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161.
Low resolution of the continental sedimentary record is a common source of skepticism about the application of geomorphology and sedimentology to Quaternary studies. In spite of this, when supported by independent proxy data, geomorphology and sedimentology may favor palaeo-hydrologic interpretation. This paper associates geomorphologic, stratigraphic, sedimentologic, isotopic, palynologic and geochronologic data. The research was conducted in valley head sites in southern Brazilian highlands, under mild subtropical climate. The results point to environmental changes, the ages of which coincide to Marine Isotopic Stages (MIS) 5b, 3, 2 and 1. Although late-Pleistocene temperatures and precipitation were lower than those of today, the study valley heads seem to have sustained locally wetter environments, which fed shallow soil–water saturated zones. These saturated zones are believed to have expanded during transitions between stadial and interstadial states, contributing to hillslope erosion and sedimentation regardless of the sign of the climatic change. The interior organization of holocenic slope-wash deposits suggests that the mid-Holocene climate was drier than today’s and was under the influence of seasonally contrasting precipitation regimes. The predominance of overland flow-related sedimentary records suggests that an excess of precipitation over evaporation influenced local palaeo-hydrology. This palaeo-hydrologic condition seems to have been recurrent and also explains the alternating periods of pedogenesis and sedimentation.  相似文献   
162.
This article describes the implementation of a monitoring system on the breakwater at the Funchal Port (Madeira Island, Portugal) for the purpose of understanding its dynamic behavior and the temporal evolution of structural health. The monitoring system focuses on the breakwater superstructure and aims to identify the evolution of damage on the breakwater and analyze the impact of cruise ships docking and undocking. The system includes the measurement of displacements through geodetic techniques using global navigation satellite systems and the measurement of vibrations using accelerometers. Ten observation campaigns were performed over almost 3 years. As the measured displacements during this period were less than 7.5 mm it can be concluded that, despite some visible cracks, the breakwater superstructure did not suffer significant structural changes. It was shown from the measured acceleration records that some of the main modal parameters could be identified, namely the main natural frequencies of the superstructure. Through an analysis of the natural frequencies progression over time, it will be possible to identify deterioration effects on the foundation and/or the superstructure. The comparison of natural frequencies identified could be useful to evaluate the impact of these events on structural health.  相似文献   
163.
This study evaluates the on use of crushed rocks(remineralizers)to increase soil fertility levels and which contributed to increase agricultural productivity,recovery of degraded areas,decontamination of water,and carbon sequestration.The use of these geological materials is part of the assumptions of rock technology and,indirectly,facilitates the achievement of sustainable development goals related to soil management,climate change,and the preservation of water resources.Research over the past 50 years on silicate rocks focused on soil fertility management and agricultural productivity.More recently,the combined use with microorganisms and organic correctives have shown positive results to mitigate soil degradation;to expand carbon sequestration and storage;and to contribute to the adsorption of contaminants from water and soil.In this article we show results obtained in several countries and we show that this technology can contribute to the sustainability of agriculture,as well as to reverse global warming.Although mineral nutrients are released more slowly from these types of inputs,they remain in the soil for a longer time,stimulating the soil biota.In addition,they are a technology to soluble synthetic fertilizers replace,since the few nutrients derived from such inputs not consumed by plants are lost by leaching,contaminating groundwater and water resources.In addition,conventional methods rely heavily on chemical pesticides which cause damage to soil’s microfauna(responsible for the decomposition of organic matter and nutrient cycling)and the loss of organic carbon(in the form of dioxide),which is quickly dispersed in the atmosphere.Silicate rock powders are applied in natura,have long-lasting residual effects and reduce greenhouse gas emissions.  相似文献   
164.
The ceramics industry,resulting from developments of modern compounds,is a segment of great influence in worldwide sustainability.Artisanal ceramic factories based on wood combustion have significant risks for the creation and discharge of atmosphere nanoparticles(NPs)and ultra-fine particles(UFPs).At present,there is insufficient recognition on the influence of engineered-NPs on the atmosphere and health.Real improvements are indispensable to diminish contact with NPs.The present study demonstrates the main NPs and UFPS present in an area of intense artisanal wood-combustion ceramic manufacturing.Particulate matter was sampled for morphological,chemical,and geochemical studies by sophisticated electron microbeam microscopy,X-Ray Diffraction,and Raman spectroscopy.From NPs configuration(<10 nm)we identify nucleation.Several amorphous NPs(>10 nm)were produced around the studied artisanal ceramic factories.This study presents an indication of the recent information on population and work-related contact to NPs in the artisanal ceramic factories and their influence on health.  相似文献   
165.
A study of the Calcidiscus genus in Lisbon Bay has revealed the presence of Calcidiscus quadriperforatus and Calcidiscus leptoporus. Samples were collected continuously on a weekly basis for four years (July 2001–May 2005) and on a cruise carried out in summer 2005, covering Lisbon Bay. Calcidiscus quadriperforatus and C. leptoporus developed in the same range of temperature and salinity, 11.5–21.5 °C and 26.9–36.3, respectively. The two species seemed to respond independently but had a co-occurring seasonal pattern nearshore, developing in different concentrations throughout the seasons. The maxima of both species occurred in low turbulent and nutrient enriched waters, which was also favourable for the development of larger coccospheres of C. quadriperforatus. The concentrations of both species decreased from 2001 until 2005, due to the intensification and persistence of upwelling and rainy periods.From late autumn until winter, mixed populations were observed nearshore, largely dominated by Calcidiscus quadriperforatus, in colder and nutrient enriched waters, while during spring, when temperatures begin to increase, only Calcidiscus leptoporus was observed, in mature upwelled waters. Calcidiscus quadriperforatus was considered more opportunistic than C. leptoporus. The availability of nutrients seemed to have influenced the size increase of C. quadriperforatus coccospheres. Both species developed offshore during summer, when the shelf is occupied by colder turbulent upwelled waters. A short downwelling episode in summer 2005, associated with two counter-rotating mesoscale eddies, responsible for a strong north-eastward flow of warm oceanic waters into the bay, allowed the development of C. quadriperforatus nearshore. Contemporary satellite images revealed the presence and onshore displacement of these waters and C. quadriperforatus and C. leptoporus distribution highlighted these conditions. The development of each species nearshore also gave indications of local oceanographic changes during winter and spring.  相似文献   
166.
This study investigates the geochemical characteristics of the acid mine drainage discharged from the abandoned mine adits and tailing piles in the vicinity of the Lousal mine and evaluates the extent of pollution on water and on the stream sediments of the Corona stream. Atmospheric precipitation interacting with sulphide minerals in exposed tailings produces runoff water with pH values as low as 1.9–2.9 and high concentrations of (9,249–20,700 mg l−1), Fe (959–4,830 mg l−1) and Al (136–624 mg l−1). The acidic effluents and mixed stream water carry elevated Cu, Pb, Zn, Cd and As concentrations that exceed the water quality standards. However, the severity of contamination generally decreases 4 km downstream of the source due to mixing with fresh waters, which causes the dilution of dissolved toxic metals and neutralization of acidity. Some natural attenuation of the contaminants also occurs due to the general reduced solubility of most trace metals, which may be removed from solution, by either co-precipitation or adsorption to the iron and aluminium precipitates.  相似文献   
167.
168.
Physical and chemical characteristics of intertidal sediments and their relationships with bacteria and cyanobacteria were analyzed at four stations at Pereque Beach. Granulometric analysis showed that Pereque beach has sediment that is classified as sand. The lowest value of the sediment C/N rates (6.08), mainly due to a higher concentration of organic nitrogen, was found at the northern part of Pereque Beach, where organic matter of marine source was more prominent. In this area, density (9.6x10(6)cells cm(-3)), biomass (1992.04ngC cm(-3)) and activity of bacteria were higher than at the southern end. In contrast, cyanobacteria density varied from 2.0 to 4.0x10(5)cells cm(-3), with biomass and total chlorophyll a of the sediment being higher at the southern part, where there are water input from Pereque River and higher organic matter of continental origin. The variability in the microbial population is discussed in the light of the sediment granulometry, organic matter quality, fresh water inflow and pollution.  相似文献   
169.
The Mandovi and Chapora are two tropical estuaries lying in close geographic proximity on the west coast of India. Seasonal changes in down core variation of Fe, Mn and Total Organic Carbon (TOC) in the mangrove sediments adjoining these estuaries were studied to assess their influence on some of the representative benthic bacteria belonging to heterotrophic and autotrophic groups. Heterotrophic bacteria (HB) cultured on different nutrient concentrations (0.01%, 0.1% and 25%) together with nitrifiers (NtB; representating autotroph) were chosen to assess the influence of the above-mentioned abiotic parameters on the former. The experimental site located along the Mandovi is under the influence of extensive ferromanganese ore mining, while the control site at Chapora is relatively free from such influences. Geoaccumulation index computed for Mandovi showed that sediments (0-10cm) were 'uncontaminated to moderately contaminated' by Fe during the pre monsoon and monsoon seasons, while in the post monsoon season the 4-10cm fraction was almost completely restored from contamination. Similar computations for Mn showed that in pre monsoon, sediments fell in the 'moderately contaminated' and 'moderately to strongly contaminated' categories, while in the monsoon and post monsoon seasons all the sections were 'Uncontaminated'. The difference observed in correlation between Fe and Mn with the various fractions of heterotrophs and nitrifiers indicated that though these two elements shared a similar chemistry in the environment, microbes involved in biogeochemical processes might prefer them differentially. The relationship between TOC and HB enumerated on 0.01% dilute nutrient agar remained at r=0.50, p<0.05 throughout the year. Hence, it could be apparently linked to their preferred concentration of organic carbon requirement. A relationship of r=0.61, p<0.01 between manganese concentration and heterotrophs recovered on different strengths of nutrient agar is suggestive of their response to the metal enrichment. They could thus contribute towards maintaining the level of Mn at par with reference levels at Chapora. A positive correlation between Mn with NtB (n=10, p<0.05, r=0.58) at the experimental site during the non-monsoon months is suggestive of the latter's contribution to regulation of the metal concentration in the sediment probably through anaerobic nitrification at the expense of manganese. The study therefore supports our hypothesis that both autochthonous autotrophs and heterotrophs work in tandem to mitigate concentration of Mn and related metals in mangrove sediments.  相似文献   
170.
The objective of the present study was to use the simple cokriging methodology to characterize the spatial variability of Penman–Monteith reference evapotranspiration and Thornthwaite potential evapotranspiration methods based on Moderate Resolution Imaging Spetroradiometer (MODIS) global evapotranspiration products and high-resolution surfaces of WordClim temperature and precipitation data. The climatic element data referred to 39 National Institute of Meteorology climatic stations located in Minas Gerais state, Brazil and surrounding states. The use of geostatistics and simple cokriging technique enabled the characterization of the spatial variability of the evapotranspiration providing uncertainty information on the spatial prediction pattern. Evapotranspiration and precipitation surfaces were implemented for the climatic classification in Minas Gerais. Multivariate geostatistical determined improvements of evapotranspiration spatial information. The regions in the south of Minas Gerais derived from the moisture index estimated with the MODIS evapotranspiration (2000–2010), presented divergence of humid conditions when compared to the moisture index derived from the simple kriged and cokriged evapotranspiration (1961–1990), indicating climate change in this region. There was stronger pattern of crossed covariance between evapotranspiration and precipitation rather than temperature, indicating that trends in precipitation could be one of the main external drivers of the evapotranspiration in Minas Gerais state, Brazil.  相似文献   
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