Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish

Persistent organic pollutants (POPs) encompass an array of anthropogenic organic and elemental substances and their degradation and metabolic byproducts that have been found in the tissues of exposed animals, especially POPs categorized as organohalogen contaminants (OHCs). OHCs have been of concern in the circumpolar arctic for decades. For example, as a consequence of bioaccumulation and in some cases biomagnification of legacy (e.g., chlorinated PCBs, DDTs and CHLs) and emerging (e.g., brominated flame retardants (BFRs) and in particular polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanic acid (PFOA) found in Arctic biota and humans. Of high concern are the potential biological effects of these contaminants in exposed Arctic wildlife and fish. As concluded in the last review in 2004 for the Arctic Monitoring and Assessment Program (AMAP) on the effects of POPs in Arctic wildlife, prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects in relation to OHC exposure, and attempts to assess known tissue/body compartment concentration data in the context of possible threshold levels of effects to evaluate the risks. This review concentrates mainly on post-2002, new OHC effects data in Arctic wildlife and fish, and is largely based on recently available effects data for populations of several top trophic level species, including seabirds (e.g., glaucous gull (Larus hyperboreus)), polar bears (Ursus maritimus), polar (Arctic) fox (Vulpes lagopus), and Arctic charr (Salvelinus alpinus), as well as semi-captive studies on sled dogs (Canis familiaris). Regardless, there remains a dearth of data on true contaminant exposure, cause-effect relationships with respect to these contaminant exposures in Arctic wildlife and fish. Indications of exposure effects are largely based on correlations between biomarker endpoints (e.g., biochemical processes related to the immune and endocrine system, pathological changes in tissues and reproduction and development) and tissue residue levels of OHCs (e.g., PCBs, DDTs, CHLs, PBDEs and in a few cases perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs)). Some exceptions include semi-field studies on comparative contaminant effects of control and exposed cohorts of captive Greenland sled dogs, and performance studies mimicking environmentally relevant PCB concentrations in Arctic charr. Recent tissue concentrations in several arctic marine mammal species and populations exceed a general threshold level of concern of 1 part-per-million (ppm), but a clear evidence of a POP/OHC-related stress in these populations remains to be confirmed. There remains minimal evidence that OHCs are having widespread effects on the health of Arctic organisms, with the possible exception of East Greenland and Svalbard polar bears and Svalbard glaucous gulls. However, the true (if any real) effects of POPs in Arctic wildlife have to be put into the context of other environmental, ecological and physiological stressors (both anthropogenic and natural) that render an overall complex picture. For instance, seasonal changes in food intake and corresponding cycles of fattening and emaciation seen in Arctic animals can modify contaminant tissue distribution and toxicokinetics (contaminant deposition, metabolism and depuration). Also, other factors, including impact of climate change (seasonal ice and temperature changes, and connection to food web changes, nutrition, etc. in exposed biota), disease, species invasion and the connection to disease resistance will impact toxicant exposure. Overall, further research and better understanding of POP/OHC impact on animal performance in Arctic biota are recommended. Regardless, it could be argued that Arctic wildlife and fish at the highest potential risk of POP/OHC exposure and mediated effects are East Greenland, Svalbard and (West and South) Hudson Bay polar bears, Alaskan and Northern Norway killer whales, several species of gulls and other seabirds from the Svalbard area, Northern Norway, East Greenland, the Kara Sea and/or the Canadian central high Arctic, East Greenland ringed seal and a few populations of Arctic charr and Greenland shark.     

Trends of legacy and new persistent organic pollutants in the circumpolar arctic: Overview, conclusions, and recommendations

This article provides an overview of key findings in the reviews in this special issue on the assessment of persistent organic pollutants (POPs) under the Arctic Monitoring and Assessment Program (AMAP), identifies knowledge gaps, and presents conclusions and recommendations for future work. The articles in this special issue summarize the peer reviewed literature and selected technical reports on trends of concentrations and possible biological effects of POPs in the Arctic published up to early 2009.     

公共卫生事件中医疗数据访问控制与安全共享研究

随着新冠疫情的持续发展, 许多国家和地区都对确诊患者及密接者的个人信息数据和位置数据进行了严密的监管。与此同时, 如何在共享患者必要信息的同时, 确保患者及密接者的个人隐私不被泄露, 访问过程透明化、可溯源、数据不被篡改, 已成为当今亟需解决的关键问题。基于此, 本文提出了一种可追责的医疗属性通行证(AMAP)访问控制方案, 方案首先将区块链与基于属性的访问控制模型相结合, 在引入区块链对访问过程进行溯源的同时, 将访问控制策略和访问时系统中的关键步骤以智能合约的形式部署到区块链上, 使整个系统既能保障用户对数据的安全访问, 又能够对整个访问过程进行溯源。特别地, 方案引入了医疗属性通行证模块, 用户以通行证的方式申请访问, 避免了传统访问控制模型中主体属性与访问控制策略的多次匹配,在实现医疗数据细粒度访问控制的同时, 一定程度上提高了访问效率。最后, 通过安全性分析表明本方案可以抵抗拒绝服务攻击、恶意篡改攻击、单点失效攻击、主体伪装攻击、重放攻击等。实验及性能分析表明本方案与其他方案相比, 在相同访问控制策略的情况下访问次数越多, 本方案的优势越明显; 在相同访问次数情况下访问控制策略个数越多, 本方案的优势越明显。     

O2/CO2主动自发气调对采后松露贮藏品质及微观结构的影响

目的:寻找一种新型且有效的松露鲜贮方法。方法:设定80%O₂+20%CO₂(AMAP1)、60%O₂+40%CO₂(AMAP2)、40%O₂+60%CO₂(AMAP3)、10%O₂+90%CO₂(AMAP4)4个气调组和1个自然空气不封装对照组(CK),于4℃下贮藏,定期检测松露贮藏期间的营养品质及生理生化指标,并观察松露子实体贮藏0,14,28 d的微观结构。结果:CK组在采后7 d内就快速腐败,品质急剧下降;AMAP4处理的松露存在高失重和维生素C加剧降解的现象;而适宜的初始气体比例不仅可以推迟呼吸高峰,维持可溶性固形物、维生素C含量以及抑制软化、减少失重和延缓腐败对品质的影响,还可降低丙二醛、多酚氧化酶和纤维素酶对松露子实体的损害,从而保持微观结构的相对完整,保证松露正常生理功能的行使。结论:AMAP3处理的松露的保鲜性能最佳。     

基于聚乳酸的草莓自发气调包装薄膜设计

目的研究材料气体透过性及选择透过性对草莓自发气调包装效果的影响。方法以密闭系统法测定草莓的呼吸速率,结合米氏方程推导呼吸速率与包装膜渗透性的关系式。采用已知渗透性的薄膜结合渗透系统法测定实际贮藏中达到动态平衡时草莓的呼吸速率,根据米氏和动态平衡方程推导适宜草莓自发气调材料的气体选择比。在此基础上,选用对CO_2具有较强选择溶解性的聚乙二醇(PEG)对聚(L-乳酸)(PLLA)进行改性,调整其透气性和CO_2/O_2选择透过性。结果在一定使用面积下,经PEG改性后的PLGL35G20膜包装内的气氛组成可以达到较理想的草莓的AMAP气调浓度。结论PEG起到了良好的调节PLLA薄膜气调包装性能的效果,推测通过调节PEG嵌段和PLLA嵌段的长度及PEG在共聚物薄膜中的含量,可调控薄膜的气体渗透性和选择性,最终使其满足不同果实自发气调包装的最佳要求。