938 resultados para Pools
Resumo:
Phosphorus is an essential nutrient for life. In the ocean, phosphorus burial regulates marine primary production**1, 2. Phosphorus is removed from the ocean by sedimentation of organic matter, and the subsequent conversion of organic phosphorus to phosphate minerals such as apatite, and ultimately phosphorite deposits**3, 4. Bacteria are thought to mediate these processes**5, but the mechanism of sequestration has remained unclear. Here, we present results from laboratory incubations in which we labelled organic-rich sediments from the Benguela upwelling system, Namibia, with a 33P-radiotracer, and tracked the fate of the phosphorus. We show that under both anoxic and oxic conditions, large sulphide-oxidizing bacteria accumulate 33P in their cells, and catalyse the nearly instantaneous conversion of phosphate to apatite. Apatite formation was greatest under anoxic conditions. Nutrient analyses of Namibian upwelling waters and sediments suggest that the rate of phosphate-to-apatite conversion beneath anoxic bottom waters exceeds the rate of phosphorus release during organic matter mineralization in the upper sediment layers. We suggest that bacterial apatite formation is a significant phosphorus sink under anoxic bottom-water conditions. Expanding oxygen minimum zones are projected in simulations of future climate change**6, potentially increasing sequestration of marine phosphate, and restricting marine productivity.
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The fine-scale depth distribution of major carbon pools and their stable carbon isotopic signatures (d13C) were determined in a cyanobacterial mat (Salin-de-Giraud, Camargue, France) to study early diagenetic alterations and the carbon preservation potential in hypersaline mat ecosystems. Particular emphasis was placed on the geochemical role of extracellular polymeric substances (EPS). Total carbon (Ctot), organic carbon (Corg), total nitrogen (Ntot), total hydrolysable amino acids (THAA), carbohydrates, cyanobacteria-derived hydrocarbons (8-methylhexadecane, n-heptadec-5-ene, n-heptadecane) and EPS showed highest concentrations in the top millimetre of the mat and decreased with depth. The hydrocarbons attributed to cyanobacteria showed the strongest decrease in concentration with depth. This correlated well with the depth profiles of oxygenic photosynthesis and oxygen, which were detected in the top 0.6 and 1.05 mm, respectively, at a high down-welling irradiance (1441 µmol photons m**-2 s**-1). At depths beneath the surface layer, the Corg was composed mainly of amino acids and carbohydrates. A resistance towards microbial degradation could have resulted from interactions with diverse functional groups present in biopolymers (EPS) and with minerals deposited in the mat. A 13C enrichment with depth for the total carbon pool (Ctot) was observed, with d13C values ranging from -16.3 permil at the surface to -11.3 permil at 9-10 mm depth. Total lipids depicted a d13C value of -17.2 permil in the top millimetre and then became depleted in 13C with depth (-21.7 to -23.3 permil). The d13C value of EPS varied only slightly with depth (-16.1 to -17.3 permil) and closely followed the d13C value of Corg at depths beneath 4 mm. The EPS represents an organic carbon pool of preservation potential during early stages of diagenesis in recent cyanobacterial mats as a result of a variety of possible interactions. Their analyses might improve our understanding of fossilized microbial remains from mat ecosystems.
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Climate warming is predicted to increase summer air temperatures in the Arctic, warming soils and enhancing microbial decomposition of soil organic matter. Given the size of the soil carbon stores in the Arctic, even a fraction of its release as CO2 to the atmosphere could result in a positive feedback to climate warming. Fertilizers have been used in the past to quickly increase soil solution nutrients pools to mimic predicted concentrations under climate warming. However, because it may have inadvertent affects on the soil microbial community, fertilizer-induced patterns in microbial decomposition may be unrealistic. This study aimed to better understand the proposed mechanism of enhanced microbial decomposition under nutrient addition and warming treatments to discern whether warming alone is enough to stimulate enhanced microbial decomposition, or if nutrients in excess (i.e. chronic high nutrient additions) are necessary to yield such a response. I investigated the impacts of 10 years of greenhouse summer warming, chronic low nutrient factorial addition (5 g N and 1g P m-2 year-1, respectively), and chronic high nutrient factorial addition (10 g N and 5g P m-2 year-1, respectively) treatments on a mesic birch hummock tundra ecosystem near Daring Lake, NWT, Canada. Soil microbial nutrient pools, soil solution nutrient pools, and microbial community structure were measured in the upper organic, lower organic, and uppermost mineral soil depth intervals of all treatment plots in Spring 2014. Interestingly, the low nutrient additions did not yield any significant trends, yet the warming treatment increased soil bacterial richness suggesting a legacy effect of warming from the previous summers. Enhanced microbial nutrient uptake occurred only in the high nutrient addition treatments, and did not significantly alter soil carbon at least within the ten year period of this experiment. Together, these results and the absence of significant impacts of the low nutrient and greenhouse warming treatments suggests that nutrient and carbon cycling in these low arctic soils may be resilient against climate warming, at least over the initial decades.
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The West African Monsoon (WAM) and its representation in numerical models are strongly influenced by the Saharan Heat Low (SHL), a low-pressure system driven by radiative heating over the central Sahara and ventilated by the cold and moist inflow from adjacent oceans. It has recently been shown that a significant part of the southerly moisture flux into the SHL originates from convective cold pools over the Sahel. These density currents driven by evaporation of rain are largely absent in models with parameterized convection. This crucial issue has been hypothesized to contribute to the inability of many climate models to reproduce the variability of the WAM. Here, the role of convective cold pools approaching the SHL from the Atlas Mountains, which are a strong orographic trigger for deep convection in Northwest Africa, is analyzed. Knowledge about the frequency of these events, as well as their impact on large-scale dynamics, is required to understand their contribution to the variability of the SHL and to known model uncertainties. The first aspect is addressed through the development of an objective and automated method for the generation of multi-year climatologies not available before. The algorithm combines freely available standard surface observations with satellite microwave data. Representativeness of stations and influence of their spatial density are addressed by comparison to a satellite-only climatology. Applying this algorithm to data from automated weather stations and manned synoptic stations in and south of the Atlas Mountains reveals the frequent occurrence. On the order of 6 events per month are detected from May to September when the SHL is in its northernmost position. The events tend to cluster into several-days long convectively active periods, often with strong events on consecutive days. This study is the first to diagnose dynamical impacts of such periods on the SHL, based on simulations of two example cases using the Weather Research and Forecast (WRF) model at convection-permitting resolution. Sensitivity experiments with artificially removed cold pools as well as different resolutions and parameterizations are conducted. Results indicate increases in surface pressure of more than 1 hPa and significant moisture transports into the desert over several days. This moisture affects radiative heating and thus the energy balance of the SHL. Even though cold pool events north of the SHL are less frequent when compared to their Sahelian counterparts, it is shown that they gain importance due to their temporal clustering on synoptic timescale. Together with studies focusing on the Sahel, this work emphasizes the need for improved parameterization schemes for deep convection in order to produce more reliable climate projections for the WAM.
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Land-use change can have a major influence on soil organic carbon (SOC) and above-ground C pools. We assessed a change from native vegetation to introduced Pinus species plantations on C pools using eight paired sites. At each site we determined the impacts on 0–50 cm below-ground (SOC, charcoal C, organic matter C, particulate organic C, humic organic C, resistant organic C) and above-ground (litter, coarse woody debris, standing trees and woody understorey plants) C pools. In an analysis across the different study sites there was no significant difference (P > 0.05) in SOC or above-ground tree C stocks between paired native vegetation and pine plantations, although significant differences did exist at specific sites. SOC (calculated based on an equivalent soil mass basis) was higher in the pine plantations at two sites, higher in the native vegetation at two sites and did not differ for the other four sites. The site to site variation in SOC across the landscape was far greater than the variation observed with a change from native vegetation to introduced Pinus plantation. Differences between sites were not explained by soil type, although tree basal area was positively correlated with 0–50 cm SOC. In fact, in the native vegetation there was a significant linear relationship between above-ground biomass and SOC that explained 88.8% of the variation in the data. Fine litter C (0–25 mm diameter) tended to be higher in the pine forest than in the adjacent native vegetation and was significantly higher in the pine forest at five of the eight paired sites. Total litter C (0–100 mm diameter) increased significantly with plantation age (R2 = 0.64). Carbon stored in understorey woody plants (2.5–10 cm DBH) was higher in the native vegetation than in the adjacent pine forest. Total site C varied greatly across the study area from 58.8 Mg ha−1 at a native heathland site to 497.8 Mg ha−1 at a native eucalypt forest site. Our findings suggest that the effects of change from native vegetation to introduced Pinus sp. forest are highly site-specific and may be positive, negative, or have no influence on various C pools, depending on local site characteristics (e.g. plantation age and type of native vegetation).
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Increasing the amount of detergent industries in world in spite of having abundant benefits; entering a new kind of contamination into environment and attract the attention of environment liable of different countries to itself. Entering detergents into an aqueous solution cause pollution of water sources and environment in respect of appearing e problem and charges like: nutritive phenomenon, decomposition of hard group of detergent and producing foam. After using Detergents, they were poured into rivers, seas and lakes and have destructive effect on environment. A lot of hygiene problems were attributed to the water having detergents more than allowed value. So, it is specified the importance of eliminating detergents from contaminated water and it is application for secondary use. In order to attain to this aim, we can use inorganic nano and micro-caolin. In this study the adsorptive properties of detergent on the micro and nano caolin adsorbents were studied and the effect of various parameters like the amount of adsorptive materials, initial concentration of detergent, speed of stirring, electrolyte, temperature, time and pH were determined. The surface area of micro- and nano-caoline was reported 11.867 and 49.1438 m2 g-1, respectively. That increasing in nano-caoline surface area confirms increasing in capacity and more rate of adsorption. The results gained by this research recommend using micro- and nano-caolin as a plentiful, available and effective adsorbents. Also in comparison, using nano-caoline was recommended in order to have more effectiveness.
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To describe the epidemiology of domestic swimming pool drowning and near-drowning in Brisbane and to examine the efficacy of a broad range of preventive options, including pool fences.A prospective, hospital-based, injury surveillance system to describe the epidemiology of drowning and near-drowning and a community survey to describe pool fencing.The surveillance questionnaire was completed at presentation in the Emergency Department by the parent, nurse and doctor. Personal interviews in households that were randomly selected by means of a stratified sampling scheme provided the pool fencing description.All 139 children suffering from an immersion injury resulting in presentation at a hospital in the catchment area of The Mater Children's Hospital were included. There were 204 households with a swimming pool in the 1024 households interviewed in the community survey.The 100 domestic pool drownings and near-drownings were equivalent to 15.5 incidents per year per 100,000 children aged 0-13 years and 64.9 per year per 100,000 for the critical 1-3 years age group. Of 72 children who gained unintended access to a domestic pool, 88.9% were less than 3 years of age and 52.8% were less than 2 years. All 10 of the children who drowned and five who were severely brain damaged (age range, 12-32 months) were in this group. The risk of a drowning or near-drowning involving unintended access to an unfenced pool is 3.76 times higher than the risk associated with a fenced pool (95% confidence limits for relative risk: 2.14, 6.62).Pool fences are an effective method of preventing child drownings and near-drownings. This effectiveness can be further improved if compliance with gate closure can be enhanced. This should be emphasised in health promotion accompanying the introduction of universal pool fencing. Article in The Medical journal of Australia 154(10):661-5 · June 1991
Resumo:
Common bean (Phaseolus vulgaris) is present in the daily diet of various countries and, as for other legumes, has been investigated for its nutraceutical potential. Thus, 16 genotypes from different gene pools, representing seven types of seed coats and different responses to pathogens and pests, were selected to verify their isoflavone contents. The isoflavonoids daidzein and genistein and the flavonols kaempferol, myricetin, and quercetin were found. Grains of the black type showed the highest concentrations of isoflavonoids and were the only ones to exhibit daidzein. IAC Formoso, with high protein content and source of resistance to anthracnose, showed the greatest concentration of genistein, representing around 11% of the content present in soybean, as well as high levels of kaempferol. Arc 1, Raz 55, and IAC Una genotypes showed high content of coumestrol. The results suggest the use of IAC Formoso to increase the nutraceutical characteristics in common bean.
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Pregnant women have a 2-3 fold higher probability of developing restless legs syndrome (RLS - sleep-related movement disorders) than general population. This study aims to evaluate the behavior and locomotion of rats during pregnancy in order to verify if part of these animals exhibit some RLS-like features. We used 14 female 80-day-old Wistar rats that weighed between 200 and 250 g. The rats were distributed into control (CTRL) and pregnant (PN) groups. After a baseline evaluation of their behavior and locomotor activity in an open-field environment, the PN group was inducted into pregnancy, and their behavior and locomotor activity were evaluated on days 3, 10 and 19 of pregnancy and in the post-lactation period in parallel with the CTRL group. The serum iron and transferrin levels in the CTRL and PN groups were analyzed in blood collected after euthanasia by decapitation. There were no significant differences in the total ambulation, grooming events, fecal boli or urine pools between the CTRL and PN groups. However, the PN group exhibited fewer rearing events, increased grooming time and reduced immobilization time than the CTRL group (ANOVA, p<0.05). These results suggest that pregnant rats show behavioral and locomotor alterations similar to those observed in animal models of RLS, demonstrating to be a possible animal model of this sleep disorder.
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Bacterial strains and metagenomic clones, both obtained from petroleum reservoirs, were evaluated for petroleum degradation abilities either individually or in pools using seawater microcosms for 21 days. Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) analyses were carried out to evaluate crude oil degradation. The results showed that metagenomic clones 1A and 2B were able to biodegrade n-alkanes (C14 to C33) and isoprenoids (phytane and pristane), with rates ranging from 31% to 47%, respectively. The bacteria Dietzia maris CBMAI 705 and Micrococcus sp. CBMAI 636 showed higher rates reaching 99% after 21 days. The metagenomic clone pool biodegraded these compounds at rates ranging from 11% to 45%. Regarding aromatic compound biodegradation, metagenomic clones 2B and 10A were able to biodegrade up to 94% of phenanthrene and methylphenanthrenes (3-MP, 2-MP, 9-MP and 1-MP) with rates ranging from 55% to 70% after 21 days, while the bacteria Dietzia maris CBMAI 705 and Micrococcus sp. CBMAI 636 were able to biodegrade 63% and up to 99% of phenanthrene, respectively, and methylphenanthrenes (3-MP, 2-MP, 9-MP and 1-MP) with rates ranging from 23% to 99% after 21 days. In this work, isolated strains as well as metagenomic clones were capable of degrading several petroleum compounds, revealing an innovative strategy and a great potential for further biotechnological and bioremediation applications.
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INTRODUCTION: Spotted fevers are emerging zoonoses caused by Rickettsia species in the spotted fever group (SFG). Rickettsia rickettsii is the main etiologic agent of Brazilian spotted fever (BSF) and it is transmitted by Amblyomma spp. ticks. METHODS: The study aimed to investigate SFG rickettsiae in the Arthur Thomas Municipal Park in Londrina, PR, by collecting free-living ticks and ticks from capybaras and blood samples from personnel working in these areas. Samples from A. dubitatum and A. cajennense were submitted for PCR in pools to analyze the Rickettsia spp. gltA (citrate synthase gene). RESULTS: All the pools analyzed were negative. Human sera were tested by indirect immunofluorescence assay with R. rickettsii and R. parkeri as antigens. Among the 34 sera analyzed, seven (20.6%) were reactive for R. rickettsii: four of these had endpoint titers equal to 64, 2 titers were 128 and 1 titer was 256. None of the samples were reactive for R. parkeri. An epidemiological questionnaire was applied to the park staff, but no statistically significant associations were identified. CONCLUSIONS: The serological studies suggest the presence of Rickettsiae related to SFG that could be infecting the human population studied; however, analysis of the ticks collected was unable to determine which species may be involved in transmission to humans.
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To identify natural infections by Leishmania spp. in insect vectors of cutaneous and visceral leishmaniasis, we performed field studies in natural and anthropic environments in the Guaicurus Settlement (Bodoquena Range) of the Bonito municipality, Mato Grosso do Sul state, Brazil. From October 2002 to October 2003, a total of 1395 sandfly females were captured with Shannon and light traps and dissected in search of flagellates. The sample is composed of a total of 13 species, with Lutzomyia almerioi (59.9%) and Lutzomyia longipalpis (31.4%) predominant. Infections by flagellates were directly observed in three of the dissected of Lu. almerioi females (0.36%). To increase the sensitivity of detection, DNA extracted from pools of the 1220 dissected females (Lu. almerioi 808, Lu. longipalpis 399 and Nyssomyia whitmani 13) was subjected to small subunit rRNA-based polymerase chain reactions (SSU-PCR). DNA from Leishmania (L.) infantum chagasi was detected in at least 0.37% of Lu. almerioi females and in 0.25% of Lu. longipalpis females. The DNA of the Leishmania (Viannia) sp. was detected in 0.12% of Lu. almerioi and in 0.70% of Lu. longipalpis. Leishmania (L.) amazonensis was found in 1.25% of Lu. longipalpis. Mixed infections of L. (Leishmania) sp. and L. (Viannia) sp. were found in 0.50% of Lu. longipalpis. When considering that each positive pool contained at least a single infected specimen, we found a 1.23% rate of Leishmania spp. infection among the total population of dissected female sand flies as determined by PCR. This is the first report of natural infection by L. (L.) infantum chagasi and L. (Viannia) sp. in Lu. almerioi. It is also the first report of infection by L. (Viannia) sp. in Lu. longipalpis. The observation that Lu. longipalpis and Lu. almerioi are naturally infected by agents of both cutaneous and visceral leishmaniases suggests that these two species play a role in the transmission (continua) (continuação) of these diseases within the study area. Furthermore, the finding that Lu. longipalpis has been naturally infected by L. (L.) amazonensis and L. (Viannia) sp., and Lu. almerioi by L. (L.) infantum chagasi and L. (Viannia), suggests their participation as permissive vectors