Search results for "TLA"
showing 10 items of 1764 documents
Long-term changes of precipitation in Latvia
2010
This study investigated long-term variability and trends in Latvia's annual, seasonal, monthly and daily precipitation using data from 10 meteorological stations for the period 1925–2006 and from station Riga University for the period 1850–2006. The obtained results indicate that during the 20th century a significant increase in precipitation has occurred in the cold season while the warm period showed a decreasing tendency. The annual precipitation totals showed a slight decrease, at half of the studied stations, due to opposite tendencies in cold season and warm season. The long-term trend in the annual precipitation in Riga (from 1850) was positive with large interannual and interdecadal…
Variations in Sediment Yield from the Upper Doubs River Carbonate Watershed (Jura, France) since the Late-Glacial Period
1999
AbstractThe Upper Doubs River Valley is a 910-km2watershed feeding into Lake Chaillexon. The lake was formed by a natural rockfall at the end of the Bølling Chronozone (around 14,250 cal yr B.P.) and since then has trapped material eroded from the watershed. The filling process and variations in sediment yield have been investigated by mechanical coring, seismic surveys, and electric soundings. The detrital sediment yield of the upstream watershed can be calculated by quantifying the sedimentary stocks for each climatic stage of the Late-Glacial period and Holocene Epoch and estimating the lake's entrapment capacity. This enables us to determine the intensity of the erosion processes in rel…
Effect of plant species on water balance in a pilot-scale horizontal subsurface flow constructed wetland planted with Arundo donax L. and Cyperus alt…
2015
Abstract In constructed wetland systems (CWs) for wastewater treatment, evapotranspiration (ET) is the most important water balance component in arid and semi-arid regions, where high performance levels are needed when treating contaminants and where it is also vital to preserve as much water as possible for reuse in irrigation. This study shows the results of a series of water balance measurements obtained between 2012 and 2013 from a pilot HSSF system in the West of Sicily (Italy). The system was made by two separate vegetated units: one with Arundo donax L. (giant reed) and the other with Cyperus alternifolius L. (umbrella sedge), and fed with urban wastewater following secondary treatme…
Mountain dairy wastewater treatment with the use of a 'irregularly shaped' constructed wetland (Aosta Valley, Italy)
2014
Abstract In mountain areas, economical activities related to milk processing represent both a key source of income and job opportunities. One of the main characteristics of cheese production is the seasonal variability in the volume of milk processed and wastewater production that tend to limit the capacity of ecosystems to absorb their inputs. In alpine environment, the scarcity of plain surfaces and the climatic conditions results in the need for high CW performances of variable nutrient inputs in different seasons. By evaluating a CW seasonal efficiency for dairy wastewaters in a mountain region (Aosta Valley-NW Italy), this research was aimed to understand how performances of nutrient r…
Hydrological and hydraulic behaviour of a surface flow constructed wetland treating agricultural drainage water in northern Italy.
2020
Abstract A surface flow constructed wetland (SFCW) treating agricultural drainage water was investigated with the aim to detect modifications in hydrological and hydraulic characteristics after more than a decade of operation. Ponded infiltration tests were conducted to estimate the saturated hydraulic conductivity, Ks, of the surface soil layer at the point scale. At the global scale, infiltration rate, i, was computed from the water balance to detect leakages from the pervious wetland surface. Tracer tests were conducted to analyse the existence of preferential flow inside the system and to estimate its hydraulic retention time (HRT). Clogging phenomena occurred given a mean Ks value of 3…
Hydrogeochemistry and Water Balance in the Coastal Wetland Area of “Biviere di Gela,” Sicily, Italy
2006
In the study area physical and chemical factors control the composition of surface and groundwaters, which in turn determine the water quality of the "Biviere di Gela" lake. These factors combine to create diverse water types which change their compositional character spatially as rainfall infiltrates the soil zone, moves down a topographically defined flow path, and interacts with bedrock minerals. Low-salinity waters, which represent the initial stage of underground circulation, start dissolving calcium carbonate from the local rocks. The progressive increase in salinity, characterized by substantially higher Ca, SO4, Na and Cl concentrations, suggests that dissolution of CaSO4 and NaCl i…
Sensitivity of Bunker Cave to climatic forcings highlighted through multi-annual monitoring of rain-, soil-, and dripwaters
2017
The last two decades have seen a considerable increase in studies using speleothems as archives of past climate variability. Caves under study are now monitored for a wide range of environmental parameters and results placed in contextwith speleothemdata. The present study investigates trends froma seven year longmonitoring of Bunker Cave, northwestern Germany, in order to assess the hydraulic response and transfer time of meteoric water fromthe surface to the cave. Rain-, soil-, and dripwaterwere collected fromAugust 2006 to August 2013 at a monthly to bimonthly resolution and their oxygen and hydrogen isotope composition wasmeasured. Furthermore, drip rates were quantified. Due to differe…
Distribution of soil organic carbon in Wadi Al-Thulaima, Saudi Arabia: A hyper-arid habitat altered by wastewater reuse
2018
The carbon cycle is being altered as a result of human-induced changes in the Earth's system. Therefore, ecosystems such as wetlands, authentic CO2 sinks, are becoming especially important. Little information exits on the soil organic carbon (SOC) stock for the middle east-countries man-made wetlands making wadis permanent with the outflow of wastewater treatment plants. This paper presents the vertical distribution of SOC content, soil bulk density (SBD) and SOC density in soil of vegetated and bare sites in Wadi Al-Thulaima, one of the artificial wetlands in central Saudi Arabia. The mean distribution of SBD in the vegetated and bare sites increased significantly with depth. Inversely, th…
Hydrology is reflected in the functioning and community composition of methanotrophs in the littoral wetland of a boreal lake
2010
In lake ecosystems a major proportion of methane (CH4) emissions originate from the littoral zone, which can have a great spatial variability in hydrology, soil quality and vegetation. Hitherto, spatial heterogeneity and the effects it has on functioning and diversity of methanotrophs in littoral wetlands have been poorly understood. A diagnostic microarray based on the particulate methane monooxygenase gene coupled with geostatistics was used to analyse spatial patterns of methanotrophs in the littoral wetland of a eutrophic boreal lake (Lake Kevaton, Eastern Finland). The wetland had a hydrology gradient with a mean water table varying from −8 to −25 cm. The wettest area, comprising the h…
The effects of long-term drainage and subsequent restoration on water table level and pore water chemistry in boreal peatlands
2014
Summary Degradation by drainage threatens biodiversity and globally important peatland ecosystem functions such as long-term carbon sequestration in peat. Restoration aims at safeguarding peatland values by recovering natural hydrology. Long-term effects of drainage and subsequent restoration, especially related to within-site variation of water table level and pore water chemistry, are poorly known. We studied hydrological variation at 38 boreal Sphagnum peatland sites (pristine, drained and restored) in Finland. The average water table level was significantly lower at Drained than Pristine sites especially near the ditches. We also observed large pore water chemical differences between Dr…