NSF workshop: Drilling, sampling, and imaging the depths of the critical zone

了解调节地球表面的化学、物理和生物过程在各种问题上都很重要，从评估人类时间尺度上的土壤可持续性，到了解地球长期气候演变中与风化有关的反馈。这些问题正越来越多地在“临界区”(CZ)的令人兴奋的跨学科研究中得到解决。尽管CZ被认为延伸到自由循环地下水的最低限度，但大多数地下CZ研究仅集中在景观中风化岩石和土壤的上层1-2米左右。因此，深层CZ(即任何太深而不能轻易获取和手工采样的东西)是流域水文学、地球生物学、地貌学、土壤学和低温地球化学进展的关键前沿。研究深部CZ的障碍之一是深度本身；风化层、孔隙水和地下生物群很难现场描述，因为它们大多埋藏在难以接近的深度。应对深层CZ研究的挑战将需要协调调查，利用地下表面的钻探、采样、监测和成像方面的最新进展。该奖项将支持一个研讨会，该研讨会旨在就如何克服深层CZ研究的传统困难达成全社会范围的跨学科共识。研讨会将汇集45人，包括CZ研究人员和近地表地球物理学家，以及在钻井、取心和井下仪器方面经验丰富的工程师。它利用了以下机会：(I)世界各地的CZ科学家最近达成的共识中表示，对深部CZ研究进展的需求日益增长；(Ii)近地表地球物理方面的最新进展，包括改进的深CZ成像技术和从CZ架构解释地球物理性质的技术；以及(Iii)最近在美国建立正式的大陆科学钻探计划方面的新势头。为了有效，研讨会将需要弥合差距，促进来自不同学科的科学家和工程师之间富有成效的新合作。

Understanding the chemical, physical, and biological processes that modulate Earth's surface is important across a diverse range of problems, from assessing soil sustainability over human timescales, to understanding weathering-related feedbacks in Earth's longtermclimatic evolution. Increasingly, these problems are being tackled in exciting, crossdisciplinary studies of the "critical zone" (CZ). Although, the CZ is considered to extend to the lowest limits of freely circulating groundwater, most subsurface CZ research hasfocused on just the upper 1-2 m or so of weathered rock and soil in landscapes. Hence the deep CZ (i.e., anything that is too deep to readily access and sample by hand) represents a crucial frontier for advances in watershed hydrology, geobiology, geomorphology, soilscience, and low-temperature geochemistry. One of the hurdles in studying the deep CZ is depth itself; regolith, pore waters, and subsurface biota are difficult to characterize in situ because they are mostly buried at difficult-to-access depths. Tackling the challenge of deep CZ research will require coordinated investigations that exploit recent advances in drilling, sampling, monitoring and imaging of the subsurface.This award will support a workshop designed to develop a community-wide, crossdisciplinary consensus on how to overcome the traditional difficulties of deep CZ research. The workshop will bring together 45 people, including CZ researchers and near surface geophysicists, as well as engineers with experience in drilling, coring and borehole instrumentation. It exploits the chance alignment of: (i) an increasing need for advances in deep CZ research, voiced in a recent consensus of CZ scientists from aroundthe world; (ii) recent advances in near-surface geophysics, including improved techniques for imaging the deep CZ and interpreting geophysical properties in terms of CZ architecture; and (iii) recently renewed momentum behind establishing a formal programof continental scientific drilling in the US. To be effective, the workshop will need to bridge gaps, fostering productive new collaborations among scientists and engineers from diverse disciplines.