属于持久性有机污染物（persistent organic pollutants, POPs）的农药—历史使用的农药（historic-use pesticides，HUPs）仍在各种环境介质中普遍检出，因此我们对HUPs的监测仍需继续。很多当前使用的农药（current-use pesticides, CUPs）在偏远地区（高山、北极和偏远海区）检出，意味着它们也具有类似POPs的特性—长距离传输潜力。目前，对CUPs的研究一般局限于一个小区域。我们难以了解其跨境传输或全球传输的状态，难以评估对CUPs采取全球行动的必要性。海洋在农药的环境归趋中扮演重要角色，气—水交换是农药在海洋环境归趋的重要过程。目前，关于海洋环境的CUPs的研究不多，对中国近海的CUPs或HUPs的气—水交换状况了解不多。
    本博士工作分析了西北太平洋至北冰洋、北海德国湾，以及黄渤海海洋大气和海水的CUPs和/或HUPs。讨论的基本内容包括农药的浓度、来源和气—水交换。这些研究将让我们对CUPs在海洋大气和海水的污染现状有所了解。对于大空间尺度的研究（西北太平洋至北冰洋）能使我们从中获得一些CUPs全球传输状态的启示；对于区域尺度的研究（北海德国湾和黄渤海）能使我们了解农药在这些农业活动频繁的海岸带的迁移特征。这些研究为我们在全球或者区域范围内对农药采取适当的管理策略提供支持。
    2010年6月至9月采集自西北太平洋至北冰洋（33.23-84.5°N）的大气和海水样品用于分析6个CUPs（硫丹、毒死蜱、百菌清、氟乐灵、三氯杀螨醇、敌草索）。这可能是关于这些CUPs的首次跨洋尺度的调查。这六个CUPs空气和海水颗粒相的浓度基本上占总浓度很低的比例（<0.001%）。它们在气相检出的浓度介于0.01-150 pg m-3，在海水溶解相检出的浓度介于0.004至111 pg L-1。α-硫丹、毒死蜱和三氯杀螨醇是空气和海水样品中具有最高浓度的化合物。这些化合物的最高浓度都出现在日本海。百菌清和敌草索在高纬度的海水浓度显著地高于低纬度。α-硫丹和毒死蜱的大气浓度表现出温度依赖。CUPs的气—水交换以净沉降为主，但各CUPs的沉降趋势（即逸度比率）随纬度的变化各异。毒死蜱在低纬度（<40°N）的一个点有很强的净挥发（逸度比率 = 0.05）。敌草索在高纬度区域（>71.5°N）处于净挥发。
    2010年3月，5月和7月在德国湾采集的大气和海水样品用于分析硫丹、毒死蜱、氟乐灵、敌草索、五氯硝基苯这5个CUPs及代谢物五氯苯甲醚，以及六氯苯、六六六这两种HUPs。农药在空气或海水颗粒相的浓度基本上占总浓度很低的比例。目标物（除了氟乐灵）的大气浓度基本上是7月高，3月低。海水浓度则没有一致的季节变化。大气HCHs、α-硫丹、敌草索、五氯硝基苯和五氯苯甲醚主要来自近岸陆地地表挥发。这些化合物大气浓度的季节变化与温度相关。有更多化合物在3月表现出河流输入。农药在德国湾的气—水交换以净沉降为主，且7月由于有更高的大气浓度而有更强的沉降通量。氟乐灵在3月和5月因为有更高的海水浓度而表现出挥发。毒死蜱在所有季节的气—水交换为净挥发，且各季节挥发通量相当。 
    2012年5月在黄渤海采集的空气和海水用于分析氟乐灵、五氯硝基苯、百菌清、三氯杀螨醇、毒死蜱和敌草索这6个CUPs，硫丹、六氯苯、六六六这3种HUPs，以及降解产物五氯苯甲醚和硫丹硫酸盐。CUPs在大气和海水的组成基本上反映这些农药在中国的消费组成。硫丹硫酸盐在海水的浓度接近或者超过α-硫丹浓度。海水中β-HCH占总HCHs浓度的比例很大。大气的HCB，α-HCH，β-HCH，α-硫丹，β-硫丹，硫丹硫酸盐，五氯苯甲醚，三氯杀螨醇和敌草索在南黄海有更高浓度。这个区域受经过华东的气团影响。γ-HCH，氟乐灵，五氯硝基苯，毒死蜱在渤海有更高浓度。这个区域受经过环渤海陆地、蒙古和俄罗斯的气团影响。三氯杀螨醇、毒死蜱、氟乐灵、五氯硝基苯和硫丹硫酸盐有明显的河流输入。HCB和HCHs没有明显的河流输入。多数化合物表现出气—水交换净沉降，除了氟乐灵和毒死蜱主要表现出净挥发；HCB接近平衡或轻微挥发；β-HCH在渤海接近平衡。近年大量使用的硫丹、三氯杀螨醇和百菌清有很强的沉降趋势；消费量低的五氯硝基苯、敌草索沉降趋势较弱。

Historic-use pesticides (HUPs), which were persistent organic pollutants (POPs), are still commonly detected in the environment. Therefore, monitoring of HUPs should be continuted. Most current-use pesticides (CUPs) are detected in remote areas (high mountains, the Arctic and remote seas). It indicates these CUPs have similar characteristics as POPs, i.e. the potential of long-range transport. Current studies on CUPs are focus on small scale. That’s not enough for us to learn the trans-boundary transport or global transport of CUPs, so it is difficult to evaluate the necessity for global action on these CUPs. Marine environment play an important role in the environmental fate of pesticides. Air-water exchange is an important process of the environmental fate of pesticides in marine environment. Studies on CUPs in marine environment are sparse and we have little knowledge on the air-water exchange of CUPs and HUPs at Chinese coastal water.

This Ph. D. work analyzed CUPs and / or HUPs in the air and seawater from the western North Pacific, the Arctic, the German Bight (North Sea) and the Bohai and Yellow seas. Levels, possible sources and air-water exchange are discussed. These studies give us basic information on the pollution of CUPs in marine air and seawater. The large-scale study (from the western North Pacific to the Arctic) give us revelation on the global transport mechanism of CUPs and the regional-scale studies (the German Bight, and the Bohai and Yellow seas) improve our understanding of the migration of pesticides in these places, where agricultural activities frequently take place. All these studies could support the management policy of pesticides on global or regional scale.

Results and discussions of every part of this Ph. D. work were given in this thesis:

Chapter 2: Air and seawater samples taken from the western North Pacific and the Arctic from July to September 2010 were analyzed for six CUPs (endosulfan, chlorpyrifos, chlorothalonil, trifluralin, dicofol and dacthal). This is probably the first study on CUPs in a trans-ocean scale. CUPs were rarely detected in particulate phase (<0.001%). Gaseous concentrations ranged from 0.01-150 pg m^-3. Dissolved concentrations ranged from 0.004-111 pg L^-1. α-endosulfan, chlorpyrifos and dicofol were the most abundant compounds in the air and seawater. The highest concentrations appeared in the Sea of Japan. Chlorothalonil and dacthal showed higher concentrations in the seawater of high latitudes. The air concentrations of α-endosulfan and chlorpyrifos showed temperature dependence. The air-sea gas exchange of CUPs were dominanted by net deposition, but the latitudinal trends of fugacity ratio (FR) varied from compound to compound. Strong deposition (FR = 0.05) of chlorpyrifos existed at a site <40°N. Dacthal was net volatilization at high latitudes (>71.5°N).

Chapter 3: Air and seawater taken from German Bight in March, May and July 2010 were analyzed for six CUPs (endosulfan, chlorpyrifos, trifluralin, quintozene and dacthal), one degradation product (pentachloroanisole) and HCB and HCHs. Particule phase accounted for low percentages of the air and seawater concentrations. Air concentrations were higher in July and lower in March except for trifluralin. There was no consistent seasonal trends of seawater concentrations. HCHs, α-endosulfan dacthal, quintozene and pentachloroanisole in the air volatile and transported from the surfaces of the adjacent continents. The seasonal trends of air concentrations of these compounds can be explained by temperature changes. More compounds showed significant riverine input in March. Air-water exchange was dominated by net deposition and the deposition fluxes were higher in July for the high atmospheric concentrations. The exception are trifluralin were net volatilizaiton in March and May for its high water concentrations in these months, and chorpyrifos underwent net volatilization with comparable exchange fluxes in all sampling periods.

Chaper 4: Air and seawater taken from Bohai and Yellow Seas in May 2012 were analyzed for six CUPs (trifluralin, quintozene, chlorothalonil, dicofol, chlorpyrifos and dacthal), HCB, HCHs and endosulfan, and two degradation products (pentachloroanisole and endosulfan sulfate). The patterns of CUPs in the air and seawater generally reflected the consumption patterns of these CUPs in China. The seawater concentrations of endosulfan sulfate were comparable with or higher than those of α-endosulfan. The seawater concentrations of β-HCH accounted for high percentages of total HCHs (α-, β- and γ-HCH). Concentrations of HCB, α-HCH, β-HCH, α-endosulfan, β-endosulfan, endosulfan sulfate, pentachloroanisle, dicofol and dacthal were higher in the air of southern Yellow Sea, where the air was influenced by air masses passing East China. Concentrations of γ-HCH, trifluralin, quintozene and chlorpyrifos were higher in the air of Bohai Sea, where the air was influcned by air masses passing the surrounding continents, Mongolia and Russia. Dicofol, chlorpyrifos, trifluralin, quintozene and endosulfan sulfate showed riverine input. HCB and HCHs showed no riverine input. Most chemicals underwent air-sea gas exchange net deposition, except that trifluralin and chlorpyrifos were net volatilization, HCB approached equilibrium or slight volatilization and β-HCH approached equilibrium at Bohai Sea. Pesticides with high consumption amount recent years (endosulfan, dicofol and chlorothalonil) showed stronger deposition trend than those with low consumption amount (quintozene and dacthal).