Identification of bird and frog species from recordings

Monitoring of wildlife populations is important for assessing ecosystem health, and its response to natural and human-caused threats. However, traditional visual or audio monitoring requires significant human effort and is expensive. Automated acoustic monitoring can overcome these problems. For example, stand-alone recording stations can provide valuable information on amphibian and bird species present in an area, timing of migration and breeding, and some indication of the level of activity. These methods will be most useful with reliable rapid automated methods for analyzing the captured acoustic data. Through work with the University of Vermont and the US Geologic Survey, I've developed new software tools in R for identifying and quantifying bird and frog calls in recordings.

Cattle feed and air quality

Emission measurements made over the past few years have demonstrated that silage (fermented cattle feed) emits significant amounts of volatile organic compounds (VOCs), which contribute to poor air quality in central California and possibly other areas. But elimination of silage is not practical; silage is an important feed source for both dairy and beef cattle, and has been for more than a century. Therefore, predicting the magnitude of VOC emission from silage, and the effect of management practices on emission rates will be essential for understanding and controlling this source of VOCs. In previous work with the USDA Agricultural Research Service, I helped quantify emission rates of important VOCs, and developed mathematical models for predicting the magnitude of emissions. Currently, I am working with researchers at the University of Califorinia at Davis to refine my previous models. You can read more about the work I've done on this topic in the papers below.

Hafner, S.D., Montes, F., Rotz, C.A. 2012. A mass transfer model for VOC emission from silage. Atmospheric Environment 54: 134-140.


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Hafner, S.D., Montes, F., Rotz, C.A., Mitloehner, F. 2010.Ethanol emission from loose corn silage and exposed silage particles. Atmospheric Environment 44: 4172-4180.


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Montes, F., Hafner, S.D., Rotz, C.A., Mitloehner, F. 2010. Temperature and air velocity effects on ethanol emission from corn silage with the characteristics of the exposed face of a bunker silo. Atmospheric Environment 44: 1987-1995.


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An inexpensive method for measuring gaseous ammonia

Ammonia is a significant air pollutant from agricultural systems, and it contributes to poor air quality and pollution of terrestrial and aquatic ecosystems. In confined spaces such as barns, ammonia may reach high enough levels to become an irritant to humans and animals. Measurement of gaseous ammonia is therefore essential for quantifying and addressing this problem. Various approaches are used to measure and better understand ammonia emission from agricultural systems, but they are either expensive, requiring tens of thousands of dollars for instruments, or inexpensive but labor-intensive and time consuming.

In 2011 I developed a new approach that is both inexpensive and rapid, based on measurement of pH change in a citric acid trap. Captured ammonia is determined by applying a speciation model, which can be applied using algorithms available in both R and Excel. Currently, Hafner Consulting is working on new applications for the method. You can read more about the method in the paper below. And, if you are interested in using the method, you can download an Excel-based tool for applying the method below. Or, contact me for a more powerful approach written in R.

Hafner, S.D., Meisinger, J., Mulbry, W., Ingram, S. 2012. A pH-based method for measuring gaseous ammonia. Nutrient Cycling in Agroecosystems 92: 195-205


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CA-pH method


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