The concentration levels of cadmium and lead in 250 horizon samples from 125 different soil profiles of undisturbed soils of La Rioja, Spain, were determined. Knowledge of regional contents as well as the variability and background values of trace elements in soils is of critical importance to assess human impact on the soil environment and to determine baseline values and quality standards. Heavy-metal horizontal distribution was mainly affected by the nature of the bedrock and, to a smaller extent, anthropogenic activity. Vertical distributions were mainly of a natural origin depending first on the bedrock and second on the result of soil processes.

Land degradation can be triggered by the abuse of chemicals that damage soil quality. Agriculture is changing the chemical and physical properties of soils, and in vineyards, those changes are due to the use of pesticides. In order to assess the Pb and Cd content, 212 soil samples from La Rioja D.O.Ca were analysed. Concentrations of Pb in soil ranged from 0·96 to 64·31 mg kg À1 with a mean concentration of 21·26 mg kg À1 in the surface layer, while they ranged from 7·97-43·93 mg kg À1 with a mean of 20·83 mg kg À1 in the subsurface layer. The mean content of bioavailable lead was 1·03 mg kg À1 in the surface layer and 0·76 mg kg À1 in the subsurface. Cd overall average concentration was 0·29 mg kg À1 in the surface; in the subsurface, the mean was 0·31 mg kg À1 and ranged from 0·10 to 1·22 mg kg À1 . The values in the surface layers were 0·15 mg kg À1 and in the subsurface layer 0·01 of Cd bioavailability. On the basis of pedogeochemical Pb and Cd distribution, balanced fertilization will be of great importance for sustainable development of agricultural wine-producers.

The goal of the present work was to increase our knowledge on the behavior of manganese and nickel in soil within a Mediterranean environment. The study assessed the concentration levels of Mn and Ni (heavy metals selected for their essential role in the development of plants) in 250 soil horizon samples within 125 soil profiles of undisturbed soils in La Rioja (Spain). The study was undertaken to investigate and predict Mn and Ni concentrations on a regional scale. The analysis of spatial distribution of the elements was found to be affected by the nature of bedrock and, to a lesser extent, the anthropogenic origin. The variation of vertical distributions can be related, first, to natural sourcesmainly the bed rocks-and, second, to soil processes. The geographical distribution of soil Mn is important to agriculture, nutrition, and health. Soil Mn and Ni maps of the area were elaborated, using geostatistics and geographic information systems. Mapping of geographical distributions will be useful in future research to determine regional patterns of Mn and Ni bioavailability, Mn and Ni deficiencies, and the possible consequences of land disposal of Mn-and Ni-laden wastes.

The aim of this study was to determine the concentrations of Cu and Zn in soils in the vineyards of La Rioja and to calculate reference values for the two elements. Samples were taken from the surface horizon (0–20 cm) and the subsurface horizon (40–60 cm) in 106 locations. Some physico-chemical properties were analyzed along with the total and bioavailable contents of these elements. Various statistical parameters were calculated, and distribution maps were then created using the ordinary-Kriging method. The Cu content was in the range of 2.46–121.52 mg kg–1, and the Zn content was 9.05–125.67 mg kg–1. These values fell within the normal ranges in comparison with other areas of Spain and the rest of Europe. The concentrations in the surface and in the subsurface were compared; in the case of Cu, the concentration was higher at the surface, whereas significant differences in the vertical distribution of Zn were not observed. Both metals had a heterogeneous distribution across the entire area of study. In the case of Zn, the similarity of the maps between surface and depth was verified, while the case of Cu was different. The main source of these metals was the parent material from which the soil had been formed, but in the case of Cu, maps showed increased Cu at the surface, which was especially marked at certain points and seemed to indicate the presence of an exogenous contribution at these locations. That means that the copper concentrations in the topsoil resulted from the yearlong grapevine protection with copper-based agents. Reference values were calculated to be 85.28 and 48.88 mg kg–1 of Cu and 83.69 and 72.05 mg kg–1 for Zn at the surface and at depth, respectively.

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