Salinity mapping of coastal groundwater aquifers using hydrogeochemical and geophysical methods: a case study from north Kelantan,Malaysia

Integrated hydrogeochemical and geophysical methods were used to study the salinity of groundwater aquifers along the coastal area of north Kelantan. For the hydrogeochemical investigation, analysis of major ion contents of the groundwater was conducted, and other chemical parameters such as pH and total dissolved solids were also determined. For the geophysical study, both geoelectrical resistivity soundings and reflection seismic surveys were conducted to determine the characteristics of the subsurface and groundwater contained within the aquifers. The pH values range from 6.2 to 6.8, indicating that the groundwater in the study area is slightly acidic. Low content of chloride suggests that the groundwater in the first aquifer is fresh, with an average concentration of about 15.8 mg/l and high geoelectrical resistivity (>45 ohm m). On the other hand, the groundwater in the second aquifer is brackish, with chloride concentration ranging from 500 mg/l to 3,600 mg/l and very low geoelectrical resistivity (<45 ohm m) as well as high concentration of total dissolved solids (>1,000 mg/l). The groundwater in the third aquifer is fresh, with chloride concentrations generally ranging from 2 mg/l to 210 mg/l and geoelectrical resistivity of greater than 45 ohm m. Fresh and saltwater interface in the first aquifer is generally located directly in the area of the coast, but, for the second aquifer, both hydrogeochemical and geoelectrical resistivity results indicate that the fresh water and saltwater interface is located as far as 6 km from the beach. The considerable chloride ion content initially suggests that the salinity of the groundwater in the second aquifer is probably caused by the intrusion of seawater. However, continuous monitoring of the chloride content of the second aquifer indicated no significant changes with time, from which it can be inferred that the salinity of the groundwater is not affected by seasonal seawater intrusion. Schoeller diagrams illustrate that sulphate concentrations of the groundwater of the second aquifer are relatively low compared to those of the recent seawater. Therefore, this result suggests that the brackish water in the second aquifer is probably from ancient seawater that was trapped within the sediments for a long period of time, rather than due to direct seawater intrusion.     

Reclamation planning for coal mine in Istanbul, Agacli Region

This paper outlines mining aspect of view to reclamation studies based on rather simpler but more practical analyses in terms of legislations and regulations in Turkey. This paper also presents the results of various multi-disciplinary experimental studies aimed at the development of a reclamation proposal for an open pit mine located in the Istanbul Agacli region. Within the scope of this study, the current conditions and environmental features of the working area and its surrounding were evaluated. Various experimental studies were carried out on the representative samples taken from the overburden material and water sources in order to detect the existence of any contamination and also to determine the properties of samples subjected to the reclamation. Then, both environmental features and the results of experimental studies of the working area were evaluated. At the end of the evaluation, a simple and practicable reclamation proposal was developed.     

Evidence that Lake Cheko is not an impact crater

In a provocative paper Gasperini et al. (2007) suggest that Lake Cheko, a ～300‐m‐wide lake situated a few kilometres downrange from the assumed epicentre of the 1908 Tunguska event, is an impact crater. In this response, we present several lines of observational evidence that contradicts the impact hypothesis for the lake’s origin: un‐crater‐like aspects of the lake morphology, the lack of impactor material in and around the lake, and the presence of apparently unaffected mature trees close to the lake. We also show that a tensile strength of 10–40 MPa is required for an asteroid fragment to traverse the Earth’s atmosphere and reach the surface intact and with sufficient velocity to excavate a crater the size of Lake Cheko. Inferred tensile strengths of large stony meteorites during atmospheric disruption are 10–100 times lower. We therefore conclude that Lake Cheko is highly unlikely to be an impact crater.     

Evidence for photic‐zone euxinia in the Early Albian Santana Formation (Araripe Basin,NE Brazil)

Organic matter from two black shale units in the Santana Formation, Araripe Basin, NE Brazil, has been studied to investigate the palaeoenvironmental conditions prevailing during formation of this famous fossil lagerstätte. Optical and organic geochemical analyses indicate a predominantly autochthonous source with very limited terrestrial input. Molecular fossils of green sulphur bacteria show that the water column was stratified with euxinic conditions reaching up into the photic zone. Thus, mass‐mortality events of fish may be explained by intrusion of sulphide‐containing waters. The low quantity of material derived from land plants in this interior marine setting is interpreted to reflect a consequence of enhanced marine productivity, resulting in dilution of the continental signal. Different depositional scenarios are proposed to explain our findings including (1) coastal erosion and nutrient leaching during a transgressive event, (2) intrusion of euxinic waters during an early Albian OAE or (3) an estuarine circulation pattern associated with thermohaline stratification.     

The solubility of molybdenum dioxide and trioxide in HCl-bearing water vapour at 350 °C and pressures up to 160 bars

The solubility and speciation of the assemblage MoO₂-MoO₃ in water vapour were investigated in experiments conducted at 350 °C, P_total from 59 to 160 bar and fHCl from 0 to 3.4 bar (0-2.0 mol%). Measured solubility at these conditions ranges from 22 to 2500 ppm (∑fMo from 4.4 × 10⁻⁴ to 6.5 × 10⁻² bar). The concentration of Mo in the vapour at fHCl below 0.1 bar is similar to that in pure water vapour, but increases by two orders of magnitude at fHCl above 0.1 bar. The fugacity of gaseous Mo species is independent of chloride concentration at fHCl below 0.1 bar, but increases with increasing fHCl above this pressure. The dominant Mo species at fHCl below 0.1 bar is interpreted to be the same as it is in pure water vapour, and to form as a result of the reaction

(A1)     

A new method for three-carrier GNSS ambiguity resolution

A new method for resolving the carrier-phase integer ambiguity in Global Navigation Satellite Systems (GNSS) is presented: the MOdified Cholesky factorization for Ambiguity (MOCA) resolution. The characteristics and features of this method are described and results obtained using a software simulator and an emulator are presented to validate its efficiency. The results are then compared to those obtained using another existing method and good performance of the MOCA method in new GNSS systems is shown. Furthermore, the proposed method yields accurate results even when short time spans are used or when there are poor estimations of measurement error, making it immune to non-ideal conditions and ultimately a practical solution for real applications.     

Grid-based performance evaluation of GCM-RCM combinations for rainfall reproduction

Prior to hydrological assessment of climate change at catchment scale, an applied methodology is necessary to evaluate the performance of climate models available for a given catchment. This study presents a grid-based performance evaluation approach as well as an intercomparison framework to evaluate the uncertainty of climate models for rainfall reproduction. For this purpose, we used outputs of two general circulation models (GCMs), namely ECHAM5 and CCSM3, downscaled by a regional climate model (RCM), namely RegCM3, over ten small to mid-size catchments in Rize Province, Turkey. To this end, five rainfall-borne climatic statistics are computed from the outputs of ECHAM5-RegCM3 and CCSM3-RegCM3 combinations in order to compare with those of observations in the province for the reference period 1961–1990. Performance of each combination is tested by means of scatter diagram, bias, mean absolute bias, root mean squared error, and model performance index (MPI) measures. Our results indicated that ECHAM5-RegCM3 overestimates the total monthly rainfall observations whereas CCSM3-RegCM3 tends to underestimate. In terms of maximum monthly and annual maximum rainfall reproduction, ECHAM5-RegCM3 shows higher performance than CCSM3-RegCM3, particularly in the coastland areas. In contrast, CCSM3-RegCM3 outperforms ECHAM5-RegCM3 in reproducing the number of rainy days, especially in the inland areas. The results also revealed that if a GCM-RCM combination performs well for a portion (statistic) of a catchment, it is not necessarily appropriate for the other portions (statistics). Moreover, the MPI measure demonstrated the superiority of ECHAM5-RegCM3 to CCSM3-RegCM3 up to 33 % excelling for annual rainfall reproduction in Rize Province.     

A review of volunteered geographic information quality assessment methods

With the ubiquity of advanced web technologies and location-sensing hand held devices, citizens regardless of their knowledge or expertise, are able to produce spatial information. This phenomenon is known as volunteered geographic information (VGI). During the past decade VGI has been used as a data source supporting a wide range of services, such as environmental monitoring, events reporting, human movement analysis, disaster management, etc. However, these volunteer-contributed data also come with varying quality. Reasons for this are: data is produced by heterogeneous contributors, using various technologies and tools, having different level of details and precision, serving heterogeneous purposes, and a lack of gatekeepers. Crowd-sourcing, social, and geographic approaches have been proposed and later followed to develop appropriate methods to assess the quality measures and indicators of VGI. In this article, we review various quality measures and indicators for selected types of VGI and existing quality assessment methods. As an outcome, the article presents a classification of VGI with current methods utilized to assess the quality of selected types of VGI. Through these findings, we introduce data mining as an additional approach for quality handling in VGI.     

Isoprene and Its Oxidation Products Methyl Vinyl Ketone, Methacrolein, and Isoprene Related Peroxides Measured Online over the Tropical Rain Forest of Surinam in March 1998

Airborne measurements of volatile organic compounds (VOC) were performed overthe tropical rainforest in Surinam (0–12 km altitude,2°–7° N, 54°–58° W) using the proton transferreaction mass spectrometry (PTR-MS) technique, which allows online monitoringof compounds like isoprene, its oxidation products methyl vinyl ketone,methacrolein, tentatively identified hydroxy-isoprene-hydroperoxides, andseveral other organic compounds. Isoprene volume mixing ratios (VMR) variedfrom below the detection limit at the highest altitudes to about 7 nmol/molin the planetary boundary layer shortly before sunset. Correlations betweenisoprene and its product compounds were made for different times of day andaltitudes, with the isoprene-hydroperoxides showing the highest correlation.Model calculated mixing ratios of the isoprene oxidation products using adetailed hydrocarbon oxidation mechanism, as well as the intercomparisonmeasurement with air samples collected during the flights in canisters andlater analysed with a GC-FID, showed good agreement with the PTR-MSmeasurements, in particular at the higher mixing ratios.Low OH concentrations in the range of 1–3 × 10⁵molecules cm^-3 averaged over 24 hours were calculated due to lossof OH and HO₂ in the isoprene oxidation chain, thereby stronglyenhancing the lifetime of gases in the forest boundary layer.     

Gewässergütebewertung und Bewertung von Abwasserfahnen in Rhein und Main auf der Basis mikrobieller Enzymaktivitäten

Quality Mapping of Surface Water and Assessment of Treated and Untreated Waste-water Inputs into the Rhine and Main River Based on Microbial Enzyme Activities Microbial enzyme activities are used for an extension of the traditional quality mapping of surface water. In the following study, the enzymatic parameters were proved and validated on samples from various creeks and rivers in Baden-Württemberg and on samples gathered from the Rhine and Main Rivers (Germany). The test parameters should also be used for the control and the preservation of the capacity of the biological self-purification, which is the only natural and essential process in drinking-water conditioning of surface water. Main subject of the surveys was the development of criteria for an assessment of the measured enzymatical inhibition effects. Therefore, classes of inhibition and indices of inhibition are defined.