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Chemical Attenuation
Published in Patrick V. Brady, Michael V. Brady, David J. Borns, Natural Attenuation, 2018
Patrick V. Brady, Michael V. Brady, David J. Borns
All this being said, there may be some real down sides to routine collection of isotopic data. A dissenting view. Stable carbon isotope analysis requires an additional level of site characterization that is more costly, subject to greater interpretation, and less uniform from site to site. For example, the 13C signature of the soil would have to be characterized for each site. The heterogeneity of a soil gas sample is less than other media but site-specific geology controls the likelihood of collecting a soil gas sample that reflects the contaminant levels in the groundwater. There are many more problems associated with soil gas sampling than with groundwater sampling. An analysis of BTEX in groundwater costs $85 and is a direct measure of the medium of concern, and is preferred to a measurement of an indicator parameter (13C) from a secondary medium (soil gas).
The importance of compound-specific radiocarbon analysis in source identification of polycyclic aromatic hydrocarbons: A critical review
Published in Critical Reviews in Environmental Science and Technology, 2022
Miaolei Ya, Yuling Wu, Xinhong Wang, Yongyu Li, Guanyong Su
In the last century, the development of compound-specific isotope analysis based on gas chromatography-isotope ratio mass spectrometry (GC-irMS) made it possible to trace the source of single organic compounds (or homologs) (Close, 2019). The approach focuses on the stable carbon isotope composition (represented by δ13C) of up to hundreds of compound molecules (mass peaks) in a micro mixed sample (Close, 2019). The compound-specific isotope analysis has since been gradually developed for application in PAH source identification (Ahad et al., 2015; Fabbri et al., 2003; Mazeas & Budzinski, 2002). Fundamentally, compound-specific isotope analysis involves the evaluation of biogeochemical cycles and contamination sources based on the 13C signatures of PAHs (Gao et al., 2018). The source appointment of PAHs using compound-specific isotope analysis relies on the premise that the δ13C ranges of specific PAHs emitted by different sources are distinct and distinguishable, as well retain the isotopic signature of their original precursors from the source to the receptor under normal environmental conditions (Lima et al., 2005). The similarities and differences of 13C signatures can thus be used as an essential basis for distinguishing the potential PAH sources.
Stable C and N isotope analysis elucidated the importance of zooplankton in a tropical seagrass bed of Santiago Island, Northwestern Philippines
Published in Chemistry and Ecology, 2019
Ephrime B. Metillo, Ronald Villanueva, Ken-ichi Hayashizaki, Satoru Tamada, Masayoshi Sano, Shuhei Nishida
Based on the assumption that the isotopic signature of a consumer reflects that of its diet, stable isotope analysis provides a powerful tool in clarifying basal food source, trophic interactions and energy transfer in many coastal ecosystems [18–22]. For example, Connolly and Waltham [23] used C stable isotope analysis to elucidate the reliance by 60–90% of energy intake in the giant mud crab Scylla serrata on seagrasses and epiphytes of seagrasses. Fisheries species of penaeid shrimps depend more on seagrasses and their epiphytes than mangroves as shown in dual C and N stable isotope analysis [24]. Applied in eutrophication studies, stable isotope analysis has shown elevated N than C isotopes in seagrass bed organisms [7]. C and N stable isotope analysis also provide unequivocal evidence that excessive aquaculture fish feeds enter into and alter benthic ecosystems which are often characterised by the disappearance of seagrass stands with the remaining bare sediment dominated by opportunistic and r-selected species [16,25]. However, the use of C and N stable isotope analysis in tracing the importance of zooplankton in seagrass ecosystems is very limited [14,16].
New age constraints for the Tommy Creek Domain of the Mount Isa Inlier, Australia
Published in Australian Journal of Earth Sciences, 2023
A. Brown, C. Spandler, T. G. Blenkinsop
The widespread adoption of laser ablation inductively couple mass spectrometry (LA-ICPMS) over the past decade for radiogenic isotope analysis has had a profound impact on the volume, cost and accessibility of geochronology (Harrison et al., 2015; Spencer et al., 2016). This has dramatically broadened the collective knowledge of age constraints across the globe but has also allowed geochronology to contribute to other aspects of Earth Science, such as geomorphological processes and paleoclimate. In this case study from the TCD, an integrated and iterative approach of detailed mapping, sample collection and geochronology analysis has yielded significant new insights into this enigmatic part of a well-studied terrane that has a robust existing geochronological framework.