Use of hydrophilic polymers from disposable diapers to restore metal contaminated soils

RAMIRAN International ConferenceHydrophilic polymers swell to form gels that contain many times their dry weight in water. They are marketed as ‘superabsorbent polymers’, with different trade names, for incorporation into soils and substrates. YunKai et al. (2002) reviewed the effects of these polymers on agricultural soils and crops. Another use of hydrophilic polymers is in disposable diapers and similar products. A layer of polyacrylate polymer is located between cellulose fibres, and the whole contained by a plastic cover. Effects of metals on ecosystems and biological resources are increasingly recognised (Izquierdo et al., 2005; Pérez-de-Mora et al., 2006). It is too expensive to remove metals from severely contaminated soils, and the restoration of these sites does not imply a decrease in the total contents of toxic metals, but rather a change in their availability. Factors that influence the flow of metals from solid phases towards soil solution govern their bioavailability. In this manuscript, the emphasis is set on the effect of polyacrylate polymers on plant growth and quality of metal-contaminated soils, deriving from their effect on metal availability

Relationships between nutrient composition of flowers and fruit quality in orange trees grown in calcareous soil

To determine if flower nutrient composition can be used to predict fruit quality, a field experiment was conducted over three seasons (1996-1999) in a commercial orange orchard (Citrus sinensis (L.) Osbeck cv. 'Valencia Late', budded on Troyer citrange rootstock) established on a calcareous soil in southern Portugal. Flowers were collected from 20 trees during full bloom in April and their nutrient composition determined, and fruits were harvested the following March and their quality evaluated. Patterns of covariation in flower nutrient concentrations and in fruit quality variables were evaluated by principal component analysis. Regression models relating fruit quality variables to flower nutrient composition were developed by stepwise selection procedures. The predictive power of the regression models was evaluated with an independent data set. Nutrient composition of flowers at full bloom could be used to predict the fruit quality variables fresh fruit mass and maturation index in the following year. Magnesium, Ca and Zn concentrations measured in flowers were related to fruit fresh mass estimations and N, P, Mg and Fe concentrations were related to fruit maturation index. We also established reference values for the nutrient composition of flowers based on measurements made in trees that produced large (> 76 mm in diameter) fruit.info:eu-repo/semantics/publishedVersio

Use of organic residues in the recovery of organic matter pools, after forest fires

RAMIRAN International ConferenceIn Portugal, as in other Mediterranean countries, fire events are common primarily due to climate and progressive rural abandon, and contribute largely to desertification. Top layers of soil are constituted mostly by organic residues and decomposed organic matter, and are the most sensitive layers to fire damages. Soil organic matter is an important factor on physical, chemical and biological properties of soil. Quantity and duration of heat transfer and soil thermal conductivity, which varies according to soil conditions (humidity, organic matter, texture, etc), are the main responsible factors for the more or less physical, chemical and biological changes in soil after fire (Neary et al,1999). A soil temperature of only forty degrees is enough to initiate biological changes that may begin with plant and roots death caused by dehydration, and protein degradation. Microbial populations have different thermal resistances and most are killed between 50 and 120 ºC. Organic matter (OM) losses may occur at low temperatures, through the volatilization of volatile compounds which may occur between 100º and 180 ºC or OM distillation at 200 to 315 ºC (DeBanno et al, 1998). Under 200 ºC, decomposition of resistant compounds as hemicelullose and lignin starts (Chandler et al, 1983, cit by González-Pérez et al, 2004). At 300 ºC, decarboxylation and loss of Oxigen-containing functional groups (as phenols) occur in the Humic (HA) and Fulvic acids (FA) (Knoepp, 2005). Humin content increases, due to formation of aromatic compounds, because the more soluble fraction, the FA fraction, is transformed into insoluble acids like HA, and this last ones suffer dehydratation and decarboxylation, becoming insoluble – Black Carbon – resembling the Humin fraction (González-Pérez et al, 2004, Tinoco et al, 2006, Hatten and Zabowski, 2009). Above 450 ºC, all OM is loss. The main purpose of this work was to evaluate the effect of soil heating in forest soils, using a natural burned (B) and an unburned (U) soils and thermally treated soils at different temperatures (65, 105 and 250ºC). Further, we examined the benefic effects of application of organic residues to soils that had been exposed to fire, we added digested pig slurry, municipal solid waste compost and a mixture of both, and evaluated organic matter composition after 2 months of incubation

Remediation of a mine soil with insoluble polyacrylate polymers enhances soil quality and plant growth

We investigated the effects of different application rates of insoluble hydrophilic polyacrylate polymers on plant growth and soil quality from a Pb-contaminated mine soil. The polymer increased the waterholding capacity of the soil from about 250 g ⁄ kg in unamended soil to almost 1000 g ⁄ kg in soil with 0.6% polymer. However, the capacity of the polymer to retain water decreased progressively, presumably as the polymer sorbed Pb. Growth of orchardgrass (Dactylis glomerata L. cv. Amba) was stimulated in the polymer-amended soil. The greatest accumulated biomass over four cuts was obtained in soil amended with 0.4% of polymer. After orchardgrass had been growing for 101 days, the amounts of CaCl2-extractable Pb present in the polymer-amended soil were 15–66% of those in the unamended soil, depending on polymer application rate. The number of bacteria culturable on agar enriched with ‘Nutrient’ and yeast extract, and the activities of dehydrogenase, phosphatase, b-glucosidase, protease and cellulase increased following polymer application. In contrast, urease activity was impaired by polymer application, presumably due to the presence of ammonium as a counter ion. Principal component analysis was used to compare the effects of the different rates of polymer application. Overall, the application of 0.2 or 0.4% polymer resulted in closer values for the indicators of soil quality used than the treatment with 0.6% polymer

Recovery of burned forest soil by organic residue application - substrate induced respiration in soil

RAMIRAN International ConferenceThe Mediterranean is one of the most vulnerable regions to climatic changes. One of the impacts of these changes is a substantial increase in the meteorological risk of fire. The forest fire regime instantaneously responds to climatic changes and may become the dominant factor of alteration in forest communities (Santos & Miranda, 2006). Therefore, understanding the impact of fire on natural ecosystems may be important in the recovery of post-fire ecosystems, hence allowing a better forest restoration. A fire impacted soil can recover, namely through soil organic matter (OM) correction by the application of organic residues. Applying agricultural (e.g. pig slurry) and municipal solid wastes as organic matter sources to soil may represent a good way to recycle these wastes. Fire leads to important changes in the physical, chemical and biological properties of soils, which are relevant for the future productivity and sustainability of ecosystems (Neary et al., 2005). The extent and duration of these effects on soil properties depend on the intensity and residence time, ergo fire severity (Certini, 2005). Soil microorganisms perform an important and essential role in soil biological processes. Biological properties however, are extremely sensitive to soil warming, where lethal temperature thresholds for most organisms are below 100 oC. Biological diversity represents a sensitive means to determine soil quality. This is related to functional diversity, which comprises the ability of organisms to use a vast range of carbon substrates and be able to perform several biochemical reactions. Soil health and quality can be assessed by microbial community level physiological profiles (CLPP), using different carbon substrates. MicroRespTM can be applied to a vast range of soils and has good sensibility to detect changes in microbial communities, offering a rapid and sensitive method to determine CLPP (Chapman et al., 2007). Soil (Litosol) was collected in Sintra Mountain (Portugal), on a Pinus Pinaster forest, 11 days after a forest fire. The impact on recovery of burned soil by organic residue application and its influence on soil microorganisms was studied using the MicroRespTM method, concerning fire effects on soil microorganisms and the need to recycle wastes

Amendment of an acid mine soil with compost and polyacrylate polymers enhances enzymatic activities but may change the distribution of plant species

Many soils derived from pyrite mines spoils are acidic, poor in organic matter and plant nutrients, contaminated with trace elements, and support only sparse vegetation. The establishment of a plant cover is essential to decrease erosion and the contamination of water bodies with acid drainage containing large concentrations of trace elements. We tested the application of compost and polyacrylate polymers to promote the growth of indigenous plant species present in the mine area. Soil treatments consisted of unamended soil (control), soil with mineral fertilizers only, soil with fertilizer plus compost, soil with fertilizer plus polyacrylate polymers, and soil with fertilizer plus both amendments. Half of the soil was grown with Briza maxima L.(greater quaking grass), Chaetopogon fasciculatus (Link) Hayek (chaetopogon), and Spergularia purpurea(Persoon) G. Don fil. (purple sandspurry),while the remainder was left bare. In the absence of plants, the greatest improvements in soil conditions were obtained by the application of both amendments,which was associated with the greatest values of protease, acid phosphatase, and β-glucosidase, whereas the activity of cellulase and microbial respiration were similar in soil amended with compost or polymer. Dehydrogenase activity was greatest in soil with compost (with or without polymer), whereas urease activity was impaired by both amendments. In the presence of plants, the application of both amendments led to the greatest activities of protease,urease, β-glucosidase, cellulase, and microbial respiration, but acid phosphatase was mainly enhanced by polymer and dehydrogenase was increased by compost. Plant growth was stimulated in all treatments compared with unamended soil, but the greatest value for total accumulated biomass was obtained in fertilized soil receiving both amendments. However, species responded differently to treatment: while the growth of B. maxima was greatest in soil with compost and polymer, the growth of C. fasciculatus responded better to soil with compost, and S. purpurea grew better in polymer-amended soil. The amendments tested improved the quality of a mine soil and stimulated plant growth. However, botanical composition likely changes over time with amendments, and this needs to be considered when a large scale application of amendments is projected

Nitrogen distribution, remobilization and re-cycling in young orchard of non-bearing Rocha pear trees

In newly planted orchards, special attention must be paid to fertilization to build up the permanent structure of the trees so that high yield and fruit quality can be reached later on. Nitrogen (N) plays a major role in the fertilization plan, although few studies have assessed its use efficiency in young nonbearing trees, especially in field conditions. In this work, 1–3 years old ‘Rocha’ pear trees, grafted on quince BA29, were planted in a Mediterranean region, and fertigated with 6 g N tree 1 year 1 as ammonium nitrate with 5 at.% 15N enrichment to study the fertilizer N uptake during the vegetative cycle, the overall fertilizer N use efficiency at the end of each year, and the plant–soil N balance for this period. Nitrogen remobilization and the re-cycling of N from senescent leaves were also studied by fertilizing some pear trees with 10 at.% 15N enrichment. Nitrogen uptake was minimum at bud break and peaked in June/July remainingmore or less constant until leaf fall. About 25% of the fertilizer N taken up by 3 years old trees in the previous year was found in the new tissues formed (flowers, leaves and 1-year-old shoots), reaching 27% when fine roots were also included. In those trees, 32% and 54% of the 15N stored in the previous year in the trunk and older shoots, respectively, were mobilized to the new growth in the following year. Fertilizer N use efficiency by trees increased from the first to the third year but was generally small (6%, 14% and 33%), and estimated N losses were large (89%, 46% and 53%, respectively in the first, second and third years). Irrigation water and soil provided more N to the trees than fertilizer N

Evaluation of amendments in the rehabilitation of sulfide mine tailings from São Domingos

RAMIRAN International ConferenceThe São Domingos mining area is located in the Iberian Pyrite Belt, SE Portugal, and represents a serious environmental hazard (Matos and Martins, 2006). Exploitation dated back to pre-roman and roman times with extraction of Ag, Au and Cu exploitation, mainly in the gossan (resulting from the ore weathering). The intense exploitation started in the middle of 19th century, both in the gossan and sulfide ore-containing Cu, Zn, As and Pb, and lasted until 1960, with the exhaustion of the ore (Quental et al., 2002). Different types of waste materials were left: gossan, host rocks (volcanic with shales, and shales), roman and modern slags, smelting ashes and brittle and blocks of pyrite (Matos, 2004; Álvarez-Valero et al., 2008). All sulfide mine wastes are typically heterogeneous and contain high amounts of trace elements, acidic pH and small contents of organic matter and nutrients. The large dumps containing pyrite and other metal sulfides generate, by oxidation, acidic mine drainage (AMD) which increases the availability of trace elements for microorganisms and plants in the surrounding soils. All of these characteristics contribute towards a system that is barely capable of supporting the establishment or survival of plants. The use of amendments and spontaneous colonization (vegetation) from mining areas (phytostabilization) are cost-effective and environmentally sustainable methods to rehabilitate these contaminated and degraded areas even in arid and semi-arid conditions (Tordoff et al., 2000; Mendez and Maier, 2008). Thus, the preparation of Technosols from mixtures of organic and inorganic wastes can be an attractive option to rehabilitate mining areas because they can improve physical, chemical and biological properties contributing, at the same time, towards a strategy of wastes valorisation (Macías, 2004). The use of mixtures composed of residues with different C:N ratios can be used to manipulate the rate of mineralization. Nevertheless, the amendments used should also promote other soil functions (Arbestain et al., 2008). The objective of this study was to evaluate the influence of cost-effective organic and inorganic amendments, available in the region, in the rehabilitation of sulfide materials from the São Domingos mine are

Microbial characterization of a mine soil subjected to different remediation technologies combining organic and inorganic treatments and plant cultivation

RAMIRAN International ConferenceIn Portugal, additional research is needed if technologies based on the combined action of plants and the microbial communities they support within the rhizosphere are to be adopted in large-scale remediation actions (Nabais et al., 2008). Plants growing in abandoned mines are useful to indicate the mineral composition of the soil and they are able to accumulate or exclude toxic metals (Pratas et al., 2005). Taking into account that the mine degraded soils have low concentrations of plant nutrients, it is necessary to apply amendments to ensure plant cover when remediation technologies are present. But soil amendments and the development of a root system might induce shifts in the microbial community structure among the different treatments (Pérez-de-Mora et al., 2006). Moreover, data about the toxic effects of heavy metals on soil microorganisms indicated that heavy metal-sensitive bacteria are probably responsible for the decrease in bacterial activity and the competitive advantage of more tolerant ones resulted in a change in community composition (Díaz-Raviña and Bååth, 1996). Hence, relationships between the soil composition, plant species occurring above-ground and the soil microbial communities have been revealed in many research (Kourtev et al., 2003) providing an important link between above and below-ground processes in terrestrial ecosystems. Soil microbial community structure is increasingly being marketed as ecologically-relevant endpoint and it can realistically be incorporated for assessing the potential risks associated with soil amendment strategies on sustainability of soil ecosystems. Studies of different remediation technologies with mine soils in Portugal, including amendment materials from farming and industrial sources and the use of native plant species (Guiwei et al., 2008; de Varennes et al., 2009) revealed differential effects of treatments on soil enzymes and microbial respiration, suggesting a change in microbial communities. The information about this fact is scarce and had focused on soil biochemical properties, producing no clear results. Phospholipid fatty acid (PLFA) patterns are sensitive indicators of changes in microbial community structure. This technique has been used to elucidate different strategies employed by microorganism to adapt to changed environmental conditions under wide ranges of soil types, management practices, climatic origins and different perturbations (Zelles, 1999). The present study is the first attempt to characterize, by means of the analysis of PLFA patterns, soil microbial population from a Pb-contaminated mine soil subjected to different remediation technologies including revegetation with native herbaceous species

Microbial community structure in a unlimed and limed mine contaminated soil (Pb, Cu, As) with different organic and inorganic treatments

RAMIRAN International ConferenceMine contaminated soils are very unfavourable environments with limiting factors, in particular residual high levels of heavy metals, soil acidity, lack of organic matter and poor substrate structure. Toxic effects of HM on soil microorganisms have been extensively studied (Frostegård et al., 1993; Bååth et al., 1998) and the measurements of community structure indicated that the HM had an effect resulting in a change in community composition (Ellis et al., 2003; Rajapaksha et al, 2004). Nowadays molecular biology techniques, such as the analysis of phospholipid fatty acid (PLFA) patterns, make it possible to study the microbial community structure of soil microorganisms. The PLFA technique has been used to elucidate different strategies employed by microorganism to adapt to changed environmental conditions under wide ranges of soil types, management practices, climatic origins and different perturbations (Zelles, 1999). By phospholipid fatty acid analysis it is possible to examine broad scale patterns in microbial community structure (Bååth et al. 2005) and generally, after the application of multivariate statistical analyses, whole community fatty acids profiles indicate which communities are similar or different. Determination both microbial community composition and biomass size by this direct method gives results that very closely represent the in situ soil conditions and is currently used for soil monitoring purposes (Nielsen and Winding, 2002). This study aimed to evaluate the effect of different remediation technologies in a mine contaminated soil including several organic and inorganic treatments combined with liming by the soil microbial community structure analysi