Chapelle Francis H, Bradley Paul M, Goode Dan J, Tiedeman Claire, Lacombe Pierre J, Kaiser Karl, Benner Ronald
U.S. Geological Survey, South Carolina Water Science Center, Columbia, SC 29210, USA.
Ground Water. 2009 Jan-Feb;47(1):108-21. doi: 10.1111/j.1745-6584.2008.00493.x. Epub 2008 Sep 12.
The bioavailability of total organic carbon (TOC) was examined in ground water from two hydrologically distinct aquifers using biochemical indicators widely employed in chemical oceanography. Concentrations of total hydrolyzable neutral sugars (THNS), total hydrolyzable amino acids (THAA), and carbon-normalized percentages of TOC present as THNS and THAA (referred to as "yields") were assessed as indicators of bioavailability. A shallow coastal plain aquifer in Kings Bay, Georgia, was characterized by relatively high concentrations (425 to 1492 microM; 5.1 to 17.9 mg/L) of TOC but relatively low THNS and THAA yields (approximately 0.2%-1.0%). These low yields are consistent with the highly biodegraded nature of TOC mobilized from relatively ancient (Pleistocene) sediments overlying the aquifer. In contrast, a shallow fractured rock aquifer in West Trenton, New Jersey, exhibited lower TOC concentrations (47 to 325 microM; 0.6 to 3.9 mg/L) but higher THNS and THAA yields (approximately 1% to 4%). These higher yields were consistent with the younger, and thus more bioavailable, TOC being mobilized from modern soils overlying the aquifer. Consistent with these apparent differences in TOC bioavailability, no significant correlation between TOC and dissolved inorganic carbon (DIC), a product of organic carbon mineralization, was observed at Kings Bay, whereas a strong correlation was observed at West Trenton. In contrast to TOC, THNS and THAA concentrations were observed to correlate with DIC at the Kings Bay site. These observations suggest that biochemical indicators such as THNS and THAA may provide information concerning the bioavailability of organic carbon present in ground water that is not available from TOC measurements alone.
利用化学海洋学中广泛使用的生化指标，对来自两个水文特征不同的含水层的地下水进行了总有机碳（TOC）的生物可利用性研究。总可水解中性糖（THNS）、总可水解氨基酸（THAA）的浓度，以及以THNS和THAA形式存在的TOC的碳归一化百分比（称为“产率”）被用作生物可利用性的指标进行评估。佐治亚州金斯湾的一个浅层沿海平原含水层的特点是TOC浓度相对较高（425至1492微摩尔/升；5.1至17.9毫克/升），但THNS和THAA产率相对较低（约0.2%-1.0%）。这些低产率与从含水层上方相对古老（更新世）沉积物中迁移出来的TOC的高度生物降解性质一致。相比之下，新泽西州西特伦顿的一个浅层裂隙岩含水层的TOC浓度较低（47至325微摩尔/升；0.6至3.9毫克/升），但THNS和THAA产率较高（约1%至4%）。这些较高的产率与从含水层上方现代土壤中迁移出来的、生物可利用性更高的较年轻TOC一致。与TOC生物可利用性的这些明显差异一致，在金斯湾未观察到TOC与有机碳矿化产物溶解无机碳（DIC）之间的显著相关性，而在西特伦顿则观察到强相关性。与TOC不同，在金斯湾站点观察到THNS和THAA浓度与DIC相关。这些观察结果表明，诸如THNS和THAA之类的生化指标可能提供有关地下水中有机碳生物可利用性的信息，而这些信息仅通过TOC测量是无法获得的。
