Regeneration of Nothofagus pumilio [Poepp. et Endl.] Krasser forests after five years of seed tree cutting

Nothofagus pumilio [Poepp. et Endl.] Krasser is a deciduous tree species that grows in Chile and adjacent Argentina between 36 and 56 degrees S, often forming the Andean tree line. Silvicultural systems proposed for this species integrate both regeneration and intermediate level operations in an orderly process for managing forest stands. The seed-tree method of regeneration has been used to manage even-aged stands of this species. This paper investigates the effect of seed tree cuttings on the regeneration of Nothofagus pumilio [Poepp. et Endl.] Krasser forest located in the Magallanes region (Chile). The studied forest was managed on an even-aged basis using a seed tree silvicultural system for regeneration with an intensity of cutting of 65-70% of the basal area and a minimum of 15 dominant lenga trees per hectare retained. A regeneration inventory sampling was used to quantify regeneration attributes in the study area. Regeneration was found to be significantly affected by the seed tree cuttings. In fact, the number of established individuals rose from 0.39 to 26.7 plants m(-2) pre-harvest to 9.2-21.5 plants m(-2) post-harvest, depending on the particular development stage. Total regeneration ranged from 9.5 to 48.2 plants m(-2). The number of plants established over the period 1992-1997 was related to the residual basal area, coverage and number of trees. However, mean tree height was not significantly related to any regeneration variable. Significant variables were used to establish a regeneration prediction model using single and multiple linear equations (R2<0.418). Consequently, the seed tree method of regeneration can be considered feasible for commercially valuable lenga forests, although this method, in its strictest application, will create many large, irregularly shaped, even-aged groups.     

Impacts of multidisciplinary actions on environmental lead exposure in Uruguay

Environmental lead contamination in Uruguay became a matter of public concern in 2001, when cases of children with blood lead levels (BLL) higher than 20 μg/dl appeared in some low-income neighborhoods of Montevideo, being 10 μg/dl the intervention reference BLL. The aim of this paper is to show the results of multidisciplinary actions taken by decisions makers in social, environmental and healthcare aspects, to minimize lead exposure risks. We evaluated changes in blood lead levels of different children and non-exposed adult populations before and after the actions were taken, from 2001 on. For children populations and non-exposed adults, we found a significant decrease of almost 50% in BLL compared with studies done before the actions were taken. The main action to consider was the phasing out process of leaded gasoline in our country among other. We conclude that the integration of inter and multidisciplinary actions promoted was of high impact on the population, bringing about a public sensitization and growing awareness of the lead environmental risks.     

Effect of tannins on survival and development of Daphnia menucoensis and the abundances of bacteria

Polyphenols – products of organic-matter decomposition entering water bodies from autochthonous and especially allochthonous sources – affect primary producers, bacterioplankton, and zooplankton to consequently modify food webs. Cladocerans are widely used in research experiments because they constitute the most frequent prey of high-trophic-level organisms in the majority of lakes, and certain species symbolise the ecologic prototype of the generalist filter feeder. In our study area’s shallow lakes, cladocerans, though generally of low abundance, do attain significantly high biomasses. We accordingly evaluated the mortality of the cladoceran Daphnia menucoensis Paggi, 1996 exposed to different tannin concentrations along with the bacterial abundance. In two experiments D. menucoensis females exposed to high tannin concentrations reproduced inefficiently, exhibited high mortality, and manifested altered behaviour, such as reduced reflexes and diminished mobility. Though tannins apparently affected algal abundances, the cladoceran herbivory strongly reduced those numbers. Positive effects on bacteria, however, were not recorded. High-allochthonous-organic-matter-containing water bodies support trophic webs because bacterioplankton provide an alternative energetic base for the zooplankton, as possibly occurs in shallow lakes of the Salado-River basin, characterised by cyclic hydrologic periods alternating between draught and flooding and intensive land use. In conclusion, tannins diminish D. menucoensis’s survival, locomotion, and the capacity to respond to stimuli.     

Chemistry of soil solutions under different kinds of vegetation in the vicinity of a thermal power station

The influence of atmospheric deposition on the chemical characteristics of soil solutions in a small catchment area in NW Spain was studied. The soils, developed from slates, were sampled from seven sites supporting different forms of vegetation (deciduous and pine forest and heath). Soil solutions were extracted, by the column displacement method, from soil samples collected monthly from March 1992 until November 1993. The solutions were acidic with a low content of basic cations. The most common ions in all horizons were Cl(-) and Na(+), due to marine influence. In the surface horizons (0-10 cm), relatively high concentrations of SO(2-)4 (150-380 micromol litre(-1)) and Zn (approximately 2 micromol litre(-1)) were obtained, with good correlation between the two ions. These results, along with the prevalence of inorganic forms of Al (50-90% of total Al), were related to the effects of acidic deposition in the catchment area. The more rapid breakdown of litter in the soils under deciduous forest explains the greater ionic concentrations obtained in these solutions.     

Comparison of bioaugmentation and biostimulation for the enhancement of dense nonaqueous phase liquid source zone bioremediation.

Two 11.7-m(3) experimental controlled release systems (ECRS), packed with sandy model aquifer material and amended with tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) source zone, were operated in parallel with identical flow regimes and electron donor amendments. Hydrogen Releasing Compound (Regenesis Bioremediation Products, Inc., San Clemente, California), and later dissolved lactate, served as electron donors to promote dechlorination. One ECRS was bioaugmented with an anaerobic dechlorinating consortium directly into the source zone, and the other served as a control (biostimulated only) to determine the benefits of bioaugmentation. The presence of halorespiring bacteria in the aquifer matrix before bioaugmentation, shown by nested polymerase chain reaction with phylogenetic primers, suggests that dechlorinating catabolic potential may be somewhat widespread. Results obtained corroborate that source zone reductive dechlorination of PCE is possible at near field scale and that a system bioaugmented with a competent halorespiring consortium can enhance DNAPL dissolution and dechlorination processes at significantly greater rates than in a system that is biostimulated only.     

Influence of tree species composition,thinning intensity and climate change on carbon sequestration in Mediterranean mountain forests: a case study using the CO2Fix model

Prediction of future forest carbon (C) stocks as influenced by forest management and climate is a crucial issue in the search for strategies to mitigate and adapt to global change. It is hard to quantify the long-term effect of specific forest practices on C stocks due to the high number of processes affected by forest management. This work aims to quantify how forest management impacts C stocks in Mediterranean mountain forests based on 25 combinations of site index, tree species composition and thinning intensity in three different climate scenarios using the CO2Fix v.3.2 model Masera et al. (Ecol Modell 164:177–199, 2003). The study area is an ecotonal zone located in Central Spain, and the tree species are Scots pine (Pinus sylvestris L.) and Pyrenean oak (Quercus pyrenaica Willd.). Our results show a strong effect of tree species composition and a negligible effect of thinning intensity. Mixed stands have the highest total stand C stocks: 100 % and 15 % more than pure oak and pine stands respectively, and are here suggested as a feasible and effective mitigation option. Climate change induced a net C loss compared to control scenarios, when reduction in tree growth is taken into account. Mixed stands showed the lowest reduction in forest C stocks due to climate change, indicating that mixed stands are also a valid adaptation strategy. Thus converting from pure to mixed forests would enhance C sequestration under both current and future climate conditions.     

Bottom sediment as a source of organic contaminants in Lake Mead, Nevada, USA

Treated wastewater effluent from Las Vegas, Nevada and surrounding communities’ flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however, partitioning between the sediment and the overlying water could result in the sediment acting as a secondary contaminant source. Locating the chemical plumes may be important to understanding possible chemical stressors to aquatic organisms. Passive sampling devices (SPMDs and POCIS) were suspended in LVB at depths of 3.0, 4.7, and 6.7 (lake bottom) meters in June of 2008 to determine the vertical distribution of SOCs in the water column. A custom sediment probe was used to also bury the samplers in the sediment at depths of 0-10, 10-20, and 20-30 cm. The greatest number of detections in samplers buried in the sediment was at the 0-10 cm depth. Concentrations of many hydrophobic SOCs were twice as high at the sediment-water interface than in the mid and upper water column. Many SOCs related to wastewater effluents, including fragrances, insect repellants, sun block agents, and phosphate flame retardants, were found at highest concentrations in the middle and upper water column. There was evidence to suggest that the water infiltrated into the sediment had a different chemical composition than the rest of the water column and could be a potential risk exposure to bottom-dwelling aquatic organisms.     

Hydrogeological definition and applicability of abandoned coal mines as water reservoirs

Hydrogeologically, the Central Coal Basin (Asturias, Spain) is characterized by predominantly low-permeability materials that make up a multilayer aquifer with very low porosity and permeability values, where the sandstones act as limited aquifers, and wackes, mudstones, shales and coal seams act as confining levels. Preferential groundwater flow paths are open fractures and zones of decompression associated with them, so the hydraulic behaviour of the system is more associated with fracturing than lithology. Thus, abandoned and flooded mines in the area acquire an important role in the management of water resources, setting up an artificial "pseudo-karst" aquifer. This paper evaluates the potential application of the abandoned mines as underground reservoirs, both for water supply and energetic use, mainly through heat pumps and small hydropower plants. In particular, the groundwater reservoir shaped by the connected shafts Barredo and Figaredo has been chosen, and a detailed and multifaceted study has been undertaken in the area. The exposed applications fit with an integrated management of water resources and contribute to improve economic and social conditions of a traditional mining area in gradual decline due to the cessation of such activity.     

Study of Graft Copolymerization of Soy Protein-Methyl Methacrylate: Preparation and Characterization of Grafted Films

Hybrid materials represent the family of compounds comprising mixtures of natural and synthetic materials. The study of this field is in a marked expansion since their preparation represents a valid methodology for optimizing the insufficient properties exhibited by materials integrally formed from naturally-occurring sources. In the present work, we describe soy protein modification by grafting reaction with methyl methacrylate. The reaction was confirmed by Fourier Transform Infrared Analysis and Carbon Nuclear Magnetic Resonance. In addition, films were prepared with the material by heat compression. Films were physically and mechanically characterized by determining contact angle with water, total soluble matter, moisture content, swelling in water, water vapor permeability, tensile strength, elongation at break and Young’s modulus. These measurements suggest that the material increased its hydrophobic character as compared with that of the control film since marked reductions in water vapor permeability, swelling and water solubility were determined. Moreover, their mechanical properties were improved by obtaining a more rigid material. These results represent an interesting advance in the preparation of hybrid biocomposites.