The Potential Impact of Saharan Dust and Polluted Aerosols on Microbial Populations in the East Mediterranean Sea, an Overview of a Mesocosm Experimental Approach
The Potential Impact of Saharan Dust and Polluted Aerosols on Microbial Populations in the East Mediterranean Sea, an Overview of a Mesocosm Experimental Approach
复制标题
DOI：
10.3389/fmars.2016.00226
复制
发表时间：
2016-01-01
影响因子：
3.7
通讯作者：
Paraskevi, Pitta
中科院分区：
文献类型：
--
作者：
Herut, Barak;Rahav, Eyal;Paraskevi, Pitta
最近对东地中海营养平衡的估计表明，大气气溶胶作为其低营养、低叶绿素水的宏观和微观营养物质的供应者，发挥着重要作用。在这里，我们提供了第一项中尺度实验研究，考察了稀养型EMS地表混合层(克雷坦海，2012年5月)对两种不同类型的自然气溶胶添加的总体响应，即“纯”撒哈拉沙尘(SD，1.6毫克L(-1))和混合气溶胶(A污染和沙漠来源，1毫克L(-1))。我们描述了这种方法的基本原理、实验装置、环境水和气溶胶的化学特性以及添加气溶胶所产生的相对最大的生物影响。两个处理，运行三个(每个3米(3))，与对照-未修改运行进行比较。每毫克SD和A分别测量到类似于2.1-2.8和2.2-3.7nmolPO4和20-26和53-55nmolNOx的淋溶，相当于环境磷酸盐浓度的30%。A处理添加的硝酸盐/磷酸盐比是SD处理的两倍。两种类型的干气溶胶在大多数测量的速率和状态变量上都发生了正变化(每添加1 mg L(-1)，归一化25-600%)：细菌丰度(BA)、细菌产量(BP)、聚球藻(Syn)丰度、叶绿素-a(Chl-a)、初级生产力(PP)和固氮(N-2-FIX)，它们之间的相对变化顺序为BP>；PIP近似N2-FIX>；Chl-AP近似BK近似Syn。我们的结果表明，与SD改进剂相比，“被污染”的气溶胶引发了相对更大的生物变化(按类似质量添加量)，特别是对于BP和PP。我们推测，尽管P和N在EMS中存在共同限制，但与SD相比，A处理释放的额外N可能在大多数速率和状态变量中触发了相对更大的反应。我们研究的一个含义是，未来大气变暖可能会增加沙尘排放，并影响EMS中已经很好分层的水柱的强度和长度，从而影响气溶胶作为新营养物的重要外部来源的影响。
Recent estimates of nutrient budgets for the Eastern Mediterranean Sea (EMS) indicate that atmospheric aerosols play a significant role as suppliers of macro- and micro- nutrients to its Low Nutrient Low Chlorophyll water. Here we present the first mesocosm experimental study that examines the overall response of the oligotrophic EMS surface mixed layer (Cretan Sea, May 2012) to two different types of natural aerosol additions, "pure" Saharan dust (SD, 1.6 mg l(-1)) and mixed aerosols (A-polluted and desert origin, 1 mg l(-1)). We describe the rationale, the experimental set-up, the chemical characteristics of the ambient water and aerosols and the relative maximal biological impacts that resulted from the added aerosols. The two treatments, run in triplicates (3 m(3) each), were compared to control-unamended runs. Leaching of similar to 2.1-2.8 and 2.2-3.7 nmol PO4 and 20-26 and 53-55 nmol NOx was measured per each milligram of SD and A, respectively, representing an addition of similar to 30% of the ambient phosphate concentrations. The nitrate/phosphate ratios added in the A treatment were twice than those added in the SD treatment. Both types of dry aerosols triggered a positive change (25-600% normalized per 1 mg l(-1) addition) in most of the rate and state variables that were measured: bacterial abundance (BA), bacterial production (BP), Synechococcus (Syn) abundance, chlorophyll-a (chl-a), primary production (PP), and dinitrogen fixation (N-2-fix), with relative changes among them following the sequence BP> Pip approximate to N2-fix>chl-aP approximate to Bk approximate to Syn. Our results show that the "polluted" aerosols triggered a relatively larger biological change compared to the SD amendments (per a similar amount of mass addition), especially regarding BP and PP. We speculate that despite the co-limitation of P and N in the EMS, the additional N released by the A treatment may have triggered the relatively larger response in most of the rate and state variables as compared to SD. An implication of our study is that a warmer atmosphere in the future may increase dust emissions and influence the intensity and length of the already well stratified water column in the EMS and hence the impact of the aerosols as a significant external source of new nutrients.