Identification of Metal Contamination Sources and Evaluation of the Anthropogenic Effects in Soils near Traffic-Related Facilities

Traffic-related facilities typically have much lower metal emissions than other sources; however, they can be numerous and widespread as well. Subdividing pollution sources is necessary to assess soil contamination characteristics and identify sources according to the contamination cause. Anthropogenic contamination by metals was quantitatively determined using contamination factor (Cf) and evaluated using multivariate analysis. More than half of the concentrations for Zn, Pb, and Cu in soils were higher than that in the natural background (NB). Cf of metals was, in decreasing order, Zn > Pb = Cu > Ni = As. Zn, Pb, and Cu were identified as anthropogenic contaminants in correlation analysis. Principal component analysis showed that the two main contamination causes were coarse particles from the maintenance or crushing activities of vehicles and nonexhaust/exhaust emissions. Clusters were classified according to those two anthropogenic and lithogenic causes and included Group I (Zn, Pb, and Cu in garages, auto repair shops, and auto salvage yards), Group II (Zn, Pb, and Cu in parking lots, driving schools, and roadsides), and Group III (As and Ni with high lithogenic properties). Anthropogenic input and sources of soil contamination by metals in traffic-related facilities were appropriately estimated through the combination of Cf and multivariate analysis.

Spatial Distribution of Available Trace Metals in Four Typical Mediterranean Soils: The Caia Irrigation Perimeter Case Study

There is a small sample of edaphic geochemistry studies over large geographic areas, especially studies that consider major reference soil groups (RSG) that evaluate both native concentrations of elements and anthropogenically contaminated soils in agricultural settings, considering the long-term effect of agricultural practices on landscape sustainability. In this study, four RSGs were analyzed for the available trace elements Ni, Cr, Cd, Pb, Cu, Mn, and Zn, including other edaphic properties from 2002 to 2012. The main objectives were to assess the range of concentrations of the selected elements in the four typical Mediterranean soils, Cambisols, Luvisols, Calcisols, and Fluvisols, with heavy anthropogenic input (HAI) and compare them to minimal anthropogenic input (MAI). For MAI, the background levels of Pb, Ni, Cd, and Cr were highest in Calcisols, differing from those of Cambisols, Luvisols, and Fluvisols (p < 0.01), Cu is highest both in Calcisols and Luvisols while Mn is higher in Cambisols and Fluvisols (p < 0.05). The background concentration of Zn was the same in all RSGs (p > 0.05). For HAI, the reference levels of Pb, Ni, Cd, Mn, and Cr were highest in the Calcisols, and Cu was high in all RSGs except Fluvisols, while Zn presented the lowest concentrations in the Luvisol RSG, with all these results considering a confidence interval of 95%. Predictive maps for the sampled elements, as well as the edaphic bioavailability, are provided. This environmental impact assessment suggests that the land use is departing from sustainable ecosystem service development and that territorial management practices, with conservation goals in mind, should be adopted.

Radiocarbon in modern carbon cycle research

&lt;p&gt;Atmospheric nuclear weapon testing in the 1950s and 1960s has been worrying, however, in many aspects it was extremely beneficial for environmental sciences. The artificial production of more than 6 x 10&lt;sup&gt;28&lt;/sup&gt; atoms or about 0.6 tons of radiocarbon (&lt;sup&gt;14&lt;/sup&gt;C), leading to a doubling of the &lt;sup&gt;14&lt;/sup&gt;C/C ratio in tropospheric CO&lt;sub&gt;2&lt;/sub&gt; of the Northern Hemisphere, has generated a prominent spike in 1963. This &amp;#8220;bomb-spike&amp;#8221; has been used as transient tracer in all compartments of the carbon cycle, but also to study atmospheric dynamics, such as inter-hemispheric and stratosphere-troposphere air mass exchange. Moreover, our attempt to accurately determine total bomb produced &lt;sup&gt;14&lt;/sup&gt;C led to improved estimates of the atmosphere-ocean gas exchange rate and to a new constraint of the residence time of carbon in the terrestrial biosphere. Today, the transient bomb-radiocarbon signal has levelled off, and the anthropogenic input of radiocarbon-free fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; into the atmosphere has become the dominant driver of the &lt;sup&gt;14&lt;/sup&gt;C/C ratio in global atmospheric CO&lt;sub&gt;2&lt;/sub&gt;. The observed decreasing &lt;sup&gt;14&lt;/sup&gt;C/C trend in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; may thus help scrutinising the total global release of fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; into the atmosphere. On the local and regional scale, atmospheric &lt;sup&gt;14&lt;/sup&gt;C/C measurements are already routinely conducted to separate fossil fuel from biogenic CO&lt;sub&gt;2&lt;/sub&gt; signals and to estimate trends of regional fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; emissions. Some prominent examples where the bomb &lt;sup&gt;14&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; disturbance has been successfully used to study dynamic processes in the carbon cycle are discussed as well as our current activities applying this unique isotope tracer for continental scale carbon cycle budgeting.&lt;/p&gt;

Hydrogeochemistry and groundwater flow mechanisms in shallow aquifer in Yaoundé, Cameroon

Hydrogeochemical processes and flow mechanisms of groundwater in the urban area of Yaoundé were investigated using major chemical constituents, stable isotopes (18O and 2H), and multivariate statistical analysis. Thirty five groundwater samples were collected and analysed for various parameters. Hydrogeochemical evolution visualized with the Gibbs diagram showed that the groundwater is mainly controlled by water–rock interactions. Factor analysis on the other hand identified three major groups of geochemical constituents and showed that weathering and anthropogenic inputs are the dominant factors controlling groundwater chemistry in the study area. Isotopic analyses revealed that oxygen-18 of groundwater (18O = −2.96 ‰ VSMOW) is close to that of rainfall (18O = −2.47), indicating that the groundwater is recharged by rainwater without evaporation. The geogenic composition of urban groundwater in Yaoundé is modified by secondary processes and anthropogenic input.

Radiocarbon in modern Carbon Cycle research

&lt;p&gt;Atmospheric nuclear weapon testing in the 1950s and 1960s has been worrying, however, in many aspects it was extremely beneficial for environmental sciences. The artificial production of more than 6 x 10&lt;sup&gt;28&lt;/sup&gt; atoms or about 0.6 tons of &lt;sup&gt;14&lt;/sup&gt;C, leading to a doubling of the &lt;sup&gt;14&lt;/sup&gt;C/C ratio in tropospheric CO&lt;sub&gt;2&lt;/sub&gt; of the Northern Hemisphere has generated a prominent &lt;sup&gt;14&lt;/sup&gt;C spike in 1963. This &amp;#8220;bomb-spike&amp;#8221; has been used as transient tracer in all compartments of the carbon cycle, but also to study atmospheric dynamics, such as inter-hemispheric and stratosphere-troposphere air mass exchange. Moreover, our attempt to accurately determine total bomb produced &lt;sup&gt;14&lt;/sup&gt;C led to improved estimates of the atmosphere-ocean gas exchange rate and to a new constraint of the residence time of carbon in the terrestrial biosphere. Today, the transient bomb-radiocarbon signal has levelled off, and the anthropogenic input of radiocarbon-free fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; into the atmosphere has become the dominant driver of the decreasing &lt;sup&gt;14&lt;/sup&gt;C/C ratio in atmospheric CO&lt;sub&gt;2&lt;/sub&gt;; the observed trend may thus help scrutinising the total global release of fossil fuel CO&lt;sub&gt;2&lt;/sub&gt; into the atmosphere. Prominent examples where the bomb &lt;sup&gt;14&lt;/sup&gt;C disturbance has been successfully used to study dynamic processes in the carbon cycle are discussed as well as our current activities applying this unique isotope tracer for continental scale carbon cycle budgeting.&lt;/p&gt;

Seasonal movement of trace-element discharge in a typical south-Indian suburban community

Four conventional activated sludge sewage treatment plants (STPs) in Southern India were chosen to investigate the occurrence of major ions and trace metals in dissolved fraction of the wastewater. Samples were collected from inlet and outlet of STPs during the pre-monsoon and monsoon seasons. Except for a few elements (Mn, Mo and Ni), the concentrations of the rest increased at the outlet of STPs, suggesting that there is an addition of these elements during the treatment process. The increase in concentrations at the STP outlet ranged from 1.25 times for Mn to 3,254 times for Ag during the pre-monsoon. In the monsoon, the increase ranged from 1.75 (Fe) to 1,510 (Ag). This suggests that there is a substantial anthropogenic input of these elements as they pass through the treatment process. Removal rates of elements in STPs also varied. 59% of Mn was removed during the treatment process during pre-monsoon as compared to 67% removal during monsoon.