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91.
92.
Matthias Schmid Torsten Hothorn Kelly O. Maloney Donald E. Weller Sergej Potapov 《Environmental and Ecological Statistics》2011,18(4):709-733
Indices of biotic integrity have become an established tool to quantify the condition of small non-tidal streams and their
watersheds. To investigate the effects of watershed characteristics on stream biological condition, we present a new technique
for regressing IBIs on watershed-specific explanatory variables. Since IBIs are typically evaluated on an ordinal scale, our
method is based on the proportional odds model for ordinal outcomes. To avoid overfitting, we do not use classical maximum
likelihood estimation but a component-wise functional gradient boosting approach. Because component-wise gradient boosting
has an intrinsic mechanism for variable selection and model choice, determinants of biotic integrity can be identified. In
addition, the method offers a relatively simple way to account for spatial correlation in ecological data. An analysis of
the Maryland Biological Streams Survey shows that nonlinear effects of predictor variables on stream condition can be quantified
while, in addition, accurate predictions of biological condition at unsurveyed locations are obtained. 相似文献
93.
Anwar Zahid M. Q. Hassan G. N. Breit K.-D. Balke Matthias Flegr 《Environmental geochemistry and health》2009,31(Z1):69-84
Accumulations of iron, manganese, and arsenic occur in the Chandina alluvium of southeastern Bangladesh within 2.5 m of the
ground surface. These distinctive orange-brown horizons are subhorizontal and consistently occur within 1 m of the contact
of the aerated (yellow-brown) and water-saturated (gray) sediment. Ferric oxyhydroxide precipitates that define the horizons
form by oxidation of reduced iron in pore waters near the top of the saturated zone when exposed to air in the unsaturated
sediment. Hydrous Fe-oxide has a high specific surface area and thus a high adsorption capacity that absorbs the bulk of arsenic
also present in the reduced pore water, resulting in accumulations containing as much as 280 ppm arsenic. The steep redox
gradient that characterizes the transition of saturated and unsaturated sediment also favors accumulation of manganese oxides
in the oxidized sediment. Anomalous concentrations of phosphate and molybdenum also detected in the ferric oxyhydroxide-enriched
sediment are attributed to sorption processes. 相似文献
94.
Matthias Demuzere Nicole P.M. van Lipzig 《Atmospheric environment (Oxford, England : 1994)》2010,44(10):1341-1355
In order to make projections for future air-quality levels, a robust methodology is needed that succeeds in reconstructing present-day air-quality levels. At present, climate projections for meteorological variables are available from Atmospheric-Ocean Coupled Global Climate Models (AOGCMs) but the temporal and spatial resolution is insufficient for air-quality assessment. Therefore, a variety of methods are tested in this paper in their ability to hindcast maximum 8 hourly levels of O3 and daily mean PM10 from observed meteorological data. The methods are based on a multiple linear regression technique combined with the automated Lamb weather classification. Moreover, we studied whether the above-mentioned multiple regression analysis still holds when driven by operational ECMWF (European Center for Medium-Range Weather Forecast) meteorological data. The main results show that a weather type classification prior to the regression analysis is superior to a simple linear regression approach. In contrast to PM10 downscaling, seasonal characteristics should be taken into account during the downscaling of O3 time series. Apart from a lower explained variance due to intrinsic limitations of the regression approach itself, a lower variability of the meteorological predictors (resolution effect) and model deficiencies, this synoptic-regression-based tool is generally able to reproduce the relevant statistical properties of the observed O3 distributions important in terms of European air quality Directives and air quality mitigation strategies. For PM10, the situation is different as the approach using only meteorology data was found to be insufficient to explain the observed PM10 variability using the meteorological variables considered in this study. 相似文献
95.
Jörn Budde Monika Heiermann Teresa Suárez Quiñones Matthias Plöchl 《Waste management (New York, N.Y.)》2014,34(2):522-529
Lab-scale experiments were conducted to assess the impact of thermobarical treatment of cattle waste on anaerobic digestion. Treatment was at temperatures of 140–220 °C in 20 K steps for a 5-min duration. Methane yields could be increased by up to 58% at a treatment temperature of 180 °C. At 220 °C the abundance of inhibitors and other non-digestible substances led to lower methane yields than those obtained from untreated material. In an extended analysis it could be demonstrated that there is a functional correlation between the methane yields after 30 days and the formation rate and methane yield in the acceleration phase. It could be proved in a regression of these correlation values that the optimum treatment temperature is 164 °C and that the minimum treatment temperature should be above 115 °C. 相似文献
96.
Wolke Tobón Tania Urquiza‐Haas Patricia Koleff Matthias Schröter Rubén Ortega‐Álvarez Julio Campo Roberto Lindig‐Cisneros José Sarukhán Aletta Bonn 《Conservation biology》2017,31(5):1086-1097
Ecological restoration has become an important strategy to conserve biodiversity and ecosystems services. To restore 15% of degraded ecosystems as stipulated by the Convention on Biological Diversity Aichi target 15, we developed a prioritization framework to identify potential priority sites for restoration in Mexico, a megadiverse country. We used the most current biological and environmental data on Mexico to assess areas of biological importance and restoration feasibility at national scale and engaged stakeholders and experts throughout the process. We integrated 8 criteria into 2 components (i.e., biological importance and restoration feasibility) in a spatial multicriteria analysis and generated 11 scenarios to test the effect of assigning different component weights. The priority restoration sites were distributed across all terrestrial ecosystems of Mexico; 64.1% were in degraded natural vegetation and 6% were in protected areas. Our results provide a spatial guide to where restoration could enhance the persistence of species of conservation concern and vulnerable ecosystems while maximizing the likelihood of restoration success. Such spatial prioritization is a first step in informing policy makers and restoration planners where to focus local and large‐scale restoration efforts, which should additionally incorporate social and monetary cost–benefit considerations. 相似文献
97.
Baumann Matthias Israel Christoph Piquer-Rodríguez María Gavier-Pizarro Gregorio Volante José Norberto Kuemmerle Tobias 《Regional Environmental Change》2017,17(4):1179-1191
Regional Environmental Change - The dry forests of Latin America are among the most dynamic deforestation frontiers in the world and are important carbon and biodiversity reservoirs. Our knowledge... 相似文献
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Lakes in surface mining areas are often subject to continuous loads of acid mine drainage. The knowledge of internal alkalinity generation in a lake is necessary to predict if the lake will stay circumneutral or may acidify. The most important processes of alkalinity production in lakes are sulfate reduction, denitrification, and the burial of N in the sediment. By summarizing data from the literature, we present probable rates of these different processes in circumneutral mining lakes. The critical acidity load that can probably be compensated for by internal processes, is 5.09 mmol(-) m(-2) d(-1) in productive lakes and 0.50 mmol(-) m(-2) d(-1) in less productive lakes. Under the assumption that methanogenesis is inhibited by high sulfate concentrations, the highest probable acidity loads in such lakes are 6.85 mmol(-) m(-2) d(-1) and 1.06 mmol(-) m(-2) d(-1), respectively. Denitrification, sulfate reduction, and N burial contributed significantly to total alkalinity production. Sulfate reduction had the largest potential. However, existing models cannot predict alkalinity generation from sulfate concentrations alone because the long-term stability of reduced S compounds in the sediment is crucial for a sustainable biological alkalinity generation. The larger acid-neutralizing potential of higher trophic lakes is caused both by higher rates of microbial activity and by a greater stability of reduced reaction products in the sediment. The largest uncertainties in our knowledge with respect to the total alkalinity budget are related to microbial processes in sulfate-rich freshwater lakes and the long-term stability of reduced reaction products in the sediment. 相似文献