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Institution

Colorado State University

EducationFort Collins, Colorado, United States
About: Colorado State University is a education organization based out in Fort Collins, Colorado, United States. It is known for research contribution in the topics: Population & Radar. The organization has 31430 authors who have published 69040 publications receiving 2724463 citations. The organization is also known as: CSU & Colorado Agricultural College.
Topics: Population, Radar, Poison control, Laser, Soil water


Papers
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Journal ArticleDOI
TL;DR: In this paper, the effects of no-tillage (NT) and conventional tillage (CT) management on bacterial and fungal abundance and biomass were examined to examine potential controls on the relative abundances of bacteria and fungi in these two systems.
Abstract: Microbial community composition may be an important determinant of soil organic matter (SOM) decomposition rates and nutrient turnover and availability in agricultural soils. Soil samples were collected from six long-term tillage comparison experiments located along two climatic gradients to examine the effects of no-tillage (NT) and conventional tillage (CT) management on bacterial and fungal abundance and biomass and to examine potential controls on the relative abundances of bacteria and fungi in these two systems. Samples were divided into 0–5 and 5–20 cm depth increments and analyzed for bacterial and fungal abundance and biomass, total C and N, particulate organic matter C and N (POM-C and N), soil water content, texture, pH, and water-stable aggregate distributions. Soil moisture, which varied by tillage treatment and geographically with climate, ranged from 0.05 to 0.35 g g−1 dry soil in the surface 0–5 cm and 0.15 to 0.28 g g−1 dry soil at 5–20 cm. Measured organic matter C and N fractions and mean weight diameter (MWD) of water-stable aggregates were significantly higher in NT relative to CT at three of the six sites. Fungal hyphal length ranged from 19 to 292 m g−1 soil and was 1.9 to 2.5 times higher in NT compared to CT surface soil across all sites. Few significant tillage treatment differences in soil physical and chemical properties or in fungal abundance and biomass were observed at 5–20 cm. Bacterial abundance and biomass were not consistently influenced by tillage treatment or site location at either depth. The proportion of the total biomass composed of fungi ranged from 10 to 60% and was significantly higher in NT compared to CT surface soil at five of six sites. Proportional fungal biomass was not strongly related to soil texture, pH, aggregation, or organic C and N fractions, but was positively related to soil moisture (r=0.67; P<0.001). The relationship between soil moisture and the degree of fungal dominance was due to the positive response of fungal biomass and the lack of response of bacterial biomass to increasing soil moisture across the range of measured soil water contents. Tillage treatment effects on fungal biomass and proportional fungal abundance were not significant when the data were analyzed by analysis of covariance with soil moisture as the covariate. These results suggest that observed tillage treatment and climate gradient effects on fungi are related to differences in soil moisture. Further research is needed, however, to determine how tillage-induced changes in the soil environment shape microbial community composition in agroecosystems.

602 citations

Journal ArticleDOI
TL;DR: In this paper, a statistical method is developed to determine the locations of major pollutant sources affecting a distant downwind receptor, provided that air trajectories can be estimated, and a source contribution function is formulated to indicate the relative contribution of different source regions to high concentrations at the receptor.

601 citations

Journal ArticleDOI
TL;DR: In this article, the integrity of freshwater ecosystems depends upon adequate quantity, quality, timing, and temporal variability of water flow, and these attributes impart relatively unique characteristics of productivity and biodiversity to each ecosystem.
Abstract: Human society has used freshwater from rivers, lakes, groundwater, and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilization for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life—and these are costly, if not impossible, to replace. Long-term benefits include the sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations, such as climate change. Thus, maintenance of the processes and properties that support freshwater ecosystem integrity should be included in debates over sustainable water resource allocation. The purpose of this report is to explain how the integrity of freshwater ecosystems depends upon adequate quantity, quality, timing, and temporal variability of water flow. Defining these requirements in a comprehensive but general manner provides a better foundation for their inclusion in current and future debates about allocation of water resources. In this way the needs of freshwater ecosystems can be legitimately recognized and addressed. We also recommend ways in which freshwater ecosystems can be protected, maintained, and restored. Freshwater ecosystem structure and function are tightly linked to the watershed or catchment of which they are a part. Because riverine networks, lakes, wetlands, and their connecting groundwaters, are literally the “sinks” into which landscapes drain, they are greatly influenced by terrestrial processes, including many human uses or modifications of land and water. Freshwater ecosystems, whether lakes, wetlands, or rivers, have specific requirements in terms of quantity, quality, and seasonality of their water supplies. Sustainability normally requires these systems to fluctuate within a natural range of variation. Flow regime, sediment and organic matter inputs, thermal and light characteristics, chemical and nutrient characteristics, and biotic assemblages are fundamental defining attributes of freshwater ecosystems. These attributes impart relatively unique characteristics of productivity and biodiversity to each ecosystem. The natural range of variation in each of these attributes is critical to maintaining the integrity and dynamic potential of aquatic ecosystems; therefore, management should allow for dynamic change. Piecemeal approaches cannot solve the problems confronting freshwater ecosystems. Scientific definitions of the requirements to protect and maintain aquatic ecosystems are necessary but insufficient for establishing the appropriate distribution between societal and ecosystem water needs. For scientific knowledge to be implemented science must be connected to a political agenda for sustainable development. We offer these recommendations as a beginning to redress how water is viewed and managed in the United States: (1) Frame national and regional water management policies to explicitly incorporate freshwater ecosystem needs, particularly those related to naturally variable flow regimes and to the linking of water quality with water quantity; (2) Define water resources to include watersheds, so that freshwaters are viewed within a landscape, or systems context; (3) Increase communication and education across disciplines, especially among engineers, hydrologists, economists, and ecologists to facilitate an integrated view of freshwater resources; (4) Increase restoration efforts, using well-grounded ecological principles as guidelines; (5) Maintain and protect the remaining freshwater ecosystems that have high integrity; and (6) Recognize the dependence of human society on naturally functioning ecosystems.

599 citations

Journal ArticleDOI
TL;DR: In this article, the long-term pattern of physicochemical variability in conjunction with the complexity and stability of the substratum establishes a physical habitat template that theoretically influences which combinations of behavioral, physiological and life history characteristics constitute appropriate "ecological strategies" for persistence in the habitat.
Abstract: Spatial and temporal environmental heterogeneity in lotic ecosystems can be quantitatively described and identified with characteristic levels of ecological organization. The long-term pattern of physicochemical variability in conjunction with the complexity and stability of the substratum establishes a physical habitat template that theoretically influences which combinations of behavioral, physiological and life history characteristics constitute appropriate “ecological strategies” for persistence in the habitat. The combination of strategies employed will constrain ecological response to and recovery from disturbance. Physical habitat templates and associated ecological attributes differ geographically because of biogeoclimatic processes that constrain lotic habitat structure and stability and that influence physicochemical variability and disturbance patterns (frequency, magnitude, and predictability). Theoretical considerations and empirical studies suggest that recovery from natural and anthropogenic disturbance also will vary among lotic systems, depending on historical temporal variability regime, degree of habitat heterogeneity, and spatial scale of the perturbation. Characterization of physical habitat templates and associated ecological dynamics along gradients of natural disturbance would provide a geographic framework for predicting recovery from anthropogenic disturbance for individual streams. Description of lotic environmental templates at the appropriate spatial and temporal scale is therefore desirable to test theoretical expectations of biotic recovery rate from disturbance and to guide selection of appropriate reference study sites for monitoring impacts of anthropogenic disturbance. Historical streamflow data, coupled with stream-specific thermal and substratum-geomorphologic characteristics, are suggested as minimum elements needed to characterize physical templates of lotic systems.

598 citations

Journal ArticleDOI
TL;DR: In this paper, the first use of sol−gel chemistry to prepare semiconductor nanofibrils and tubules within the pores of an alumina template membrane was described, and 200 nm diameter TiO2 fibrils were used as photocatalysts for the decomposition of salicylic acid.
Abstract: The template method for preparing nanostructures entails synthesis of the desired material within the pores of a nanoporous membrane or other solid. A nanofibril or tubule of the desired material is obtained within each pore. Methods used previously to deposit materials within the pores of such membranes include electrochemical and electroless deposition and in situ polymerization. This paper describes the first use of sol−gel chemistry to prepare semiconductor nanofibrils and tubules within the pores of an alumina template membrane. TiO2, WO3, and ZnO nanostructures have been prepared. TiO2 nanofibrils with diameters of 22 nm were found to be single crystals of anatase with the c-axis oriented along the fibril axis. Bundles of these fibrils were also found to be single crystalline, suggesting that the indiviual fibrils are arranged in a highly organized fashion within the bundle. Finally, 200 nm diameter TiO2 fibrils were used as photocatalysts for the decomposition of salicylic acid.

597 citations


Authors

Showing all 31766 results

NameH-indexPapersCitations
Mark P. Mattson200980138033
Stephen J. O'Brien153106293025
Ad Bax13848697112
David Price138168793535
Georgios B. Giannakis137132173517
James Mueller134119487738
Christopher B. Field13340888930
Steven W. Running12635576265
Simon Lin12675469084
Jitender P. Dubey124134477275
Gregory P. Asner12361360547
Steven P. DenBaars118136660343
Peter Molnar11844653480
William R. Jacobs11849048638
C. Patrignani1171754110008
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023159
2022500
20213,596
20203,492
20193,340
20183,136