Ana Jesús Hernández

Accumulating behaviour of Lupinus albus L. growing in a normal and a decalcified calcic luvisol polluted with Zn

Lupinus albus L. is a leguminous plant that is starting to generate interest for the phytoremediation soils showing intermediate metal pollution. Among these metals, Zn causes major phytotoxicity problems and is common in polluted soils of central Spain. The purpose of this study was to explore the nutritional behaviour of this plant species towards increasing Zn concentrations in two calcic luvisol soils: a normal basic soil and a decalcified acid soil. For this purpose the effects of different Zn concentrations on mineral nutrition, growth, nodulation and nitrogenase activity of nodulated Lupinus albus cv. Multolupa plants has been investigated. A 12-week trial was performed in pots under greenhouse conditions. In each soil, four replicate pots were set up per treatment (100, 150, 300, 500 and 700 ppm Zn). Seeds were inoculated with a Bradyrhizobium sp. (Lupinus) strain ISLU-16. Statistical analysis of data revealed significant effects of soil Zn on grown, plant mineral composition and nodulation. Lupin growth was better in acid soil than in basic soil with the low dose of Zn applied, although plant growth in acid soil was severely affected from 300 ppm Zn, where the pH of the soil was 4.7. Zn application produce nutritional imbalances, especially with the higher dose added. Most of Zn accumulation occurred in the roots in both types of soils. In acid soil, lupin absorbs high amounts of Zn in both root (4650 ppm) and aerial part (3605 ppm), when the doses of Zn applied was 300 ppm. This feature permits Lupinus albus cv. Multolupa to be considered as potential phytoremediator and also for the revegetation of degraded landfill areas with slightly acid or neutral soils polluted with Zn.

Biotic indices based on soil nematode communities for assessing soil quality in terrestrial ecosystems.

Nematode communities offer several advantages for assessing the quality of soils. Diversity and maturity indices as well as trophic structure defining parameters based on the composition of soil nematode communities have been used to detect various kinds of man-induced disturbances and monitor ecological recovery. In the present paper we examined the response of these indices in herbaceous Mediterranean ecosystems. Incipient soils, which were developed on the top of waste dumping sites were compared with agricultural soils under fallow. Grasslands and old-fields were considered as reference systems. Either diversity or maturity indices were shown to be very sensitive to changes in soil system caused by waste dumping. However, they were less useful for the categorisation of perturbation in agroecosystems. Trophic composition related parameters were more meaningful for this aim. Plant parasite index (PPI) may be a good generic indicator of recovery processes after perturbation in these annual herbaceous ecosystems.

Soil salination from landfill leachates: effects on the macronutrient content and plant growth of four grassland species

In a greenhouse pot bioassay, four wild herbaceous species were tested for their response to three landfill leachates with different degrees of contamination. Irrigation with leachates gradually increased soil salinity significantly. The responses of each species to soil salination were different. H. murinum was the most salt-tolerant species and the legumes were the most sensitive, especially T. tomentosum. The Na content in grasses and legumes gradually increased under the leachate treatments, while the Ca and Mg content also increased, in the legume species. The phytomass production was altered by the leachate supply. The dry weight of legumes and grasses decreased significantly when they were under the most contaminated leachate treatment.

Assessment of field portable X-ray fluorescence spectrometry for the in situ determination of heavy metals in soils and plants

In soil pollution studies, large numbers of soil samples collected at random need to be processed and analyzed to determine their heavy metal contents. This study was designed to assess the use of a field portable X-ray fluorescence (FPXRF) spectrometry system for the in situ determination of heavy metal levels in both soil and plant samples. First, we optimised the method using 84 reference soil standards and soil samples from known polluted sites. The optimised method was then used to determine heavy metals at three abandoned mine sites and two sealed landfills in central Spain. Given that knowledge of heavy metal levels in plants is important for the ecotoxicological study of these sites, the FPXRF device was also used to determine heavy metals in plants. Our results indicate the acceptable to high quality of the data provided by the system especially for soil samples. The cost-benefits and sustainability of this instrument in relation to other techniques were also examined. The use of the FPXRF system for the study of potentially polluted sites was found to save on costs, time and materials. Results indicate its suitable use for the preliminary screening of heavy-metal polluted sites.

Impact of Municipal Waste on Mediterranean Dry Environments

We studied the physical characteristics and the main chemical components found in sealed municipal landfills in semi‐arid environments. This research was focused primarily on the identification of the main limiting factors for establishment and growth of plants on landfill surfaces, and the comparison of these factors with other soils in the area. Such information may be applicable to the future use of landfill sites. Variance analysis of our soil data showed that significant differences existed for 20 of the 36 parameters analyzed. The percentage of bare soil was much higher in landfills. Fine sand, silt, apparent density, and structural instability were greater in landfill covers than in other types of habitats. Field capacity and wilting point were low, and soil permeability to water was very low in the landfill covers. Electrical conductivity and pH were clearly higher in these environments, while organic matter and total N were much lower. Chloride, sulfate, fluoride, and sodium content were higher i...

Chemical characteristics of sedimentary soils in the Mediterranean environment: a comparison of undisturbed and disturbed soils

Abstract In many ecosystems, especially in siliceous soils, the mobile anion balance controls the entire ionic equilibrium. However, the equilibrium of the mobile anion cycle is very fragile, and many factors—abiotic, biotic and, above all, human—constantly disturb it. This paper reports a study of the principal anions found in the surhcial layer of soils situated over sedimentary substrates in a continental Mediterranean environment, primarily in semiarid regions. Human (deforestation) and animal activities over decades (overgrazing, trampling) have altered these soils to different degrees. Recently, their use in some cases as landfills for solid waste has become one of the major causes of disturbance. Comparisons are made in order to highlight the differences among soil types and those between the disturbed sites and surroundings. The results show that natural soils are poor in soluble anions. It is also possible to distinguish clear differences in the average concentrations found in three different natural substrates. Finally, there are notable elevated concentrations of Cl and SO4 in landfill soils.

Ecotoxicological studies on effects of landfill leachates on plants and animals in Central Spain

Abstract Actually the production of domestic waste is increasing so much that waste disposal has become a serious problem in many countries in terms of both difficulty in obtaining a location for their disposal and concern for the hazard to the human-environment system. In Spain, landfill is the most common method of municipal solid waste disposal. Water percolating through wastes dissolves inorganic and organic components, thereby producing contaminated leachates which in many cases join water superficial streams. In this paper we study the effects of leachates from landfills located on siliceous soils on plants and animals. In addition some inorganic components of leachates (SO 4 2− and F − ) are considered individually. For animal experimentation a population of Rattus norvegicus is used, and weight increase is the main parameter studied. In the case of plants, the growth of two species — a grass Hordeum murinum L. and a legume Trifolium tomentosum L., both representative of the flora of the area, is tested. In the case of animals results show differences between treatments, synthetical leachates being the most toxic. For plant species the ecotoxicological impact is not so important and differences between species are minor too.

Integrated approach to assessing the effects of soils polluted with heavy metals on a plant population

This study addresses the effects of soil polluted with more than one heavy metal in a grass species. A 16-week bioassay with Avena sativa L. was conducted in microcosms using soils from two abandoned mines in central Spain that contained levels above World Health Organization (WHO) reference limits for soils of more than three heavy metals. Pollution effects were examined at cell, tissue, organ, plant and population levels. For this purpose, dry weight, maximum height and number of leaves were determined; leaf tissues were observed by low temperature scanning electron microscopy; the metal contents of roots and shoots were determined by plasma emission spectroscopy and their distribution in different tissues was analyzed by X-ray microanalysis using an environmental scanning electron microscope. The results explain the accumulation and translocation of soil metals by this plant species; their effects in cells, tissues and growth of plants; and allow inference on population effects. The discussion of the methodological approach leads us to propose a valid protocol to assess the effects of a set of heavy metals present in the topsoil of polluted sites on a plant population. We recommend its use for an ecotoxicological diagnosis and risk analysis of similarly polluted sites.

Heavy-Metal phytostabilizing potential of Agrostis castellana Boiss. & Reuter

The soils of many abandoned mine sites in the central region of Spain are heavily polluted with a number of different metals. Having frequently found Agrostis castellana growing at these old mine sites, this study was designed to assess its remediation capacity for this type of setting. In an initial field study, plant specimens were collected from 4 abandoned mine sites to determine pollutant concentrations in their roots and shoots. This was followed by a 4-year bioassay in a controlled environment in which soils collected from the mines were used to set up microcosms. Maximum root concentrations of the most polluting elements present in the bioassay were 3625 mg kg−1 Zn, 2793 mg kg−1 Cu, 13042 mg kg−1 Pb, 49 mg kg−1 Cd and 957 mg kg−1 As. These concentrations represent root bioaccumulation indices of over 1 and usually >2. In contrast, indices of transfer to above-ground phytomass were always < 1, indicating this species is a good candidate for use as a phytostabilizer. However, the high metal concentrations that could reach the above-ground mass of this plant determines a need for close monitoring and avoiding the use of areas under restoration for hunting or grazing.

Soil fertility and GIS raster models for tropical agroforestry planning in economically depressed and contaminated Caribbean areas (coffee and kidney bean plantations)

In the jaragua-bahoruco-enriquillo biosphere reserve, located on the southern border between the Dominican Republic and Haiti, there are depressed rural areas with soils with high content in Cadmium and other heavy metals which originate naturally in the geological substrate. Data from 80 soils and an inventory of 76 plantations (coffee and kidney bean were used) to design a GIS (geographic information systems) tool which integrated statistical multivariate methods, soil parameters including heavy metal content into models of land planning, agricultural development, forests and protection of the health of the area’s inhabitants and the natural environment. This GIS tool is based on raster models of an open source, which use combination and reclassification operations based on the maps, geostatistical methods (Kriging), statistical analyses external to the GIS, and cartography of limiting and excluding particular factors for crops (including heavy metal soil content). The GIS tool developed discriminates extreme situations in sustainable agroforestry planning in contaminated rural areas of the Caribbean, Central America and other tropical regions.