Hydrogeological and hydrochemical features of an area polluted by heavy metals in central Nicaragua

Geophysical and hydrochemical surveys were used to investigate the hydrogeological conditions in one of the Río Sucio microbasins, in central Nicaragua. Zones of vertical structures (i.e. fractures and quartz veins) and weathering were mapped using Continuous Vertical Electrical Soundings (CVES), as such zones are of major importance for groundwater transport. Water from the springs was analysed to determine concentrations of major ions and heavy metals. Low ion concentrations and ¹⁸O analyses indicate that the springs occur close to their recharge areas and there is a relatively rapid groundwater circulation. Mercury (Hg) content in the springs was low, while comparatively high amounts of lead (Pb) were found. The results presented here demonstrate the important function of weathering and tectonics in the occurrence of groundwater systems in the basin. Hg and Pb found in the springs’ water reveal the existence of an increase in pollution sources disseminating in the area. More than 100 years of using mercury in the gold-mining industry and releasing wastes into rivers has affected water quality and ecosystems. Further investigations are needed in this area to determine the groundwater vulnerability to this pollution as this resource may be needed in the future.The online version of the original article can be found at     

Temperature variability in central Mexico and its possible association to solar activity

Minimum extreme temperature variability from five meteorological stations in the central part of Mexico covering a period from 1920 to 1990 is examined. We found a correlation coefficient (r=0.65) between these temperature records and geomagnetic activity. Furthermore, by performing spectral analysis peaks were obtained with similar periodicities to those found in the sunspot number, the magnetic solar cycle, cosmic ray fluxes and geomagnetic activity; all of these phenomena are modulated by solar activity. Signals with periodicities comparable to those observed in El Niño and the Quasi-Biennial Oscillation were also identified. We conclude that the solar signal is probably present in the minimum extreme temperature record of the central part of Mexico.     

The year-long unprecedented European heat and drought of 1540 – a worst case

The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km², we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.     

A reassessment of the soil sink for atmospheric carbon tetrachloride based upon static flux chamber measurements

Static flux chamber measurements of CCl₄ uptake by soils in boreal, subtropical and tropical forests have been used to reassess the sink strength for this ozone depleting chemical. Happell and Roche (Geophys. Res. Lett. 30(2), 1088–1091, 2003) used flux estimates from soil concentration gradients to calculate a partial CCl₄ atmospheric lifetime (τ_soil) of 90 years. More recently, it is has been assumed that a better estimate of τ_soil is 195 years (Montzka et al. 2011). In the work here, the rate of CCl₄ uptake was calculated from 453 flux chamber measurements using an exponential fit to the chamber CCl₄ concentration change with time. This analysis indicated that the flux rate estimate in Happell and Roche (Geophys. Res. Lett. 30(2) 1088–1091, 2003) was overestimated by 2.75, yielding a new estimate of τ_soil for CCl₄ of 245 years. Significant correlations of CCl₄ uptake to temperature, soil moisture, or time of year were not observed. This work provides additional evidence that CCl₄ uptake by soils is a common process and needs to be considered when developing an atmospheric budget for this compound.     

软性海洋沉积物中水含量对XRF测试的影响

Avaatech型X荧光扫描仪是由计算机控制的柱状样扫描装置,可以从剖开样品表面直接获得沉积物的化学组成,无需破坏样品的整体性。能够实现几乎连续的测试,快速地得到从Al到u的所有元素的相对含量。XRF扫描仪已经成功地应用于高分辨率、不同时间序列和时间尺度的地层对比以及沉积相和古气候重建。