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  • Water Pollutants, Chemical  (14)
  • Chemistry
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  • 1
    Language: English
    In: Chemosphere, 2001, Vol.45(4), pp.543-551
    Description: Spray drift and edge-of-field runoff are regarded as important routes of nonpoint-source pesticide input into aquatic surface waters, with current regulatory risk assessment in Europe focussing largely on spray drift. However, the two routes of entry had rarely been compared directly in the same catchment. To this end, the concentrations and loads of the current-use insecticides azinphos-methyl (AZP) and endosulfan (END) were monitored in the Lourens River, South Africa downstream of a 400-ha fruit orchard area during normal farming practice. Spray drift-related peak pesticide levels in the tributaries were in the range of 95th-percentiles of standard drift values according to regulatory risk assessment procedures. Resulting concentrations in Lourens River water samples (n = 3) at a discharge of 0.28 m super(3)/s were as high as 0.04 plus or minus 0.01 mu g/l AZP and 0.07 plus or minus 0.02 mu g/l END. Pesticide levels at the same site during runoff following 3 storm events varying in rainfall between 6.8 and 18.4 mm/d (discharge: 7.5-22.4 m super(3)/s) were considerably higher: by factors between 6 and 37 for AZP (0.26-1.5 mu g/l) and between 2 and 41 for END (0.13-2.9 mu g/l). Levels of pesticides associated with suspended particles were increased during runoff only up to 1247 mu g/kg AZP and 12082 mu g/kg END. A possible reason for the relative importance of runoff is that runoff largely integrates potential pesticide input over both time and space, because the prerequisites for the occurrence of runoff in terms of application and plot characteristics as well as meteorological conditions are far less specific than for spray drift. A probability analysis based on pesticide application patterns and 10-yr rainfall data indicates that the frequencies of rainfall events greater than or equal to 10 and greater than or equal to 15 mm/d are 3.4 and 1.7 per spraying season, respectively.
    Keywords: Catchment ; Exposure Assessment ; Insecticides ; Nonpoint-Source Pollution ; Orchards ; Runoff ; Spray Drift ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 2
    Language: English
    In: Chemosphere, July 2014, Vol.107, pp.13-22
    Description: Quantitative information on the processes leading to the retention of plant protection products (PPPs) in surface waters is not available, particularly for flow-through systems. The influence of aquatic vegetation on the hydraulic- and sorption-mediated mitigation processes of three PPPs (triflumuron, pencycuron, and penflufen; log 3.3–4.9) in 45-m slow-flowing stream mesocosms was investigated. Peak reductions were 35–38% in an unvegetated stream mesocosm, 60–62% in a sparsely vegetated stream mesocosm (13% coverage with ), and in a similar range of 57–69% in a densely vegetated stream mesocosm (100% coverage). Between 89% and 93% of the measured total peak reductions in the sparsely vegetated stream can be explained by an increase of vegetation-induced dispersion (estimated with the one-dimensional solute transport model OTIS), while 7–11% of the peak reduction can be attributed to sorption processes. However, dispersion contributed only 59–71% of the peak reductions in the densely vegetated stream mesocosm, where 29% to 41% of the total peak reductions can be attributed to sorption processes. In the densely vegetated stream, 8–27% of the applied PPPs, depending on the log values of the compounds, were temporarily retained by macrophytes. Increasing PPP recoveries in the aqueous phase were accompanied by a decrease of PPP concentrations in macrophytes indicating kinetic desorption over time. This is the first study to provide quantitative data on how the interaction of dispersion and sorption, driven by aquatic macrophytes, influences the mitigation of PPP concentrations in flowing vegetated stream systems.
    Keywords: Pesticide ; Plant Protection Product ; Dispersion ; Sorption ; Vegetated Stream Mesoscosms ; Tracer ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 3
    Language: English
    In: Aquatic Toxicology, 15 January 2013, Vol.126, pp.163-168
    Description: ► nTiO concentrations one order of magnitude above the PEC caused adverse chronic effects. ► Particle size and product composition, i.e. crystalline structure, trigger differences in nTiO toxicity. ► nTiO accumulation at the bottom of the test vessel is an important effect pathway. ► Dissolved organic carbon influences fate and finally nTiO toxicity. The increasing use of titanium dioxide nanoparticles (nTiO ) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO among others to . These studies indicated a large variability – several orders of magnitude – in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO products with varying crystalline structure (A-100; P25) to . A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06 mg/L A-100 (∼330 nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (∼140 nm). Likewise, P25 (∼130 nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO at the bottom of the test vessel – the latter is relevant for a semi-static test design – may be suggested as factors potentially triggering differences in nTiO toxicity to . Hence, these factors should be considered to improve environmental risk assessment of nanoparticles.
    Keywords: Inorganic Nanoparticles ; Reproduction ; Growth ; Flow-through ; Crustacea ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 4
    Language: English
    In: Aquatic Toxicology, 2014, Vol.150, pp.133-143
    Description: Fungicides are frequently applied in agriculture and are subsequently detected in surface waters in total concentrations of up to several tens of micrograms per liter. These concentrations imply potential effects on aquatic communities and fundamental ecosystem functions such as leaf litter breakdown....
    Keywords: Other Biological Topics ; Annan Biologi
    ISSN: 0166-445X
    E-ISSN: 18791514
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  • 5
    Language: English
    In: Aquatic Toxicology, February 2017, Vol.183, pp.46-53
    Description: Selection of appropriate test species is a critical issue when assessing effects of environmental contamination on fish because the ecological relevance of commonly used test species might be restricted due to their exotic origin. In the present study, a European freshwater fish with frequent occurrence in agricultural areas is suggested as a potential alternative: the European weatherfish ( ). Its suitability for acute embryo toxicity tests (FET) was investigated with regard to practical implementation, sensitivity to contaminants and tolerance against environmental conditions of concern. For this purpose, weatherfish embryos were exposed (72 h) to the reference substance 3,4-dichloroaniline (DCA) in three independent tests. Furthermore, the effects of dissolved oxygen (DO) deficiency on weatherfish embryos were studied to evaluate their suitability e.g. for sediment bioassays. Obtained results revealed that the sensitivity of weatherfish embryos towards DCA (72 h-EC = 0.52 mg/l; 72 h-LC = 0.71 mg/l) was highest compared to other species and three times higher than that reported for the commonly used zebrafish ( ). Even though knowledge of DO requirements during the embryonic period of European fish species is scarce, weatherfish can be stated as one of the most tolerant native species (LC for DO = 0.53 mg/l after 48 h exposure plus 72 h post-exposure). Its high ecological relevance for Europe, the particular sensitivity towards DCA and high tolerance against DO depletion highlight the potential of weatherfish as additional species for toxicity testing.
    Keywords: Fish Embryo Toxicity Test ; 3,4-Dichloroaniline ; Dissolved Oxygen Requirements ; Alternative Test Method ; Early Life Stages ; Sediment Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 6
    Language: English
    In: Aquatic Toxicology, 2011, Vol.104(1), pp.32-37
    Description: The energy stored in coarse particulate organic matter, e.g. leaf litter, is released to aquatic ecosystems by breakdown processes involving microorganisms and leaf shredding invertebrates. The palatability of leaves and thus the feeding of shredders on leaf material are highly influenced by microorganisms. However, implications in the colonization of leaves by microorganisms (=conditioning) caused by chemical stressors are rarely studied. Our laboratory experiments, therefore, investigated for the first time effects of a fungicide on the conditioning process of leaf material by means of food-choice experiments using (Crustacea: Amphipoda). Additionally, microbial analyses were conducted to facilitate the mechanistic understanding of the observed behavior. Gammarids significantly preferred control leaf discs over those conditioned in presence of the fungicide tebuconazole at concentrations of 50 and 500 μg/L. Besides the decrease of fungal biomass with increasing fungicide concentration, also the leaf associated fungal community composition showed that species preferred by gammarids, such as , , or , were more frequent in the control. , however, which is rejected by gammarids, was abundant in all treatments suggesting an increasing importance of this species for the lower leaf palatability – as other more palatable fungal species were almost absent – in the fungicide treatments. Hence, the food-choice behavior of seems to be a suitable indicator for alterations in leaf associated microbial communities, especially fungal species composition, caused by chemical stressors. Finally, this or similar test systems may be a reasonable supplement to the environmental risk assessment of chemicals in order to achieve its protection goals, as on the one hand, indirect effects may occur far below concentrations known to affect gammarids directly, and on the other hand, the observed shifts in leaf associated microbial communities may have perpetuating implications in leaf shredding invertebrates.
    Keywords: Fungal Community ; Leaf Litter Decomposition ; Confidence Interval Testing ; Aquatic Hyphomycetes ; Azole Fungicide ; Bacteria ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 7
    Language: English
    In: Aquatic Toxicology, December 2016, Vol.181, pp.94-103
    Description: For in situ remediation of groundwater contaminated by halogenated hydrocarbons Carbo-Iron , a composite of microscale activated carbon and nano Fe , was developed. Against the background of intended release of Carbo-Iron into the environment in concentrations in the g/L-range, potential ecotoxicological consequences were evaluated in the present study. The nano Fei in Carbo-Iron acts as reducing agent and is oxidized in aqueous systems by chlorinated solvents, groundwater constituents (e.g. dissolved oxygen) and anaerobic corrosion. As Carbo-Iron is generally oxidized rapidly after application into the environment, the oxidized state is environmentally most relevant, and Carbo-Iron was used in its oxidized form in the ecotoxicological tests. The amphipod was selected as a surrogate test species for functionally important groundwater crustaceans. Effects of Carbo-Iron on were determined in a 10-d acute test, a 7-d feeding activity test and a 42-d chronic test. Additionally, a 56-d life cycle test was performed with a modified design to further evaluate effects of Carbo-Iron on adult and their offspring. The size of Carbo-Iron particles in stock and test suspensions was determined via dynamic light scattering. Potential uptake of particles into test organisms was investigated using transmission and scanning electron microscopy. At the termination of the feeding and acute toxicity test (i.e. after 7 and 10 d of exposure, respectively), Carbo-Iron had a significant effect on the weight, length and feeding rate of at the highest test concentration of 100 mg/L. While an uptake of Carbo-Iron into the gut was observed, no passage into the surrounding tissue was detected. In both chronic tests, the number of offspring was the most sensitive endpoint and significant effects were recorded at concentrations ≥50 mg/L (42-d experiment) and ≥12.5 mg/L (56-d experiment). Parental exposure to oxidized Carbo-Iron significantly exacerbated the acute effects of the nanocomposite on the subsequent generation of by a factor 〉10. The present study indicates risks for groundwater species at concentrations in the mg/L range. Carbo-Iron may exceed these effect concentrations in treated aquifers, but the presence of the pollutant has most likely impaired the quality of this habitat already. The benefit of remediation has to be regarded against the risk of ecological consequences with special consideration of the observed increasing sensitivity of juvenile .
    Keywords: Iron-Based Nanomaterial ; Nanocomposite ; Groundwater Remediation ; Environmental Risk ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 8
    Language: English
    In: Chemosphere, 2003, Vol.51(6), pp.509-513
    Description: A water-sampling device to monitor the quality of water periodically and temporarily flowing out of concrete tubes, sewers or channels is described. It inexpensively and easily enables a qualitative characterization of contamination via these point-source entry routes. The water sampler can be reverse engineered with different sizes and materials, once installed needs no maintenance, passively samples the first surge, and the emptying procedure is short. In an agricultural catchment area in Germany we monitored an emergency overflow of a sewage sewer, an outlet of a rainwater sewer and two small drainage channels as input sources to a small stream. Seven inflow events were analysed for 20 pesticide agents (insecticides, fungicides and herbicides). All three entry routes were remarkably contaminated. We found parathion-ethyl concentrations of 0.3 mu g l super(-1), diuron up to 17.3 mu g l super(-1), ethofumesate up to 51.1 mu g l super(-1), metamitron up to 92 mu g l super(-1) and prosulfocarb up to 130 mu g l super(-1).
    Keywords: Herbicides ; Fungicides ; Insecticides ; Small Streams ; Point Sources ; Sewage Plant ; Rainwater Sewer ; Pipes ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 9
    Language: English
    In: Chemosphere, 2007, Vol.68(4), pp.605-612
    Description: Spraydrift and edge-of-field runoff are important routes of pesticide entry into streams. Pesticide contamination originating from spraydrift usually resides in the water phase, while pesticides in contaminated runoff are to a large extent associated with suspended particles (SPs). The effects of two organophosphorous insecticides (OPs), chloropyrifos (CPF) and azinphos-methyl (AZP), on acetylcholinesterase (AChE) activity in rainbow trout were compared between two exposure scenarios, simulating spraydrift- and runoff-borne contamination events in the Lourens River (LR), Western Cape, South Africa. NOECs of brain AChE inhibition, determined after 1 h of exposure followed by 24 h of recovery, were 0.33 μg l for aqueous CPF, 200 mg kg for SP-associated CPF and 20 mg kg for SP-associated AZP (at 0.5 g l SP). The highest aqueous AZP concentration tested (3.3 μg l ) was without significant effects. Previously reported peak levels of aqueous CPF in the LR (∼0.2 μg l ) are close to its NOEC (this study), suggesting a significant toxicological risk to fish in the LR. By contrast, reported levels of SP-associated OPs in the LR are 20–200-fold lower than their NOECs (this study). In a comparative in situ study, trout were exposed for seven days at agricultural (LR2, LR3) and upstream reference (LR1) sites. No runoff occurred during the study. Brain AChE was significantly inhibited at LR3. However, OP levels at LR3 (CPF 0.01 μg l ; AZP 0.14 μg l ) were minor compared to concentrations having effects in the laboratory (see above). Additionally, muscle AChE activity was significantly higher in caged trout from LR1 than in animals maintained in laboratory tanks.
    Keywords: Biomonitoring ; Fish ; Biomarker ; Spraydrift ; Runoff ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 10
    Language: English
    In: Aquatic Toxicology, August 2015, Vol.165, pp.154-159
    Description: In aquatic ecosystems, titanium dioxide nanoparticles (nano-TiO ) may adsorb co-occurring chemical stressors, such as copper (Cu). This interaction has the potential to reduce the concentration of dissolved Cu due to surface binding to the nanoparticles. The subsequent sedimentation of nano-TiO agglomerates may increase the exposure of benthic species towards the associated Cu. This scenario was assessed by employing the amphipod as model species and taking advantage of a 2 × 2-factorial design investigating absence and presence of 2 mg nano-TiO /L and 40 μg Cu/L ( = 45; = 24 d) in darkness, respectively. Nano-TiO alone did not affect mortality and leaf consumption, whereas Cu alone caused high mortality (〉70%), reduced leaf consumption (25%) and feces production (30%) relative to the control. In presence of nano-TiO , Cu-induced toxicity was largely eliminated. However, independent of Cu, nano-TiO decreased the gammarids’ assimilation and weight. Hence, nano-TiO may be applicable as Cu-remediation agent, while its potential long-term effects need further attention.
    Keywords: Heavy Metal ; Benthic Invertebrates ; Energy Processing ; Remediation ; Combined Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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