baseline) and immediately after each session (post). Results The interaction effect of intensity and duration was significant for percentage changes of MDA (FIxD=3.59, df=4, p<0.05) and CAT activity (FIxD =3.38, df=2.146, p<0.05). Repeated Measures ANOVA analysis revealed that intensity is the major controlling factor for MDA (FI =54.24, df=2, p<0.05 vs FD=8.62, df=2, p<0.05), and CAT responses (FI =14.24, df=1.619, p<0.05 vs FD = 5.96, df=1.347, p<0.05). However, the main determinant factor for SOD (FD =11.82, df=1.166, p<0.05 vs FI =5.58, df=1.289, p<0.05) and AE (FD =11.63, df=1.201, p<0.05 vs. FI =3.035, df=1.32, p>0.05) is exercise duration. Conclusions These findings suggest that exercise intensity was an essential factor of acute oxidative stress and antioxidant enzyme responses compared with the duration of exercise.

Occurrence, Geochemistry and Speciation of Elevated Arsenic Concentrations in a Fractured Bedrock Aquifer System

The presence of elevated arsenic concentrations (≥10 µg L-1) in groundwaters has been widely reported in areas of south east Asia with recent studies showing its detection in fractured bedrock aquifers mainly in regions of north-eastern United States. Data within Europe remains limited; therefore, the objective of this work was to understand the geochemical mobilisation mechanism of arsenic in this geologic setting. Physiochemical (pH, Eh, d-O2), trace metals, major ion and arsenic speciation samples were collected and analysed using a variety of field and laboratory-based techniques and evaluated using statistical analysis including multivariate analysis. Elevated dissolved arsenic concentrations (up to 73.95 µg L-1) were observed in oxic-alkali groundwaters with the co-occurrence of other oxyanions (e.g. Mo, Se, Sb and U), low dissolved concentrations of Fe and Mn and low Na/Ca ratios indicating that arsenic was mobilised through alkali desorption of Fe oxyhydroxides. Arsenic speciation using a solid-phase extraction methodology (n=20) showed that the dominant species of arsenic present in groundwater was arsenate, with pH being a major controlling factor. The expected source of arsenic is sulfide minerals within fractures of the bedrock aquifer with transportation of arsenic and other oxyanion-forming elements facilitated by secondary Fe mineral phases. However, the presence of methylarsenical compounds detected in the groundwaters illustrates that microbially mediated mobilisation processes were also (co)-occurring. This study demonstrates how field speciation of arsenic can be utilised to overcome analytical limitations of conventional laboratory speciation and to facilitate in the interpretation of the environmental mobility of arsenic within groundwaters.

Functional Mechanisms of Green Tea Polyphenols and Their Molecular Targets in Prevention of Multiple Cancers

Cancer is portrayed as a group of disease characterized by alteration in the normal regulation of cell growth by the successive acquisition of genetic, somatic, and epigenetic alteration. Synthetic drugs are single targets while natural products are multi-targeted to prevent cancer. NF-κB is persistently active in a number of disease states, including cancer, and therefore has a critical role in cancer development and progression. It also provides a mechanistic link between inflammation and cancer and is a major controlling factor resistant to apoptosis in both pre-neoplastic and malignant cells. Importantly, NF-kB and the signaling pathways that mediate its activation have become attractive targets for the development of new chemopreventive and chemotherapeutic approaches. Natural antioxidants have been shown to possess chemopreventive and chemotherapeutic potential via targeting NF-κB signaling, among which tea polyphenols have been studied extensively. In this chapter, the authors summarize the regulation of NF-κB pathway by green tea polyphenols in different cancer types.

Exploring Ichnofacies Distribution in Ancient Seaways: The Late Miocene Rifian Corridor as a Natural Laboratory

Oceanic gateways have modulated ocean circulation and have influenced climatic variations throughout the Earth´s history. During the Late Miocene (7.8 - 7.35 Ma), the Atlantic Ocean and the Mediterranean Sea were connected through the Rifian Corridor (Morocco). This gateway is one of the few examples of deep ancient seaways with a semi-continuous sedimentary record. Deposits comprise turbidites intercalated between deep-sea fine grain sediments (i.e., hemipelagites and drift deposits), channelized sandstone contourite facies, and shallow marine sandstones. Herein an ichnological analysis was conducted in these upper Miocene sediments to improve characterisation of palaeoenvironmental conditions. In addition, ichnofacies were analysed to elucidate how bottom currents control ichnofacies distribution and can modified their attributes. Turbidite deposits are typified by vertical trace fossils (i.e., Ophiomorpha), conforming the Ophiomorpha rudis ichnosubfacies. Contouritic sandstones exhibit high density and low diverse trace fossil assemblage, with predominant Macaronichnus and Scolicia, resembling a proximal expression of Cruziana ichnofacies. Shallow marine environments are dominated by vertical trace fossils (e.g., Conichnus, Ophiomorpha and Skolithos), allowing an assignation to Skolithos ichnofacies. This study reveals energy to be a major controlling factor determining ichnofacies attributes and distribution in ancient deep seaways. Within these seaways, highly energetic conditions typical of shallower settings are present in deeper environments (i.e., slope), contributing to ichnodiversity impoverishment in ichnofacies.

Spatiotemporal distribution of grassland NPP in Gansu province, China from 1982 to 2011 and its impact factors

The modified Carnegie–Ames–Stanford Approach (CASA) model based on the comprehensive and sequential classification system of grasslands (CSCS, a unique vegetation classification system) was used to determine grassland net primary production (NPP) in Gansu province from 1982 to 2011 and its spatio-temporal variability. The relationship between NPP and climate drivers was analyzed. The results showed that annual NPP of grasslands in Gansu province averaged 139.30 gC m-2 yr -1 during the study period. NPP decreased from southeast to northwest across the province. Grassland NPP showed an increasing trend during the period 1982–2011, and the increase rate over the whole period was 92.91%. The highest NPP appeared in summer with more precipitation and higher cumulative temperature conditions; while the lowest values existed in winter. The largest correlation coefficient was found between the average annual NPP and the average annual precipitation (r = 0.77), followed by annual NPP and solar radiation (r = 0.70) or NDVI (r = 0.69), Annual NPP had no significant correlation with annual cumulative temperature (>0°C) or moisture index (K-value). Thus, precipitation is the major controlling factor on the average annual NPP in Gansu grassland. Solar radiation and NDVI also have important effects on grassland NPP in Gansu. These results may provide basic information for sustainable development and utilization of grassland and for the improvement and protection of the ecological environment as well.

Impacts of hydrogeological heterogeneity on groundwater transit time

&lt;p&gt;Groundwater transit time refers to the travel time of a water molecule through an aquifer from recharge at the water table to discharge at a surface water body (e.g., river). Analysing transit times provides a primary way to understand the overall transport characteristics of a hydrological system and is of interest in many aspects of environmental management. For example, studying transit time distribution can facilitate the mitigation of pollutant transport risks and ecosystem restoration. Hydrogeological heterogeneity of an aquifer is a major controlling factor for groundwater flow paths and transit time distributions. In this study, we investigate the impacts of spatial variability of hydrogeological properties on transit times by combining measurements and a new semi-analytical numerical modelling scheme. Passive tracer transport data from several catchments in Europe are obtained from open databases. Groundwater transit time in these catchments are inferred from both tracer transport data and numerical modelling. Comparing the results in different catchments provides a comprehensive way of understanding the impact of hydrogeological heterogeneity on groundwater transit time.&lt;/p&gt;

Effect of soil saturation on denitrification in a grassland soil

Nitrous oxide (N2O) is of major importance as a greenhouse gas and precursor of ozone (O3) destruction in the stratosphere mostly produced in soils. The soil-emitted N2O is generally predominantly derived from denitrification and, to a smaller extent, nitrification, both processes controlled by environmental factors and their interactions, and are influenced by agricultural management. Soil water content expressed as water-filled pore space (WFPS) is a major controlling factor of emissions and its interaction with compaction, has not been studied at the micropore scale. A laboratory incubation was carried out at different saturation levels for a grassland soil and emissions of N2O and N2 were measured as well as the isotopocules of N2O. We found that flux variability was larger in the less saturated soils probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. The results agreed with denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71 % WFSP). The isotopocules data indicated isotopic similarities in the wettest treatments vs. the two drier ones. The results agreed with previous findings where it is clear there are two N pools with different dynamics: added N producing intense denitrification vs. soil N resulting in less isotopic fractionation.

Structure and Filling Characteristics of Paleokarst Reservoirs in the Northern Tarim Basin, Revealed by Outcrop, Core and Borehole Images

The Ordovician paleokarst reservoirs in the Tahe oilfield, with burial depths of over 5300 m, experienced multiple phases of geologic processes and exhibit strong heterogeneity. Core testing can be used to analyse the characteristics of typical points at the centimetre scale, and seismic datasets can reveal the macroscopic outlines of reservoirs at the >10-m scale. However, neither method can identify caves, cave fills and fractures at the meter scale. Guided by outcrop investigations and calibrations based on core sample observations, this paper describes the interpretation of high longitudinal resolution borehole images, the identification of the characteristics of caves, cave fills (sedimentary, breccia and chemical fills) and fractures in single wells, and the identification of structures and fill characteristics at the meter scale in the strongly heterogeneous paleokarst reservoirs. The paleogeomorphology, a major controlling factor in the distribution of paleokarst reservoirs, was also analysed. The results show that one well can penetrate multiple cave layers of various sizes and that the caves are filled with multiple types of fill. The paleogeomorphology can be divided into highlands, slopes and depressions, which controlled the structure and fill characteristics of the paleokarst reservoirs. The results of this study can provide fundamental meter-scale datasets for interpreting detailed geologic features of deeply buried paleocaves, can be used to connect core- and seismic-scale interpretations, and can provide support for the recognition and development of these strongly heterogeneous reservoirs.