Masters Theses

Date of Award

12-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

Raj Raman

Committee Members

Robert Burns, Alice Layton, Michael Mullen

Abstract

Naturally occurring estrogens in animal wastes may cause negative environmental impacts in some watersheds. However, there is little published data regarding the concentrations of these estrogenic compounds in full-scale animal waste treatment and storage structures, thus making risk assessment difficult. To address this knowledge gap, the research described herein explores estrogen concentrations at 19 animal waste storage and treatment structures at dairy and swine production facilities in and around Tennessee during the winter and summer months of one year. Samples were collected from eight dairy and eleven swine facilities, representing a range of waste storage and treatment structures typical of Tennessee, and much of the southeastern US. Swine waste samples were collected from both swine farrowing operations that are populated by farrowing sows and piglets, and swine finishing operations that are populated by growing, non-pregnant male and female pigs. Dairy waste samples were collected from dairy operations populated by lactating cows in various stages of their hormonal and reproductive cycles. The 17β-estradiol concentrations in all samples were assayed in triplicate serial dilutions by means of an enzyme linked immunosorbent assay (ELISA). In addition, concentrations of 17β-estradiol, 17α-estradiol, and estrone were determined by gas-chromatography mass-spectroscopy (GC-MS). All samples were also assayed for total solids, volatile solids, ash, total Kjeldahl nitrogen (TKN), total phosphorus, potassium, and chemical oxygen demand. An estrogen to macronutrient (N, P, and K) mass ratio was determined for all waste samples. This was done because the raw waste value does represent the true estrogen pollution potential.

Several tentative conclusions have been drawn from the data presented here, as follow; (1) Using ELISA to assay 17β-estradiol (E2), there were statistically significant differences (α=0.05) between all the farm types sampled (dairy, swine farrowing, and swine finishing) for E2/N, E2/P, and E2/K ratios (where N, P, and K represent nitrogen, phosphorus, and potassium respectively). Swine farrowing operations showed the highest estrogen to macronutrient mass ratios, averaging 19.2 ppt E2/ppm N (1.1 sd), 65.6 ppt E2/ppm P (4.7 sd), and 24.3 ppt E2/ppm K (1.7 sd). Average swine finishing and dairy ratios were approximately 2 and 5 times lower, respectively. The same trend was seen in GC-MS 17β-estradiol, estrone, and total estrogen ratios (the sum of 17β-estradiol, 17α-estradiol, and estrone concentrations). In contrast, dairy operations had a significantly (α=0.05) higher estrogen to macronutrients mass ratio for GC-MS 17α-estradiol as compared to swine farrowing, averaging 16.5 ppt 17α/ppm N (5.7 sd), 62.6 ppt 17α/ppm P (6.9 sd), and 30.9 ppt 17α/ppm K (4.1 sd).

(2) Dairy waste structures (holding ponds, dry stack-solid, and semisolid) did not have statistically significantly different (α=0.05) for ELISA 17β-estradiol and GC-MS 17β-estradiol and estrone ratios. However, dairy dry stack-semisolid waste had significantly (α=0.05) higher estrogen to macronutrients mass ratios for GC-MS 17α-estradiol than holding ponds and dry stack-solid structures. Dairy dry stack-semisolid showed the highest ratios for 17α-estradiol to P, which were 85.2 ppt/ppm (8.5 sd). Dairy dry stack-semisolid also had statistically significantly higher total estrogen to macronutrient ratios (α=0.05) than did the other structures. The highest values were for P, averaging 129.2 ppt total estrogen/ppm (27.1 sd).

(3) Swine finishing lagoon structures had statistically significantly higher (α=0.05) estrone/N and estrone/P ratios than did swine finishing hoop structures. For example, swine finishing lagoons had P ratios of 202 ppt El/ppm P (40.8 sd) as compared to 13.2 ppt El/ppm P (47 sd) observed in swine finishing hoop structures. In contrast, ELISA 17β-estradiol ratios were not statistically significantly different for any of the swine finishing structures. GC-MS 17β-estradiol and 17α-estradiol concentrations were below the detection limits for the structures.

These results suggest that it is probable that wastes from swine farrowing facilities pose the greatest threat as environmental estrogen pollutants. Specifically, swine farrowing wastes had statistically significantly higher (α=0.05) ratios of 17β-estradiol and estrone to the macronutrients N and P than did swine finishing and dairy waste. (Although dairy wastes had the highest ratios of 17α-estradiol to macronutrients, 17α-estradiol is not as potent an estrogen as 17β-estradiol and estrone.) Ultimately, the actual threat of estrogenic pollution posed by these wastes must be determined by additional runoff studies, supplemented by watershed-scale studies. This thesis helps identify the wastes most likely to cause problems, and therefore most worthy of additional study.

Phosphorus-based application of the manures studied would result in lower mass application rates of estrogen to fields (ca. 2 - 3x). In this sense, the increasing trend toward P-based application will help mitigate the likelihood of estrogen pollution from the land application of animal manures.

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