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Abstract Headwater catchments have strong impacts on downstream waterways, near‐shore ecosystems, and the quality of water available for growing human populations. Thus, understanding how water and solutes are exported through these upland landscapes is critically important. A growing body of literature highlights the interaction of topography, climate, and the critical zone structure as a key control on streamflow and chemical export. However, more focused work is needed to pinpoint how variability in subsurface structure across lithologically complex regions impacts streamflow and chemical signals at catchment outlets. Here, we aim to better understand how lithology and subsurface critical zones modulate streamflow response and solute export patterns in two central coastal California headwater catchments that are similar in topography, vegetation, and climate but have different lithologies. We monitored streamflow and collected surface water samples at the catchment outlets for dissolved major ions and organic carbon (DOC) for two consecutive water years. The catchment with mélange bedrock displayed much flashier hydrologic behavior with 7.8 times higher peak flow values and 1.9 times higher mean event concentrations of DOC, suggesting shorter and shallower hydrologic flow paths that likely arise from regions of shallower bedrock. Despite distinct hydrologic behavior and DOC export, dissolved major ion concentrations were broadly similar and chemostatic, which may be driven by rapid chemical reactions in the critical zone of both catchments. Our work contributes to building an integrated understanding of how subtle differences in catchment structure can have profound impacts on how water and solutes are routed through headwater catchments. 

Wildfires are a worldwide disturbance with unclear implications for stream water quality. We examined stream water chemistry responses immediately (<1 month) following a wildfire by measuring over 40 constituents in four gauged coastal watersheds that burned at low to moderate severity. Three of the four watersheds also had pre‐fire concentration‐discharge data for 14 constituents: suspended sediment (SS_fine), dissolved organic and inorganic carbon (DOC, DIC), specific UV absorbance (SUVA), major ions (Ca²⁺, K⁺, Mg²⁺, Na⁺, Cl⁻, SO₄²⁻, NO₃⁻, F⁻), and select trace elements (total dissolved Mn, Fe). In all watersheds, post‐fire stream water concentrations of SS_fine, DOC, Ca²⁺, Cl⁻, and changed when compared to pre‐fire data. Post‐fire changes in , K⁺, Na⁺, Mg²⁺, DIC, SUVA, and total dissolved Fe were also found for at least two of the three streams. For constituents with detectable responses to wildfire, post‐fire changes in the slopes of concentration‐discharge relationships commonly resulted in stronger enrichment trends or weaker dilution trends, suggesting that new contributing sources were surficial or near the surface. However, a few geogenic solutes, Ca²⁺, Mg²⁺, and DIC, displayed stronger dilution trends at nearly all sites post‐fire. Moreover, fire‐induced constituent concentration changes were highly discharge and site‐dependent. These similarities and differences in across‐site stream water chemistry responses to wildfire emphasize the need for a deeper understanding of landscape‐scale changes to solute sources and pathways. Our findings also highlight the importance of being explicit about reference points for both stream discharge and pre‐fire stream water chemistry in post‐fire assessment of concentration changes. 

Abstract The structure of the critical zone (CZ) is a product of feedbacks among hydrologic, climatic, biotic, and chemical processes. Past research within snow‐dominated systems has shown that aspect‐dependent solar radiation inputs can produce striking differences in vegetation composition, topography, and soil depth between opposing hillslopes. However, far fewer studies have evaluated the role of microclimates on CZ development within rain‐dominated systems, especially below the soil and into weathered bedrock. To address this need, we characterized the CZ of a north‐facing and south‐facing slope within a first‐order headwater catchment located in central coast California. We combined terrain analysis of vegetation distribution and topography with soil pit characterization, geophysical surveys and hydrologic measurements between slope‐aspects. We documented denser vegetation and higher shallow soil moisture on north facing slopes, which matched previously documented observations in snow‐dominated sites. However, average topographic gradients were 24° and saprolite thickness was approximately 6 m across both hillslopes, which did not match common observations from the literature that showed widespread asymmetry in snow‐dominated systems. These results suggest that dominant processes for CZ evolution are not necessarily transferable across regions. Thus, there is a continued need to expand CZ research, especially in rain‐dominated and water‐limited systems. Here, we present two non‐exclusive mechanistic hypotheses that may explain these unexpected similarities in slope and saprolite thickness between hillslopes with opposing aspects. 

Around the world, people increasingly generate data through their everyday activities. Much of this happens unwittingly through sensors, cameras, and other surveillance tools on roads, in cities, and at the workplace. However, how individuals and governments think about privacy varies significantly around the world. In this article, we explore differences between people’s attitudes toward privacy and data collection practices in the United States and the Netherlands, two countries with very different regulatory approaches to governing consumer privacy. Through a factorial vignette survey deployed in the two countries, we identify specific contextual factors associated with concerns regarding how personal data are being used. Using Nissenbaum’s framework of privacy as contextual integrity to guide our analysis, we consider the role that five factors play in this assessment: actors (those using data), data type, amount of data collected, reported purpose of data use, and inferences drawn from the data. Findings indicate nationally bound differences as well as shared concerns and indicate future directions for cross-cultural privacy research. 

Voice-controlled intelligent personal assistants (IPAs) have seen tremendous growth in recent years on smartphones and as standalone devices in people’s homes. While research has examined the potential benefits and drawbacks of these devices for IPA users, few studies have empirically evaluated the role of privacy and trust in individual decision to adopt IPAs. In this study, we present findings from a survey of IPA users and non-users (N=1160) to understand (1) the motivations and barriers to adopting IPAs and (2) how concerns about data privacy and trust in company compliance with social contract related to IPA data affect acceptance and use of IPAs. We discuss our findings in light of social contract theory and frameworks of technology acceptance. 

Fitness trackers are an increasingly popular tool for tracking one’s health and physical activity. While research has evaluated the potential benefits of these devices for health and well-being, few studies have empirically evaluated users’ behaviors when sharing personal fitness information (PFI) and the privacy concerns that stem from the collection, aggregation, and sharing of PFI. In this study, we present findings from a survey of Fitbit and Jawbone users (N=361) to understand how concerns about privacy in general and user- generated data in particular affect users’ mental models of PFI privacy, tracking, and sharing. Findings highlight the complex relationship between users’ demographics, sharing behaviors, privacy concerns, and internet skills with how valuable and sensitive they rate their PFI. We conclude with a discussion of opportunities to increase user awareness of privacy and PFI. 

Fitness trackers are an increasingly popular tool for tracking one’s health and physical activity. While research has evaluated the potential benefits of these devices for health and well-being, few studies have empirically evaluated users’ behaviors when sharing personal fitness information (PFI) and the privacy concerns that stem from the collection, aggregation, and sharing of PFI. In this study, we present findings from a survey of Fitbit and Jawbone users (N=361) to understand how concerns about privacy in general and user- generated data in particular affect users’ mental models of PFI privacy, tracking, and sharing. Findings highlight the complex relationship between users’ demographics, sharing behaviors, privacy concerns, and internet skills with how valuable and sensitive they rate their PFI. We conclude with a discussion of opportunities to increase user awareness of privacy and PFI.