Effects of experimental stem burial on radial growth and wood anatomy of pedunculate oak
Copini, P. ; Decuyper, M. ; Sass-Klaassen, U.G.W. ; Gärtner, H. ; Mohren, G.M.J. ; Ouden, J. den - \ 2015
Dendrochronologia 33 (2015). - ISSN 1125-7865 - p. 54 - 60.
coastal dunes - white spruce - tree roots - erosion - netherlands - sediments - dynamics - plants - water
In dendrogeomorphology, abrupt changes in wood anatomy are frequently used to date the exact year of burial and exposure events. However, few studies have addressed the precision and underlying mechanisms of these changes. In a field experiment, performed in a drift-sand area in the Netherlands, we buried the stems of mature pedunculate oak trees (Quercus robur L.) up to a height of 50 cm and analysed the responses in ring width and earlywood-vessel characteristics, while monitoring the course of temperature above and below the soil surface. After 3 years of stem burial, we found no significant differences in ring width and earlywood-vessel characteristics between control and buried trees both above and below the burial level. Burial however strongly reduced temperature amplitude and the occurrence of sub-zero temperatures around the buried stems. All buried trees formed epitropic roots that grew upward into the new sediment layer, but no adventitious roots were formed on the buried stems. Irrespective of the burial treatments, we found that the mean ring width was largest at the original stem base and lowest at breast height. In contrast, vessel sizes were significantly larger at breast height compared with the stem base. Differences in vessel density barely differed between years and heights. In our field experiment on mature pedunculate oak trees, the burial of stems by 50 cm of drift sand did not induce any local growth suppression or detectable changes in wood anatomy. As wood-anatomical changes in response to burial have previously been reported for trees that had formed adventitious roots, we stress the role of adventitious-root formation as a possible trigger behind the local changes in wood anatomy, reflecting a functional change of a buried stem towards a root. Based on our field experiment, it seems unlikely that years of shallow or moderate burial events (=50 cm) can be reconstructed using the wood structure of buried stems. As epitropic roots develop quickly after burial, dating such roots may potentially yield better estimates of burial events. Further research on the relation between adventitious root and changes in stem anatomy is needed to ascertain the precision of dating sand-burial events using tree rings.
Homo erectus at Trinil on Java used shells for tool production and engraving
Joordens, J.C.A. ; d’Errico, F. ; Wesselingh, F.P. ; Munro, S. ; Vos, J. de; Wallinga, J. ; Ankjaergaard, C. ; Reimann, T. ; Wijbrans, J.R. ; Kuiper, K.F. ; Mücher, H.J. ; Coqueugniot, H. ; Prié, V. ; Joosten, I. ; Os, B. van; Schulp, A.S. ; Panuel, M. ; Haas, V. van der; Lustenhouwer, W. ; Reijmer, J.J.G. ; Roebroeks, W. - \ 2015
Nature 518 (2015). - ISSN 0028-0836 - p. 228 - 231.
quartz osl ages - luminescence signals - south-africa - indonesia - sediments - reliability - sangiran - record - rates
The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour1. Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens, and whether it has a uniquely African origin1. Here we report on a fossil freshwater shell assemblage from the Hauptknochenschicht (‘main bone layer’) of Trinil (Java, Indonesia), the type locality of Homo erectus discovered by Eugène Dubois in 1891 (refs 2 and 3). In the Dubois collection (in the Naturalis museum, Leiden, The Netherlands) we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool, and a shell with a geometric engraving. We dated sediment contained in the shells with 40Ar/39Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated. Together, our data indicate that the engraving was made by Homo erectus, and that it is considerably older than the oldest geometric engravings described so far4, 5. Although it is at present not possible to assess the function or meaning of the engraved shell, this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control.
Are feldspar SAR protocols appropriate for post-IR IRSL dating?
Kars, R.H. ; Reimann, T. ; Wallinga, J. - \ 2014
Quaternary Geochronology 22 (2014). - ISSN 1871-1014 - p. 126 - 136.
anomalous fading correction - infrared stimulated luminescence - regenerative-dose protocol - k-feldspar - chinese loess - quartz - sediments - samples - deposits - signals
Recently proposed post-infrared infrared stimulated luminescence (post-IR IRSL or pIR) dating protocols have largely overcome problems associated with anomalous fading and have become increasingly important for age determination of Quaternary sediments. Here, we investigate the suitability of the proposed post-IR IRSL protocols for accurate equivalent-dose estimation on K-feldspar extracts. Our research focuses on potential sensitivity changes between the natural signal and the first test dose signal in single-aliquot regenerative dose (SAR) procedures that are not detected and thus not corrected using test-dose responses. For these investigations, we employed the Single Aliquot Regeneration and Added dose (SARA) procedure, which combines equivalent-dose estimation with a dose recovery test. Results indicated that high-temperature preheats (>260 °C for 60 s) may induce a trapping sensitivity change in IRSL signals measured at low temperature (100 °C) after a high temperature preheat. Our results indicate that the SAR protocol is appropriate for equivalent-dose determination using elevated-temperature pIR signals (e.g. pIR at 290 °C or multiple elevated temperature pIR at 250 °C). The SAR protocol may also be appropriate for equivalent-dose determination using low temperature pIR signals, provided that the combination of preheat and measurement temperature
Oral bioaccessibility and human exposure to anthropogenic and geogenic mercury in urban, industrial and mining areas
Rodrigues, S.M. ; Coelho, C. ; Cruz, N. ; Monteiro, R.J.R. ; Henriques, B. ; Duarte, A.C. ; Romkens, P.F.A.M. ; Pereira, E. - \ 2014
Science of the Total Environment 496 (2014). - ISSN 0048-9697 - p. 649 - 661.
atomic-absorption-spectrometry - potentially toxic elements - chloralkali plant - inorganic mercury - part i - contaminated soils - asturias spain - speciation - sediments - portugal
The objective of this study was to characterize the link between bioaccessibility and fractionation of mercury (Hg) in soils and to provide insight into human exposure to Hg due to inhalation of airborne soil particles and hand-to-mouth ingestion of Hg-bearing soil. Mercury in soils from mining, urban and industrial areas was fractionated in organometallic forms; mobile; semi-mobile; and non-mobile forms as well as HCl-extractable Hg. The in vitro bioaccessibility of Hg was obtained by extracting soils with (1) a simulated human gastric fluid (pH 1.5), and (2) a simulated human lung fluid (pH 7.4). Total soil Hg concentrations ranged from 0.72 to 1.8 mg kg- 1 (urban areas), 0.28 to 94 mg kg- 1 (industrial area) and 0.92 to 37 mg kg- 1 (mining areas). Both organometallic Hg as well as 0.1 M HCl extractable Hg were lower (<0.5% of total Hg) than Hg extracted by gastric fluid (up to 1.8% of total Hg) and lung fluid (up to 12% of total Hg). In addition, Hg extracted by lung fluid was significantly higher in urban and industrial soils (average 5.0–6.6% of total Hg) compared to mining soils. Such differences were related to levels of mobile Hg species in urban and industrial soils compared to mining soils. These results strengthen the need to measure site-specific Hg fractionation when determining Hg bioaccessibility. Results also show that ingestion and/or inhalation of Hg from soil particles can contribute up to 8% of adult total Hg intake when compared to total Hg intake via consumption of contaminated fish and animal products from contaminated areas.
Use, fate and ecological risks of antibiotics applied in tilapia cage farming in Thailand
Rico, A. ; Oliveira, R. ; McDonough, S. ; Matser, A. ; Khatikarn, J. ; Satapornvanit, K. ; Nogueira, A.J.A. ; Soares, A.M.V.M. ; Domingues, I. ; Brink, P.J. van den - \ 2014
Environmental Pollution 191 (2014). - ISSN 0269-7491 - p. 8 - 16.
fluoroquinolone antibiotics - veterinary antibiotics - ubiquitous occurrence - asian aquaculture - sediments - china - water - river - oxytetracycline - tetracyclines
The use, environmental fate and ecological risks of antibiotics applied in tilapia cage farming were investigated in the Tha Chin and Mun rivers in Thailand. Information on antibiotic use was collected through interviewing 29 farmers, and the concentrations of the most commonly used antibiotics, oxytetracycline (OTC) and enrofloxacin (ENR), were monitored in river water and sediment samples. Moreover, we assessed the toxicity of OTC and ENR on tropical freshwater invertebrates and performed a risk assessment for aquatic ecosystems. All interviewed tilapia farmers reported to routinely use antibiotics. Peak water concentrations for OTC and ENR were 49 and 1.6 µg/L, respectively. Antibiotics were most frequently detected in sediments with concentrations up to 6908 µg/kg d.w. for OTC, and 2339 µg/kg d.w. for ENR. The results of this study indicate insignificant short-term risks for primary producers and invertebrates, but suggest that the studied aquaculture farms constitute an important source of antibiotic pollution.
Palaeofloods and ancient fishing weirs in NW Iberian rivers
Viveen, W. ; Sanjurjo-Sanchez, J. ; Goy-Dizc, A. ; Veldkamp, A. ; Schoorl, J.M. - \ 2014
Quaternary Research 82 (2014)1. - ISSN 0033-5894 - p. 56 - 65.
regenerative-dose protocol - north-atlantic oscillation - quartz - luminescence - climate - single - australia - peninsula - sediments - records
A 15-m-thick, fluvial sedimentary record of the NW Iberian lower Miño River was studied. Grain-size analyses were performed and twelve samples were dated using optically stimulated luminescence dating techniques, documenting a 1300-yr-old reconstructed fluvial record that does not match with known climate fluctuations in the area, but is linked instead to the construction of a series of ancient fishing weirs (pesqueiras). The sedimentation phases are in agreement with known episodes of increased population density, which suggests active use of the pesqueiras. A number of sedimentation hiatuses in the fluvial record point towards damage to the pesqueiras during large-scale flooding in the Miño River basin, and a sudden drop in population probably due to the arrival of the plague in the 13th century AD. The oldest sedimentation phases started just after 700 AD, and we infer that the first pesqueiras were constructed around this time. This timing coincides with the transition of the NW Iberian landscape towards a more intensively used agricultural landscape, as evidenced from other geo-archeological investigations. The results demonstrate that the pesqueiras are several hundreds of years older than known from historical records, but not so old as to date back to the Roman occupation.
Factors influencing polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emissions and control in major industrial sectors: Case evidence from Shandong Province, China
Wang, L. ; Lu, Y. ; He, G. ; Mol, A.P.J. ; Wang, T. ; Gosens, J. ; Ni, K. - \ 2014
Journal of Environmental Sciences 26 (2014)7. - ISSN 1001-0742 - p. 1513 - 1522.
organic pollutants pops - decomposition analysis - energy-consumption - co2 emissions - management - sediments
Analyzing determinants that influence polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emissions is helpful for decision-makers to find effective and efficient ways to mitigate PCDD/F emissions. The PCDD/F emissions and the contributions of the scale effect, structure effect and technology effect to emissions fromeightmain industrial sectors in 2006, 2008 and 2010 in Shandong Province, were calculated in this article. Total PCDD/F emissions in Shandong increased by 52.8% in 2008 (614.1 g I-TEQ) and 49.7% in 2010 (601.8 g I-TEQ) based on 2006 (401.9 g I-TEQ). According to the decomposition method, the largest influencing factor on PCDD/F emission changes was the composition effect (contributed 43.4% in 2008 and 120.6% in 2010 based on 2006), which was also an emission-increasing factor. In this case, the present industrial restructuring policy should be adjusted to control the proportion of production capacities with high emission factors, such as iron ore sintering and steelmaking and the secondary non-ferrous metal sector. The scale effect increased the emissions in 2008 (contributed 21.9%) and decreased the emissions in 2010 (contributed -28.0%). However, as a source control measure, the excess capacity control policy indeed had a significant role in emission reduction. The main reason for the technology effect (contributed 34.7% in 2008 and 7.4% in 2010 based on 2006) having an emission-increasing role was the weakness in implementing policies for restricting industries with outdated facilities. Some specific suggestions were proposed on PCDD/F reduction for local administrators at the end.
Denitrification in restored and unrestored Danish streams
Veraart, A.J. ; Audet, J. ; Rocha Dimitrov, M. ; Hoffmann, C.C. ; Gillissen, F. ; Klein, J.J.M. de - \ 2014
Ecological Engineering 66 (2014). - ISSN 0925-8574 - p. 129 - 140.
16s ribosomal-rna - denitrifying bacteria - headwater streams - nosz genes - nutrient-uptake - restoration - water - sediments - nirk - pcr
Stream restoration often aims at mitigating nutrient pollution in aquatic ecosystems. However, despite recent research efforts, effects of restoration practices on in-stream nitrogen removal remain unclear. In this study, denitrification rates as well as factors controlling denitrification in unrestored and restored sections of two Danish streams (S1 and S2) were compared. The 15N isotope pairing technique was used to measure denitrification in situ. Denitrifier presence was analyzed by denaturing gradient gel electrophoresis (DGGE) and quantitative PCR of nitrite reductase (nirK and nirS) and nitrous oxide reductase (nosZ) genes. Denitrification rates were highly variable, with denitrification rates of 3106 µmol N m-2 h-1 in the unrestored section of S1, but no detectable denitrification in the restored section of S1, whereas in S2 restored and unrestored sections had similar denitrification rates of around 250 µmol N m-2 h-1. These large differences in denitrification rates were mainly due to differences in hydrologic conditions and sediment characteristics. High nitrate fluxes from upwelling groundwater created denitrification hotspots in the unrestored section of S1. Moreover, a lack of organic matter in the restored section of S1 likely caused a low abundance of denitrifiers and consequently no detectable denitrification. Our results indicate the importance of hydrology and sediment organic matter for stream nitrogen dynamics, which should be considered in restoration design
Sulphate reduction and calcite precipitation in relation to internal eutrophication of groundwater fed alkaline fens
Cirkel, D.G. ; Beek, C.G.E.M. van; Witte, J.P.M. ; Zee, S.E.A.T.M. van der - \ 2014
Biogeochemistry 117 (2014)2-3. - ISSN 0168-2563 - p. 375 - 393.
organic-matter - calcareous fens - phosphate - sulfur - soils - water - netherlands - sediments - adsorption - peatland
Although in Europe atmospheric deposition of sulphur has decreased considerably over the last decades, groundwater pollution by sulphate may still continue due to pyrite oxidation in the soil as a result of excessive fertilisation. Inflowing groundwater rich in sulphate can change biogeochemical cycling in nutrient-poor wetland ecosystems. Incoming sulphate loads may induce internal eutrophication as well as the accumulation of dissolved sulphide, which is phytotoxic. We, however, argue that upwelling sulphate rich groundwater may also promote the conservation of rare and threatened alkaline fens, since excessive fertilisation and pyrite oxidation also produces acidity, which invokes calcite dissolution, and increased alkalinity and hardness (Ca2+ + Mg2+) of the inflowing groundwater. Our observations in a very species-rich wetland nature reserve show that sulphate is reduced and effectively precipitates as iron sulphides when this calcareous and sulphate rich groundwater flows upward through the organic soil of the investigated nature reserve. Furthermore, we show that sulphate reduction coincides with an increase in alkalinity production, which in our case results in active calcite precipitation in the soil. In spite of the occurring sulphate reduction we found no evidence for internal eutrophication. Extremely low phosphorous concentration in the pore water could be attributed to a high C:P ratio of soil organic matter and co-precipitation with calcite. Our study shows that seepage dependent alkaline fen ecosystems can be remarkably resilient to fertilisation and pyrite oxidation induced groundwater quality changes.
Relationship between soil properties and the bias of N2O reduction by acetylene inhibition technique for analyzing soil denitrification potential
Qin, S.P. ; Yuan, H.J. ; Dong, W.X. ; Hu, C.S. ; Oenema, O. ; Zhang, Y.M. - \ 2013
Soil Biology and Biochemistry 66 (2013). - ISSN 0038-0717 - p. 182 - 187.
nitrous-oxide reduction - pseudomonas-aeruginosa - cultures - catchment - oxidation - sediments - nitrate - manure - assay - no
The acetylene inhibition technique (AIT) has been widely used to measure soil denitrification potential (SDP), but has been criticized also for underestimating the actual SDP due to limitations of the AIT. Possible effects of soil properties on the bias of the AIT-derived SDP have not been thoroughly investigated yet. The study presented here therefore aimed at quantifying the relationships between soil texture and nutrient contents and the bias of AIT-derived SDP. A total of 26 soils with a wide range of clay and nutrient contents were incubated according to the standard procedure of AIT for assaying SDP. Incubation flasks were made anaerobic by gas substitution with pure helium (99.999%). Changes in the N-2 and N2O concentrations in the He headspace were measured using gas chromatography. The emission rates of N2O and N-2 were calculated to quantify the bias of the AIT-derived SDP (expressed as the percentage of the actual SDP that was not accounted for by AIT). The results showed that the bias ranged from 8 to 98%. The bias was negatively correlated (P <0.05) with the clay, silt, organic matter and nutrient contents of the soils. These results indicate that the bias of the AIT-derived SDP was higher in low-fertility soils than in fertile soils. We recommend that soil properties are taken into account when interpreting results of AIT-derived SDP values. (C) 2013 Elsevier Ltd. All rights reserved.
Soil organic matter: chemistry and physical characteristics and analytical methods. A review
Branco de Freitas Maia, C.M. ; Novotny, E.H. ; Francischinelli Rittl, T. ; Bermingham Hayes, M.H. - \ 2013
Current Organic Chemistry 17 (2013)24. - ISSN 1385-2728 - p. 2985 - 2990.
nuclear-magnetic-resonance - black carbon - humic substances - reflectance spectroscopy - light fraction - amazon region - sediments - acids - charcoal - forest
Soil organic matter (SOM) holds a prominent place among the many indicators that are studied in relation to soil function. Different viewpoints are reflected in characterizing SOM, depending on the study procedures used, or the focus of the researchers. There are many possibilities for the isolation and fractionation of SOM and this has led to a plurality of interpretations and conclusions. Transformations to organic materials that lead to the more recalcitrant components of SOM are outlined, and the associations which these materials can have in the soil environment, and aspects of their compositions are referred to. A review is given of the organic matter pools in soils, of their functions, and of the controls which they have in soil systems. A succinct review is given of physical fractionation procedures for SOM. This approach is highly relevant, though rarely used in modern studies of SOM. The merits and demerits of wet oxidation procedures, relative to dry combustion for determining soil organic carbon contents are discussed, and reference is made to the emerging chemometric techniques based on the use of Near (NIR) and Mid (MIR) infrared spectroscopy.
The effect of phosphorus binding clay (Phoslock) in mitigating cyanobacterial nuisance: A laboratory study on the effects on water quality variables and plankton
Oosterhout, J.F.X. ; Lurling, M. - \ 2013
Hydrobiologia 710 (2013)1. - ISSN 0018-8158 - p. 265 - 277.
rare-earth-elements - organic-matter - lake restoration - eutrophication - microcystis - netherlands - sediments - blooms - complexation - speciation
This laboratory study examined the lanthanum modified clay Phoslock® for its effectiveness to bind soluble reactive phosphorus (SRP), release of nutrients from this modified clay, its influence on water quality variables (pH, oxygen saturation %, conductivity and turbidity), effects on phytoplankton growth (green alga Scenedesmus obliquus, cyanobacteria Microcystis aeruginosa and Anabaena sp.), and, lastly, its effect on the population growth of the rotifer Brachionus calyciflorus. A clear dose–response for SRP binding by the modified clay was observed. A small amount of ammonium is released from Phoslock®. We found no effect of Phoslock® on pH or oxygen saturation. Conductivity increased with the increasing concentration of Phoslock®. An application of Phoslock® caused a transient increase of turbidity up to 211 NTU. However, due to rapid settlement, turbidity fell below 13 NTU (~1 m Secchi depth), after 6 h. Phoslock® addition caused a reduction in growth of all phytoplankton species tested that we attribute to the combined effects of light limitation, flocculation with the bentonite and binding of SRP to Phoslock®. We estimated the EC50 of Phoslock® on the population growth of rotifer B. calyciflorus to be 0.15 g Phoslock® l-1. Overall, the results of our study indicate Phoslock® seems to be suitable for field applications.
Identifying and dating buried micropodzols in Subatlantic polycyclic drift sands
Wallinga, J. ; Mourik, J.M. van; Schilder, M.L.M. - \ 2013
Quaternary International 306 (2013). - ISSN 1040-6182 - p. 60 - 70.
soil organic-matter - luminescence - radiocarbon - netherlands - chronologies - sediments - curves - single - quartz - acid
Polycyclic soil sequences provide valuable archives of alternating unstable periods (sand drifting) and stable periods (soil formation) in NW-European coversand landscapes during the Subatlantic. Here we study six polycyclic soil sequences at the Weerterbergen (The Netherlands) to investigate how to read and interpret this geological archive. At each of the sites a micropodzol forms a clear stratigraphic marker between drift sand beds. We show that soil micromorphology is a practical method to distinguish geogenetic humic layers (containing redeposited organic material) from true pedogenic micropodzols. Optically stimulated luminescence dating of drift sand deposits above and below the micropodzols provides robust ages for periods of aeolian activity, and confines the timing and maximum duration of soil formation. We show that a pedogenic micropodzol was formed in many places in the study area around 1900 AD, and that the duration of this period of landscape stability differed between sites from decades to centuries. Radiocarbon dates, when carried out on soil organic matter, grossly overestimate the burial time of the micropodzols because the organic material in the micropodzols is a mix of geogenic particles and pedogenic carbon.
|Biovailability of copper and zinc in pig and cattle slurries
Jakubus, M. ; Dach, J. ; Starmans, D.A.J. - \ 2013
Fressenius Environmental Bulletin 22 (2013)4. - ISSN 1018-4619 - p. 995 - 1002.
sequential extraction procedures - heavy-metals - soils - fractionation - speciation - sediments - manganese - sludge - nickel - lead
Slurry is an important source of macronutrients, micro-nutrients and organic matter. Despite the considerable fertilizer value of slurry, it may be abundant in amounts of copper and zinc originating from dietary. The study presents quantitative changes in copper and zinc in individual slurries (pig and cattle slurries). The bioavailability of copper and zinc was estimated on the basis of amounts of the metals in isolated fractions using the sequential extraction method. Sequential techniques identify fractions which describe different connections of metals with the compost solid phase beginning with those that are easiest soluble up to those that dissolve with the greatest difficulties.Pig slurry was characterized by 2-fold higher amounts of copper and zinc in comparison to the levels detected in cattle slurries. Quantitative changes of the elements in the sequentially isolated fractions of analyzed slurries differed. First of all, this was dependent on the chemical character of a given metal, followed by the animal species, or the type of management. Irrespective of the type of slurry, 40-56% of the total amounts of copper were found in hardly available combinations, while available copper forms accounted for only 6.6–10.9%. Zinc was found predominantly in com-binations with iron and manganese oxides which, irrespective of the tested slurry, ranged from 130.64 mg·kg-1 to 293.60 mg·kg-1. Bioavailable metal contents, potentially introduced to soil with slurry doses, calculated as 170 kg total N/ha/year, ranged from 63.6 to 124.5 g for copper, and from 349.5 to 696.4 g for zinc. The estimated amounts of metal inputs to agricultural land demonstrate that soils are potentially at risk of heavy metal accumulation from the application of pig and cattle slurries.
Chemical and spectroscopic characteristics of humic acids
Ferreira, F. ; Vidal-Torrado, P. ; Otero, X.L. ; Buurman, P. - \ 2013
Journal of Soils and Sediments 13 (2013)2. - ISSN 1439-0108 - p. 253 - 264.
soil organic-matter - estuarine soils - nmr-spectroscopy - salt marshes - substances - spain - resonance - sediments - c-13 - environments
To characterise soil humic acids (HAs) extracted from Spanish marshes formed under different vegetation types (Spartina maritima (GSp), Juncus maritimus (GJc), Phragmites australis (GPh), and Scirpus maritimus (VSc)), soil depths (0-20, 20-40 and 40-60 cm), physiographic position (low and high marshes), wetland types (salt marshes and lagoons) and environmental conditions (Atlantic and Mediterranean coast). Soil samples were collected in five Spanish marshes, three on the Galicia province and two on the Valencia province. Humic acids were extracted and their elemental composition, semiquinone-type free radical (SFR) content, FTIR and CPMAS C-13 NMR spectra determined. Total carbon (TC), total nitrogen (TN), total sulphur (TS), CaCO3 content, and field pH and Eh (mV) in the marsh soils sampled were also measured. The field pH and Eh values were typical of coastal areas submitted to periodic inundations and the highest TC, TN and TS contents were found in the soil of lagoon marshes as an effect of physiographic position and wetland type. The HAs, in general, were highly aliphatic and exhibited a low SFR content, which suggests a low humification degree of the SOM formed in the studied areas. This is a result of the anaerobic decomposition to which SOM is submitted and the high input of plant-derived organic matter (OM) by vegetation. However, among the studied sites low salt marsh and subsurface layer of the high salt marsh showed higher SFR content, simpler FTIR spectra, higher lignin degradation and lower O-alkyl C/alkyl C ratio than the lagoon marshes, thus suggesting the presence of a more humificated SOM in these sites. From the different factors analysed, only physiographic position (low versus high salt marshes) and wetland type (marshes versus lagoons) caused variations in the HAs characteristics, because as the studied soils are under anaerobic conditions, they control the exportation of plant-derived OM and the allochthonous OM contribution in the studied areas.
Biodegradation of aged diesel in diverse soil matrixes: impact of environmental conditions and bioavailability on microbial remediation capacity
Sutton, N.B. ; Gaans, P. van; Langenhoff, A.A.M. ; Maphosa, F. ; Smidt, H. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. - \ 2013
Biodegradation 24 (2013)4. - ISSN 0923-9820 - p. 487 - 498.
oil-contaminated soil - real-time pcr - crude-oil - bioremediation - community - sediments - hydrocarbons - degradation - scale - site
While bioremediation of total petroleum hydrocarbons (TPH) is in general a robust technique, heterogeneity in terms of contaminant and environmental characteristics can impact the extent of biodegradation. The current study investigates the implications of different soil matrix types (anthropogenic fill layer, peat, clay, and sand) and bioavailability on bioremediation of an aged diesel contamination from a heterogeneous site. In addition to an uncontaminated sample for each soil type, samples representing two levels of contamination (high and low) were also used; initial TPH concentrations varied between 1.6 and 26.6 g TPH/kg and bioavailability between 36 and 100 %. While significant biodegradation occurred during 100 days of incubation under biostimulating conditions (64.4-100 % remediation efficiency), low bioavailability restricted full biodegradation, yielding a residual TPH concentration. Respiration levels, as well as the abundance of alkB, encoding mono-oxygenases pivotal for hydrocarbon metabolism, were positively correlated with TPH degradation, demonstrating their usefulness as a proxy for hydrocarbon biodegradation. However, absolute respiration and alkB presence were dependent on soil matrix type, indicating the sensitivity of results to initial environmental conditions. Through investigating biodegradation potential across a heterogeneous site, this research illuminates the interplay between soil matrix type, bioavailability, and bioremediation and the implications of these parameters for the effectiveness of an in situ treatment
The Role of Propagule Banks from Drainage Ditches Dominated by Free-Floating or Submerged Plants in Vegetation Restoration
Zuidam, J.P. van; Raaphorst, E.P. ; Peeters, E.T.H.M. - \ 2012
Restoration Ecology 20 (2012)3. - ISSN 1061-2971 - p. 416 - 425.
sloten - waterplanten - zoetwaterecologie - plantengemeenschappen - ecologisch herstel - ditches - aquatic plants - freshwater ecology - plant communities - ecological restoration - seed bank - biodiversity - communities - sediments - constraints - macrophytes - germination - emergence - runoff - meadow
Dominance by free-floating plants results in a loss of plant species in many waters. An important source for re-establishment of non-floating aquatic plants can be the propagule bank. This study focuses on whether the propagule bank of free-floating plantdominated ditch sediments can serve as potential source for recovery of a diverse plant community. The first objective was to determine differences in propagule germination from sediments of ditches in the Netherlands that differ in vegetation composition through a seedling-emergence experiment. The second objective was to analyze the effect of sediment disturbance on the number of germinating propagules. The results show that, compared to sediments from ditches with submerged vegetation, sediments from free-floating plantdominated ditches produced significantly lower numbers of individuals and species of submerged and emergent plants, while numbers of individuals and species of free-floating plants were higher. These results suggest that sediments from free-floating plantdominated ditches have lower potential to recover a diverse plant community probably resulting from positive feedback mechanisms caused by the vegetation present, maintaining the free-floating plantdominated state. Sediment disturbance strongly favors the germination of free-floating plant propagules, especially from free-floating plantdominated ditch sediments. Ditch maintenance activities such as mowing and dredging will therefore likely favor persistence of the free-floating plantdominated state. To shift from dominance by free-floating plants to a more diverse plant community, alternative maintenance methods should be considered that cause less sediment disturbance together with measures that promote colonization such as temporary drawdown or re-introduction of species.
Organotins in North Sea brown shrimp (Crangon crangon L.) after implementation of the TBT ban
Verhaegen, Y. ; Monteyne, E. ; Neudecker, T. ; Tulp, I.Y.M. ; Smagghe, G. ; Cooreman, K. ; Roose, P. ; Parmentier, K. - \ 2012
Chemosphere 86 (2012)10. - ISSN 0045-6535 - p. 979 - 984.
plaice pleuronectes-platessa - butyltin compounds - bioaccumulation - sediments - accumulation - tributyltin - predation - selection - areas - field
The organotin (OT) compounds tributyltin (TBT) and triphenyltin (TPhT) are potent biocides that have been used ubiquitously in antifouling paints and pesticides since the mid-1970s. These biocides are extremely toxic to marine life, particularly marine gastropod populations. The European Union therefore took measures to reduce the use of TBT-based antifouling paints on ships and ultimately banned these paints in 2003. Despite sufficient data on OT concentrations in marine gastropods, data are scarce for other species such as the North Sea brown shrimp (Crangon crangon), a dominant crustacean species in North Sea inshore benthic communities. The present study provides the first spatial overview of OT concentrations in North Sea brown shrimp. We have compared these data with historical concentrations in shrimp as well as with sediment concentrations. We have also addressed the effect on the shrimp stock and any human health risks associated with the OT concentrations found. TBT and TPhT in shrimp tail muscle ranged from 4 to 124 and from 1 to 24 µg kg-1 DW, respectively. High levels are accumulated in estuarine areas and are clearly related with sediment concentrations (biota-sediment accumulation factor ~10). Levels have decreased approximately 10-fold since the ban took effect, coinciding with a recovery of the shrimp stock after 30 years of gradual regression. Furthermore, the OT levels found in brown shrimp no longer present a human health risk
Quantifying the underestimation of soil denitrification potential as determined by the acetylene inhibition method
Qin, S. ; Hu, C. ; Oenema, O. - \ 2012
Soil Biology and Biochemistry 47 (2012). - ISSN 0038-0717 - p. 14 - 17.
nitrous-oxide reduction - emissions - sediments - fluxes
The acetylene inhibition technique (AIT) is commonly used for the determination of soil denitrification potential (SDP). However, the results obtained with this technique have intrinsic uncertainties. This study aimed at quantifying these uncertainties. A silt loam topsoil from an experimental station was incubated under standard conditions for SDP measurements, with and without acetylene additions. Changes in the concentrations of N2O and N2 in the headspace of incubation vials were monitored during the incubation, using a robotized sampling and analyzing system. Our results showed that the AIT did not completely inhibit the reduction of N2O to N2. As much as 11.7% of the produced N2O was reduced into N2 in the presence of acetylene. We conclude that SDP has to be corrected when determined by the AIT. The procedures used in this study will allow the estimation of correction factors, possibly as function of soil type and environmental conditions. --------------------------------------------------------------------------------
Mapping soil clay contents in Dutch marine districts using gamma-ray spectrometry
Klooster, E. van der; Egmond, F.M. van; Sonneveld, M.P.W. - \ 2011
European Journal of Soil Science 62 (2011)5. - ISSN 1351-0754 - p. 743 - 753.
plant-available potassium - radiometric data - water-content - topsoil - netherlands - sediments - spectra - models - part
Conventional soil sampling methods to obtain high-resolution soil data are labour intensive and costly. Recently, gamma ray spectrometry has emerged as a promising technique to overcome these obstacles. The objective of our study was to investigate the prediction of soil clay contents using gamma-ray spectrometry in three marine clay districts in the Netherlands: the southwestern marine district (SMD), the IJsselmeerpolder district (IJPD) and the northern marine district (NMD). The performance of linear regression models was investigated at field (1000 km2) scales and for all the Dutch marine districts together. For this study, a database was available with 1371 gamma-ray spectra measured on arable fields in marine clay districts during the period 2005–2008 and these were all linked to laboratory analyses of clay contents. At the field scale, linear regression models based on 40K, 232Th, or a combination of these revealed much smaller root mean squared error (RMSE) values (2–3%) compared with a model based on the field mean (8–10%). At the district scale, the regression models for the SMD and IJPD, which have comparable sediments, performed better than for the NMD. This indicates that the prediction of clay contents in late Holocene marine sediments may be made with gamma-ray spectrometry provided that the origin of the parent material results in a unique fingerprint. Because of the heterogeneous parent material of all marine districts taken together, our study shows that no unique and precise fingerprint exists, and the RMSE of 6% between clay contents and gamma-ray spectra is not much different from the RMSE of 7% when using the overall mean as a predictor.