A decentralized approach for the aerial manipulator robust trajectory tracking.

This paper introduces a new decentralized control strategy for an unmanned aerial manipulator (UAM) constrained to the vertical plane. The control strategy comprises two loops: the first compensates for the aerial vehicle's impact on the manipulator; and the second one implements independent controllers for the aerial vehicle and the manipulator. The controller for the aerial vehicle includes an estimator to compensate for the dynamic influence of the manipulator, even if it is affected by external wind-gust disturbances. The manipulator has two revolute joints; however, it is modeled as an dynamically equivalent manipulator, with one revolute and one prismatic joint. The proposed control strategy's performance is evaluated using a simulator that includes the vehicle's aerodynamics and the manipulator's contact force and moment.

Spatial distribution and pollution evaluation in dry riverbeds affected by mine tailings.

The objective of this study was to evaluate the level of pollution, sources and potential risk of heavy metals (Zn, Cu, Mn, Cd, Cr, Ni, Fe and Pb) and arsenic (As) in four dry riverbeds affected by mine tailing, which drain into one of the biggest coastal lagoon of Europe (Mar Menor). El Beal, La Carrasquilla, Las Matildes and Ponce dry riverbeds sediments were sampled along its course (20, 18, 13, 19 samples were collected, respectively), and total/soluble metal(loid)s, water soluble ions, nitrogen, and organic/inorganic carbon contents were analyzed. Spatial distribution, principal component analysis (PCA), hierarchical cluster analysis (HCA), contamination factor (Cf), pollution load index (PLI) and potential ecological risk index (RI) were used to identify the possible sources of metal(loid)s and to assess the sediment pollution status. The results showed that the mean total concentrations of As, Cu, Cd, Mn, Zn and Pb exceeded the natural background levels of the study area, with the highest values located close to the mining areas. Correlation and cluster analysis identified that Cd and Zn were associated mainly with anthropogenic activities for all riverbeds, while Cr and Ni come from parent. PLI graded the four riverbeds as contaminated by heavy metals, while RI manifested that 100% of samples located in El Beal, La Carrasquilla and Las Matildes had a significantly high ecological risk. Therefore, this study suggests that mine wastes are the main source of metal(loids) contamination in the dry riverbeds, which results can be used to design actions and measures to reduce the environmental impact of metal(loid)s in the Mar Menor coastal lagoon.

Are the soils and vegetation of a forest close to tailings ponds affected by metals and arsenic?

This study aimed to determine the transfer of metals (Cd, Pb and Zn) and As to a Mediterranean forest close to five tailings ponds in Cartagena-La Union mining district (SE Spain). In addition, the effect of the rhizosphere of two native plant species, Olea europaea (OE) and Pistacia lentiscus (PL), on soil properties and chemical speciation of metal(oid)s was evaluated. Results showed there was no influence of the rhizosphere in the total concentration of metal(loid)s in soil, decreasing as Pb > Zn > As > Cd. Chemical partitioning revealed that only Cd and As can be considered hazardous, with a high percentage of these elements in the soil-labile fractions (20-40%). The accumulation in vegetal tissues was only high for Pb in PL roots, which makes it a suitable species for phytostabilization. Additionally, translocation factors showed transfer of Pb and Zn in OE, and Zn in PL to aerial parts, although no toxicity evidences for plants or animals were found. Finally, soil properties affected metal(loid)s accumulation in plants. The OE species was related to soil-labile metal(loid) fractions and pH, total N, organic carbon and silt content. The PL species were associated with immobilized metal(loid) fractions, sand content, electrical conductivity and total concentrations of As, Cd and Pb. Hence, mining activity has affected native adjacent soils, with accumulation of metals in plant species, although translocation was low, likely due to physiological strategies of the studied species to protect themselves against hazardous elements, and to the high soil pH, which limits metals' mobility.

Assessing the behaviour of heavy metals in abandoned phosphogypsum deposits combining electrical resistivity tomography and multivariate analysis.

This study presents the results of a physical-chemical characterisation of phosphogypsum deposits generated with hydrochloric and sulphuric acid during the wet acid process. The paper aims to establish an efficient methodology based on electrical resistivity tomography (ERT), chemical analysis and multivariate analysis identifying the areas most contaminated by heavy metals in an abandoned factory where fertiliser was derived from phosphoric rock. This fertiliser has provided many benefits to agriculture; however, it generates a vast amount of waste (5 tonnes phosphoric rock/1 tonne fertiliser). The chemical composition of this by-product varies according to the industrial process performed. Hydrochloric acid (HCl) recovers more than 90% of phosphorus, while sulphuric acid (H2SO4) recovers around 30%. Therefore, a chemical assessment of the remaining waste is a necessary step prior to initiating any remediation process. ERT provided the geometry of the deposits and the distribution of the phosphogypsum. The chemical analyses consistently validated the electrical contrast found within the deposits. We employed a correlation analysis combined with multivariate analysis to identify the relationships among the metal concentrations and resistivity. Principal component analysis (PCA) reduced the information contained in all the variables to a few principal components. The first three principal components accounted for 74% of the variability of all the studied variables. Partial least squares-discriminant analysis (PLS-DA) for classification allowed the discrimination of the two populations. Electrical resistivity was the most influential variable for separating HCl waste from that of H2SO4. The use of ERT saves time and reduces costs yielding a methodology which facilitates the environmental assessment of large areas.

Distribution of metal(loid)s in particle size fraction in urban soil and street dust: influence of population density.

Assessment of street dust is an invaluable approach for monitoring atmospheric pollution. Little information is available on the size distribution of contaminants in street dusts and urban soils, and it is not known how the population density would influence them. This research was carried out to assess the size distribution of trace metal(loid)s in street dust and urban soil, and to understand how population density might influence the size-resolved concentration of metal(loid)s. Three urban areas with a high, medium and low population density and a natural area were selected and urban soil and street dust sampled. They were fractionated into 8 size fractions: 2000-850, 850-180, 180-106, 106-50, 50-20, 20-10, 10-2, and < 2 µm. The concentration of Pb, Zn, Cu, Cd, Cr, Ni, As, and Fe was determined, and enrichment factor and grain size fraction loadings were computed. The results indicated that the concentration of Pb, Zn, Cu, Cd, and Cr was highly size dependent, particularly for particles < 100 µm, especially for street dust. Low concentrations of Ni and As in street dust and urban soil were size and population density independent. Higher size dependency of the metals concentration and the higher degree of elemental enrichment in the street dust fractions than the urban soils indicate higher contribution of human-induced pollution to the dust. Findings also confirm the inevitability of size fractionation when soils or dusts are environmentally assessed, particularly in moderately to highly polluted areas. Otherwise, higher concentrations of certain pollutants in fine-sized particles might be overlooked leading to inappropriate decisions for environmental remediation.

Liquid biopsy and prostate cancer. Current evidence applied to clinical practice. / Biopsia líquida y cáncer de próstata. Evidencia actual aplicada a la clínica.

CONTEXT: Despite being a validated source of biomarkers, liquid biopsy has not yet succeeded in becoming part of the standard clinical practice in prostate cancer patients. Few biomarkers undergo adequate validation, prospective and independent, of their predictive and/or prognostic value, which results in a lack of the different available tests in the clinical practice. OBJECTIVE: To carry out a pragmatic synthesis of current scientific evidence on liquid biopsy for prostate cancer patients. EVIDENCE ACQUISITION: Non-systematic literature review, narrowing the search to papers on liquid biopsy from blood samples in prostate cancer patients. We mainly selected works evaluating clinical endpoints in prostate cancer. EVIDENCE SYNTHESIS: The most clinically advanced forms of liquid biopsy are circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Both CTCs and ctDNA have demonstrated their prognostic value in metastatic disease. ARV7 determination is the first predictive biomarker of the disease. Its implementation into routine clinical practice requires methodological standardization and adequate clinical validation of the different available ways to detect it. The detection of CTCs in the early stages of the disease still depends on the optimization of the diagnostic methods and on the development of the biological characterization of these cells. The biological information provided by CTCs and ctDNA is different; therefore, the study of its adequate combination is the object of cutting-edge research. CONCLUSIONS: The absence of protocols and methodological standards is the limiting factor when aiming to reach conclusions that could have a potential impact on clinical practice. Therefore, the real short-term challenge for liquid biopsy is the establishment of consensus and common criteria.

[Knowledge and attitude among general practitioners in Andalusia (Spain) on the identification of subjects at high risk of breast and colorectal cancer]. / Conocimientos y actitudes de los médicos de Atención Primaria de Andalucía (España) sobre la detección de personas con riesgo elevado de cáncer de mama y colorrectal.

AIMS: To assess the knowledge and attitude among general practitioners in Andalusia on the identification of subjects with elevated risk for breast cancer, colorectal cancer, and hereditary cancers, as well as to detect barriers to accessibility to the screening programs. METHODS: A descriptive, cross-sectional study was conducted based on an online survey of 24 questions. Data are shown as frequencies, and association tests were statistically used. The level of significance was set at<.05. RESULTS: Survey response rate was 32%, of which 224 were valid, and included 56% men, and a mean age±DE of 46±12 years. Established criteria for high risk breast cancer were already known by 71.4% [95% CI 65-76], being worst in those living in big cities (P<.014). Among general practitioners, 86% were allowed to order mammography in women with lumps or at moderate to high risk for breast cancer. As regards colorectal cancer, 87.9% of general practitioners knew the risk factors. Among general practitioners, 58.2% [95% CI 49-62] were allowed to order a colonoscopy if clinical suspicion was present, especially if they lived in large cities (P<.0001). CONCLUSIONS: The screening program for breast cancer is well-known by general practitioners, and the access to mammography is successful. Most of the general practitioners consider the follow-up program for persons at high risk for colorectal cancer appropriate, although half of those surveyed had some barriers to ordering colonoscopy. Knowledge on hereditary cancer is limited, and varies among areas. There is also a general lack of awareness on hereditary cancer and genetic counselling units.

Composition and risk assessment of roasted pyrite ash from fertiliser production.

Pyrite ash is a residue from the roasting of pyrite ores to obtain sulphuric acid used in the fertiliser industry and its production is widely extended worldwide. The mismanagement of this waste may result in environmental and health damages due to its physico-chemical characteristics. The main objective of this study was to examine the physico-chemical and mineralogical composition of roasted pyrite ash from an abandoned fertiliser company, and to evaluate the environmental risk caused by the wind and water dispersion of metals posed by this waste. In order to achieve these objectives, a sequential extraction procedure and a physical fractionation into six size fractions: >100, 100-50, 50-20, 20-10, 10-2.5 and < 2.5 µm were applied. Results showed that pyrite ash is composed mainly of iron-oxides such as hematite (46%) and secondary minerals as anglesite and shows high concentrations of Pb (7464 mg kg-1), Zn (2663 mg kg-1) and Cu (585 mg kg-1). The highest Risk Assessment Code (RAC) values were found for Cd, Pb and Zn, bound to the more labile fractions. Conversely, Pb showed the lowest water solubility due to the covering effect provided by a coating of anglesite in the pyrite ash surface. Most of the metals were associated to both the coarsest (>100 µm) and the finest (2.5-10 µm) fractions, although none represented an environmental risk according to the ecological risk index results. However, 30% of the metals were bound to the respirable fraction (≤100 µm) posing a potential risk for human health and a high potential dispersion by wind to the surrounding areas.

Phytoremediation of mine tailings with Atriplex halimus and organic/inorganic amendments: A five-year field case study.

Mine tailings have adverse chemical and physical conditions, including high concentrations of metals and salts, low organic matter content, and unbalanced rates of nutrients which limit the development of vegetation. A large scale field experiment was conducted to reclaim a tailing pond by triggering the growth of native species by spontaneous colonization by tilling (TL) the tailing pond surface and using marble waste (CaCO3; MW), pig slurry (PS) and their combination (MW + PS) as soil amendments. Soil physicochemical properties and water and DTPA extractable metal concentrations of bulk and rhizosphere soils were analyzed after five year from the application of the treatments. In addition, plants of Atriplex halimus from each treatment were collected and metals in roots, leaves and stems analyzed. Before amendments application, the studied pond showed a neutral pH, high salinity and a moderate organic carbon content. After five years, the pH value was significantly increased only in MW plot. The results showed significant increases of DTPA-extractable Zn in MW and MW + PS plots, Pb in all treatments except MW plot, Cd only in PS plot, and Cu only in MW + PS plot. A. halimus was the most dominant species, growing spontaneously in all plots, with lower vegetation cover in CT and MW plots, 6% and 2% respectively. Application of MW increased leaf Pb accumulation by 2.5-fold and Cd by 55%, when compared to the CT. The high initial salinity and probable substitution of metals by Ca2+ on exchangeable surfaces of soil particles may be the reasons for higher uptake of metals in MW plot when compared to the other plots. Although this plant is widely utilized in contaminated sites for phytostabilization purposes, it may absorb and translocate high concentrations of metals to the aboveground tissues in saline contaminated sites.

Change in metals and arsenic distribution in soil and their bioavailability beside old tailing ponds.

The objectives of this study were to determine the metals and arsenic transfer from mining ponds to agricultural and forest soils, and identify the dynamic of metal(loid)s in the soil-plant system for a native plant species (Ballota hirsuta) in two old mining districts: La Unión and Mazarrón (Spain). Soils and plants from mining ponds and natural and agricultural areas were collected and analyzed for soil properties, and chemical partitioning of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn and As. Results showed that mine, forest and agricultural soils were contaminated by As, Cd, Cu, Pb, and Zn. Chemical partitioning revealed higher mobility of metals in mining ponds than natural and agricultural soils except for Fe and As which were mostly bound to soil matrix due to the mineralogical compositions of soils. The accumulation of metal(loid)s in B. hirsuta in La Unión decreased as Fe > As > Cr > Ni > Cu > Zn > Cd > Mn > Co > Pb while in Mazarrón was As > Fe > Cr > Pb > Cu > Ni > Co > Mn > Zn > Cd, showing that B. hirsuta has high ability to bio-accumulate Fe, As, Cr, Cu and Ni; and Pb (in Mazarrón), transferring a significant concentration of theses metal(loid)s, except Pb, to edible parts without exceeding the toxicity limits for animals. Therefore, B. hirsuta could be useful as phytoextractor species for Cr, Cu, As and Ni, while it can be used as phytostabilizer species for Zn, Co, Pb and Cd.

Use of multivariable and redundancy analysis to assess the behavior of metals and arsenic in urban soil and road dust affected by metallic mining as a base for risk assessment.

The vicinity of abandoned mining ponds to populated areas may suppose a high environmental and health risk being necessary evaluate unreclaimed ponds as source of metal(loid)s. In order to evaluate the behaviour of metals and arsenic from tailing ponds and their effects in urban areas, 10 mine wastes samples, 10 urban soil and 10 urban road dust samples were collected from two mining districts (La Unión and Mazarrón, SE Spain). Physicochemical properties and total, available and water-soluble concentration of metals (Cd, Co, Cr, Cu, Fe, Ni, Mn, Pb, Zn) and As were analyzed. Results suggest enrichment in Fe, Mn, Pb and Zn of urban soil and road dust in both studied towns. Multivariable analysis indicated that Cd, Mn, Pb and Zn in La Unión urban soil, and As, Cd, Cu, Pb and Zn in soil and Fe in road dust of Mazarrón come from mining districts. In addition, redundancy analysis showed that mobility of metal(loid)s related to mining sources were more influenced by their total concentration, while metals with a lithogeny origin were more affected by physicochemical properties.

Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties.

While pyrochlore iridate thin films are theoretically predicted to possess a variety of emergent topological properties, experimental verification of these predictions can be obstructed by the challenge in thin film growth. Here we report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi2Ir2O7. The films were epitaxially grown on yttria-stabilized zirconia substrates and have lattice constants that are a few percent larger than that of the bulk single crystals. The film composition shows a strong dependence on the oxygen partial pressure. Density-functional-theory calculations indicate the existence of BiIr antisite defects, qualitatively consistent with the high Bi: Ir ratio found in the films. Both Ir and Bi have oxidation states that are lower than their nominal values, suggesting the existence of oxygen deficiency. The iridate thin films show a variety of intriguing transport characteristics, including multiple charge carriers, logarithmic dependence of resistance on temperature, antilocalization corrections to conductance due to spin-orbit interactions, and linear positive magnetoresistance.

Soil or Dust for Health Risk Assessment Studies in Urban Environment.

To identify the best material (soil or dust) to be selected for health-risk assessment studies, road dust and urban soil from three cities with different population densities were collected, and size fractions were analysed for metal content (Pb, Zn, Cu, Cd, Cr, Co, and Ni). Results showed similar distribution of the size particles among cities, predominating fractions between 75 and 2000 µm in road dust and particles below 75 µm in soil. Metals were mainly bound to PM10 in both soil and road dust increasing the risk of adverse health effects, overall through inhalation exposure. The risk assessment showed that the most hazardous exposure pathway was the ingestion via, followed by dermal absorption and inhalation route. Values of hazard quotient showed that the risk for children due to the ingestion and dermal absorption was higher than adults, and slightly larger at PM10 comparing to <75-µm fraction for the inhalation route. Higher risk values were found for road dust, although any hazard index or cancer risk index value did not overreach the safe value of 10-6.

Digestion and nitrogen balance using swine diets containing increasing proportions of coproduct ingredients and formulated using the net energy system.

Rising feed expenditures demand that our industry pursues strategies to lower the cost of production. One option is the adoption of the NE system, although many producers are hesitant to proceed without proof that NE estimates are reliable. The objective of this experiment was to compare the apparent total tract digestibility (ATTD) of energy and nutrients and the N retention (NR) of diets formulated using the NE system with increasing quantities of coproduct ingredients. The 5 dietary treatments included a control corn-soybean meal diet (CTL); the CTL plus 6% each of corn distiller's dried grains with solubles (DDGS), corn germ meal, and wheat middlings and NE equal to the CTL by adding soybean oil (CONS-18); the CONS-18 diet, without oil added, with NE content lower than the CTL (DECL-18); the CTL plus 12% each of corn DDGS, corn germ meal, and wheat middlings and NE equal to the CTL by adding soybean oil (CONS-36); and the CONS-36 diet, without oil added, with NE content lower than the CTL (DECL-36). Diets were formulated for both the growing period (GP; 40 to 70 kg) and the finishing period (FP; 70 to 110 kg). Forty gilts (PIC 337 × C22 or C29; 38.5 ± 0.4 kg initial BW) were randomly assigned to treatment and received feed and water ad libitum (8 pigs per treatment). For the last 13 d of the GP and FP, pigs were transferred to metabolism crates, where 2 total urine and fecal collections (d 4 to 6 and d 11 to 13) were performed. The GP fed diets with coproduct ingredients had lower ATTD of DM, N, and GE than those fed the CTL ( < 0.050). The ATTD of N and GE progressively decreased as coproduct inclusion increased from 0 to 18 to 36% in the FP ( < 0.010). In the GP and FP, there were no differences in ATTD of DM, N, or GE between CONS-18 and DECL-18 or between CONS-36 and DECL-36 ( > 0.050). The NR declined on all coproduct diets in the GP ( = 0.010) and tended to decline in the FP ( = 0.079). There were no differences in NR between CONS-18 and DECL-18 or between CONS-36 and DECL-36 ( > 0.050). In conclusion, digestion of diets containing up to 36% coproducts and formulated using NE resulted in expected DE and ME values; NR of diets with coproducts was lower than that of the simple CTL, which is not related to the accuracy of the energy estimations but rather to other factors such as imbalances in the AA concentrations or to postabsorptive energy metabolism, factors not accounted for by the current energy systems approach.

Stability, nutrient availability and hydrophobicity of biochars derived from manure, crop residues, and municipal solid waste for their use as soil amendments.

We aimed to study the influence of feedstock properties, pyrolysis temperature and holding time on stability, nutrient contents and hydrophobicity of biochars derived from pig manure, crop residues and municipal solid waste. Biochars were prepared at 300 °C, 400 °C, 500 °C and 700 °C for 1 h, 2 h, 4 h and 5 h. All properties were influenced by feedstock except for pH and hydrophobicity. Temperature influenced all properties, whereas no effect of holding time was observed except for hydrophobicity and thermal stability. Increasing temperature increased aromatization and stability. Low temperatures provided higher cation exchange capacity and available nutrients, and lower salinity and alkalinity. Precipitation of phosphates and carbonates occurred with charring, explaining the decrease of available nutrients. Biochars produced at 300 °C showed high hydrophobity, which disappeared over 500 °C owing to the loss of labile aliphatic compounds. The high pH and carbonates contents at >500 °C resulted in suitable biochars for soil liming and decreasing soil metals availability.

Influence of population density on the concentration and speciation of metals in the soil and street dust from urban areas.

Street dust and soil from high, medium and low populated cities and natural area were analysed for selected physical-chemical properties, total and chemical speciation of Zn, Pb, Cu, Cr, Cd, Co, Ni to understand the influence of human activities on metal accumulation and mobility in the environment. The pH, salinity, carbonates and organic carbon contents were similar between soil and dust from the same city. Population density increases dust/soil salinity but has no influence on metals concentrations in soils. Increases in metal concentrations with population density were observed in dusts. Cu, Zn, Pb, Cr can be mobilized more easily from dust compared to the soil. In addition, population density increase the percentage of Pb and Zn associated to reducible and carbonate phase in the dust. The behaviour of metals except Cd in soil is mainly affected by physico-chemical properties, while total metal influenced the speciation except Cr and Ni in dusts.

Syrian bean-caper (Zygophyllum fabago L.) improves organic matter and other properties of mine wastes deposits.

The omni-presence of Zygophyllum fabago L. (Syrian bean-caper) natural colonies in post mining areas prompted us to investigate its contributions to reclamation of mine wastes deposits in southeast Spain. Select plant-related (edaphic) characteristics and bio- and water soluble-Cd, Cu, Pb and Zn in rhizosphere of Z. fabago were compared to deposits one year since application of pig slurry and marble waste. Total N in rhizosphere increased up to a factor of 20X (339 vs 17 mg N kg(-1)) in El Gorguel and 27X (85 vs 3.1 mg N kg(-1)) in El Lirio sites. Organic matter accumulation in rhizosphere from litter and roots of Z. fabago increased organic C from 6.6 to 19.5 g kg(-1) in El Gorguel and from 2.1 to 5.7 g kg(-1) in El Lirio in one year. Dissolution of inorganic C takes place due to organic acids from root exudates of Z. fabago. Reduction in bio-available Cd, Cu, Pb, and Zn in rhizosphere of Z. fabago at El Lirio is attributed to increase in pH from 5.3 to 7.7 through marble waste addition, although increased cation exchange capacity may also have played a role. Addition of marble waste to encourage colonization by Z. fabago in acidic mine wastes deposits was recommended.

Marble wastes and pig slurry improve the environmental and plant-relevant properties of mine tailings.

Poor soil fertility is often the biggest challenge to the establishment of vegetation in mine wastes deposits. We conducted field trials in the El Gorguel and El Lirio sites in SE Spain, two representative tailing ponds of similar properties except for pH, to understand the environmental and plant-relevant benefits of marble waste (MW) and pig slurry (PS) applications to mine tailings. Low pH (5.4) tailings (El Lirio) exhibit reduction of up to fourfold in bio-availability of metals as shown by the DTPA-Zn, Pb, water-soluble Zn, Pb and up to 3× for water-soluble Cd. Tailings in El Gorguel have high pH (7.4) and did not exhibit significant trends in the reductions of water-extractable Zn, Pb, Cd and Cu. Improvements to the edaphic (plant-relevant) properties of tailings after the amendments are not as sensitive to pH compared to the environmental characteristics. The two sites had increases in aggregate stability, organic matter (total N and organic C) although total N is higher in the El Gorguel (up to 212 µg N kg(-1)) than the El Lirio (up to 26 µg N kg(-1)). However, cation exchange capacities are similar in both sites at 15.2 cmol(+) kg(-1). We conclude that the characteristics, especially pH, of tailing materials significantly influence the fate of metals but not improvements to plant-relevant properties such as cation exchange capacity and aggregate stability 1 year after the application of MW and PS amendments.

Salinity increases mobility of heavy metals in soils.

The effect of salinity induced by CaCl(2), MgCl(2), NaCl and Na(2)SO(4) on the mobility of Cu, Cd, Pb and Zn was studied. An increase of ionic strength by any salts promoted a higher release of Cd than the others metals. When CaCl(2) and NaCl were applied, Cd and Pb showed the highest degree of mobilization. When MgCl(2) was applied, Cd and Cu were mobilized the most. Finally, an increase of Na(2)SO(4) also promoted the strongest mobilization of Cd and Cu. As the total heavy metal content was higher, the percentage of Pb and Cu released upon salinization decreased, indicating that these metals are strongly bound to soil constituents. An increase of carbonates in the soil promoted a higher release of Pb for all used salts and for Zn when MgCl(2) and NaCl were used. This indicates that Pb and Zn are adsorbed on the surface of carbonate crystals. An increase of fine particles promoted a decrease of percentage of released Cd for all salts, indicating that Cd is strongly retained in the fine fractions. The main mechanism regulating Pb and Cd mobility was competition with Ca(2+) for sorption sites followed for metal chloro-complexation, association between the Cd/Pb-sulfates and competition with Mg(2+). The main mechanism regulating Cu mobility was the formation of Cu-sulfate, followed by competition with cations (Mg > Ca) and chloride. For Zn, competition with Ca(2+) for sorption sites was the most important process for its mobility; followed by Zn-sulfate association and, finally, chloride and competition with Mg with the same effect.