Archeological and Historical Investigations for the Proposed 323.0-acre City of Pflugerville Community Park and Athletic Complex, Pflugerville, Travis County, Texas

Horizon Environmental Services, Inc. (Horizon) was selected by Schrickel, Rollins and Associates, Inc. (SRA) on behalf of the City of Pflugerville to conduct an intensive cultural resources inventory and assessment of an approximately 130.7-hectare (323.0-acre) tract in Pflugerville, Travis County, Texas. This tract represents the proposed location of the City of Pflugerville Community Park and Athletic Complex, and it is located off the northeast side of Cameron Road approximately 1.9 miles (3.1 kilometers) southeast of its intersection with State Highway (SH) 130. For purposes of the cultural resources investigations, the project area was considered to consist of the entire 130.7-hectare (323.0-acre) tract. The proposed undertaking is being sponsored by the City of Pflugerville, which represents a political subdivision of the state of Texas, on land owned by the City of Pflugerville; as such, the project falls under the jurisdiction of the Antiquities Code of Texas (Texas Natural Resources Code of 1977, Title 9, Chapter 191). No federal jurisdiction has been identified for the project at this time; however, the cultural resources investigations conducted within the project area would be suitable for review under Section 106 of the National Historic Preservation Act (NHPA) of 1966 in the event that any federal jurisdiction is identified in the future. As the project represents a publicly sponsored undertaking with the potential to impact significant cultural resources, the City of Pflugerville was required to provide for a cultural resources inventory of the project area. From April 5 to 6, 2016, Horizon archeologists Russell K. Brownlow, Jeffrey D. Owens, and Briana N. Smith, under the overall direction of Jeffrey D. Owens, Principal Investigator, performed an intensive cultural resources survey of the southern 98.3 hectares (243.0 acres) of the project area, which represented the portion of the larger project area to which the City of Pflugerville was able to provide access at that time. From July 20 to 22, Horizon archeologists Briana N. Smith and Jared Wiersema conducted an intensive cultural resources survey of the northern 32.4 hectares (80.0 acres) of the project area, which became accessible subsequent to completion of the initial fieldwork in April 2016. Horizon’s archeologists traversed the project area in parallel, linear transects spaced no more than 30.5 meters (100.0 feet) apart and thoroughly inspected the modern ground surface for aboriginal and historic-age cultural resources. The majority of the project area consists of a mix of cattle pastures and active agricultural fields that had been plowed but not yet planted for the season. Moderately densely wooded areas are present along the banks and terraces of Wilbarger Creek and one of its tributaries, which meander through the northern portion of the project area. Visibility of the modern ground surface was excellent in the agricultural fields (100%), though ground surface visibility in pastures and forested areas was obscured by vegetation (\u3c30%). In addition to pedestrian walkover, the Texas State Minimum Archeological Survey Standards (TSMASS) require the excavation of one shovel test per three acres for project areas measuring more than 80.9 hectares (200.0 acres) in size; thus, a minimum of 108 shovel tests were required within the 130.7-hectare (323.0-acre) project area to meet the TSMASS. Horizon excavated a total of 202 shovel tests during the survey, thereby exceeding the TSMASS for a project area of this size. The cultural resources survey was conducted under Texas Antiquities Permit No. 7608. Five newly recorded archeological sites—41TV2518, 41TV2519, 41TV2520, 41TV2521, and 41TV2522—were documented within the project area during the survey, and one previously recorded archeological site—41TV2453—was reinvestigated and its boundaries were expanded. In addition, one cemetery—the Pfluger Cemetery (TV-C077)—was investigated during the survey. While prehistoric cultural components are present on two of the sites (41TV2453 and 41TV2520), the majority of the cultural resources documented during the survey are associated with mid-19th- to mid-20th-century farmsteads related to two of the founding German immigrant families of the area—the Pflugers and the Bohls. The City of Pflugerville intends not to disturb the Pfluger Cemetery during the proposed development and use of the property and to maintain a surrounding construction buffer of at least 7.6 meters (25.0 feet). Based on the results of the survey-level investigations documented in this report, no potentially significant cultural resources would be affected by the proposed undertaking. In accordance with 36 CFR 800.4, Horizon has made a reasonable and good-faith effort to identify historic properties within the project area. No cultural resources were identified within the project area that meet the criteria for designation as State Antiquities Landmarks (SAL) according to 13 TAC 26, and no further archeological work is recommended in connection with the proposed undertaking. However, human burials, both prehistoric and historic, are protected under the Texas Health and Safety Code. In the event that any human remains or burial objects are inadvertently discovered at any point during construction, use, or ongoing maintenance in the project area, even in previously surveyed areas, all work should cease immediately in the vicinity of the inadvertent discovery, and the Texas Historical Commission (THC) should be notified immediately. With further research to determine the integrity, the project area potentially could be considered part of a rural historic landscape. A rural historic landscape is defined by the National Park Service (NPS) as a geographical area that has historically been shaped or modified by human activity, occupancy, or intervention, and that possesses a significant concentration, linkage, or continuity of areas of land use, vegetation, buildings and structures, roads, waterways, and natural features. This level of evaluation would require a survey extending far beyond the physical boundaries of the current project area (and also including the project area), including intensive archival research to document the integrity of the landscape, historic and current land uses, topography, circulation patterns, vegetation, and archeology. The project area has historically functioned and currently functions as an agricultural property (though the dwellings on the property have been abandoned for decades), a gravel driveway and farm roads connect some of the recorded historic-age resources, the cemetery associated with the early settlers of the property is located within the project area, and neighboring parcels may have been part of the Pfluger family’s holdings at one time. For example, the farm complex located across Cameron Road from the project area was determined to be eligible for listing on the National Register of Historic Places (NRHP) based on a historical resources survey of northeastern Travis County prepared by Hicks & Company for the Travis County Historical Commission in 2010 entitled Historic Resource Survey of Northeast Travis County, Texas (Bound by SH 130, US 290 North, and East County Lines). The Hicks & Company report identified the Pfluger family farm within the current project area as a possible contributing element of a rural historic landscape requiring further research to document and assess its level of integrity. The project area therefore potentially could be considered part of a larger landscape that possesses historical significance. The Agricultural Theme Study for Central Texas, prepared by the Texas Department of Transportation’s (TxDOT) Historical Studies Branch of the Environmental Affairs Division, along with the National Park Service’s Guidelines for Evaluating and Documenting Rural Historic Landscapes, Bulletin No. 30, would provide useful guidance on evaluating the property and surrounding parcels as a historic landscape. However, evaluating the eligibility of the project area as a component of a potential rural historic landscape is outside the scope of the current project, and this level of evaluation does not fall within the jurisdiction of the Antiquities Code of Texas. It should be noted that, while the standing National Folk house on site 41TV2453, designated as Resource 2, is herein recommended as ineligible for designation as an SAL and for inclusion in the NRHP, the City of Pflugerville has elected to proactively pursue a limited mitigative strategy regarding this structure. At the City of Pflugerville’s request, Horizon conducted a detailed documentation effort for this house. This process included collecting detailed measurements of the exterior and interior of the house that were used to produce measured drawings of exterior elevations and floor plans; taking numerous photographs of the building and keying the photographs to the measured drawings; and producing a detailed report noting the construction materials, architectural features, building description, and historical context. The architectural renderings and building documentation can be submitted to the THC as a courtesy under separate cover when the final draft of this report is submitted

Intensive Cultural Resources Survey of the 1,753.7-acre Waterstone Tract, San Marcos, Hays County, Texas

Horizon Environmental Services, Inc. (Horizon) was selected by Wolff Enterprises II, LLC (Wolff), on behalf of La Salle Municipal Utility District (MUD) Nos. 1, 2, 3, 4, and 5, to conduct a cultural resources inventory survey and assessment of the 709.7-hectare (1,753.7-acre) Waterstone tract. The Waterstone tract consists of a series of undeveloped agricultural fields located roughly midway between Kyle and San Marcos in southeastern Hays County, Texas. The proposed undertaking would involve construction of mixed-use commercial and residential development on the tract. The tract is located a short distance east of Interstate Highway (IH) 35 and is bounded on the northeast by Farm-to-Market Road (FM) 158, on the southeast by State Highway (SH) 21 (a.k.a. Camino Road), and on the southwest by Yarrington Road. At the time the cultural resources survey was conducted, design plans were not yet available and the specific locations of utility easements that would be constructed, owned, and operated by La Salle MUD Nos. 1 to 5 were unknown. Consequently, for purposes of the cultural resources survey, the project area was considered to consist of the entire 709.7-hectare (1,753.7-acre) tract. The proposed project includes utility easements that would be constructed, owned, and operated by La Salle MUD Nos. 1 to 5, which represent public utilities within the state of Texas. Consequently, the proposed undertaking falls under the jurisdiction of the Antiquities Code of Texas (Natural Resources Code, Title 9, Chapter 191). At this time, no federal permits or agency involvement have been identified for the project. As the project includes a publicly sponsored undertaking with the potential to impact cultural resources, a cultural resources inventory and assessment of the project area was required. From March 20 to 30, 2017, Horizon Project Archeologist Briana Smith, with the assistance of archeological technicians Jacob Lyons and Ben Johnson and under the overall direction of Jeffrey D. Owens, Principal Investigator, performed an intensive survey of the project area to locate any cultural resources that may be impacted by the proposed undertaking. Kathryn St. Clair, architectural historian, assisted with architectural evaluations and historical research on sites containing standing architecture or remnants of standing structures. Horizon’s archeologists traversed the project area on foot and thoroughly inspected the modern ground surface for aboriginal and historic-age cultural resources. The vast majority of the project area is characterized by active agricultural fields that had recently been planted for the season. Small copses of hackberry and cedar trees are scattered throughout the project area; these are typically associated with historic-age standing structures on archeological sites. The Clear Fork of Plum Creek and two of its tributaries flow eastward through the northern portion of the project area, and unnamed tributaries of Hemphill Creek drain the southern portion of the project area to the south. Typically, the channels associated with these drainages were dry at the time of the survey, though one poorly drained segment of the Clear Fork of Plum Creek retained water. Standing water was also present in scattered, poorly drained areas in the northern portion of the project area, though the agricultural fields that characterize the vast majority of the project area were typically dry. Two large stock ponds or small, artificial lakes are present in the north-central portion of the project area north of the only currently operating farm within the project area (recorded as site 41HY539). Two main roads traverse the project area—FM 158 crosses the project area from southwest to northeast, and a private gravel road crosses the project area between SH 21 on the southeast and FM 158 on the northwest—and a number of ephemeral field roads skirt the edges of the active fields. Visibility of the modern ground surface was characteristically excellent in the agricultural fields (100%), though ground surface visibility in the small forested patches was typically obscured by grasses and shrubs (\u3c30%). In addition to pedestrian walkover, the Texas State Minimum Archeological Survey Standards (TSMASS) require a minimum of 1 shovel test per 1.2 hectares (3.0 acres) within project areas measuring more than 40.5 hectares (100.0 acres) in size. As such, 585 shovel tests would be required within the 709.7-hectare (1,753.7-acre) project area. Horizon excavated a total of 223 shovel tests during the survey. While the shovel testing density did not meet the TSMASS requirements, the shovel testing regimen is considered to be more than adequate to assess the subsurface cultural resources potential of the project area. The vast majority of the project area consists of recently plowed fields, and visibility of the modern ground surface was excellent across most of the project area, with the exception of a few isolated stands of vegetation. As such, shovel testing was employed judgmentally to determine whether or not the potential existed for intact archeological deposits to occur below the active plowzone, which averaged approximately 30.0 to 35.0 centimeters (11.8 to 13.8 inches) in depth within the project area. The majority of the cultural materials observed during the survey were constrained to the modern ground surface, and all of the subsurface cultural materials observed were found within the plowzone. As such, the shovel testing confirmed that all cultural materials within the project area are confined to disturbed contexts on the modern ground surface and within the active plowzone. Eleven newly recorded archeological sites were documented during the survey— 41HY536 to 41HY546. Nine of the 11 sites (41HY436 to 41HY543 and 41HY546) consist of the remnants of early to mid-20th-century farmsteads and/or scatters of historic-age domestic debris. Two of the 11 sites (41HY544 and 41HY545) consist exclusively of aboriginal artifact scatters dated to unspecified prehistoric timeframes, and secondary cultural components composed of sparse scatters of aboriginal artifacts were also observed on three of the nine historic-age sites (41HY537, 41HY540, and 41HY543). All 11 sites are recommended as ineligible for designation as State Antiquities Landmarks (SAL) and for inclusion in the National Register of Historic Places (NRHP) based on the poor condition of the sites and their low potential to contribute meaningfully to an understanding of the historic and/or prehistoric past No further investigations are warranted on these sites in connection with the proposed undertaking. In addition, the mapped location of one previously recorded site located within the project area, 41HY426, was revisited in an attempt to re-locate and re-investigate the site. When it was originally recorded in 2006, this site consisted only of an ephemeral field scatter of early 20thcentury domestic debris, including two glass shards. Horizon inspected the modern ground surface at the mapped site location and excavated several shovel tests in the surrounding area. No cultural resources were observed at the mapped location of site 41HY426. The two isolated artifacts that composed the site in 2006 have probably been reincorporated into the plowzone. Site 41HY426 was previously determined to be ineligible for inclusion in the NRHP, and no further archeological investigations are warranted on this site. Based on the results of the survey-level investigations documented in this report, no potentially significant cultural resources would be affected by the proposed undertaking. In accordance with 36 CFR 800.4, Horizon has made a reasonable and good-faith effort to identify historic properties within the project area. No cultural resources were identified that meet the criteria for designation as SALs according to 13 TAC 26 or for inclusion in the NRHP according to 36 CFR 60.4. Horizon recommends a finding of “no historic properties affected,” and no further archeological work is recommended in connection with the proposed undertaking. However, human burials, both prehistoric and historic, are protected under the Texas Health and Safety Code. In the event that any human remains or burial objects are inadvertently discovered at any point during construction, use, or ongoing maintenance in the project area, even in previously surveyed areas, all work should cease immediately in the vicinity of the inadvertent discovery, and the Texas Historical Commission (THC) should be notified immediately

Intensive Cultural Resources Survey of the Proposed Galveston County Project, Texas City, Galveston County, Texas

On behalf of Florida Gas Transmission Company, LLC (FGT), EDGE Engineering and Science, LLC (EDGE) has selected Horizon Environmental Services, Inc. (Horizon) to conduct a cultural resources survey and assessment for the proposed Galveston County Project. The project includes a proposed pipeline that will allow the delivery of natural gas to a new delivery point off the FGT mainline. The facilities to be installed include approximately 4.0 kilometers ([km] 2.5 miles) of 30.5-centimeter ([cm]12.0-inch) and 50.8-cm (20.0-inch) lateral piping as well as a measurement and regulation (M&R) station located at the southwest end of the new pipeline, referred to as the Attwater-Topaz M&R station. This portion of the proposed project is located approximately 2.9 km (1.8 miles) northwest of Texas City and crosses State Highway (SH) 146 in Galveston County, Texas. As part of the Galveston County Project, FGT will also be uprating a unit at their existing CS 4 compressor station in Matagorda County, Texas to maintain a sufficient delivery pressure to the proposed Attwater-Topaz M&R station. In accordance with Section 7(b) of the Natural Gas Act, the project requires Prior Notice authorization to the Federal Energy Regulatory Commission (FERC), which will serve as the lead federal agency for the undertaking. Because the undertaking is regulated by FERC, the undertaking falls under the regulations of Section 106 of the National Historic Preservation Act (NHPA) of 1966, as amended. The Antiquities Code of Texas (ACT) governs proposed undertakings by political subdivisions of the State of Texas and/or projects located on publicly owned lands. Approximately 11.3 hectares (27.8 acres) of the project area are owned by the Gulf Coast Water Authority (GCWA). Since the GCWA is a public entity, this portion of the project falls under the jurisdiction of the ACT. Survey of the GCWA property was carried out under Antiquities Permit No. 9449. Less than 0.1 hectare (0.2 acres) of additional temporary workspace (ATWS) falls within the State Highway (SH) 146 ROW, which is controlled by the Texas Department of Transportation (TxDOT). Since TxDOT is a State agency, survey of this area would also require an Antiquities Permit. However, this area has already been disturbed from road construction and underground utilities. Horizon therefore recommends no additional survey or shovel testing in this ATWS. Horizon sent a letter with this recommendation to the Texas Historical Commission (THC) on June 30, 2020. Originally, FGT did not define the actual limits of the proposed right-of-way (ROW) for the project. Rather, they elected to wait until after the environmental assessments on larger overall parcels were complete in order to select a route with the least amount of environmental impacts. As such, the cultural resources survey initially consisted of 100% survey of the entire 203.2 hectares (502.0 acres) that comprise the parcels traversed by the proposed pipeline. After FGT selected a proposed route, Horizon archeologists conducted additional fieldwork to ensure adequate survey coverage within the proposed ROW. From May 12 to 15, and June 17, 2020, Horizon archeologists Charles E. Bludau, Jr. and Luis Gonzales performed an intensive cultural resources survey of the project area to locate any cultural resources that would potentially be impacted by the proposed undertaking. Horizon’s archeologists traversed the project area on foot and thoroughly inspected the modern ground surface for aboriginal and historic-age cultural resources. The project area consists of an extensive, largely featureless coastal flat. An existing FGT pipeline corridor passes from northeast to southwest through the northern portion of the project area. In addition to pedestrian walkover, the recently revised 2020 Texas State Minimum Archeological Survey Standards (TSMASS) require at least 50 shovel tests for the first 10.1 hectares (25.0 acres) of a project plus at least one shovel test for every 2.0 hectares (5.0 acres) over the original 10.1 hectares (25.0 acres). This equates to a minimum of 145 shovel tests within the original 203.2-hectare (502.0-acre) project area. Horizon excavated156 shovel tests within this area, thereby exceeding the TSMASS for a project area of this size. The TSMASS require a minimum of 16 shovel tests per mile for projects measuring 30.0 m (98.4 feet) or less in width; this equates to a minimum of 40 shovel tests within the proposed ROW. Horizon exceeded this minimum by excavating 46 shovel tests within the proposed ROW. Shovel testing typically revealed shallow deposits of hydric, dark gray clay extending from the modern ground surface to depths ranging from 5.0 to 60.0 cm (2.0 to 23.6 inches) below surface, though most shovel tests were terminated at depths of 30.0 to 50.0 cm (11.8 to 19.7 inches) below surface. Shovel testing was capable of penetrating Holocene-age soils with the potential to contain subsurface archeological resources. No archeological sites or historic-aged structures were recorded within the project area during the survey. A modern cattle corral, constructed with modern lumber, is present in the northeast corner of the project area, south of Skyline Drive. The corral does not appear on any historical topographic maps. It is first visible in a 1981 aerial image, which indicates the corral is not of historic age. Based on the results of the survey-level investigations documented in this report, no significant cultural resources would be affected by the proposed undertaking. In accordance with 36 CFR 800.4, Horizon has made a reasonable and good faith effort to identify historic properties within the project area. No cultural resources were identified within the project area that meet the criteria for inclusion in the National Register of Historic Places (NRHP) under 36 CFR 60.4. Horizon recommends a finding of “no historic properties affected,” and no further archeological work is recommended in connection with the proposed undertaking. However, human burials, both prehistoric and historic, are protected under the Texas Health and Safety Code. In the event that any human remains or burial objects are inadvertently discovered at any point during construction, use, or ongoing maintenance in the project area, even in previously surveyed areas, all work should cease immediately in the vicinity of the inadvertent discovery, and the THC should be notified immediately

Doxorubicin-Induced Elevated Oxidative Stress and Neurochemical Alterations in Brain and Cognitive Decline: Protection by MESNA and Insights into Mechanisms of Chemotherapy-Induced Cognitive Impairment ( Chemobrain )

Chemotherapy-induced cognitive impairment (CICI) is now widely recognized as a real and too common complication of cancer chemotherapy experienced by an ever-growing number of cancer survivors. Previously, we reported that doxorubicin (Dox), a prototypical reactive oxygen species (ROS)-producing anti-cancer drug, results in oxidation of plasma proteins, including apolipoprotein A-I (ApoA-I) leading to tumor necrosis factor-alpha (TNF-α)-mediated oxidative stress in plasma and brain. We also reported that co-administration of the antioxidant drug, 2-mercaptoethane sulfonate sodium (MESNA), prevents Dox-induced protein oxidation and subsequent TNF-α elevation in plasma. In this study, we measured oxidative stress in both brain and plasma of Dox-treated mice both with and without MESNA. MESNA ameliorated Dox-induced oxidative protein damage in plasma, confirming our prior studies, and in a new finding led to decreased oxidative stress in brain. This study also provides further functional and biochemical evidence of the mechanisms of CICI. Using novel object recognition (NOR), we demonstrated the Dox administration resulted in memory deficits, an effect that was rescued by MESNA. Using hydrogen magnetic resonance imaging spectroscopy (H1-MRS) techniques, we demonstrated that Dox administration led to a dramatic decrease in choline-containing compounds assessed by (Cho)/creatine ratios in the hippocampus in mice. To better elucidate a potential mechanism for this MRS observation, we tested the activities of the phospholipase enzymes known to act on phosphatidylcholine (PtdCho), a key component of phospholipid membranes and a source of choline for the neurotransmitter, acetylcholine (ACh). The activities of both phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D were severely diminished following Dox administration. The activity of PC-PLC was preserved when MESNA was co-administered with Dox; however, PLD activity was not protected. This study is the first to demonstrate the protective effects of MESNA on Dox-related protein oxidation, cognitive decline, phosphocholine (PCho) levels, and PC-PLC activity in brain and suggests novel potential therapeutic targets and strategies to mitigate CICI

High fidelity: extra-pair fertilisations in eight Charadrius plover species are not associated with parental relatedness or social mating system

Extra-pair paternity is a common reproductive strategy in many bird species. However, it remains unclear why extra-pair paternity occurs and why it varies among species and populations. Plovers (Charadrius spp.) exhibit considerable variation in reproductive behaviour and ecology, making them excellent models to investigate the evolution of social and genetic mating systems. We investigated inter- and intra-specific patterns of extra-pair parentage and evaluated three major hypotheses explaining extra-pair paternity using a comparative approach based on the microsatellite genotypes of 2049 individuals from 510 plover families sampled from twelve populations that constituted eight species. Extra-pair paternity rates were very low (0 to 4.1% of chicks per population). No evidence was found in support of the sexual conflict or genetic compatibility hypotheses, and there was no seasonal pattern of extra-pair paternity (EPP). The low prevalence of EPP is consistent with a number of alternative hypotheses, including the parental investment hypothesis, which suggests that high contribution to care by males restricts female plovers from engaging in extra-pair copulations. Further studies are needed to critically test the importance of this hypothesis for mate choice in plovers

Oxidative Stress-Induced JNK/AP-1 Signaling is a Major Pathway Involved in Selective Apoptosis of Myelodysplastic Syndrome Cells by Withaferin-A

Myelodysplastic syndromes (MDS) are a diverse group of malignant clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, dysplastic cell morphology in one or more hematopoietic lineages, and a risk of progression to acute myeloid leukemia (AML). Approximately 50% of MDS patients respond to current FDA-approved drug therapies but a majority of responders relapse within 2-3 years. There is therefore a compelling need to identify potential new therapies for MDS treatment. We utilized the MDS-L cell line to investigate the anticancer potential and mechanisms of action of a plant-derived compound, Withaferin A (WFA), in MDS. WFA was potently cytotoxic to MDS-L cells but had no significant effect on the viability of normal human primary bone marrow cells. WFA also significantly reduced engraftment of MDS-L cells in a xenotransplantation model. Through transcriptome analysis, we identified reactive oxygen species (ROS)-activated JNK/AP-1 signaling as a major pathway mediating apoptosis of MDS-L cells by WFA. We conclude that the molecular mechanism mediating selective cytotoxicity of WFA on MDS-L cells is strongly associated with induction of ROS. Therefore, pharmacologic manipulation of redox biology could be exploited as a selective therapeutic target in MDS

Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations

The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 ± 0.25 × 10^6 cm^(−3)), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss

Missing OH reactivity in the global marine boundary layer

The hydroxyl radical (OH) reacts with thousands of chemical species in the atmosphere, initiating their removal and the chemical reaction sequences that produce ozone, secondary aerosols, and gas-phase acids. OH reactivity, which is the inverse of OH lifetime, influences the OH abundance and the ability of OH to cleanse the atmosphere. The NASA Atmospheric Tomography (ATom) campaign used instruments on the NASA DC-8 aircraft to measure OH reactivity and more than 100 trace chemical species. ATom presented a unique opportunity to test the completeness of the OH reactivity calculated from the chemical species measurements by comparing it to the measured OH reactivity over two oceans across four seasons. Although the calculated OH reactivity was below the limit of detection for the ATom instrument used to measure OH reactivity throughout much of the free troposphere, the instrument was able to measure the OH reactivity in and just above the marine boundary layer. The mean measured value of OH reactivity in the marine boundary layer across all latitudes and all ATom deployments was 1.9 s⁻¹, which is 0.5 s⁻¹ larger than the mean calculated OH reactivity. The missing OH reactivity, the difference between the measured and calculated OH reactivity, varied between 0 and 3.5 s⁻¹, with the highest values over the Northern Hemisphere Pacific Ocean. Correlations of missing OH reactivity with formaldehyde, dimethyl sulfide, butanal, and sea surface temperature suggest the presence of unmeasured or unknown volatile organic compounds or oxygenated volatile organic compounds associated with ocean emissions

Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations

The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 ± 0.25 × 10^6 cm^(−3)), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss