RAPID: Wildfire, Wine, and Water Quality: Immediate Changes to Biogeochemical and Hydrological Flows from Vineyards After the Northern California Fires

2017年10月初，北方加州（CA）主要葡萄种植区发生多起野火，烧毁了葡萄园和邻近社区，对水文、地球化学循环、水质以及人类和生态系统健康造成了未知的后果。这是研究野火影响的一个特别重要的地区，因为土壤和水文的变化可能会影响每年用于葡萄园控制白粉病的大量活性硫（S）负荷的命运。硫的广泛使用可能对邻近的生态系统产生类似于无意的大气硫沉积的后果（即，酸雨），如刺激甲基汞的生产，一种强大的神经毒素。考虑到野火可能会加速S和其他材料向邻近水生生态系统的迁移，因此现在迫切需要进行这项研究。这项研究将解决野火对水文流动路径和S从葡萄园到溪流的动员的直接影响。项目团队将使用地下土壤水和地表水（径流和溪流）收集器对燃烧和未燃烧的葡萄园集水区进行检测。他们将在雨季的第一场大雨事件期间对水文流量进行实地观察，以量化动员的S，C和沉积物，进行实验室实验以确定随着时间的推移从燃烧和未燃烧的土壤中的化学损失，并开发方法来跟踪环境中的S。这项研究将提供一个数据集进行长期的努力，开发实地研究，实验和模型，以阐明最终的命运和后果的农业S使用在流域尺度-一个新的研究领域，以了解人类操纵的S循环。这个为期一年的项目将由一名女助理教授领导，培训一名女研究生，并提供对农民和其他利益攸关方至关重要的数据。该研究小组将在研究区域内的多个研讨会上广泛交流他们的研究结果。这项为期一年的实地和实验室研究的目标是提供一个重要的数据集，详细说明最近大范围野火对农业硫（S）从葡萄园到北海岸加州葡萄种植区溪流的影响。这些数据是一个关键的基线，以捕捉之前，开始了新一轮的研究：确定在区域农业系统中的高S应用程序的意外后果。高硫使用的地球化学和生态影响可能与无意中大气硫沉积的影响相似（即，“酸雨”），但它们尚未在葡萄园或其他作物系统中进行研究。特别是，农业来源的S可能会刺激来源地区下游水生生态系统中甲基汞的产生，威胁人类和野生动物的健康。这项研究将首次测量雨季开始时从燃烧的葡萄园到溪流的S，碳（C）和沉积物，并开发新的地球化学和同位素方法来追踪环境中农业来源的S物种。为此，项目团队将使用径流收集器、ISCO溪流采样器、土壤水采样器和土壤湿度传感器对燃烧和未燃烧的葡萄园集水区进行测量，以量化水文流动路径并评估其化学成分。他们还将进行燃烧和未燃烧的土壤芯浸提实验，以确定模拟雨季过程中化学品损失的演变情况。这些活动将检验两个假设：（1）如果来自火灾的热量输入相对于未燃烧的葡萄园显著改变了表层土壤特性，那么中到高强度的降雨事件将迅速导致地表径流。（分钟到小时）运输S，C，和沉积物从燃烧的葡萄园流，（2）如果地表径流占主导地位的水文响应在燃烧的葡萄园，则被移动的S物种将具有轻同位素值，反映与土壤基质的最小相互作用。

In early October 2017, multiple wildfires ignited across Northern California's (CA) premier winegrowing region, incinerating vineyards and neighboring communities, with as yet unknown consequences for hydrology, biogeochemical cycling, water quality, and human and ecosystem health. This is a particularly important region to study the impacts of wildfire, as changes to soils and hydrology will likely affect the fate of the large reactive sulfur (S) loads applied to vineyards each year for powdery mildew control. Widespread S use may have consequences for adjacent ecosystems similar to those of inadvertent atmospheric S deposition (i.e., 'acid rain'), such as stimulating production of methylmercury, a potent neurotoxin. Given that wildfire may accelerate mobilization of S and other materials to adjacent aquatic ecosystems, the need to pursue this research has now become urgent. The study will address the immediate effects of wildfire on hydrological flow paths and mobilization of S from vineyards to streams. The project team will instrument a burned and unburned vineyard catchment with subsurface soil water and surface water (runoff and stream) collectors. They will conduct field observations of hydrologic flows during the first large rain events of the wet season to quantify mobilized S, C, and sediment, perform a laboratory experiment to determine chemical losses from burned and unburned soils over time, and develop methods to trace S in the environment. This study will provide a dataset critical for proceeding with longer-term efforts to develop field studies, experiments, and models to elucidate the ultimate fates and consequences of agricultural S use at the basin scale - a new area of research to understand human manipulation of the S cycle. This one-year project will be led by a female assistant professor, train a female graduate student, and provide data that will be important for farmers and other stakeholders. The research group will communicate their findings broadly in multiple workshops within the study region.The goal of this one-year field- and laboratory-based study is to provide an important dataset detailing the effects of recent, widespread wildfire on mobilization of agricultural sulfur (S) from vineyards to streams in the North Coast California winegrowing region. These data are a critical baseline to capture prior to initiating a new wave of research: determining the unintended consequences of high S applications in regional agricultural systems. The biogeochemical and ecological effects of high S use may be similar to those of inadvertent atmospheric S deposition (i.e., "acid rain"), but they have not yet been studied in vineyards or other crop systems. In particular, agriculturally-derived S may stimulate production of methylmercury in aquatic ecosystems downgradient of source areas, threatening the health of humans and wildlife. This study will make the first measurements of S, carbon (C), and sediment mobilized from burned vineyards to streams during the onset of the rainy season, and develop new geochemical and isotopic methods for tracing agriculturally-derived S species in the environment. To this end, the project team will instrument a burned and an unburned vineyard catchment with runoff collectors, ISCO stream samplers, soil water samplers, and soil moisture sensors to quantify hydrological flow paths and assess their chemical composition. They will also conduct burned and unburned soil core leaching experiments to determine the evolution of chemical losses over the course of a simulated wet season. These activities will test two hypotheses: (1) If the heat input from fire has dramatically changed surface soil properties relative to unburned vineyards, moderate-to-high intensity rain events will cause surface runoff that rapidly (minutes to hours) transports S, C, and sediment from burned vineyards to streams, and (2) If surface runoff dominates the hydrologic response in burned vineyards, then mobilized S species will have a light isotopic value, reflecting minimal interaction with the soil matrix.