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Berlin Brandenburg

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  • SpringerLink  (10)
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  • 1
    Language: English
    In: Biogeochemistry, 2014, Vol.121(3), pp.505-517
    Description: Many soils around the globe are contaminated with metals due to inputs from anthropogenic activities; however, the long-term processes that retain these metals in soils or flush them into river systems remain unclear. Soils at the Susquehanna/Shale Hills Critical Zone Observatory, a headwater catchment in central Pennsylvania, USA, are enriched in manganese due to past atmospheric deposition from industrial sources. To investigate how Mn is retained in the catchment, we evaluated the spatial distribution and speciation of Mn in the soil–plant system using X-ray fluorescence and X-ray Absorption Near Edge Structure spectroscopies. Weathered soils near the land surface were enriched in both amorphous and crystalline Mn(III/IV)-oxides, presumably derived from biogenic precipitation and atmospheric deposition, respectively. In contrast, mineral soils near the soil–bedrock interface contained Mn(II) in clays and crystalline Mn(III/IV)-oxides that formed as Mn(II) was leached from the parent shale and oxidized. Roots, stems, and foliar tissue were dominated by organic-bound and aqueous Mn(II); however, a small portion of foliar Mn was concentrated as organic-bound Mn(III) in dark spots that denote Mn toxicity. During decomposition of leaves and roots, soluble Mn(II) stored in vegetation was rapidly oxidized and immobilized as mixed-valence Mn-oxides. We propose that considerable uptake of Mn by certain plant species combined with rapid oxidation of Mn during organic matter decomposition contributes to long-term retention in soils and may slow removal of Mn contamination from watersheds.
    Keywords: Manganese ; Spectroscopy ; Critical zone ; Soil geochemistry ; Metal contamination
    ISSN: 0168-2563
    E-ISSN: 1573-515X
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  • 2
    Language: English
    In: Wetlands, 2015, Vol.35(4), pp.803-813
    Description: We assessed aquatic invertebrate response to ecological rehabilitation treatment in 20 depression wetlands on the Savannah River Site, South Carolina, USA. All wetlands had been ditched for 50+ years. Sixteen of the 20 wetlands received rehabilitation treatment, and four wetlands remained untreated as a control group. Treatment included logging of all trees, plugging drainage ditches, and planting wetland trees and grasses. Hydroperiods were consequently extended in most of the treatment wetlands. As part a larger study, we sampled macroinvertebrates and microcrustaceans during the pre-habilitation (1998–2000) and rehabilitation (2001–2003) phases. Our study spanned 2 years of high rainfall (1998 and 2003) and 4 years of low rainfall (1999–2002). Samples were collected bimonthly from any wetlands holding water. Macroinvertebrate assemblages in treatment wetlands in 2003 had changed from previous years (1998–2002) and compared to control wetlands (1998–2003), with abundances of Baetidae, Coenagrionidae, Dytiscidae, Chironomidae, and Chaoboridae driving variation. For microcrustaceans (Copepoda and Branchiopoda, including Cladocera, Anostraca and Laevicaudata), assemblage composition and species richness responded mainly to hydrologic conditions. Rehabilitation efforts in these wetlands induced diverse and abundant invertebrate communities to develop, but some responses appeared opportunistic; several taxa that benefitted were not typical residents of depressional wetlands in the region.
    Keywords: Carolina bays ; Hydrology ; Macroinvertebrates ; Microcrustaceans ; Opportunism ; Wetland restoration
    ISSN: 0277-5212
    E-ISSN: 1943-6246
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  • 3
    Language: English
    In: Environmental Geochemistry and Health, 2018, Vol.40(2), pp.865-885
    Description: To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO 4 ], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO 4 ] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO 4 ] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO 4 ] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO 4 ] are related to releases from coal mining or burning rather than oil and gas development.
    Keywords: Water quality ; Human impact ; Shale gas ; Historical data ; Pristine river
    ISSN: 0269-4042
    E-ISSN: 1573-2983
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  • 4
    Language: English
    In: Wetlands, 2002, Vol.22(4), pp.767-775
    Description: Water levels fluctuate widely in Carolina bay wetlands and most dry periodically. Aquatic organisms inhabiting these wetlands have the capacity to either resist desiccation or to recolonize newly flooded habitats. The objective of this study was to determine which invertebrates aestivate in the soil of dry Carolina bays and to describe how differences in habitat affect the composition of aestivating invertebrates. Eight Carolina bays located on the Savannah River Site (SRS) near Aiken, South Carolina, USA were examined for this study. Although all of the wetlands dried seasonally, three of the wetlands were relatively wet (inundated 47–92% of the year on average), one was intermediate, and four were relatively dry (inundated 20% of year on average). Sections of soil were removed from each bay during August and November when all sites were dry, placed into tubs, flooded, and covered with fine mesh. Invertebrates were sampled from the water biweekly for four weeks. Invertebrate assemblages were contrasted between naturally inundated bays and rehydrated samples, wetter and drier bays, August and November collections, and remnant ditches and the main basins. Common aestivating fauna included midges, dytiscid beetles, copepods, and cladocerans. The Jaccard’s coefficient of similarity for invertebrates emerging from dry substrate and from naturally flooded wetlands (with both aestivators and colonizers) averaged 0.22. More taxa emerged from rehydrated samples from wetter bays than drier bays. Season affected which taxa emerged. Remnant ditches supported fewer taxa than basins. Aestivating invertebrates make up a significant component of Carolina bya fauna.
    Keywords: aestivation ; rehydration ; invertebrates ; wetland ponds
    ISSN: 0277-5212
    E-ISSN: 1943-6246
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  • 5
    Language: English
    In: Journal of Porous Materials, 2002, Vol.9(4), pp.243-256
    Description: The surface charge properties of two SiO 2 and three Al 2 O 3 mineral adsorbents with varying degrees of framework porosity were investigated using discontinuous titration and ion adsorption methodologies. Points of zero net charge (p.z.n.c) for porous and non-porous SiO 2 were 〈2.82 and for Al 2 O 3 minerals ranged from 6.47–6.87. Silica surfaces possessed very slight negative charge in the acid pH range (pH 〈 7) and significant dissociation of silanol groups occurred at pH 〉 7. Variation of surface charge density with aqueous proton concentration was nearly identical within a mineral type (i.e., SiO 2 or Al 2 O 3 ) irrespective of the degree of framework porosity, indicating that the densities of dissociable surface sites are equivalent, when normalized to surface area. The results suggest that the use of titration methods alone may be insufficient for thorough surface charge characterization, particularly at low and high pH. Proton titrations should be coupled with concurrent ion adsorption measurements to confirm surface charge development. Discontinuous proton titration and ion adsorption data, which were in agreement in the slightly acidic through slightly basic pH range, both indicated that p.z.n.c. was equal to the point of zero net proton charge (p.z.n.p.c.) for the variable charge minerals investigated.
    Keywords: surface charge ; proton adsorption ; ion adsorption ; site density ; alumina ; silica ; p.z.n.p.c
    ISSN: 1380-2224
    E-ISSN: 1573-4854
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  • 6
    Language: English
    In: Aquatic Sciences, 1993, Vol.55(4), pp.262-272
    Description: Analysis of the etch-pit size distributions (PSDs) observed on potassium feldspar and hornblende grains in a soil catena in loess (age = 12,500 y) reveals natural mineral etching rates. Rates estimated for hornblende (6 to 9×10 −15 mol/m 2 s) are based on consistent crystallographically controlled etch pits, while rates estimated for potassium feldspar (2×10 −15 mol/m 2 s) are based on irregularly shaped pits. Although little difference in etching rate is observed between soil horizons, the highest etching rates generally occur in the upper B horizons where pH values are lowest. Decreasing soil drainage correlates with an increase in pit density, n °, probably due to increased grain wetting, while decreased drainage correlates with a decrease in pit growth rate ( G ), probably due to increased dissolved solute concentrations. The PSD model predicts that etching rate is a function of n ° and of G 4 . Etching rates calculated for potassium feldspar do not vary with drainage, while those of hornblende decrease with decreasing drainage. Estimated etching rates are lower than bulk dissolution rates measured in the laboratory.
    Keywords: Weathering rates ; etch pits ; mineral dissolution kinetics ; mineral surfaces
    ISSN: 1015-1621
    E-ISSN: 1420-9055
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  • 7
    Language: English
    In: Bulletin of Volcanology, 1992, Vol.54(6), pp.494-503
    Description: Monitoring of crater lake chemistry during the recent decline and disappearance of the crater lake of Poás Volcano revealed that large variations in SO 4 /Cl, F/Cl, and Mg/Cl ratios were caused by the enhanced release of HCl vapor from the lake surface due to increasing lake temperature and solution acidity. Variation in the concentration of polythionic acids (H 2 S x O 6 , x=4–6) was the most reliable predictor of renewed phreatic eruptive activity at the volcano, exhibiting sharp decreases three months prior to the initiation of phreatic eruptions in June 1987. Polythionic acids may offer a direct indicator of changing subsurface magmatic activity whereas chloride-based element ratios may be influenced by surface volatilization of HCl and subsequent recycling of acidic fluids in crater lake volcanoes.
    Keywords: Hydrochemistry ; Quaternary Geology ; Central America ; Costa Rica ; Craters ; Eruptions ; Geochemistry ; Geomorphology ; Hydrochemistry ; Lacustrine Features ; Lakes ; Phreatomagmatism ; Poas ; Prediction;
    ISSN: 0258-8900
    E-ISSN: 1432-0819
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  • 8
    Language: English
    In: AIDS and Behavior, 2017, Vol.21(10), pp.3047-3056
    Description: Women who are structurally vulnerable are at heightened risk for HIV/STIs. Identifying typologies of structural vulnerability that drive HIV/STI risk behavior is critical to understanding the nature of women’s risk. Latent class analysis (LCA) was used to classify exotic dancers (n = 117) into subgroups based on response patterns of four vulnerability indicators. Latent class regression models tested whether sex- and drug-related risk behavior differed by vulnerability subgroup. Prevalence of vulnerability indicators varied across housing instability (39%), financial insecurity (39%), limited education (67%), and arrest history (36%). LCA yielded a two-class model solution, with 32% of participants expected to belong to a “high vulnerability” subgroup. Dancers in the high vulnerability subgroup were more likely to report sex exchange (OR = 8.1, 95% CI, 1.9–34.4), multiple sex partnerships (OR = 6.4, 95% CI, 1.9–21.5), and illicit drug use (OR = 17.4, 95% CI, 2.5–123.1). Findings underscore the importance of addressing inter-related structural factors contributing to HIV/STI risk.
    Keywords: HIV ; Sexually transmitted infections ; Social determinants ; Exotic dance club
    ISSN: 1090-7165
    E-ISSN: 1573-3254
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  • 9
    Language: English
    In: AIDS and Behavior, 2017, Vol.21(7), pp.2147-2155
    Description: Exotic dancers have received little research attention despite evidence of high-risk behaviours within exotic dance clubs (EDCs). We developed and assessed the reliability and validity of a risk environment score, examining differences between dancers (n = 107) and other staff (n = 172). In the summer of 2013, anonymous surveys were administered via A-CASI in EDCs (N = 26) in Baltimore among exotic dancers and staff. Surveys consisted of a brief demographic section followed by 65 statements. The overall domain had an alpha = 0.77 and subdomains had the following: social (alpha = 0.87), economic (alpha = 0.92), drug (alpha = 0.89), and policy (alpha = 0.66). In a factor analysis, each domain contributed significantly to the overall latent construct. The results indicate a high level of HIV/STI risk for dancers in EDCs and underscore the need for targeted interventions in these environments. As we continue to unpack the function of the broader environment in STI/HIV risk transmission, the scale could be instructive for other settings. Existen pocos estudios sobre las bailarinas exóticas a pesar de la evidencia de que tienen comportamientos de alto riesgo dentro de clubes de danza exótica. Desarrollamos una puntuación de riesgo del entorno y evaluamos su validez y confiabilidad al examinar las diferencias entre bailarinas (n = 107) y otro personal (n = 172). En el verano de 2013, bailarinas y otro personal completaron una encuesta anónima en clubes de danza exótica (N = 26) en Baltimore usando la tecnología ACASI. La encuesta constó de una breve sección demográfica y de 65 declaraciones. Calculamos el coeficiente alfa para el dominio global (alfa = 0.77) y para los siguientes subdominios: social (alfa = 0.87), económico (alfa = 0.92), droga (alfa = 0.89) y política (alfa = 0.66). En un análisis factorial, cada dominio contribuyó significativamente al constructo latente global. Los resultados indican que hay un alto nivel de riesgo de VIH/ITS para las bailarinas en clubes de danza exótica y recalcan la necesidad de intervenciones formuladas específicamente para estos lugares. Esta escala podría ser útil para otros lugares a medida que continuemos a determinar la función del entorno más amplio en el riesgo de la transmisión de VIH/ITS.
    Keywords: HIV risk environment ; Exotic dance clubs ; Strippers ; Validation
    ISSN: 1090-7165
    E-ISSN: 1573-3254
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  • 10
    Language: English
    In: Journal of Psycholinguistic Research, 1980, Vol.9(3), pp.205-217
    Description: Twenty-five mothers of all social class levels were asked to tell, as if to a 6-year-old child, the stories suggested by several cartoon picture sequences. These stories, tape-recorded, were played to a hundred 6-year-old white male children of high and low social class levels, who were then asked standard comprehension questions about their content. Analysis of the comprehension scores revealed significant main effects of social class of adult speaker and of social class of child listener but no interaction of these two variables. Further analysis of transcriptions of the stories revealed two characteristics, namely the factual information included in the stories and the use of nonstandard grammar, which seemed to mediate the effects of both social class and speaker IQ on comprehension.
    Keywords: Child Language (Ch1) ; Sociolinguistics (So2) ; Adult Language (Ad3) ; Listening Comprehension (Li4) ; Sociolinguistics; Sociolinguistics ; Psycholinguistics; Child Language Acquisition ; Article ; Adult Language, Children'S Comprehension ; Social Class Difference ; Six-Year-Old White Males;
    ISSN: 0090-6905
    E-ISSN: 1573-6555
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