Despite the paucity of studies, there is a range of psychotropics that may be used in the early stages of psychotic illness in youths. Drug choice is influenced by several factors, including the clinical picture, side effect profile, and patient preference. In certain situations, the decision may be not to use medication.
Purpose Understanding fluxes of soil organic carbon (OC) from the terrestrial to aquatic environments is crucial to evaluate their importance within the global carbon cycle. Sediment fingerprinting (SF) is increasingly used to identify land use-specific sources of OC, and, while this approach estimates the relative contribution of different sources to OC load in waterways, the high degree of spatial heterogeneity in many river catchments makes it challenging to precisely align the source apportionment results to the landscape. In this study, we integrate OC SF source apportionment with a carbon loss model (CLM) with the aim of: (i) reducing ambiguity in apportioning OC fluxes when the same land use exists in multiple locations within a catchment; and (ii) identifying factors affecting OC delivery to streams, e.g., buffer zones. Methods Two main approaches were used in this study: (i) identification of the sources of freshwater bed sediment OC using n-alkane biomarkers and a Bayesian-based unmixing model; and (ii) modelling and analysis of spatial data to construct a CLM using a combination of soil OC content modelling, RUSLE soil erosion modelling and a connectivity index. The study was carried out using existing OC and n-alkane biomarker data from a mixed land use UK catchment. Results Sediment fingerprinting revealed that woodland was the dominant source of the OC found in the streambed fine sediment, contributing between 81 and 85% at each streambed site. In contrast, CLM predicted that arable land was likely the dominant source of OC, with negligible inputs from woodland. The areas of the greatest OC loss in the CLM were predicted to be from arable land on steeper slopes surrounding the stream channels. Results suggest extensive riparian woodland disconnected upslope eroded soil OC and, concomitantly, provided an input of woodland-derived OC to the streams. It is likely the woodland contribution to streambed OC is derived from litter and leaves rather than soil erosion. Conclusion This study demonstrates how location-specific OC sources and delivery processes can be better determined using sediment fingerprinting in combination with CLM, rather than using sediment fingerprinting alone. It highlights that, although wooded riparian buffer strips may reduce the impact of upslope, eroded soil OC on waterways, they could themselves be a source of OC to stream sediments through more direct input (e.g., organic litter or leaf debris). Characterising this direct woodland OC as a separate source within future fingerprinting studies would allow the contributions from any eroded woodland soil OC to be better estimated.
<p>Quantifying land use sources and understanding the dynamics of organic carbon (OC) in river catchments is essential to reduce both on-site and off-site impacts of soil OC erosion. The lake area of Loch Davan, located in Aberdeenshire, Scotland, has been significantly reduced over the last century due to sediment inputs and, in this study, we aimed to identify the primary source(s) and delivery of OC to the loch&#8217;s main feeder stream, Logie Burn and its major tributaries.</p><p>The relative contribution of different land use sources to organic matter load in waterways can be assessed using sediment fingerprinting (SF) with plant-specific biomarkers such as <em>n</em>-alkanes. However, application of the land use sources based on SF in catchment management is hindered by the following issues: i) broad land use classifications cannot provide accurate OC origins if the same land use exists in multiple locations within a catchment; each with its own susceptibility to erosion and connectivity to the streams, and ii) eroded soil is not the only source of plant-specific biomarkers such as <em>n</em>-alkanes and direct input of leaves or litter to waterways could mask the input from eroded soils.</p><p>This inter-disciplinary study aimed to improve upon the SF method by firstly constructing a &#8220;Carbon Loss Model&#8221; (CLM) to estimate areas of a catchment most likely to provide OC to waterways. We then compared the land use sources of OC estimated using the CLM and SF to improve our insights into both the origin and fate of eroded OC. Secondly, we considered whether soil specific tracers (neutral lipids) of soil microbial or fungal origin, combined with plant specific <em>n</em>-alkanes, could help to reduce the error in SF when discriminating land cover classes, facilitating a more accurate estimation of OC origins by adding a more soil - rather than vegetation - specific fingerprint.</p><p>Results show that addition of short-chain neutral lipid fatty acid biomarkers to plant specific <em>n</em>-alkane tracers led to a significant decrease in error when distinguishing between arable, pasture, forest and moorland land uses (error reduction 1.8-9%). Comparison of the land use sources of OC estimated using the CLM and SF identified that areas of estimated high carbon loss were not always the regions contributing most sediment to the streams and that non-erosion processes within the riparian corridor are likely contributing OC to the waterways. This research highlights that to better understand the origin of sediments and OC across the terrestrial-aquatic continuum we must understand both sides of that continuum (the susceptibility of terrestrial OC to erosion and delivery, and the characteristics of OC within the waterways) as well as the role(s) of the riparian area that links the two.</p>
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