Metal concentrations in the beach sediments of Bahia Solano and Nuquí along the Pacific coast of Chocó, Colombia: A baseline study

Thirty sediment samples from four different beaches along Bahia Solano and Nuquí (Department of Chocó) of eastern Colombia, with tourism and gold mining activities, were analysed to estimate the concentrations of fourteen different acid leachable metals. Metal distribution patterns showed elevated concentrations of Co, Cr, Cu, Pb and Zn compared with the upper continental crust values. Calculation of geochemical indices confirmed that the enrichment is due to periodic gold mining activities (severe to extremely severe enrichment of Cu, Zn, V, Co, Cr and Pb) along with natural (geological) contributions (minor and moderate enrichment of Ca, Mg, Fe, Ti, Mn and Li). Potential ecological risk index revealed that Pb posed the highest risk. Our results together with a global comparison suggest that the observed metal enrichments are mainly caused by mining and to a lesser extent by tourism in this region, thus instigating continuous monitoring of metal concentrations in this region. © 201

Seasonal variability of beach characteristics between Candoliam and Colva coast, Goa, India

<p>The aim of the present study was to investigate the seasonal impact on beach dynamics and the status of heavy mineral distribution along the study area. Beach profile measurements were made in 7  profiling sites between Candoliam and Colva on seasonal basis between pre-monsoon (May 2009) and monsoon (July 2009). Beach profile<br>data was used to calculate the variation in beach width, slope and volumetric changes. The seasonal action of wind and wave currents create near-shore bar and erosion of berms during monsoon. Surface sediment samples were collected from High Tide Line, High Water Line, Water Line and Low Water line to quantify the sediment texture and heavy<br>mineral weight percentage. The results reveal that the deposited sediment has been eroded during the monsoon season and the concentration of heavy mineral percentage increased from pre-monsoon to monsoon. The long-shore current measurement also shows that the current speed varies from pre-monsoon to monsoon. The results suggested that monsoonal action has influenced the seasonal changes in beach morphology and heavy mineral distribution. The beach profile helps to understand the change in the beach morphological characteristic.</p> <p> </p

Geochemical characteristics of stream sediments from an urban-volcanic zone, Central Mexico: Natural and man-made inputs

Geochemical characteristics of stream sediments [n = 31; Upstream section: Zahuapan River (1-12) and Atoyac River (13-20); Downstream section (21-31)] from Atoyac River basin of Central Mexico have been evaluated. The study focuses on the textural, petrography and chemical composition of the fluvial sediments with the aim of analyzing their provenance, the chemical weathering signature and their potential environmental effects. The fluvial sediments are mostly composed of sand and silt sized particles dominated by plagioclase, pyroxenes, amphiboles, K-feldspar, biotite, opaque and quartz. The sediments were analyzed for determination of major (Al, Fe, Ca, Mg, Na, K, P, Si, Ti), trace elements (As, Ba, Be, Co, Cr, Cu, Mo, Mn, Ni, Pb, Sc, V, Y, Zn, Zr, Ga) and compared with Upper continental crust (UCC), source area composition and local background values. The elemental concentrations were comparable with the average andesite and dacitic composition of the source area and the local background values except for enrichment of Cu (56.27. ppm), Pb (34. ppm) and Zn (235.64. ppm) in the downstream sediments suggesting a significant external influence (anthropogenic). The fluvial sediments of Atoyac River basin display low CIA and PIA values implying predominantly weak to moderate weathering conditions in the source region. Based on the provenance discrimination diagrams and elemental ratios, it is understood that the collected sediments are derived from intermediate to felsic volcanic rocks dominated in the study region. Metal contamination indices highlight the enrichment of Cu, Pb, Zn, Mo, Cr and S clearly indicating the influences from natural (weathering and volcanic activity) and external (anthropogenic) sources. Ecological risk assessment results indicate that Cr, Ni and Zn will cause adverse biological effects to the riverine environment