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111.
de Paula FR Ferraz SF Gerhard P Vettorazzi CA Ferreira A 《Environmental management》2011,48(4):750-763
Riparian forests are important for the structure and functioning of stream ecosystems, providing structural components such
as large woody debris (LWD). Changes in these forests will cause modifications in the LWD input to streams, affecting their
structure. In order to assess the influence of riparian forests changes in LWD supply, 15 catchments (third and fourth order)
with riparian forests at different conservation levels were selected for sampling. In each catchment we quantified the abundance,
volume and diameter of LWD in stream channels; the number, area and volume of pools formed by LWD and basal area and tree
diameter of riparian forest. We found that riparian forests were at a secondary successional stage with predominantly young
trees (diameter at breast height <10 cm) in all studied streams. Results showed that basal area and diameter of riparian forest
differed between the stream groups (forested and non-forested), but tree density did not differ between groups. Differences
were also observed in LWD abundance, volume, frequency of LWD pools with subunits and area and volume of LWD pools. LWD diameter,
LWD that form pools diameter and frequency of LWD pools without subunits did not differ between stream groups. Regression
analyses showed that LWD abundance and volume, and frequency of LWD pools (with and without subunits) were positively related
with the proportion of riparian forest. LWD diameter was not correlated to riparian tree diameter. The frequency of LWD pools
was correlated to the abundance and volume of LWD, but characteristics of these pools (area and volume) were not correlated
to the diameter of LWD that formed the pools. These results show that alterations in riparian forest cause modifications in
the LWD abundance and volume in the stream channel, affecting mainly the structural complexity of these ecosystems (reduction
in the number and structural characteristics of LWD pools). Our results also demonstrate that riparian forest conservation
actions must consider not only its extension, but also successional stage to guarantee the quantity and quality of LWD necessary
to enable the structuring of stream channels. 相似文献
112.
Pincheira Roxana Zúñiga Felipe Valencia Francisco 《Environmental science and pollution research international》2021,28(46):65573-65594
Environmental Science and Pollution Research - Planetary boundaries (PB) is a novel conceptual framework that assesses the state of processes fundamental to the stability of the Earth system.... 相似文献
113.
Felipe Murtinho Hallie Eakin David López-Carr Tanya M. Hayes 《Environmental management》2013,52(5):1103-1114
Despite debate regarding whether, and in what form, communities need external support for adaptation to environmental change, few studies have examined how external funding impacts adaptation decisions in rural resource-dependent communities. In this article, we use quantitative and qualitative methods to assess how different funding sources influence the initiative to adapt to water scarcity in the Colombian Andes. We compare efforts to adapt to water scarcity in 111 rural Andean communities with varied dependence on external funding for water management activities. Findings suggest that despite efforts to use their own internal resources, communities often need external support to finance adaptation strategies. However, not all external financial support positively impacts a community’s abilities to adapt. Results show the importance of community-driven requests for external support. In cases where external support was unsolicited, the results show a decline, or “crowding-out,” in community efforts to adapt. In contrast, in cases where communities initiated the request for external support to fund their own projects, findings show that external intervention is more likely to enhance or “crowds-in” community-driven adaptation. 相似文献
114.
This paper examines ex-post 51 investment decisions made in regard to copper mines coming on stream from 1957 through 1999. It discusses two critical variables: investment timing and mine capacity choice. Using a 15% discount rate, results suggest that fewer than half of decisions were made at the right time – i.e., low price periods – confirming countercyclical investment as the optimal policy. In terms of capacity choice, the distortion is even higher, as 36 projects should have entered at least 40% larger or smaller. Realized investment decisions for timing and capacity choice would have caused a 49.1% loss over the NPV potentially achievable under optimal resolutions. Although the difference could be specifically attributed to copper price uncertainty, this paper discusses how investment evaluation methodologies could be contributing to firms not being fully rational (in the neoclassical sense) when investing. 相似文献
115.
Borges AR Niencheski LF Milani IC Milani MR 《Environmental monitoring and assessment》2012,184(9):5553-5562
The chemical speciation analysis of chromium in one of the most important South American Estuary was performed for the first time. Samples were collected in Patos Lagoon Estuary (Brazil) and were analysed by adsorptive cathodic stripping voltammetry, with the following analytical figures of merit: limit of detection, 0.1 nmol L(-1); precision RSD?=?3%, n?=?7; linearity, from limit of quantitation up to 20 nmol L(-1); and accuracy of 99.8%, expressed as recovery. No labile chromium forms were identified in samples, beside industries and a city were near the study area. It is pointed out a reverse correlation between total and non-active chromium and salinity, which could be explained by biogeochemical processes. 相似文献
116.
Anaerobic codigestion of municipal, farm, and industrial organic wastes: a survey of recent literature. 总被引:3,自引:0,他引:3
Felipe Alatriste-Mondragón Parviz Samar Huub H J Cox Birgitte K Ahring Reza Iranpour 《Water environment research》2006,78(6):607-636
Codigestion of organic wastes is a technology that is increasingly being applied for simultaneous treatment of several solid and liquid organic wastes. The main advantages of this technology are improved methane yield because of the supply of additional nutrients from the codigestates and more efficient use of equipment and cost-sharing by processing multiple waste streams in a single facility. Many municipal wastewater treatment plants (WWTPs) in industrialized countries currently process wastewater sludge in large digesters. Codigestion of organic wastes with municipal wastewater sludge can increase digester gas production and provide savings in the overall energy costs of plant operations. Methane recovery also helps to reduce the emission of greenhouse gases to the atmosphere. The goal of this literature survey was to summarize the research conducted in the last four years on anaerobic codigestion to identify applications of codigestion at WWTPs. Because the solids content in municipal wastewater sludge is low, this survey only focuses on codigestion processes operated at relative low solids content (slurry mode). Semi-solid or solid codigestion processes were not included. Municipal wastewater sludge, the organic fraction of municipal solid waste, and cattle manure (CAM) are the main wastes most often used in codigestion processes. Wastes that are codigested with these main wastes are wood wastes, industrial organic wastes, and farm wastes. These are referred to in this survey as codigestates. The literature provides many laboratory studies (batch assays and bench-scale digesters) that assess the digestibility of codigestates and evaluate the performance and monitoring of codigestion, inhibition of digestion by codigestates, the design of the process (e.g., single-stage or two-stage processes), and the operation temperature (e.g., mesophilic or thermophilic). Only a few reports on pilot- and full-scale studies were found. These evaluate general process performance and pretreatment of codigestates, energy production, and treatment costs. 相似文献
117.
Rodrigo Galbieri Thiago Luis Felipe Brito Dominique Mouette Hirdan Katarina de Medeiros Costa Edmilson Moutinho dos Santos Murilo Tadeu Werneck Fagá 《Mitigation and Adaptation Strategies for Global Change》2018,23(7):1039-1062
Energy consumption is related to local, regional and global impacts. Thus, by comparing different replacement scenarios of diesel vehicles with compressed natural gas, this article estimates pollutants and greenhouse gases emission in the city of São Paulo, Brazil. The calculation of fuel consumption is based on fleet characteristics, in terms of vehicle age, the average annual distance travelled by bus depending on the year and average fuel consumption. These values served as a basis to develop scenarios considering that a percentage of new vehicles that will be phased out and replaced with ones running on natural gas. Results show that the total avoided emissions can range from 579 thousand tons to 1.375 million tons of carbon dioxide (CO2) over 20 years, depending on the scenario. For particulate matter, accumulated avoided emissions vary from 251 thousand to 584 tons over 20 years. The replacement of diesel buses with natural gas-fuelled buses presents favourable results, in comparison with the tendency scenario for CO2 and particulate matter. Thus, a public policy for fuel replacement in largest cities, such as Sao Paulo, has an important global impact, especially when allowing the introduction of a renewable energy source, such as biogas. It will benefit from the natural gas previous infrastructure, which is largely available in Brazil. As recommendations, we explain the need to review the city of Sao Paulo Climate Change Law to allow the use of natural gas. Fuel replacement should be integrated with a public policy/public policies and operational strategies to promote citizens´ health as well as historical, cultural and heritage conservation for the city and its future generations. 相似文献
118.
119.
Quantitative PCR to estimate copepod feeding 总被引:1,自引:0,他引:1
Jens C. Nejstgaard Marc E. Frischer Paolo Simonelli Christofer Troedsson Markus Brakel Filiz Adiyaman Andrey F. Sazhin L. Felipe Artigas 《Marine Biology》2008,153(4):565-577
Copepods play a central role in marine food webs as grazers of plankton and as key prey for many predators. Therefore, quantifying
their specific trophic interactions is critical for understanding the role of copepods in ocean processes. However, because
of methodological constraints, it remains difficult to investigate in situ copepod feeding without reliance on laborious intrusive
and potentially biased incubation approaches. Recent advances in PCR-based methodologies have demonstrated the feasibility
of directly identifying copepod diets based on prey DNA sequences. Yet, obtaining quantitative information from these approaches
remains challenging. This study presents results of systematic efforts to develop a quantitative PCR (qPCR) assay targeted
to 18S rRNA gene fragments to estimate copepod gut content of specific species of prey algae. These results were first compared
to gut content estimates based on fluorescence in the copepod Calanus finmarchicus fed monocultures of two different microalgae species in controlled laboratory studies. In subsequent field studies, we compared
feeding rates obtained by microscopy and qPCR for Temora longicornis and Acartia clausi feeding on the haptophyte Phaeocystis globosa in natural blooms. These investigations demonstrate a semi-quantitative relationship between gut content estimates derived from qPCR, gut pigment,
and direct microscopy. However, absolute estimates of gut content based on qPCR methodology were consistently lower than expected.
This did not appear to be explained by the extraction methods used, or interference by non-target (predator) DNA in the PCR
reactions, instead suggesting digestion of prey-specific nucleic acids. Furthermore, the 18S rDNA target gene copy number
of the phytoplankton varied with growth phase. Nonetheless, when prey target gene copy number in the ambient water is quantified,
the qPCR-approach can be compared to other methods, and then used to semi-quantitatively estimate relative copepod grazing
on specific prey in situ without involving further incubations. A distinct advantage of a DNA-based molecular approach compared
to gut fluorescence and direct microscopic observation, is the ability to detect non-pigmented and macerated prey. Future
studies should aim to correct for breakdown in prey DNA and perform extensive calibrations to other methods in order to achieve
a quantitative measure of feeding rates in situ. 相似文献
120.
Effects of extreme variation in female morph frequencies on the mating behaviour of male damselflies
Janice J. Ting Jessica Bots Felipe Pérez Jvostov Hans van Gossum Thomas N. Sherratt 《Behavioral ecology and sociobiology》2009,64(2):225-236
Female-limited polymorphism is often attributed to selection to avoid excessive male mating attempts. It is encountered in
various taxonomic groups, but is particularly common in damselflies, where one female morph (andromorph) typically resembles
the conspecific male in colour pattern, while the other(s) (gynomorph(s)) do not. Two sets of theories have been proposed
to explain the phenomenon in damselflies, which can be classified as the learned mate recognition (LMR) and male mimicry (MM)
hypotheses. To test predictions of these hypotheses, we evaluated the rate of male sexual response towards female morphs and
conspecific males in the damselfly Nehalennia irene. The LMR hypothesis predicts that males should respond sexually to andromorphs at greater rates in populations containing
a higher relative frequency of andromorphs. The MM hypothesis predicts that males respond more often sexually to both andromorphs
and males as the ratio of andromorphs to males increases. While LMR predicts that the rate of mating attempts towards gynomorphs
should vary, the MM predicts that it should be relatively fixed. On experimentally presenting live specimens to focal males
in five different populations with extreme variation in female morph frequencies, we observed that as the andromorph frequency
and ratio of andromorphs to males increased, the proportion of male mating attempts increased on both andromorphs and males,
whereas it decreased on gynomorphs. While the simplest form of the MM hypothesis is rejected, the results support specific
predictions of both hypotheses and suggest that future studies should not treat these hypotheses as mutually exclusive. 相似文献