Geochemistry of Aluminium and Iron in Mine Soils from As Pontes,Galicia (N.W. Spain)

The geochemical processes influencing iron and aluminium mobilization and immobilization processes in mine soils are discussed. The study was carried out on 11 soils from the As Pontes mine dump, in the process of reclamation. The soils differ in age, spoils nature, reclamation tasks and type of vegetation, covering a wide range of physico-chemical conditions. Oxalate and pyrophosphate extractable Al and Fe (Alo, Alp, Feo, Fep), and dithionite extractable Fe (Fed) were analysed. These fractions were related to the solution Al and Fe forms and contents and to other soil properties (Eh, pH, sulfides, organic matter, cation exchange capacity, and composition of the soil solution). Alo ranged between 2.2 and 111.2 cmolc kg-1; 5 to 80% of this Alo was organic aluminium (Alp). Fed ranged between 8.5 and 215.6 cmolc kg-1; 20 to 70% was poorly-criystalline iron (Feo). The solution concentrations of Al and Fe ranged between <0.1 and 319.2, and between <0.1 and 46.7 mg L-1, respectively. The results showed that the spoil nature (mostly carbonaceous clays and slates differing in sulfide content) and the reclamation tasks undertaken (topsoiling, liming with fly ash) determine the forms and contents of Al and Fe in the solid phase as well as in the soil solution and also its distribution between the solid and liquid phases.     

Potassium fixation in suspensions of soils of Galicia (N.W. Spain)

Abstract

Potassium (K) fixation in soils treated with K‐rich fertilizer is important in limiting leaching of this ion, and thus the risk of high salinity in waters. We studied this capacity for aqueous suspensions of a group of soils of Galicia (N.W. Spain) and found that fixation increased with K dosage, increased slightly with contact time, and decreased with increasing temperature (between 3 and 40°C). Potassium fixation was barely influenced by the mineralogy of the clay fraction but was greater in soils with greater fine particle content. Modified Freundlich equation successfully modelled the effects of K addition, temperature, and contact time on fixation. The influence of temperature was greater in illitic soils than in mixed soils. The results indicate that Galician soils have little capacity for K fixation.     

Laboratory study of phosphate desorption kinetics in soils of Galicia (N.W. Spain)

Abstract

The kinetics of phosphate (P) desorption from surface horizons of 31 soils of Galicia (N.W. Spain) varied with the dose of added P (D = doses studied were equivalent to 200, 500, 1000, and 2000 μg P per g soil) and the soil‐P contact time (T = 7,180, and 360 days). Kinetic data for P desorption in aqueous suspensions of soil were fitted by zero order (Z), first order (F), second order (S), parabolic diffusion (PD), Elovich‐type (ET), and two‐constant equation (TC). TC equations gave the best fits (mean r² = 0.947±0.082). In linearized plots of Z, ET, and PD equations, the slope (K), which gives a measure of the rate of P desorption, increases with D and decreases with increasing T. In corresponding plots of F, S, and TC equations, K describes the constancy of the rate as P desorption progresses, and decreases with increasing D and increases with T. The y‐intercept of the above plots corresponded to a function of Co (the concentration of initially desorbable phosphate) in all cases. For all equations, Co increases dis‐ proportionately with D and exponentially with T. Since the kinetic parameters Co and K vary with sorption conditions, they cannot be considered characteristic of the tendency of a soil to release phosphate. A modified Freundlich equation with independent variables T, D, and t (soil‐water contact time) was also fitted to the kinetic data (mean R² = 0.959+0.031); the exponents (ß1, ß2, and ß3, respectively) of these independent variables indicate how each one influences P desorption in a given soil.     

Distribution of four major forms of potassium in soils of Galicia (N.W. Spain)

Abstract

The potassium (K) status of a group of Galician natural soils was evaluated, and the equilibria between the four main K forms were examined. The results indicated that the Galician soils studied contained a large mineral K fraction (97% of total K), and a smaller fraction of labile K forms, composed of non‐exchangeable (2%), exchangeable K and solution K (1%). For these soils, the exchangeable K was 38% of the non‐exchangeable K, which was consistent with the moderate development of these soils. The equilibrium between solution K and exchangeable K was displaced towards solution K.     

Isolation of amoebae of the genera Naegleria and Acanthamoeba from public fountains in Galicia (N.W. Spain)

Tests for free-living amoebae in water from 11 public fountains in Galicia were conducted at two seasons of the year, winter and summer. Only one fountain gave a negative result for the presence of amoebae in both samples. Twenty five strains were isolated, 14 belonging to the genus Acanthamoeba and 10 to the genus Naegleria. The Acanthamoeba strains were made up of the species A. polyphaga, A. quina, A. castellanii and A. paradivionensis. No relation was found between temperature, presence of free chlorine in the water and whether the water was drinkable and the presence or absence of amoebae, nor with the number of strains present in the water samples. The pathogenic capacity of the strains isolated from the genera Naegleria and Acanthamoeba was tested in vivo. It was found that of the 22 strains that would grow at 37 °C, 4 (3 strains of Acanthamoeba and 1 of Naegleria) caused the death of a statistically significant number of mice that had been inoculated intracerebrally, and the presence of amoebae was confirmed in the brains of all the animals inoculated. Intranasal inoculation caused less mice deaths than intracerebral inoculation, and less organs were found containing amoebae.     

巴西南部氧化土长期施用猪粪粪浆对土壤和地表水的影响

The accelerated expansion of swine production in Brazil has increased the generation of liquid wastes, which are usually applied to agricultural soils after a simplified treatment and pose potential environmental impacts. The objective of this study was to assess the agronomic and environmental impacts of long-term application of swine slurry(SS) on soil and stream water properties in watersheds dominated by Oxisols in Quinze de Novembro of Southern Brazil. Soil samples(0–30 cm) were collected from farms with continuous application of SS since 1990 at low(40–80 m3 SS ha-1year-1) and high(120–300 m3 SS ha-1year-1) rates of SS. Surface water samples were collected from streams adjacent to the farm fields. Long-term SS application did not change total organic C and particulate organic C compared to cropland and woodland soils without SS application. The high rates of SS increased total N, P, Cu,and Zn and available P and Cu in the topsoil(0–10 cm) compared to woodland and cropland soils without SS application. Surface water analyses showed that fecal coliform bacteria and biological oxygen demand exceeded the legal limits for high quality water(Class 1). Other water parameters(such as NO-3, phosphate and total suspended solids) were within the acceptable limits. Long-term disposal of SS in cropland under no-tillage had impaired water quality in Quinze de Novembro, especially biological parameters. Some best management practices should be adopted, including more rigorous control of SS application to cropland as well as requiring edge-of-field and riparian vegetative buffers.     

Family Dairy Farms in Galicia (N.W. Spain): Classification by Some Family and Farm Factors Relevant to Quality of Life

A survey of 103 family dairy farms in Galicia (N.W. Spain) collected information on 94 variables (78 quantitative, 16 qualitative) belonging to seven groups dealing with the location of the farm, family structure, sources of income, production variables, characteristics of the farm house (‘housing quality’), characteristics of the complex comprising farm house and farm buildings (the ‘central area’), and the characteristics and proximity to the farm house of the routes used for transit of cattle, fodder, slurry, etc. Following elimination of redundant variables, principal components analysis identified four factors accounting for about 40% of the total variance: three dominated each by a single a priori group (house–farm separation, central area, and housing quality), and one (production capacity) that combined production and source-of-income variables. Using these factors, the farms studied were subjected to hierarchical clustering by means of the Ward aggregation strategy, and a typology was established accordingly. Finally, guidelines for the design and improvement of farm installations and housing on Galician family dairy farms are sketched.     

Isolation of free-living pathogenic amoebae from thermal spas in N.W. Spain

We tested for the presence of free-living amoebae in water from 12 thermal spas in northwest Spain; 8 tested positive. No relationship was observed between temperature, pH or bacterial contamination and either the presence of amoebae or the, number of strains per sample. A total of 13 strains were found: 5 of Vahlkampfia, 2 of Naegleria, 3 of Acanthamoeba and 3 of other genera. Those Naegleria and Acanthamoeba strains which survived at 37 ? were tested for pathogenicity by intracerebral and intranasal inoculation of mice; only 2 strains (both of the species Acanthamoeba polyphaga) caused death.     

Study of buffering. Systems in soils from Galicia,N.W. Spain

Water, Air, & Soil Pollution - The effects of acid rain on surface horizons of five soils from Galicia and the buffer capacity of these soils with respect to the addition of H` were studied....     

Remediation of Pb-Contaminated Soils in the Guadiamar River Basin (SW Spain)

Soil remediation has been studied after a spill from a settling pond of a pyrite mine in Aznalcóllar (SW Spain). The affected area was approximately 55 km² and extended about 40 km from the spill. The Pb concentration in soils ranged from 35.8 to 3231.0 mg kg^-1, with a mean value of 385.8 mg kg^-1. The remediation techniques investigated included: manual and mechanical removal of the contaminated soil, mixing the upper part of the soils by ploughing, and addition of different amendment materials to reduce the Pb solubility, such as carbonates, zeolites, iron-rich soils, bentonites and yeasts. A combination of liming with iron-rich soils proved the most effective treatment.     

Arsenic Contamination in Soils Affected by a Pyrite-mine Spill (Aznalcóllar, SW Spain)

On 1998, a settling pond of a pyrite mine in Aznalcóllar (SW Spain) broke open, spilling some 3.6?×?10⁶ m³ of water and 0.9?×?10⁶ m³ of toxic tailings into the Agrio and Guadiamar river basin 40 km downstream, nearly to Doñana National Park. The soils throughout the basin were studied for arsenic pollution. Almost all the arsenic penetrated the soils in the solid phase (tailings) in variable amounts, mainly as a result of the different soil structure. The chemical oxidation of the tailings was the main cause of the pollution in these soils. A study of the relationships between the main soil characteristics and arsenic extracted with different reagents (water, CaCl₂, acetic acid, oxalic–oxalate and EDTA) indicates a direct relationship with the total arsenic concentration. The highest amount of arsenic was extracted by oxalic–oxalate (24%–36% of the total arsenic), indicating the binding with the iron oxides.     

Remediation of As-Contaminated Soils in the Guadiamar River Basin (SW, Spain)

In 1998, the pond containing the ore wastes from a pyrite mine in Aznalcóllar (SW, Spain) broke open, spilling some 36×10⁵ m³ of acidic waters and 9?×?10⁵ m³ of tailings containing high concentrations of As and heavy metals. The affected area was around 55 km² of predominantly agricultural soils. After the clean-up of the tailings, many remediation actions were undertaken and the use of blocking agents to immobilize the As was one of the most extended measure. The first experiment performed was to determine the most important soil components in As adsorption under acidic conditions. A second experiment was conducted to neutralize the acidity caused by the solution coming from the tailings undergoing oxidation; an adequate liming material (sugar-refinery scum) was selected and the application rates were established. After the remediation measures, the zone was monitored for three years. A detailed study in four experimental plots located in the most polluted sector was carried out to test the influence of iron oxides in the As immobilization. The use of red soils of the area (rich in free-iron oxides Fe_d) was established as an appropriate material in the remediation of the area.     

Limiting factors for reforestation of mine spoils from Galicia (Spain)

Mined areas are a continuing source of heavy metals and acidity that move off site in response to erosion. Revegetation of the mine tailings could limit the spread of these heavy metals and acidity. This study was conducted to evaluate, at four tailings on opencast mines of Galicia (Touro: copper mine; and Meirama: lignite mine, NW Spain), the chemical and physical soil quality indicators and limiting edaphic factors concerning forest production. Selected zones were: (1) The tailings formed by the waste materials from the depleted Touro mine; (2) the decantation site of deposited sludge coming from the copper extraction in the flotation stage; (3) and (4) tailings of 3 and 10 years old of the Meirama lignite mine. The main physical limitations of the mine soils are the low effective depth (<50 cm), high stoniness (>30 per cent) and high porosity (>60 per cent); which make them vulnerable to soil erosion and seriously interferes with the forest production. Soils coming from the decantation site of copper mine do not have physical limitations. The main chemical limitations of mine soils are their acidity (pH from 3·62 to 5·71), and aluminium saturation (>60 per cent in copper mine soils, and >20 per cent in lignite mine soils), low CECe (from 5·34 to 9·47 cmol₍₊₎ kg⁻¹), organic carbon (from 0·47 to 7·52 mg kg⁻¹) and Ca²⁺ and Mg²⁺ contents, and imbalance between exchange bases. Mine soils coming from the decantation site of copper mine soils are strongly limited by the high Cu content (1218 mg kg⁻¹). Lime and organic amendments are the most important factors in providing a suitable medium for plant growth. Copyright © 2004 John Wiley & Sons, Ltd.     

Aluminium Toxicity Risk for Pinus pinaster in Acid Soils (Galicia,NW Spain)

The influence of bedrock on aluminium toxicity and aluminium speciation in the soil solution was studied in four Pinus pinaster plots. Growth and biomass parameters in the acidic soils were also evaluated in relation to different Al toxicity indices. The plots were developed over slate, biotitic schist, mica schist and granite. Samples of rhizospheric and non‐rhizospheric soil, 1‐year‐old needles and roots were collected in each study plot. Total Al, reactive Al, acid‐soluble Al, non‐labile and labile Al and Al species (Al³⁺, Al‐OH, Al‐F and Al‐SO₄) were determined in soil solution. Reactive Al dominated over the acid‐soluble Al, and the non‐labile Al predominated over the labile Al in all soils, but particularly over mica schist. In the biotitic schist soil, the Al forms and total Al were lower, whereas concentrations were always higher over mica schist. The Al forms considered most toxic were Al³⁺ and Al‐OH, and Al concentrations were highest over slate and mica schist. Al toxicity indices in soil, needle and roots showed a risk of toxicity in mica schist, slate and granite. The stand site indices over slate and mica schist were lower, consistent with the high labile Al and Al³⁺ + Al‐OH in soil solution. Despite the high stand site index over granite, the growth efficiency was low, in accordance with very low ratios of Ca/Al in needles or fine roots. This confirmed the adaptation of maritime pine to granitic substrates. Copyright © 2016 John Wiley & Sons, Ltd.     

Regulation of Contaminated Soils in Spain - A New Legal Instrument (4 pp)

Background, Aims and Scope   This paper presents the new Spanish regulation on contaminated soils and its scientific basis. The regulation offers a regulatory framework for establishing industrial activities which may result in soil contamination, and presents the methodology for setting the generic reference levels of organic pollutants.Legal Framework   The Spanish regulation on contaminated soils is derived from the waste legislation and covers 101 industrial activities, as well as facilities handling significant amounts of hazardous chemicals (over 10,000 kg per year) or fuel (300,000 l fuel per year or storing 50,000 l fuel at any time). The regulatory framework includes initial declarations and a tiered system for selecting those soils requiring a proper site-specific risk assessment.Scientific Basis   The regulation is risk based, and covers human and environmental risks. The human health risk assessment focuses on chemical analysis; the selection of relevant exposure routes is associated to the soil uses. The environmental risk assessment includes chemical analysis and direct toxicity testing, and covers three main ecological receptors: Soil organisms, associated aquatic systems and terrestrial vertebrates. Low-risk threshold concentrations are established as generic reference levels; if exceeded, a site-specific risk assessment is required. The detection of a very high level of acute toxicity of soil or leachates led to the declaration of the soil as contaminated due to the capacity for contaminating the adjacent areas.Conclusion   Overall, the Spanish regulation offers a balance for combining regulatory needs, proper scientific basis and practicability. The use of European risk assessment protocols and the European legal framework would facilitate the pan-European extrapolation of this approach. The inclusion of direct toxicity testing as a legal method for classifying a soil as contaminated is considered a key element.     

Artificial radionuclides in waters of the lower section of the river Ebro (Northeast Spain)

The river Ebro, in Northeast Spain,discharges into the Mediterranean Sea after flowingthrough several large cities and agricultural, miningand industrial areas. The Ascó nuclear power plant(NPP) is located in the lower river section andcomprises two pressurised-water reactor (PWR) units,from which low-level liquid radioactive waste isreleased to river waters under authority control.During the period 1989 to 1993, we carried out 29sampling campaigns in order to determine ³H,⁹⁰Sr, ¹³⁴Cs, ¹³⁷Cs, ²³⁸Pu and^239,240Pu in Ebro river waters at differentlocations, both upstream and downstream from theAscó NPP. ³H, ¹³⁴Cs and ¹³⁷Csactivities showed large variability as they rangedfrom <1.4 to 117±3 Bq L^-1, <0.27 to22±1 mBq L^-1 and <0.36 to 35±1mBq L^-1, respectively. This behaviour, especiallyremarkable for tritium, was due to the detection oftank releases travelling downstream. Thecharacteristic NPP ¹³⁴Cs/¹³⁷Cs ratio wasfound to be 0.61±0.02 (N = 22). In the estuarinearea, ¹³⁷Cs traces from Mediterranean waters wereobserved and relatively enhanced tritium activitiesmight possibly be present due to the accumulation ofactivity in the estuary. ⁹⁰Sr and ^239,240Puactivities were homogeneous both in respect to timeand space, showing mean activities 6.9±0.2 mBq L^-1 (N = 10) and 1.36±0.10 mBq m^-3 (N = 3), respectively. These levels couldonly be attributed to nuclear weapons fallout leachedby continental waters, as the impact from the plantappears to be negligible and no other sources arepresent in the area.     

Energy balances and SOC and N stocks as affected by organic amendments and inorganic N fertilization in a semi-arid environment (IOSDV-Madrid)

A long-term field experiment (1984–2011), was conducted on a Calcic Haploxeralf from semi-arid central Spain to evaluate the combined effect of three treatments: farmyard manure (FYM), straw and control without organic amendments (WOA) and five increasing rates of mineral N on: (1) some energetic parameters of crop production, and (2) the effect of the different treatments on soil organic carbon (SOC) and total N stocks. Crop rotation included spring barley, wheat and sorghum. The energy balance variables considered were net energy produced (energy output minus energy input), the energy output/input ratio and energy productivity (crop yield per unit energy input). Results showed small differences between treatments. Total energy inputs varied from 9.86 GJ ha^?1 year^?1 (WOA) to 11.14 GJ ha^?1 year^?1 in the FYM system. For the three crops, total energy inputs increased with increasing rates of mineral N. Energy output was slightly lower in the WOA (33.40 GJ ha^?1 year^?1) than in the two organic systems (37.34 and 34.96 GJ ha^?1 year^?1 for FYM and straw respectively). Net energy followed a similar trend. At the end of the 27-year period, the stocks of SOC and total N had increased noticeably in the soil profile (0–30 cm) as a result of application of the two organic amendments. Most important SOC changes occurred in the FYM plots, with mean increases in the 0–10 cm depth, amounting an average of 9.9 Mg C ha^?1 (667 kg C ha^?1 year^?1). Increases in N stocks in the top layer were similar under FYM and straw and ranged from 0.94 to 1.55 Mg N ha^?1. By contrast, simultaneous addition of increasing rates of mineral N showed no significant effect on SOC and total N storage.     

Manganese Mobility in Egyptian Soils as affected by Inoculation with Manganese Reducing Organisms

The capacity of three active Mn(IV)-reducing isolates to dissolve Mn in sterilized samples of two Egyptian soils and a pure sand enriched with MnO₂ were studied. These isolates were identified as Penicillium variable (P. v.), Aspergillus niger (A. n.) and Streptomyces exfoliatus (S. e.). The data indicated that inoculation with the fungi and actinomycete mentioned increased the soil contents of water soluble + exchangeable manganese (Mn_ws+ex) but decreased the easily reducible form (Mn_er). The increase in Mn-mobility depended on soil type, organism used and time of incubation. The maximum level of Mn_ws+ex appeared after 14 days in the 3 soil samples. The release of Mn (II) ranged from 19.6 to 49.4 ppm in the sand samples, from 34.8 to 53.3 ppm in samples of a clay loam soil and from 9.9 to 19.8 ppm in samples of a calcareous sandy loam soil. The increase in Mn_ws+ex was at the expense of Mn_er but not in stochiometric amounts. The organisms tested can be ranked according to their capacity to reduce MnO₂ in the following order (for all soils) Streptomyces exfoliatus > Aspergillus niger > Penicillium variable. Statistical analysis of the data revealed significant differences due to inoculation, soil type, incubation time and their interactions.     

Organochlorinated compounds and selected metals in waters and soils from Doñana National Park (Spain)

A study on contamination levels by organochlorinated compounds (pesticides and PCBs) and heavy metals (Hg, Cd, Pb, Cu and Zn) in Doñana National Park (Spain) area and its surrounding region has been carried out. Residue levels of xenobiotics were determined in water and soils samples from seventeen sites selected through the park and nearest surrounding farm lands affecting to the inner Park. Also we analyzed some stations along the Guadiamar Basin in the north of Doñana region to determined the movement and influence of one mine situated over 40 km away, in Aznalcóllar, where the commercial expoitation of pyrites ores rich in Zn, Pb and Cu is being operated.