<span id="docs-internal-guid-955c4f22-7fff-53c6-5097-f1061670263e"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;"><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">The chemistry of Class 0/I protostars has become increasingly important due to the mounting evidence of its impact on the chemical composition of future nascent planetary systems. Prior observations of low mass protostars have revealed that not only do they contain a surprising array of complex molecules, but they also show highly-localized spatio-chemical differentiation. Observations of isotopic and isotopologue ratios in Young Stellar Objects (YSOs) are valuable for accessing the chemical evolution of circumstellar disks, envelopes and the parent molecular clouds. It is important for characterizing the domain of isotopic and isotopologue ratios in YSOs varying with evolutionary stage. We use Atacama Large Millimeter Array (ALMA) 7m dish spectral line observations in the range of 300-360 GHz of HCO</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">+</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"> line and its isomers in five low mass protostars in the southern hemisphere of varying velocities, and chemical conditions to elucidate the underlying links between physical conditions, hot corino and envelope properties, and molecular abundances in these important protostellar environments. We find the column density of H</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">13</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">CO</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">+</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"> and HC</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">18</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">O</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">+</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"> to be much higher than the general ISM values of these species. The higher abundance of these species can be attributed to isotope selective photodissociation, confirmation of which may be obtained via study of additional sources. We also detect HOC</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">+</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">, a rarely observed molecule, at a minimum significance of 5??. These observations are evidence for isotopic heterogeneity in carbon reservoirs in solar-type YSO environments, and encourage the need for refined galactic chemical evolution models to explain the </span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">12</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">C/</span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size:0.6em;vertical-align:super;">13</span></span><span style="font-size: 12pt; font-family: "Times New Roman"; font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">C discrepancy between the solar system and local ISM.</span></p><br></span>