Search results for "Sediment"
showing 10 items of 1648 documents
The toxicity and concentrations of PAHs in creosote-contaminated lake sediment
1999
Sediment samplers, divided into three layers (0 – 10, 10 – 20 and 20 – 30 cm), were collected from 16 sites in Lake Jamsanvesi, Central Finland. The acute toxicity of pore waters and elutriates (sediment + water 1:4 v/v) were studied by bioluminescence inhibition test and by immobilisation of water fleas (Daphnia magna Straus). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments and elutriates were measured by gas chromatography using flame ionization detection (GC/FID). The highest total PAH concentration was 3.3 mg/g dry weight in the sediment and up to 1.7 mg/l in the elutriate of the uppermost (0 – 10 cm) layer, also being the most toxic to photoluminencent bacteria, …
Behaviour of EDTA in marine microcosms
2000
Laboratory-scale microcosm tests were carried out in sea water with and without sediment to investigate the importance of ultraviolet (UV) light and microbes in the temperature-dependent degradation of metal complexes of ethylenediaminetetraacetic acid (EDTA). After 17 weeks, 44% and 48% of the original EDTA (initial concentration 385 microg/L) were converted at 10 degrees C and 22 degrees C, respectively. The degradation was more influenced by UV light than by sediment microbes, although the latter were very important. At both temperatures, absorption of EDTA to the sediment phase reached a maximum in the initial stage of the experiments (4 weeks): at 10 degrees C about 4% and at 22 degree…
Uptake rates of semipermeable membrane devices (SPMDs) for PCDDs, PCDFs and PCBs in water and sediment.
2000
Uptake rates of several PCDDs, PCDFs and PCBs were measured for semipermeable membrane devices (SPMDs) under controlled conditions in bulk water and sediment. The study was performed at 19 degrees C and 11 degrees C, and water and sediment concentrations were measured during the exposure. Linear uptake rates for specific PCDD/Fs and PCBs in 19 degrees C water varied from 34 to 111 l/m2 day and in 11 degrees C water from 8.8 to 96 l/m2 day for the whole SPMD. Uptake rates at 19 degrees C sediment ranged from 9.0 to 80 mgOC/m2 day and in 11 degrees C sediment, from 3.0 to 31, mgOC/m2 day. Partitioning of the compounds between membrane and lipid was also measured during the linear uptake phase…
Degradation half-life times of PCDDs, PCDFs and PCBs for environmental fate modeling.
2000
Literature search of the knowledge on the degradation of persistent organic pollutants (POPs) in environmental compartments air, water, soil and sediment was done in purpose to find properties of POPs of interest for modeling. One degradation process, hydrolysis (chemical degradation), was omitted as negligibly slow for POPs studied. The other two, photolysis and biodegradation processes, were considered separately in purpose to develop estimation procedures. The estimates can be given as pseudo first-order rate constants kP for photolysis and kB for biodegradation. For each compartment, an overall degradation rate is k(tot) = kP + kB and lifetime t(1/2) = ln 2/k(tot). The latter values, li…
Occurrence of acidic pharmaceuticals and personal care products in Turia River Basin: From waste to drinking water
2014
The occurrence of 21 acidic pharmaceuticals, including illicit drugs, and personal care products (PPCPs) in waste, surface and drinking water and in sediments of the Turia River Basin (Valencia, Spain) was studied. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the determination of these PPCPs with electrospray (ESI) in negative ionization (NI) mode. Ammonium fluoride in the mobile phase improved ionization efficiency by an average increase in peak area of 5 compared to ammonium formate or formic acid. All studied compounds were detected and their concentration was waste water>surface water>drinking water. PPCPs were in waste water treatment plants (WWT…
Biomonitoring potential of the native aquatic plant Typha domingensis by predicting trace metals accumulation in the Egyptian Lake Burullus.
2020
The ability of the native emergent macrophytes Typha domingensis for monitoring pollution with trace metals in Egyptian Lake Burullus was investigated through developing regression models for predicting their concentrations in the plant tissues. Plant samples (above-ground shoot and below-ground root and rhizome) as well as sediment samples were collected monthly during one growing season and analyzed. The association of trace metals concentration with several sediment characteristics (pH, organic matter, clay and silt) was also studied using the simple linear correlation coefficient (r). The concentration of some trace metals was significantly proportional to its values in the sediment suc…
The way forward : Can connectivity be useful to design better measuring and modelling schemes for water and sediment dynamics?
2018
For many years, scientists have tried to understand, describe and quantify water and sediment fluxes, with associated substances like pollutants, at multiple scales. In the past two decades, a new concept called connectivity has been used by Earth Scientists as a means to describe and quantify the influences on the fluxes of water and sediment on different scales: aggregate, pedon, location on the slope, slope, watershed, and basin. A better understanding of connectivity can enhance our comprehension of landscape processes and provide a basis for the development of better measurement and modelling approaches, further leading to a better potential for implementing this concept as a managemen…
Assessing the potential of Albufera de València Lagoon sediments for the restoration of charophyte meadows
2013
Abstract Albufera de Valencia Lagoon, the largest littoral lagoon on the Iberian Peninsula, has been affected by eutrophication processes since the 1970s due to the direct dumping of sewage waters of industrial, agricultural and urban origin. Consequently, the submerged vegetation that covered the bottom of the lagoon has been lost (charophytes and Potamogeton spp., Myriophyllum spp. and Ceratophyllum spp.). Despite efforts to improve water quality, this vegetation has not recovered. No information about the potential of the recent sediments to host charophyte development is available. In this study, we analysed several sediment cores taken from different areas of the lagoon to determine th…
1-D numerical simulation of sediment transport in alluvial channel beds
2011
Quantitative estimate of sediment transport processes is important especially in river-control engineering and for water management projects. In this paper the sediment routing of a 1-D model is presented and applied to some study cases. The procedure simulates the variations of bed roughness conditions due to natural sorting and to generation and migration of bed forms. The suspended-load and the bed-load are treated separatel
Recent environmental history of a large, originally oligotrophic lake in Finland: a palaeolimnological study of chironomid remains
1993
The sedimentary chironomid stratigraphy in short-core samples covering approx. the past 150 years was studied in the northernmost basin of Lake Paijanne, southern Finland (62° 11′ N, 25° 48′ E). The basin has received effluent loading from the wood-processing industry and municipal waste water. Four developmental stages were distinguished based on the changes in chironomid assemblages: 1. Pre-industrial stage (dated by the210Pb method as covering approximately the period 1838–1936), 2. Stage of increasing pollution (approx. 1944–1973), 3. The ‘black decade’, or the period of worst pollution (approx. 1973–1983), and 4. Water protection stage (approx. 1983 onwards). During the first stage the…