A Comparative Study of the Atmospheric Sulfur Budget in Different Natural Environments

P.I.计划进行实地研究，重点是(a)大陆地区羰基硫化物（COS）和二硫化碳（CS2）的生物圈-大气交换，以及(b)海洋对流层中二甲硫化物（CH2SCH3， DMS）的光化学氧化。这两个过程都是生物地球化学硫循环的重要组成部分，对全球气候调节具有潜在的重大影响。在不同的自然环境中，包括火炬松林、橡树山核桃林和不同的农业生物群落（小麦、玉米、大豆、高粱），将以昼夜和季节为基础，测量植物（和土壤）与大气之间COS、CS2和二氧化碳（CO2）的交换率。将使用不同方法的组合，包括梯度通量技术和封闭室（使用环境空气或含硫零空气作为扫气）。还将按日和季节对沿海和公海上DMS的化学转变进行研究。该计划的一个主要部分将包括协作测量，涉及新的、高灵敏度的技术，用于连续实时检测DMS、主要氧化剂，如羟基（OH）和氢氧自由基（HO2），以及DMS主要氧化产物二甲基亚砜（DMSO）、二氧化硫（SO2）、气相甲烷磺酸（MSA）和硫酸。目的是增强我们对COS、CS2和DMS在生物和气象因素影响下的大气循环的认识。

The P.I. plans to conduct field studies focused on (a) the biosphere-atmosphere exchange of carbonyl sulfide (COS) and carbon disulfide (CS2) over continental areas, and (b) the photochemical oxidation of dimethylsulfide (CH2SCH3, DMS) in the marine troposphere. Both processes are important components of the biogeochemical sulfur cycle with potentially large implications for global climate regulation. Exchange rates of COS, CS2, and carbon dioxide (CO2) between plants (and soils) and the atmosphere will be measured on a diurnal and seasonal basis in different natural environments including a loblolly pine forest, an oak-hickory forest, and different agricultural biomes with various types of crops (wheat, corn, soybeans, sorghum). A combination of different methods will be used including the gradient flux technique and enclosure chambers (using ambient air or sulfur-spiked zero air as sweep gas). Studies of the chemical transformation of DMS over coastal and open ocean waters will also be made on a diurnal and seasonal basis. A major part of this program will consist of collaborative measurements involving new, highly sensitive techniques for continuous real-time detection of DMS, major oxidants such as the hydroxy (OH) and hydroperoxy radicals (HO2), and the major DMS oxidation products dimethysulfoxide (DMSO), sulfur dioxide (SO2), and gas phase methanesulfonic acid (MSA) and sulfuric acid. The goal is to enhance our understanding of the atmospheric cycles of COS, CS2, and DMS, in response to biological and meteorological factors.