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Temporal variation of trace metal geochemistry in floodplain lake sediment subject to dynamic hydrological conditions 总被引:1,自引:0,他引:1
van Griethuysen C Luitwieler M Joziasse J Koelmans AA 《Environmental pollution (Barking, Essex : 1987)》2005,137(2):281-294
Climate change and land use may significantly influence metal cycling in dynamic river systems. We studied temporal variation of sediment characteristics in a floodplain lake, including concentrations of dissolved organic carbon, acid volatile sulfide and trace metals. The sampling period included a severe winter inundation and a dramatic water level drop during summer. Temporal changes were interpreted using multivariate analysis and chemical equilibrium calculations. Metal concentrations in sediment increased with depth, indicating a gradual improvement of sediment quality. In contrast, dissolved metal concentrations were highest in top layers due to mobilization from oxyhydroxides and precipitation with sulfides in deeper layers. Inundation had a mobilizing effect as it stimulated resuspension and oxygenation of sediment top layers. Water table lowering combined with organic matter decomposition led to immobilization due to sulfide formation. The chemistry of the sediments was consistent with model calculations, especially for macro-elements. The results illustrate the importance of seasonality for metal risk assessment. 相似文献
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Seedling growth responses to soil resources in the understory of a wet tropical forest 总被引:1,自引:0,他引:1
Plant growth responses to resources may be an important mechanism that influences species' distributions, coexistence, and community structure. Irradiance is considered the most important resource for seedling growth in the understory of wet tropical forests, but multiple soil nutrients and species have yet to be examined simultaneously with irradiance under field conditions. To identify potentially limiting resources, we modeled tree seedling growth as a function of irradiance and soil nutrients across five sites, spanning a soil fertility gradient in old-growth, wet tropical forests at La Selva Biological Station, Costa Rica. We measured an array of soil nutrients including total nitrogen (total N), inorganic N (nitrate [NO3-] and ammonium [NH4+]), phosphate (PO4-), and sum of base cations (SBC; potassium, magnesium, and calcium). Shade in the forest understory did not preclude seedling growth correlations with soil nutrients. Irradiance was a significant predictor of growth in 52% of the species, inorganic N in 54% (NO3- in 32%; NH4+ in 34%), total N in 47%, SBC in 39%, and PO4- in 29%. Overall, growth was correlated with both irradiance and soil nutrients in 45% of species and with soil nutrients only in an additional 48%; rarely was irradiance alone correlated with growth. Contrary to expectations, the magnitudes of growth effects, assessed as the maximum growth response to significant resources for each species, were similar for irradiance and most soil nutrients. Among species whose growth correlated with soil nutrients, the rank importance of nutrient effects was SBC, followed by N (total N, NO3-, and/or NH4+) and PO4-. Species' growth responsiveness (i.e., magnitudes of effect) to irradiance and soil nutrients was negatively correlated with species' shade tolerance (survival under 1% full sun). In this broad survey of species and resources, the nearly ubiquitous effects of soil nutrients on seedling growth challenge the idea that soil nutrients are less important than irradiance in the light-limited understory of wet tropical forests. 相似文献
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Wendt Müller Ellen Kalmbach Corine M. Eising Ton G. G. Groothuis Cor Dijkstra 《Behavioral ecology and sociobiology》2005,59(2):313-320
In sexually size dimorphic species, individuals of the larger sex often suffer from enhanced mortality during the nestling period. This has been attributed to higher nutritional requirements of the larger sex, which may render this sex more vulnerable to adverse food conditions. However, sex-biased mortality might not exclusively depend on the differences in food demand but also on other phenotypic differences, e.g., in competitiveness. Interference competition between the sexes and position in the laying sequence in particular may be essential components contributing to biased mortality.By creating synchronously-hatched unisex broods in the sexually size dimorphic black-headed gull, we specifically tested the effect of sex-specific food demand by excluding interference competition between the sexes as well as hatching asynchrony. To test the effect of egg quality, which varies with the position in the laying sequence, we composed each nest of chicks from eggs of all different positions in the laying sequence.All-male nests showed significantly enhanced mortality compared to all-female nests from the beginning of the development of the sexual size dimorphism onwards. This underlines the role of a higher food demand in biased mortality of the larger sex.In males but not females, asymptotic body mass and skeletal size were negatively associated with position in the laying sequence, while survival was not affected by position. As a consequence, sexual size dimorphism at the end of the nestling period was less pronounced compared to the natural situation. These data show that, although male growth is more sensitive to a decrease in egg quality, the higher mortality of last hatched chicks in natural nests is mainly due to hatching asynchrony and egg size but not egg content. 相似文献
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Removal of sorbed polycyclic aromatic hydrocarbons from soil, sludge and sediment samples using the Fenton's reagent process 总被引:4,自引:0,他引:4
The use of the Fenton's reagent process has been investigated for the remediation of environmental matrices contaminated by polycyclic aromatic hydrocarbons (PAHs). Laboratory experiments were first conducted in aqueous solutions, to study the kinetics of oxidation and adsorption of PAHs. Benzo[a]pyrene was more rapidly degraded than adsorbed, while only partial oxidation of fluoranthene occurred. In the case of benzo[b]fluoranthene, its adsorption prevented its oxidation. Besides competition effects between PAHs were found, with slower oxidation of mixtures as compared to single PAH solutions. Apparition of some by-products was observed, and a di-hydroxylated derivative of benzo[a]pyrene could be identified under our conditions. Consequently, application to solid environmental matrices (soil, sludge and sediment samples) was performed using large amounts of reagents. The efficiency of the Fenton treatment was dependent on the matrix characteristics (such as its organic carbon content) and the PAH availability (correlated to the date and level of contamination). However, no pH adjustment was required, as well as no iron addition due to the presence of iron oxides in the solid matrices, suggesting the potential application of Fenton-like treatment for the remediation of PAH-contaminated environmental solids. 相似文献
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Houtman CJ Booij P Jover E Pascual del Rio D Swart K van Velzen M Vreuls R Legler J Brouwer A Lamoree MH 《Chemosphere》2006,65(11):2244-2252
The identity of compounds responsible for estrogenic and dioxin-like activities in sediment from the harbour of the small town Zierikzee in Zeeland, The Netherlands, was investigated using a bioassay directed fractionation approach with the in vitro estrogen and dioxin responsive reporter gene assays ER- and DR-CALUX. For identification of compounds exhibiting activity in the bioassays, either one or two-dimensional GC in combination with quadrupole (MSD), ion trap (ITD) or time-of-flight mass spectrometric detection (ToF-MS) was used, depending on the biological and chemical characteristics and the complexity of the fractions. The natural estrogenic hormone 17-β-estradiol and its metabolite estrone were identified with GC–ITD as the main contributors to the estrogenic activity. After successive rounds of fractionation, the dioxin-like activity could be explained by the presence of various polycyclic aromatic hydrocarbons identified with GC–MSD and two-dimensional comprehensive GC × GC–ToF-MS. Some estrogenic activity of a relatively non-polar nature remained unidentified. 相似文献
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Laurent Lanceleur Jörg Schäfer Gérard Blanc Alexandra Coynel Cécile Bossy Magalie Baudrimont Corine Glé Aurélie Larrose Sophie Renault Emilie Strady 《Environmental science and pollution research international》2013,20(3):1352-1366
Dissolved and particulate Ag concentrations (AgD and AgP, respectively) were measured in surface water and suspended particulate matter (SPM) along the salinity gradient of the Gironde Estuary, South West France, during three cruises (2008–2009) covering contrasting hydrological conditions, i.e. two cruises during intermediate and one during high freshwater discharge (~740 and ~2,300 m3/s). Silver distribution reflected non-conservative behaviour with 60–70 % of AgP in freshwater particles being desorbed by chlorocomplexation. The amount of AgP desorbed was similar to the so-called reactive, potentially bioavailable AgP fraction (60?±?4 %) extracted from river SPM by 1 M HCl. Both AgP (0.22?±?0.05 mg/kg) and AgP/ThP (0.025–0.028) in the residual fraction of fluvial and estuarine SPM were similar to those in SPM from the estuary mouth and in coastal sediments from the shelf off the Gironde Estuary, indicating that chlorocomplexation desorbs the reactive AgP. The data show that desorption of reactive AgP mainly occurs inside the estuary during low and intermediate discharge, whereas expulsion of partially AgP-depleted SPM (AgP/ThP ~0.040) during the flood implies ongoing desorption in the coastal ocean, e.g. in the nearby oyster production areas (Marennes-Oléron Bay). The highest AgD levels (6–8 ng/L) occurred in the mid-salinity range (15–20) of the Gironde Estuary and were decoupled from freshwater discharge. In the maximum turbidity zone, AgD were at minimum, showing that high SPM concentrations (a) induce AgD adsorption in estuarine freshwater and (b) counterbalance AgP desorption in the low salinity range (1–3). Accordingly, Ag behaviour in turbid estuaries appears to be controlled by the balance between salinity and SPM levels. The first estimates of daily AgD net fluxes for the Gironde Estuary (Boyle’s method) showed relatively stable theoretical AgD at zero salinity (Ag D 0 = 25–30 ng/L) for the contrasting hydrological situations. Accordingly, AgD net fluxes were very similar for the situations with intermediate discharge (1.7 and 1.6 g/day) and clearly higher during the flood (5.0 g/day) despite incomplete desorption. Applying Ag D 0 to the annual freshwater inputs provided an annual net AgD flux (0.64–0.89 t/year in 2008 and 0.56–0.77 t/year in 2009) that was 12–50 times greater than the AgD gross flux. This estimate was consistent with net AgD flux estimates obtained from gross AgP flux considering 60 % desorption in the estuarine salinity gradient. 相似文献
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Sinsin Corine Bitossessi Laurenda Salako Kolawolé Valère Fandohan Adandé Belarmain Kouassi Konan Edouard Sinsin Brice Augustin Glèlè Kakaï Romain 《Environment, Development and Sustainability》2022,24(4):4901-4917
Environment, Development and Sustainability - Mangroves are one of the most threatened ecosystems globally. Likewise, they benefit many restoration efforts. However, these efforts have often... 相似文献
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