@article {Lin2015,
	title = {{Dissolved amino acids in oceanic basaltic basement fluids}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {164},
	year = {2015},
	pages = {175{\textendash}190},
	abstract = {The oceanic basaltic basement contains the largest aquifer on Earth and potentially plays an important role in the global carbon cycle as a net sink for dissolved organic carbon (DOC). However, few details of the organic matter cycling in the subsurface are known because great water depths and thick sediments typically hinder direct access to this environment. In an effort to examine the role of water{\textendash}rock{\textendash}microorganism interaction on organic matter cycling in the oceanic basaltic crust, basement fluid samples collected from three borehole observatories installed on the eastern flank of the Juan de Fuca Ridge were analyzed for dissolved amino acids. Our data show that dissolved free amino acids (1{\textendash}13 nM) and dissolved hydrolyzable amino acids (43{\textendash}89 nM) are present in the basement. The amino acid concentrations in the ridge-flank basement fluids are at the low end of all submarine hydrothermal fluids reported in the literature and are similar to those in deep seawater. Amino acids in recharging deep seawater, in situ amino acid production, and diffusional input from overlying sediments are potential sources of amino acids in the basement fluids. Thermodynamic modeling shows that amino acid synthesis in the basement can be sustained by energy supplied from inorganic substrates via chemolithotrophic metabolisms. Furthermore, an analysis of amino acid concentrations and compositions in basement fluids support the notion that heterotrophic activity is ongoing. Similarly, the enrichment of acidic amino acids and depletion of hydrophobic ones relative to sedimentary particulate organic matter suggests that surface sorption and desorption also alters amino acids in the basaltic basement. In summary, although the oceanic basement aquifer is a net sink for deep seawater DOC, similar amino acid concentrations in basement aquifer and deep seawater suggest that DOC is preferentially removed in the basement over dissolved amino acids. Our data also suggest that organic carbon cycling occurs in the oceanic basaltic basement, where an active subsurface biosphere is likely responsible for amino acid synthesis and degradation.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.gca.2015.04.044},
	author = {Lin, H-T and Amend, J P and LaRowe, D E and Bingham, J-P and Cowen, J P}
}
@article {Lin2012,
	title = {{Inorganic chemistry, gas compositions and dissolved organic carbon in fluids from sedimented young basaltic crust on the Juan de Fuca Ridge flanks}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {85},
	year = {2012},
	pages = {213{\textendash}227},
	abstract = {The permeable upper oceanic basement serves as a plausible habitat for a variety of microbial communities. There is growing evidence suggesting a substantial subseafloor biosphere. Here new time series data are presented on key inorganic species, methane, hydrogen and dissolved organic carbon (DOC) in ridge flank fluids obtained from subseafloor observatory CORKs (Circulation Obviation Retrofit Kits) at Integrated Ocean Drilling Program (IODP) boreholes 1301A and 1026B. These data show that the new sampling methods (Cowen et al., 2012) employed at 1301A result in lower contamination than earlier studies. Furthermore, sample collection methods permitted most chemical analyses to be performed from aliquots of single large volume samples, thereby allowing more direct comparison of the data. The low phosphate concentrations (0.06{\textendash}0.2~$μ$M) suggest that relative to carbon and nitrogen, phosphorus could be a limiting nutrient in the basement biosphere. Coexisting sulfate (17{\textendash}18~mM), hydrogen sulfide (\~{}0.1~$μ$M), hydrogen (0.3{\textendash}0.7~$μ$M) and methane (1.5{\textendash}2~$μ$M) indicates that the basement aquifer at 1301A either draws fluids from multiple flow paths with different redox histories or is a complex environment that is not thermodynamically controlled and may allow co-occurring metabolic pathways including sulfate reduction and methanogenesis. The low DOC concentrations (11{\textendash}18~$μ$M) confirm that ridge flank basement is a net DOC sink and ultimately a net carbon sink. Based on the net amounts of DOC, oxygen, nitrate and sulfate removed (\~{}30~$μ$M, \~{}80~$μ$M, \~{}40~$μ$M and \~{}10~mM, respectively) from entrained bottom seawater, organic carbon may be aerobically or anaerobically oxidized in biotic and/or abiotic processes.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2012.02.017},
	url = {http://dx.doi.org/10.1016/j.gca.2012.02.017},
	author = {Lin, H -T and Cowen, J P and Olson, E J and Amend, J P and Lilley, M D}
}
