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681.
Climate change vulnerability depends upon various factors and differs between places, sectors and communities. People in developing countries whose subsistence livelihood depends mainly upon agriculture and livestock production are identified as particularly vulnerable. Nepal, where the majority of people are in a mixed agro-livestock system, is identified as the world’s fourth most vulnerable country to climate change. However, there is limited knowledge on how vulnerable mixed agro-livestock smallholders are and how their vulnerability differs across different ecological regions in Nepal. This study aims to test two vulnerability assessment indices, livelihood vulnerability index and IPCC vulnerability index, around the Gandaki River Basin of central Nepal. A total of 543 households practicing mixed agro-livestock were surveyed from three districts, namely Dhading, Syangja and Kapilvastu representing three major ecological zones: mountain, mid-hill and Terai (lowland). Data on socio-demographics, livelihood determinants, social networks, health, food and water security, natural disasters and climate variability were collected and combined into the indices. Both indices differed for mixed agro-livestock smallholders across the three districts, with Dhading scoring as the most vulnerable and Syangja the least. Substantial variation across the districts was observed in components, sub-components and three dimensions (exposure, sensitivity and adaptive capacity) of vulnerability. The findings help in designing site-specific intervention strategies to reduce vulnerability of mixed agro-livestock smallholders to climate change.  相似文献   
682.
Observing the many and varied reactions to the Kyoto Protocol, it becomes clear that different governments find themselves in different contexts that eventually direct them toward taking dissimilar positions on energy issues. This paper, through five integrated studies, investigates whether contextualizing energy issues is (are) relevant to support energy policy formulation and evaluation and provides insights into how to operationalize the contextualization. Instead of considering the most widely accepted tools currently used to assess and evaluate energy policy, this research proposes the utilization of a holistic framework that incorporates social, economic and environmental factors as well as their relations to the energy sector to better contextualize global, regional and national energy issues. This framework, which accounts for feedback loops, delays and non-linearity, is applied to case studies to investigate the longer-term performance of selected energy policies. Results of the study indicate the likely emergence of various unexpected side effects and elements of policy resistance over the medium and longer term due to the interrelations existing between energy and society, economy and environment. Furthermore, while side effects and unintended consequences may arise both within the energy sector and in the other sectors, they simultaneously influence society, economy and environment.  相似文献   
683.
Although many avian eggs appear to be cryptically colored, many species also lay vibrant blue green eggs. This seemingly conspicuous coloration has puzzled biologists since Wallace, as natural selection should favor reduced egg visibility to minimize predation pressure. The sexual signaling hypothesis posits that blue green egg coloration serves as a signal of female quality and that males exert post-mating sexual selection on this trait by investing more in the nests of females laying more intensely blue green eggs. This hypothesis has received mixed support to date, and most previous studies have been conducted in cavity-nesting species where male evaluation of his partner’s egg coloration, relative to that of other females, may be somewhat limited. In this study, we test the sexual signaling hypothesis in colonially nesting ring-billed gulls (Larus delawarensis) where males have ample opportunity to assess their mate’s egg coloration relative to that of other females. We used correlational data and an experimental manipulation to test four assumptions and predictions of the sexual signaling hypothesis: (1) blue green pigmentation should be limiting to females; (2) extent of blue green egg coloration should relate to female quality; (3) extent of blue green egg coloration should relate to offspring quality; and (4) males should provide more care to clutches with higher blue green chroma. Our data provide little support for these predictions of the sexual signaling hypothesis in ring-billed gulls. In light of this and other empirical data, we encourage future studies to consider additional hypotheses for the evolution of blue green egg coloration.  相似文献   
684.
Nano-sized apatite particles (nAP) synthesized with carboxymethyl cellulose (CMC) have shown great application potentials in in situ heavy metal remediation. However, differences in CMC’s properties effects on the size of nAP produced are not well understood. In this paper, two types of CMC, with respective molecular weights (MW) of ~120000 and ~240000 Dalton or respective polymerization degrees of 500 (CMC-500) and 1050 (CMC-1050), were studied in a concentration range of 0.05%–0.5% (w/w) for nAP synthesis. Morphology of the particles was characterized with transmission electron microscopy (TEM). Results showed that 0.05% CMC-500 solution gave an average particle size of 148.7±134.9 nm, 0.25% CMC-500 solution produced particles of 21.8±20.4 nm, and, 0.5% CMC-500 solution contained particles of 15.8±7.7 nm. In comparison, 0.05% CMC-1050 solution produced nanoparticles of 6.8±3.2 nm, 0.25% CMC-1050 produced smaller nAP of 4.3±3.2 nm, and 0.5% CMC-1050 synthesized the smallest nanoparticles in this study, with an average diameter of 3.0±2.1 nm. Chemical composition of the products was identified with X-ray diffraction (XRD) as pure hydroxyapatite. Interactions between nAP and CMC were discussed with help of attenuated total reflection Fourier transform infrared (ATRFTIR) spectroscopic data. This study showed that CMC at higher concentration as well as higher MW facilitated to produce finer nanoparticles, showing that nAP size could be manipulated by selecting appropriate CMC MW and/or applying appropriate CMC concentration.  相似文献   
685.
Previous studies on kleptoplasty in sacoglossans have used different methodology to investigate how long the sacoglossans are able to keep photosynthetically active (functional) chloroplasts. In this study we have used Pulse Amplitude Modulated Fluorometry to measure the quantum yield of charge separation in photosystem II in dark acclimated cells (ΦIIe) to detect the status of photosynthetic activity. Seven species of sacoglossa, Plakobranchus ocellatus, Elysia timida, Elysia sp, Elysia tomentosa, Thuridilla carlsoni, T. lineolata and Elysiella pusilla, were investigated regarding their ability to retain functional chloroplasts (RFC). The results show three different levels of RFC’s where P. ocellatus has the longest RFC for more than 11 months, E. timida with a RFC 1/4 than P. ocellatus (almost 3 months) and the rest with RFC’s down to 1/22 of P. ocellatus (up to 15 days). Based on these results, and compared to previous studies, eight different levels of retention abilities of non-functional and functional chloroplasts in sacoglossans are proposed. As far as we know, this is a novel method studying chloroplast functionality in sacoglossans.  相似文献   
686.
The use of helicopter rises discussion about environmental noise propagation especially when it operates in proximity of environmentally sensitive areas (ESAs) for an extended period because of its potential implications in wildlife behaviours. In order to support decisions on helicopter logging operation management in proximity of ESAs, this study focused on (i) analysing the noise spectrum of a light-lift helicopter during logging operations and on (ii) assessing the noise propagation in the surrounding environments. This study investigated a helicopter logging operation for wood fuel extraction in the eastern part of the Italian Alps. The potential disturbance area covered for the entire helicopter logging operation was evaluated by a specific GIS application according to hearing sensitivity of the most sensitive wildlife species in the study area (different strigiform species). The noise level at the ground appeared to be affected by the location regardless both the use of equivalent continuous sound pressures level dB(A) (LAeq) and the single-event level (SEL) noise metrics. The lowest values were recorded when the helicopter was flown over the sound meter level located under the forest canopy, while the highest was recorded when the helicopter was unhooking the loads at the landing. The GIS application highlighted the consistent of the exceeded noise area (weighted to strigiform hearing range and sensitivity) for the lower frequency bands (0.016–0.250 kHz). A more restricted exceeded noise area concerned instead the most sensitive frequency bands" for the strigiform (1–2 kHz).
Graphical abstract ?
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687.
The study on the spatial distribution of forest soil organic carbon (SOC) is of great significance for accurate assessment of carbon storage in forest ecosystems. In the present study, by taking eight kinds of forest soils of Mountain Lushan in the subtropical area as the research object, we studied the spatial distribution characteristics of SOC in this mountainous area. The results showed that the SOC content and SOC density (SOCD) of main forest types in the Mountain Lushan were lower than the national and the world average. The soil layer of Lushan forest was thinner, and the SOC and active SOC (ASOC) contents of different forest types and SOCDs are the highest in the surface soil. SOCD of the topsoil accounts for 32.64–54.03% of the total SOCD in the whole soil profile. Surface litter is an important source of SOC, and the different vegetation types are the important reason for the different spatial distribution of SOC in this area. Soil SOC contents in the high-altitude forest (bamboo forest, deciduous broadleaf forest, Pinus taiwanensis forest, evergreen-deciduous forest, and coniferous-broadleaved mixed forest) were higher than those in the low-altitude forest (evergreen broadleaf forest, shrub, and Pinus massoniana forest). However, the difference in SOC content exhibited at the altitude gradient is significantly lower than that in SOC in the soil profile. This indicates that both soil depth and elevation are the important factors that affected SOC distribution. However, the influence of soil depth on spatial distribution of SOC may be more complex than that of altitude. Vegetation types and soil properties are the main reasons for the large differences of reduction rate in the contents of SOC and ASOC.  相似文献   
688.
The temporal and spatial trends in the variability of PM10 and PM2.5 from 2010 to 2015 in the metropolitan area of Lima-Callao, Peru, are studied and interpreted in this work. The mean annual concentrations of PM10 and PM2.5 have ranges (averages) of 133–45 μg m?3 (84 μg m?3) and 35–16 μg m?3 (26 μg m?3) for the monitoring sites under study. In general, the highest annual concentrations are observed in the eastern part of the city, which is a result of the pattern of persistent local winds entering from the coast in a south-southwest direction. Seasonal fluctuations in the particulate matter (PM) concentrations are observed; these can be explained by subsidence thermal inversion. There is also a daytime pattern that corresponds to the peak traffic of a total of 9 million trips a day. The PM2.5 value is approximately 40% of the PM10 value. This proportion can be explained by PM10 re-suspension due to weather conditions. The long-term trends based on the Theil-Sen estimator reveal decreasing PM10 concentrations on the order of ?4.3 and ?5.3% year?1 at two stations. For the other stations, no significant trend is observed. The metropolitan area of Lima-Callao is ranked 12th and 16th in terms of PM10 and PM2.5, respectively, out of 39 megacities. The annual World Health Organization thresholds and national air quality standards are exceeded. A large fraction of the Lima population is exposed to PM concentrations that exceed protection thresholds. Hence, the development of pollution control and reduction measures is paramount.  相似文献   
689.
690.

Background, Aim and Scope

The presence of heavy metals in wastewater is one of the main causes of water and soil pollution. The aim of the present study was to investigate the removal of Cd, Cu, Pb, Hg, Mn, Cr and Zn in urban effluent by a biological wastewater treatment, as well as to quantify the levels of As, Be, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn, Tl, V and Zn in dewatering sludge from the Biological Wastewater Treatment Plant to Ribeirão Preto (RP-BWTP), Brazil.

Materials and Methods

Concentrations of Cd, Cr, Cu, Mn and Pb in wastewater and those of Ni in sludge were determined by atomic absorption spectrophotometry with graphite furnace atomization. Mercury concentrations in wastewater were measured by hydride generation atomic spectrophotometry, and Zn levels were determined by atomic absorption spectrophotometry using acetylene flame. In sludge, the levels of As, Be, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Sn, Tl, V and Zn were determined by inductively coupled plasma-mass spectrometry.

Results

The percentages of removal efficiency (RE) were the following: Hg 61.5%, Cd 60.0%, Zn 44.9%, Cu 44.2%, PB 39.7%, Cr 16,5% and Mn 10.4%. In turn, the mean concentrations (mg/kg) of metals in dewatering sludge followed this increasing order: Tl (<0.03), Hg (0.31), Be (0.43), As (1.14), Cd (1.34), V (59.2), Pb (132.1), Sn (166.1), Cr (195.0), Mn (208.1), Ni (239.4), Cu (391.7), Zn (864.4) and Fe (20537).

Discussion

The relationship between metal levels in untreated wastewater, as well as the removal efficiency are in agreement with previous data from various investigators, It is important to note that metal removal efficiency is not only affected by metal ion species and concentration, but also by other conditions such as operating parameters, physical, chemical, and biological factors.

Conclusions

Metal values recorded for treated wastewater and sludge were within the maximum permitted levels established by the Environmental Sanitation Company (CETESB), São Paulo, Brazil.

Recommendations

There is an urgent need for the authorities who are responsible for legislation on sludge uses in agriculture of establishing safety levels for As, Be, Hg, Sn, Tl and V.

Perspectives

According to the current metal levels, RP-BWTP sludge might be used for agriculture purposes. However, for an environmentally safe use of sewage sludge, further studies including systematic monitoring are recommended. Annual metal concentrations and predicted variations of those elements in the sludge should be monitored.
  相似文献   
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