Amendments with organic and industrial wastes stimulate soil formation in mine tailings as revealed by micromorphology

Mine tailings are inhospitable to plants and soil organisms, because of low pH and poor soil organic matter contents. Vegetation establishment requires a soil system capable of supporting the nutrient and water requirements of plants and associated organisms. The objective of this study was to understand the influence of added organic and industrial wastes to the formation of soils in degraded landscapes left behind by past mining activities. Specifically, we stimulated the build up of soil organic matter (SOM) and the accumulation of calcite in mine tailing deposits. We amended field experimental plots with pig manure (PM), sewage sludge (SS) in combination with blanket application of marble wastes (MW). Soil samples were collected for physical and chemical analyses, two years after the addition of industrial wastes. Three years after amendments, we took undisturbed samples for micromorphological analysis. Soil pH increased from 2.7 to 7.4 due to dissolution of calcite from MW amendment. The acidity in tailings and low rainfall in the study area precipitated the secondary calcite as infillings within the 0-4 cm layer. Total organic carbon (TOC) increased from 0.86 to 2.5 g TOC kg − 1 soil after 24 months since the application of amendments. The build up of SOM resulted to stable SOM-calcite complex as dense incomplete infillings mixed with secondary calcite, and cappings on calcite particles from MW addition. These SOM cappings provide water and nutrient to support initial seedling establishment in mine tailings. We attribute the granular structure of amended materials to soil organisms (e.g., earthworm activity) involved in the decomposition of plant materials. We suggest that any organic matter amendments to acidic mine tailing deposits must be combined with calcium carbonate-rich materials to accelerate the build up of SOM to accelerate the establishment of functional ecosystem characterized by, among others, the presence of healthy soils with granular microstructure

Increasing soil organic matter content in mine soil through pig manure addition

Mine soils in southeast Spain have scarce vegetation due to very poor properties such as extremely low soil organic matter (SOM) (< 0.6 g carbon kg-1 soil), low pH, high salinity and metal contents. Also in southeast Spain, there is an economically-important pig husbandry faced with challenges to manage the large volumes of industry-generated animal wastes. This study will present the results of a leaching experiment to assess the retention and release of nitrogen and carbon from pig manure added to undisturbed column of mine soil. We excavated three columns (15-cm diameter and 30-cm length) from a representative mined site. The columns were amended with single (7 % by mass) and double doses of pig manure, and leached weekly with distilled water for 10 weeks to simulate annual rainfall events in the study area. Leachates were collected and analyzed for pH, electrical conductivity, redox potential, and contents of selected anions and metals. However, we will limit this presentation to carbon and nitrogen to quantify the potential contribution of pig manure addition to the build up soil organic matter in mine soils. Results showed that after addition of pig manure in the soil surface, soil pH increased from 2.2 to 4.0 after 11 weeks (single dose) and to 5.2 at week 21 (double doses). Significant increased were observed in total nitrogen contents in both single and double doses, 1.14 g kg-1 (900 %) and 1.40 g kg-1 (1100 %), respectively. Total carbon contents increased to 18.6 g kg-1 (3200%) in single dose and to 16.4 g kg-1 (2800%) in double doses. Nitrogen and carbon in soils had weekly rate of increases of 0.1 and 2.0 g kg-1, respectively. Moreover, C/N ratio increased from 5 to 12 at the end of the experiment. Leachates had significantly higher weekly release of NO3- than total dissolved organic carbon (DOC) during the first 6 weeks of leaching. Weekly rate of releases (mg L-1) were 127 (NO3-) and 5.2 (DOC) in single dose, and 35 (NO3-) and 2.8 (DOC) for double doses. Leachates contained NO3- less than the 50 mg L-1 threshold established by FAO. These results suggest that addition of pig manure may significantly accelerate the build up of SOM in mine soils without endangering the release of NO3- into sub-soil or groundwater in semiarid regions. Once there is sufficient SOM, mine soils will have an environment hospitable to various ecosystems including plant colonization and microbial community needed for its physical stability. Pig manure amendment of mine soils can be an ecologically-sound means of managing the large volume of wastes generated by the pig industry in southeast Spain

Litiasis renal secundaria a Indinavir

Indinavir sulphate is a protease inhibitor that has been found to be extremely effective in increasing CD4+ cell counts and in decreasing HIV-RNA titers in patients with HIV and AIDS. However, patients receiving indinavir also have been noted to have a significant risk of developing urolithiasis. Indinavir has high urinary excretion with poor solubility in a physiologic pH solution. The typical symptoms of indinavir urolithiasis are similar to other forms of urolithiasis. Indinavir urolithiasis is unique in that computed tomography, which was once thought to be efficacious in identifying all urinary calculi, is not useful in imaging stones that are composed of pure indinavir. Indinavir urolithiasis generally responds to a conservative regimen of hydration, pain control, and temporary discontinuation of the medication. Only a minority of patients need surgical intervention.Sulfato de indinavir es un inhibidor de la proteasa el cual se ha demostrado muy efectivo, incrementando los valores de células CD4+ y disminuyendo los títulos de ARN-VIH en pacientes VIH positivos y SIDA. No obstante, en pacientes que han recibido tratamiento con indinavir, se ha notificado un incrimento de litiasis renal. Indinavir tiene una alta excreción urinaria con una pobre solubilidad en pH urinario fisiológico. La sintomatología clínica es similar a los otros tipos de litiasis renal. Las litiasis por indinavir son las únicas en la que la TAC no es capaz de visualizarlas. El tratamiento conservador mediante hidratación y analgesia suele ser suficiente para resolver el cuadro, solo una minoría de pacientes necesitan procedimientos mas agresivos

Kaolinite formation from palygorskite and sepiolite in rhizosphere soils

Palygorskite and sepiolite are fibrous clays that occur mostly in agricultural soils of arid regions. Although many investigations have examined the environmental conditions for the formation and stability of these clays, information on the transformation of these clays in the root zone (or rhizosphere) of agricultural crops is limited. In this study, changes in palygorskite and sepiolite within the rhizosphere of selected agricultural crops were determined and the ability of plants to extract Mg from these minerals compared. Alfalfa, barley, and canola were cultivated in pots under controlled conditions in a growth chamber using growth media that consisted of a mixture of Ottawa sand and clay-sized Florida palygorskite (PF1-1) or Spanish sepiolite (SepSp-1). After 100 days of cultivation, the biomass of plant roots and shoots were determined and Mg uptake measured by inductively coupled plasma analysis of the plant biomass after microwave oven digestion. The clay fraction in each pot was separated from the sand and analyzed using X-ray diffraction (XRD) and examined using transmission electron microscopy (TEM). The XRD reflection at 0.718 nm clearly indicated kaolinite in the rhizosphere after growth of the three crops. Furthermore, hexagonal kaolinite particles were observed, using TEM, and the amount of Mg extracted by the three crops was significantly greater for sepiolite than for palygorskite. Palygorskite and sepiolite kaolinization in the rhizosphere was apparently due: (1) to high acidity in the rhizosphere caused by root activity and organic matter decomposition; and (2) to fibrous clay destabilization caused by Mg uptake by plants. This study shows that kaolinite in agricultural soils of and and semi-arid regions might be partly due to neoformation after fibrous clay dissolution and not entirely inherited from parent materials, as has been suggested in earlier literature

Granular soil structure indicates reclamation of degraded to productive soils: a case study in southeast Spain

Accelerated conversion of degraded landscapes in mining areas to productive ecosystems requires stimulation of soil formation. The evolution in microstructure and changes to chemical properties in metal mine wastes 5 yr after amendments with pig manure, sewage sludge and marble waste is reported. Mine wastes had <1% organic carbon, <0.05% total nitrogen, pH2.0, electrical conductivity up to 20 dS m−1 and high concentrations of metals such as 22000 mg zinc kg−1 and 7000 mg lead kg−1. After 5 yr, one time amendment increased total carbon (g kg−1) from 1.4 (control) to 5.6 (marble waste +sewage sludge) to 8.3 (marble waste+pig manure). Soil pH in amended plots was 6.0 compared with 2.8 in controls. Micromorphological characteristics clearly showed that primary and secondary calcite serve as active sorption sites for organic matter. These calcitic zones were areas conducive to root growth. Soil microstructure in amended mine wastes was dominantly granular, resulting from activities of soil organisms such as fungi and enchytraeds. Results suggest organic matter can be effectively enriched in mine waste deposits through simultaneous additions of pig manure, sewage sludge and calcite. Soil amendments promoting formation of granular structure can accelerate establishment of productive landscapes in degraded mine sites

Initial soil development under pioneer plant species in metal mine waste deposits

Mine waste materials are often inhospitable to plants due to extreme pH, high salinity, very low organic matter, elevated metal contents, and poor physical conditions. We investigated initial soil development in three study areas under different pioneer plant species in degraded landscapes left behind by past mining activities in southeast Spain. Soil pH, electrical conductivity, cation exchange capacity, total carbon, nitrogen, and sulfur were determined, as well as micromorphology, using 12 soil thin sections prepared from materials collected under vegetated and unvegetated sites. Soils are alkaline or highly alkaline, whereas other parameters substantially vary between sites (e.g., C:N = 9−149). pH of waste materials ranges from 6.2 to 7.9 and higher than soil pH, whereas electrical conductivity and gypsum contents were lower in soils than waste materials except for the Portman Bay site. Mine waste materials are dominated by platy/laminated microstructure, whereas incipient soils regardless of overlying pioneer species have granular structure of varying degrees of development. Roots of pioneer species break-up the dense laminae of waste deposits and initiate preferential water flow through root channels. These channels encourage biological activities, and hence enhanced the accumulation of soil organic matter. The variables we investigated are useful to assess the formation of soils in inhospitable environments in mined areas. For instance, mechanical alteration of laminated waste deposits can be initiated by plowing to encourage preferential flow paths, hence soil development. Amendment of mine wastes with organic materials can stimulate biological activities to hasten the formation of granular soil microstructure common in productive ecosystems