Agricultural Nurseries-Based Pollution Dynamics and Source Apportionment in the Canals of Miami-Dade, Florida, USA

Authors

Samuel Aaron Kent, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Earth Systems Science

First Advisor's Name

Assefa M. Melesse

First Advisor's Committee Title

Committee chair

Second Advisor's Name

René M. Price

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Leonard J. Scinto

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

John Kominoski

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Amir Khoddamzadeh

Fifth Advisor's Committee Title

Committee member

Keywords

Agricultural nurseries, nitrate + nitrite, canals, principal component analysis, positive matrix factorization

Date of Defense

6-29-2023

Abstract

Agricultural nonpoint source nutrient pollution has been shown to be a national problem and is the leading cause of water quality issues in the United States. Nitrate + nitrite (NO_x) runoff is primarily attributed to agriculture and is responsible for eutrophication which can lead to the loss of plants, fish, and biodiversity within a waterway. Agricultural runoff has been attributed to these issues within the canals of Miami-Dade County as well as within Biscayne Bay. The source of agricultural nutrients comes from fertilizer application through fertigation or in a pelletized form as controlled released fertilizers. Agricultural land use is a broad category that encompasses field crops, pastureland, tree nurseries, tree crops, and more. This study intends to narrow the contribution of agricultural land use to separate tree nurseries from other types of agriculture. Using linear regression, a relationship between NO_x concentration within the C-103 N canal and the distance and area of both tree nurseries and other types of agriculture was established. The resulting coefficient for tree nurseries is 23.2 mg NO_x L^-1 km^-2 and 16.5 mg NO_x L^-1 km^-2 for all other types of agriculture within 500 m of the C-103 N canal. The quantification of NO_x load from all tree nurseries and other types of agriculture was determined using the coefficients calculated from the regression. Throughout all Miami-Dade County, tree nurseries have been shown to contribute 9.52 kg of NO_x per km² of land use whereas other agricultural land use has contributed 11.98 kg of NO_x per km² of land use within 500 m of canals. A principal component analysis of ten water quality parameters over a 19-year dataset over 47 station locations within the canals has captured 59.6% and 70.2% of the variance in the northern canals and southern canals, respectively. The northern canals, dominated by urban land use, NO_x was significantly positively correlated to fecal coliform, total phosphorus, pH, and dissolved oxygen. The southern canals, surrounded by agriculture, have NO_x as its own component. Source apportionment using positive matrix factorization was used to determine the sources of the water quality constituents. The primary contributors in the south canals were agriculture, landfills, urban fertilizers, and sewage, whereas the north canal sources were mostly attributed to the saltwater interface and biological nonpoint sources.

Identifier

FIDC011186

ORCID

0000-0002-6680-3338

Recommended Citation

Kent, Samuel Aaron, "Agricultural Nurseries-Based Pollution Dynamics and Source Apportionment in the Canals of Miami-Dade, Florida, USA" (2023). FIU Electronic Theses and Dissertations. 5378.
https://digitalcommons.fiu.edu/etd/5378