结合在线监测和自动识别系统分析东海沿岸船舶排放特征

海运排放大气污染物对空气质量和气候具有重要影响，但是由于船舶类型及其运行工况的复杂性，人们对船舶排放特征的认识仍然不足.东海沿岸是全球航运活动最为密集的地区之一，汇集了各种国内国际运输船只.选取宁波舟山港作为研究地点，使用在线仪器长时间测量主要的环境大气气体和颗粒污染物，并利用自动识别系统（AIS），获得每种船舶的速度.根据后向轨迹区分出：1受船舶排放影响主导的时期（夏季风，由处于完全运行或停泊的船舶占主导地位）；2受内陆气流影响主导的时期（冬季风）.结果表明二氧化硫（SO₂）、氮氧化物（NO_x）和黑碳气溶胶（BC）的排放与高速运行的船舶相关，而一氧化碳（CO）可能与较低的运行速度的船舶有关，总颗粒物（PM）与船舶速度没有显著相关关系.主要污染物在巡航工况下的排放增强因子约为怠速工况1~4倍.研究通过对直接环境背景下船舶排放进行原位观测，为评估船舶排放清单提供重要参考.

Investigating the Pollutants of Marine Shipping Emissions Along the East China Sea by Combining in-situ Measurements and Automatic Identification System

Marine shipping emissions have important impacts on air quality and climate. This type of anthropogenic emission remains largely unclear due to complex vessel types and activities. A coastal site near the Ningbo-Zhoushan port along the East China Sea was selected for this study, representing one of the hotspot regions globally with the most intensive shipping activities, in combination with vessels for both domestic and international transportation. Long-term temporal variations in key gaseous and particulate pollutants were obtained at the site using in-situ measurements, and the vessel speed associated with each classified vessel type was obtained according to the automatic identification system (AIS). In combination of backward trajectories, we were able to identify the periods predominated by the surrounding vessel emissions (in warm seasons, dominated by vessels in full operation or idle mode) or influenced by continental outflow (in cold season). We found that emissions of sulphur dioxide (SO₂), nitrogen oxides (NO_x), and black carbon (BC) aerosol were highly correlated with high-speed vessels, whereas carbon monoxide (CO) was likely related to lower operation speed. The total particulate matter (PM) was not directly linked to vessel activities. The enhancement factor in operation mode compared to that in idle mode was approximately 1-4 for most pollutants. This direct ambient observation of the emissions from a range of mixed vessel types may provide a basis for evaluating the shipping emission inventory.