D.M. Carmona

Plant Cover and Soil Biochemical Properties in a Mine Tailing Pond Five Years After Application of Marble Wastes and Organic Amendments

Abstract Tailing ponds pose environmental hazards, such as toxic metals which can contaminate the surroundings through wind and water erosions and leaching. Various chemical and biochemical properties, together with extractable and soluble metals were measured five years after reclamation of a polluted soil affected by former mining activities. This abandoned mine site contains large amounts of Fe-oxyhydroxides, sulphates, and heavy metals. As a consequence, soils remain bare and the soil organic matter content is low ( −1 ). Marble waste, pig manure and sewage sludge were applied in 2004. Plant cover and richness, and soil chemical, biochemical and biological parameters were analysed five years later. Results showed that all soil biochemical properties as well as vegetation cover and richness were higher in treated soils than in the untreated contaminated plots (control), although organic matter, pH values and extractable metals concentrations were similar among treatments. Soluble cadmium and zinc were lower in the amended plots than in control. As a general pattern, soil amended with pig manure showed higher values of most biochemical properties compared to sewage sludge application, while the doses did not have a great effect, being only significant for β-glucosidase, phosphodiesterase and arylsulfatase. Significant correlations were found between vegetation cover, richness and soil biochemical properties, suggesting a high interdependence between plant colonization and reactivation of biogeochemical cycles during five years. This study confirms the high effectiveness of an initial application of the amendments tested to initialize the recovery of ecosystems in bare mine soils under Mediterranean semiarid conditions. This research also shows the high sensitivity of certain biochemical properties in order to evaluate soil quality and reactivation of nutrients cycles in reclaimed mine soils.

Carbon mineralization, microbial activity and metal dynamics in tailing ponds amended with pig slurry and marble waste

A field experiment was set up in Cartagena-La Unión Mining District, SE Spain, aimed at evaluating the short-term effects of pig slurry (PS) amendment alone and together with marble waste (MW) on organic matter mineralization, microbial activity and stabilization of heavy metals in two tailing ponds. These structures pose environmental risk owing to high metals contents, low organic matter and nutrients, and null vegetation. Carbon mineralization, exchangeable metals and microbiological properties were monitored during 67 d. The application of amendments led to a rapid decrease of exchangeable metals concentrations, except for Cu, with decreases up to 98%, 75% and 97% for Cd, Pb and Zn, respectively. The combined addition of MW+PS was the treatment with greater reduction in metals concentrations. The addition of PS caused a significant increase in respiration rates, although in MW+PS plots respiration was lower than in PS plots. The mineralized C from the pig slurry was low, approximately 25-30% and 4-12% for PS and MW+PS treatments, respectively. Soluble carbon (Csol), microbial biomass carbon (MBC) and β-galactosidase and β-glucosidase activities increased after the application of the organic amendment. However, after 3d these parameters started a decreasing trend reaching similar values than control from approximately day 25 for Csol and MBC. The PS treatment promoted highest values in enzyme activities, which remained high upon time. Arylesterase activity increased in the MW+PS treatment. Thus, the remediation techniques used improved soil microbiological status and reduced metal availability. The combined application of PS+MW reduced the degradability of the organic compounds.

Pig Manure Application for Remediation of Mine Soils in Murcia Province, SE Spain

In southern Spain, specifically in Murcia Province, an increased pig population causes large amounts of slurry production that creates a very serious environmental concern. Our aim was to use this waste to reduce the acid mine drainage process, heavy metal mobilization, and to improve soil conditions to enhance plant establishment in mine soils. Pig manure, sewage sludge, and lime were used as soil amendments in a field experiment and in undisturbed soil column. Field experiments showed an increase in pH, total nitrogen, organic carbon, and carbonate contents; a reduction of diethylene-tetramine pentaacetic acid (DTPA)– and water-extractable metals; and an improvement of plant establishment. The field studies showed that pig manure could be utilized to remediate polluted soils. Column studies in the laboratory showed that amendment of mine soil with pig manure initially increased soil pH from 2.21 to 6.34, promoted reduced conditions in the surface soil, and decreased the metal mobility. After 21 weeks, while the leachate was slightly acidic, however, the mobility of metals was substantially low. Additions of 7 and 14% of pig manure were insufficient to maintain a neutral pH in the leachate. Therefore, continuous application of the pig manure may be advised.

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. fabagowere 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. fabagoincreased organic C from 6.6 to 19.5 g kg−1in 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. fabagoat 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. fabagoin acidic mine wastes deposits was recommended.

Roman Mining Landscapes in the Murcia Region, SE Spain: Risk Assessment of Mine Ponds

The Mining District of Cartagena-La Union (SE Spain), mined since the Roman period, exhibits high levels of metal contamination and this poses a great risk to the surrounding environment. This chapter presents the results of the application of geophysical, geochemical and hydrological techniques in two mine ponds located in this area. Its aim is to determine their degree of contamination by heavy metal, to evaluate risks of mobility and dispersion of heavy metals, to study the erosive capacity of the runoff, and to discuss geotechnical stability of the ponds. Metal contents found in the ponds show that although the Descargador pond is more vulnerable to oxidation and leaching processes than Encontrada, they both could be considered polluted due to their high metal concentrations. When materials from the Descargador pond are exposed to adverse weather conditions they can be eroded, while in the Encontrada pond most of the surface is covered by a natural soil layer and vegetation which protects it against erosion. In the former, it is recommended to apply some conservation measures, including the addition of alkaline materials, natural soil and organic matter. In the latter, it is recommended to improve the present conditions in order to control acidification and to minimize risks of landslides and transport of highly contaminated materials.

Una Propuesta para Fortalecer el Énfasis Profesional del Currículo de Ingeniería Química

A proposal to strengthen the professional emphasis in the chemical engineering undergraduate curriculum at the Universidad Pontificia Bolivariana (UPB) in Colombia is presented. In recent decades, the areas of knowledge and the professional fields associated to chemical engineering have changed and increased greatly, encouraging the renovation of the undergraduate formation process. The Chemical Engineering Program of UPB has designed a strategy to bring specialized training in specific fields of knowledge and professional performance to students, integrating undergraduate and graduate education. This strategy, called Optional Training Routes, consists of a combination of 15 elective credits, of which 6 correspond to undergraduate courses and 9 to graduate courses offered by the School of Engineering. This paper shows the nine optional training routes designed, which configure nine professional profiles and promote further education at graduate level. Undergraduate students can choose one of these routes according to their individual skills and interests, strengthening their own autonomy.

Reclamation of Contaminated Mine Ponds Using Marble Wastes, Organic Amendments, and Phytoremediation

The environmental impacts of mining activities in southeast Spain include the presence of tailing ponds characterized by acidification, salinity, accumulation of metals, and null vegetation. A field trial was established in two tailing ponds, in which experimental plots were designed, using marble wastes, pig manure, and sewage sludge as amendments to reclaim the mine soils. We monitored the dynamics of heavy metals, soil properties, and vegetation along 5 years after reclamation actions. Results showed that pH increased and remained close to neutrality with time. Although soil organic matter initially increased, it decreased close to initial levels after 5 years owing to mineralization. Bioavailable metals decreased in the amended plots, although increments in some metals after 5 years of monitoring were observed, owing likely to erosion of tailings surface, oxidation of sulphides, and decreases in organic matter, which initially immobilized metals. Amendments activated microbial biomass and activity, which was highest in plots amended with pig manure. The different doses used did not have a great effect. Although untreated plots remained without vegetation, natural plant species spontaneously colonized the amended plots. Increases in vegetation cover and richness were related with the application dose, with pig manure plots having the highest values. Cd, Cu, and Zn bioaccumulation was carried out in most species, while for Pb no bioaccumulation was observed. Thus, the application of organic amendments and marble wastes has proved to be effective for long-term decrease in the bioavailability of most toxic heavy metals to permit the development of vegetation, mitigating erosion risks.