All ETDs from UAB

Advisory Committee Chair

Stephen A Watts

Advisory Committee Members

Julia M Gohlke

Mickie L Powell

Andrei V Stanishevsky

Document Type

Thesis

Date of Award

2014

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

Industrial use of reactive micro- and nano-sized carbonaceous hydrochar (CH) is expanding rapidly. These carbonaceous particulates are synthesized by the pyrolysis of biomass in an industrial process called hydrothermal carbonization (HTC) and have gained attention as a soil conditioner. Additionally, the HTC process is being expanded to coat heavy-metal nanoparticles, such as nano-copper and nano-iron, to prevent surface oxidation of these metals. These carbonaceous particles are likely to undergo secondary reactions with metals, toxicants, or other compounds. There is potential for these carbonaceous particulates to enter watersheds and have deleterious effects on aquatic food web dynamics. In this study, we investigated the direct effects of carbonaceous and metal-loaded hydrochars on a variety of aquatic species as well as vertical transfer of copper-loaded carbonaceous hydrochar (Cu-CH) among trophic levels. We determined that the marine unicellular algae Dunaliella tertiolecta exhibits reduced survivorship upon exposure to carbon hydrochars. Ciliated zooplankton (Brachionus plicatilis) as well as the larvae of the marine sea urchin (Lytechinus variegatus) and freshwater mosquito (Aedes aegypti) are capable of ingesting CH within minutes. Upon exposure to Cu-CH, reduced survivorship was noted. An LC50 of Cu-CH for the Rotifer, Brachionus plicatilis was determined to be 8mg/L. Zebrafish exposed episodically (20hr per 24hr period) to Cu-CH for 16 days had copper levels 3x higher than controls, indicating uptake of copper directly from the water column. To investigate vertical transfer of Cu-CH, newly-hatched zebrafish (Danio rerio) larvae (5 dpf) were fed three times daily ad libitum a diet of rotifers exposed previously to 10mg/L CH, 10mg/L Cu-CH (Cu-CH rotifers), or 4.1mg/L CuCl2 (an equimolar amount of Cu as Cu-CH)(Cu rotifers). Copper levels of fish fed a diet of Cu-CH rotifers or Cu rotifers did not differ significantly and had copper levels 2x higher than fish fed the control CH diet. The results of this study indicate that CHs released to the environment may pose a threat to aquatic species, particularly those hydrochars bound with toxicants, and have potential to enter and potentially disrupt food web dynamics. Additionally, hydrochars may influence biomagnification of toxicants in aquatic organisms.

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