與羅馬混凝土相似的火山岩解釋了為何義大利的火山臼能以破紀錄的速率抬升

原文網址：www.sciencedaily.com/releases/2015/07/150709144850.htm

Volcanic rocks resembling Roman concrete explain record uplift in Italian caldera

與羅馬混凝土相似的火山岩解釋了為何義大利的火山臼能以破紀錄的速率抬升

The discovery of a fiber-reinforced, concrete-like rock formed in the depths of a dormant supervolcano could help explain the unusual ground swelling that led to the evacuation of an Italian port city and inspire durable building materials in the future, Stanford scientists say.

史丹佛大學的科學家認為在已經休眠的超級火山深處形成的被纖維強化(fiber-reinforced)、類似混凝土的岩石，可以解釋造成義大利港都必須緊急撤離的不尋常地面隆起，並且對未來更耐久的建築材料有所啟發。

The "natural concrete" at the Campi Flegrei volcano is similar to Roman concrete, a legendary compound invented by the Romans and used to construct the Pantheon, the Coliseum, and ancient shipping ports throughout the Mediterranean.

發現於坎皮佛萊格瑞(Campi Flegrei)火山地區的「天然混凝土」與羅馬混凝土十分相似。由羅馬人發明的這種偉大材料被用來興建萬神殿、羅馬競技場與遍佈地中海地區的古代港口。

"This implies the existence of a natural process in the subsurface of Campi Flegrei that is similar to the one that is used to produce concrete," said Tiziana Vanorio, an experimental geophysicist at Stanford's School of Earth, Energy & Environmental Sciences.

「這代表說發生在坎皮佛萊格瑞地下的自然作用，跟一種混凝土的製程相當類似。」史丹佛大學地球、能源與環境科學學院(Stanford's School of Earth, Energy & Environmental Sciences)的實驗地球物理學家，Tiziana Vanorio說。

Campi Flegrei lies at the center of a large depression, or caldera, that is pockmarked by craters formed during past eruptions, the last of which occurred nearly 500 years ago. Nestled within this caldera is the colorful port city of Pozzuoli, which was founded in 600 B.C. by the Greeks and called "Puteoli" by the Romans.

坎皮佛萊格瑞位處一稱作火山臼(caldera)的大型低地中央。此地形內密佈著過去火山噴發時造成的火山口，最近的一次噴發發生在500年前。坐落於其中的波佐利(Pozzuoli)是一座繽紛的港都，在西元前600年由希臘人建造，被羅馬人稱為「Puteoli」。

Beginning in 1982, the ground beneath Pozzuoli began rising at an alarming rate. Within a two-year span, the uplift exceeded six feet-an amount unprecedented anywhere in the world. "The rising sea bottom rendered the Bay of Pozzuoli too shallow for large craft," Vanorio said.

1982年起波佐利的地面開始以令人擔憂的速率上升，僅僅兩年之間就抬升了超過六呎。在世上其他地方從未觀測到如此大的抬升量。「海底隆升導致波佐利灣變淺而無法讓大型船隻停泊。」Vanorio說。

Making matters worse, the ground swelling was accompanied by swarms of micro-earthquakes. Many of the tremors were too small to be felt, but when a magnitude 4 quake juddered Pozzuoli, officials evacuated the city's historic downtown. Pozzuoli became a ghost town overnight.

更糟的是，地表隆升還伴隨著許多微震(micro-earthquake)的發生。雖然大多數的震動都微弱的難以察覺，但一次規模4的地震撼動波佐利時，官方決定疏散歷史悠久的市中心。波佐利在一夜之間人去樓空。

A teenager at the time, Vanorio was among the approximately 40,000 residents forced to flee Pozzuoli and settle in towns scattered between Naples and Rome. The event made an impression on the young Vanorio, and inspired her interests in the geosciences. Now an assistant professor at Stanford, Vanorio decided to apply her knowledge about how rocks in the deep Earth respond to mechanical and chemical changes to investigate how the ground beneath Pozzuoli was able to withstand so much warping before cracking and setting off micro-earthquakes.

Vanorio在青少年時為被迫撤離波佐利，安頓在那布勒斯至羅馬之間許多小鎮的40,000名左右波佐利居民中的其中之一。這起事件深深烙印在Vanorio的腦海之中，啟發了她對地質科學的興趣。現為史丹佛大學助理教授的Vanorio，下定決心要以她對地球深處的岩石會如何因應力學與化學變化的知識，來探討為何波佐利的土地能夠在破裂並產生微震之前，承受這麼大幅度的彎曲。

"Ground swelling occurs at other calderas such as Yellowstone or Long Valley in the United States, but never to this degree, and it usually requires far less uplift to trigger earthquakes at other places," Vanorio said. "At Campi Flegrei, the micro-earthquakes were delayed by months despite really large ground deformations."

「在其他的火山臼，像是美國黃石公園或長谷(Long Valley)，地表也會有隆升現象，但從來不會到這種程度。其他地方通常抬升幅度遠小於它時就會開始發生地震了。」Vanorio說，「但在坎皮佛萊格瑞，儘管地表變形程度已經如此劇烈，微震卻還是晚了數個月才發生。」

To understand why the surface of the caldera was able to accommodate incredible strain without suddenly cracking, Vanorio and a post-doctoral associate, Waruntorn Kanitpanyacharoen, studied rock cores from the region. In the early 1980s, a deep drilling program probed the active geothermal system of Campi Flegrei to a depth of about 2 miles. When the pair analyzed the rock samples, they discovered that Campi Flegrei's caprock-a hard rock layer located near the caldera's surface-is rich in pozzolana, or volcanic ash from the region.

為了瞭解此火山臼的表面為何能夠處於那麼大的應變卻不會突然破裂，Vanorio與博士後研究員Waruntorn Kanitpanyacharoen研究了採集於此地的岩心。在1980年代早期，為了探查坎皮佛萊格瑞的活躍地熱系統，所進行的深層鑽探計畫曾鑽至地下約2哩深。這對科學家分析岩石樣品後，發現靠近火山臼地表的堅硬岩層，即坎皮佛萊格瑞的蓋岩(caprock)，富含在這個地區稱為pozzolana的火山灰。

The scientists also noticed that the caprock contained tobermorite and ettringite-fibrous minerals that are also found in humanmade concrete. These minerals would have made Campi Flegrei's caprock more ductile, and their presence explains why the ground beneath Pozzuoli was able to withstand significant bending before breaking and shearing. But how did tobermorite and ettringite come to form in the caprock?

科學家同時發現蓋岩含有雪矽鈣石(tobermorite)與鈣礬石(ettringite)，為可在人類製造的混凝土中發現的纖維狀礦物。這些礦物造成坎皮佛萊格瑞的蓋岩更具塑性，解釋了為何波佐利的地面能在破裂與剪動之前承受這麼大的彎曲。然而雪矽鈣石與鈣礬石要如何形成於蓋岩之中？

Once again, the drill cores provided the crucial clue. The samples showed that the deep basement of the caldera-the "wall" of the bowl-like depression-consisted of carbonate-bearing rocks similar to limestone, and that interspersed within the carbonate rocks was a needle-shaped mineral called actinolite.

再一次地，岩心提供了重要的線索。樣品顯示火山臼的深部基岩-即這個碗形陷落的碗壁-含有類似石灰岩的含碳酸鹽岩石，且有一種稱作陽起石(actinolite)的針狀礦物散佈在這些碳酸鹽岩石中。

"The actinolite was the key to understanding all of the other chemical reactions that had to take place to form the natural cement at Campi Flegrei," said Kanitpanyacharoen, who is now at Chulalongkorn University in Thailand.

「瞭解坎皮佛萊格瑞形成天然混凝土的所有必要化學反應的關鍵在於陽起石。」Kanitpanyacharoen說，她現在任職於泰國的朱拉隆功大學(Chulalongkorn University)。

From the actinolite and graphite, the scientists deduced that a chemical reaction called decarbonation was occurring beneath Campi Flegrei. They believe that the combination of heat and circulating mineral-rich waters decarbonates the deep basement, prompting the formation of actinolite as well as carbon dioxide gas. As the CO₂ mixes with calcium-carbonate and hydrogen in the basement rocks, it triggers a chemical cascade that produces several compounds, one of which is calcium hydroxide. Calcium hydroxide, also known as portlandite or hydrated lime, is one of the two key ingredients in humanmade concrete, including Roman concrete. Circulating geothermal fluids transport this naturally occurring lime up to shallower depths, where it combines with the pozzolana ash in the caprock to form an impenetrable, concrete-like rock capable of withstanding very strong forces.

由岩石中發現的陽起石及石墨，科學家推論坎皮佛萊格瑞下方發生了一種稱作脫碳酸鹽化(decarbonation)的化學反應。她們認為高熱與富含礦物的流水的共同作用使深部基岩脫碳酸鹽化，促進了陽起石及二氧化碳氣體的形成。當二氧化碳與基岩中的碳酸鈣及氫氣混合，發生的一連串化學反應會形成數種化合物，其中之一為氫氧化鈣。氫氧化鈣又稱作氫氧鈣石(portlandite)或熟石灰(hydrated lime)，為製造包含羅馬混凝土在內的人造混凝土的兩種關鍵材料之一。流動的地熱流體會將這些天然石灰往上運至淺部，在那裡它們會與蓋岩中的火山灰結合，而形成可以承受相當高應力、類似混凝土的堅固岩石。

"This is the same chemical reaction that the ancient Romans unwittingly exploited to create their famous concrete, but in Campi Flegrei it happens naturally," Vanorio said.

「羅馬人在不自覺的情況下利用了同樣的化學反應製造出他們舉世聞名的混凝土，但在坎皮佛萊格瑞這完全是自然發生的。」Vanorio說。

In fact, Vanorio suspects that the inspiration for Roman concrete came from observing interactions between the volcanic ash at Pozzuoli and seawater in the region. The Roman philosopher Seneca, for example, noted that the "dust at Puteoli becomes stone if it touches water."

事實上，Vanorio猜測啟發羅馬混凝土的靈感，便是來自觀查此區海水跟波佐利火山灰之間的反應。舉例來說，羅馬哲學家西尼加(Seneca)就曾經注意到「波佐利的沙石若跟海水接觸就會變成石頭。」

"The Romans were keen observers of the natural world and fine empiricists," Vanorio said. "Seneca, and before him Vitruvius, understood that there was something special about the ash at Pozzuoli, and the Romans used the pozzolana to create their own concrete, albeit with a different source of lime."

「羅馬人不但是對自然界相當敏銳的觀察者，同時也是優秀的經驗主義者。」Vanorio說。「西尼加與在他之前的維特魯威(Vitruvius)都瞭解到波佐利的火山灰必定有特殊之處，而羅馬人利用火山灰調製出他們自己的混凝土，儘管他們用的是另外一種不同的石灰來源。」

Pozzuoli was the main commercial and military port for the Roman Empire, and it was common for ships to use pozzolana as ballast while trading grain from the eastern Mediterranean. As a result of this practice, volcanic ash from Campi Flegrei-and the use of Roman concrete-spread across the ancient world. Archeologists have recently found that piers in Alexandria, Caesarea, and Cyprus are all made from Roman concrete and have pozzolana as a primary ingredient.

波佐利在羅馬帝國時期為主要的商業及軍事用港，他們在跟東地中海地區交易榖物時，常常用火山灰當作壓艙物。由於這種習慣，來自坎皮佛萊格瑞的火山灰，以及羅馬混凝土的使用傳遍了整個古代世界。考古學家最近發現亞力山卓(Alexandria)、凱撒利亞(Caesarea)與賽普勒斯(Cyprus)的港口皆是以羅馬混凝土建成，而其中的主要原料即為火山灰。

Interestingly, the same chemical reaction that is responsible for the unique properties of the Campi Flegrei's caprock can also trigger its downfall. If too much decarbonation occurs-as might happen if a large amount of saltwater, or brine, gets injected into the system-an excess of carbon dioxide, methane and steam is produced. As these gases rise toward the surface, they bump up against the natural cement layer, warping the caprock. This is what lifted Pozzuoli in the 1980s. When strain from the pressure buildup exceeded the strength of the caprock, the rock sheared and cracked, setting off swarms of micro-earthquakes. As pent-up gases and fluids vent into the atmosphere, the ground swelling subsided. Vanorio and Kanitpanyacharoen suspect that as more calcium hydroxide was produced at depth and transported to the surface, the damaged caprock was slowly repaired, its cracks "healed" as more natural cement was produced.

有趣的是，造成坎皮佛萊格瑞蓋岩獨特性質的化學反應，卻也能破壞它。如果脫碳酸鹽化反應太多，這可能發生於當有太多鹽水，或者鹵水灌入此系統時，就會產生過量的二氧化碳、甲烷與水蒸汽。隨著這些氣體往上遷移，它們會抬高這塊自然水泥層，造成蓋岩拱起。這即為1980年代造成波佐利隆升的原因。當壓力累積造成的應力超過蓋岩的強度，蓋岩便會破裂並剪動，引發許多微震。隨著封閉在地下的氣體與液體逐漸逸散至大氣，地面又會開始下沉。Vanorio與 Kanitpanyacharoen推測當深處產生的氫氧化鈣被運至表層時，會逐漸修復被破壞的蓋岩。也就是隨著天然混凝土的形成，蓋岩中的裂痕也會慢慢「癒合」。

Vanorio believes the conditions and processes responsible for the exceptional rock properties at Campi Flegrei could be present at other calderas around the world. A better understanding of the conditions and processes that formed Campi Flegrei's caprock could also allow scientists to recreate it in the lab, and perhaps even improve upon it to engineer more durable and resilient concretes that are better able to withstand large stresses and shaking, or to heal themselves after damage.

Vanorio認為造成坎皮佛萊格瑞岩石獨特性質的環境條件與過程，也會出現在其他世界各地的火山臼之下。對坎皮佛萊格瑞蓋岩的環境條件與形成過程瞭解得更加深入，有助於科學家在實驗室中複製整個條件及過程，甚至能讓工程師改良出更耐久、更有彈性的混凝土，其能夠承受更大的應力與震動，或在受損後能自我修復。

"There is a need for eco-friendly materials and concretes that can accommodate stresses more easily," Vanorio said. "For example, extracting natural gas by hydraulic fracturing can cause rapid stress changes that cause concrete well casings to fail and lead to gas leaks and water contamination."

「現在需要的是能更輕易承受應力的對生態友善材料與混凝土。」Vanorio說，「舉例來說，利用水力壓裂法抽取天然氣時，造成的應力迅速變化可能會破壞混凝土製的氣井套管，導致氣體洩漏及地下水汙染。」

引用自：Stanford's School of Earth, Energy & Environmental Sciences. "Volcanic rocks resembling Roman concrete explain record uplift in Italian caldera." ScienceDaily. ScienceDaily, 9 July 2015. 

火山爆發改變人類歷史

原文網址：www.sciencedaily.com/releases/2015/07/150708133858.htm

Volcanic eruptions that changed human history

Researchers find new evidence that large eruptions were responsible for cold temperature extremes recorded since early Roman times

火山爆發改變人類歷史

研究人員發現新的證據顯示自羅馬時代早期以來，歷史紀錄中的極端寒冷事件的罪魁禍首為大型火山噴發

It is well known that large volcanic eruptions contribute to climate variability. However, quantifying these contributions has proven challenging due to inconsistencies in both historic atmospheric data observed in ice cores and corresponding temperature variations seen in climate proxies such as tree rings.

眾所皆知的是，大型火山噴發會導致氣候動盪。然而，要定量化它們的影響卻相當困難，這是由於從冰心中觀察到的大氣成分歷史紀錄，對應到樹輪這類氣候指標中的溫度變化紀錄時，會有不一致的情形發生。

Published today in the journal Nature, a new study led by scientists from the Desert Research Institute (DRI) and collaborating international institutions, resolves these inconsistencies with a new reconstruction of the timing and associated radiative forcing of nearly 300 individual volcanic eruptions extending as far back as the early Roman period.

刊登於今日《自然》(Nature)期刊上的新研究中，科學家以新方法重建了最早可追溯至羅馬時代早期的300次火山噴發事件的發生時間與相關輻射驅動力(radiative forcing)，而解決了這些不一致。本研究由沙漠研究中心(Desert Research Institute，DRI)的科學家協同其他國際機構的科學家進行。

"Using new records we are able to show that large volcanic eruptions in the tropics and high latitudes were the dominant drivers of climate variability, responsible for numerous and widespread summer cooling extremes over the past 2,500 years," said the study's lead author Michael Sigl, Ph.D., an assistant research professor at DRI and postdoctoral fellow with the Paul Scherrer Institute in Switzerland.

「利用這些新紀錄，我們可以顯示熱帶與高緯度區域的大型火山噴發事件為氣候變化的主要推手，導致了過去2,500年來許多次的大規模極端冷夏，」此研究的第一作者Michael Sigl博士說，他是DRI的研究助理教授及瑞士保羅謝爾研究所(Paul Scherrer Institute)的博士後研究員。

"These cooler temperatures were caused by large amounts of volcanic sulfate particles injected into the upper atmosphere," Sigl added, "shielding the Earth's surface from incoming solar radiation."

「這些比平常還要低的溫度的肇因為火山往高層大氣噴射的大量硫酸鹽粒子。」Sigl補充，「它們會阻擋地表接收來自太陽的輻射。」

The study shows that 15 of the 16 coldest summers recorded between 500 BC and 1,000 AD followed large volcanic eruptions -- with four of the coldest occurring shortly after the largest volcanic events found in record.

此研究顯示從西元前1,500年至西元1,000年間記錄到的16次最冷夏季中，有15次發生在大型火山噴發之後—其中最冷的四次緊接在紀錄中最大的火山噴發事件過後。

This new reconstruction is derived from more than 20 individual ice cores extracted from ice sheets in Greenland and Antarctica and analyzed for volcanic sulfate primarily using DRI's state-of-the-art, ultra-trace chemical ice-core analytical system.

這些新的重建結果建立於DRI最先進的超微量化學冰芯分析系統(ultra-trace chemical ice-core analytical system)，對採自格陵蘭與南極冰層的二十幾根冰芯中火山硫酸鹽的分析結果。

These ice-core records provide a year-by-year history of atmospheric sulfate levels through time. Additional measurements including other chemical parameters were made at collaborating institutions.

這些冰芯可以提供過往大氣中硫酸鹽含量的年度紀錄。包括其他化學指標的更多測量則由其他合作機構進行。

"We used a new method for producing the timescale," explained Mai Winstrup, Ph.D., a postdoctoral researcher at the University of Washington, Seattle. "Previously, this has been done by hand, but we used a statistical algorithm instead. Together with the state-of-the-art ice core chemistry measurements, this resulted in a more accurate dating of the ice cores."

「我們利用新的方法來建立時間序列。」西雅圖華盛頓大學(University of Washington, Seattle)的博士後研究員，Mai Winstrup博士說。「過往這得以人工來完成，但現在我們改用統計演算法，加上最先進的冰芯化學測量技術，我們得以對冰芯做出更精準的定年。」

"Using a multidisciplinary approach was key to the success of this project," added Sigl

「採用跨領域的研究方法為這項計畫的成功關鍵。」 Sigl補充。

In total, a diverse research group of 24 scientists from 18 universities and research institutes in the United States, United Kingdom, Switzerland, Germany, Denmark, and Sweden contributed to this work -- including specialists from the solar, space, climate, and geological sciences, as well as historians.

總的而言，這個多元化的研究團隊包含了18所大學及研究機構的24名科學家，分別來自美國、英國、瑞士、德國、丹麥與瑞典。這些專家的研究領域包含了太陽能、宇宙、氣候、地質與歷史。

The authors note that identification of new evidence found in both ice cores and corresponding tree rings allowed constraints and verification of their new age scale.

作者強調從冰芯與對應的樹輪辨識出來的新證據，可以用來界定與証實他們新建立的時程表。

"With the discovery of a distinctive signature in the ice-core records from an extra-terrestrial cosmic ray event, we had a critical time marker that we used to significantly improve the dating accuracy of the ice-core chronologies," explained Kees Welten, Ph.D., an associate research chemist from the University of California, Berkeley.

「從冰芯紀錄中發現的來自地外宇宙射線事件的獨特訊號，可以當作特定的時間標記，讓我們大幅增加冰芯定年的精準度。」Kees Welten博士說，他是加州大學柏克萊分校(University of California, Berkeley)的化學副研究員。

A signature from this same event had been identified earlier in various tree-ring chronologies dating to 774-775 Common Era (CE).

在定年結果為公元774至775年的許多樹輪中，於更早之前也有辨識出同一事件的訊號。

"Ice-core timescales had been misdated previously by five to ten years during the first millennium leading to inconsistencies in the proposed timing of volcanic eruptions relative to written documentary and tree-ring evidence recording the climatic responses to the same eruptions," explained Francis Ludlow, Ph.D., a postdoctoral fellow from the Yale Climate & Energy Institute.

「過往定年第一個千禧年間的冰芯時會有五到十年的誤差，這會造成冰芯顯示的火山爆發時間，與歷史文獻及樹輪紀錄中由同一事件造成的氣候變化時間，兩者之間出現不一致的情形。」耶魯大學氣候能源研究中心(Yale Climate & Energy Institute)的博士後研究員，Francis Ludlow說。

Throughout human history, sustained volcanic cooling effects on climate have triggered crop failures and famines. These events may have also contributed to pandemics and societal decline in agriculture-based communities.

綜觀人類的歷史，持續的火山冷卻效應對氣候的影響會導致作物歉收與饑荒。這些事件可能會造成農業社會爆發瘟疫與社會衰敗。

Together with Conor Kostick, Ph.D. from the University of Nottingham, Ludlow translated and interpreted ancient and medieval documentary records from China, Babylon (Iraq), and Europe that described unusual atmospheric observations as early as 254 years before Common Era (BCE). These phenomena included diminished sunlight, discoloration of the solar disk, the presence of solar coronae, and deeply red twilight skies.

協同諾丁漢大學(University of Nottingham)的Conor Kostick博士，Ludlow翻譯與解讀來自中國、巴比倫(伊朗)與歐洲各地古代及中世紀文獻中，所描述的異常大氣現象。這些文本的年代最早可追溯至公元前254年。異常大氣現象包括陽光減弱、日輪(solar disk)顏色異常、肉眼可見日冕以及深紅色的日暮。

Tropical volcanoes and large eruptions in the Northern Hemisphere high latitudes (such as Iceland and North America) -- in 536, 626, and 939 CE, for example -- often caused severe and widespread summer cooling in the Northern Hemisphere by injecting sulfate and ash into the high atmosphere. These particles also dimmed the atmosphere over Europe to such an extent that the effect was noted and recorded in independent archives by numerous historical eyewitnesses.

像是發生在公元536年、626年及939年的熱帶或北半球高緯地區(如冰島與北美)的大型火山噴發，會往高層大氣噴出大量的硫酸鹽與火山灰，經常導致北半球發生大區域的嚴酷冷夏。這些粒子也會造成歐洲上空的大氣變得十分朦朧不清，而被歷史上的許多人目擊，記載在各自獨立的文獻中。

Climatic impact was strongest and most persistent after clusters of two or more large eruptions.

連續二個或以上的大型噴發會對氣候造成最強烈與最持久的影響。

The authors note that their findings also resolve a long-standing debate regarding the causes of one of the most severe climate crises in recent human history, starting with an 18-month "mystery cloud" or dust veil observed in the Mediterranean region beginning in March, 536, the product of a large eruption in the high-latitudes of the Northern Hemisphere.

作者認為他們的發現也解決了長久以來，對人類近代史中最嚴重的氣候危機之一的成因的爭論。此事件始於從西元536年三月開始，在地中海地區觀察到長達18個月的「神秘雲」或塵罩，其為北半球高緯度地區的大型噴發事件產物。

The initial cooling was intensified when a second volcano located somewhere in the tropics erupted only four years later. In the aftermath, exceptionally cold summers were observed throughout the Northern Hemisphere.

僅僅四年後，發生在某個熱帶地區的另一次火山噴發，加強了最初的冷化現象。結果導致了整個北半球地區都能觀察到的異常冷夏。

This pattern persisted for almost fifteen years, with subsequent crop failures and famines -- likely contributing to the outbreak of the Justinian plague that spread throughout the Eastern Roman Empire from 541 to 543 CE, and which ultimately decimated the human population across Eurasia.

這種氣候模式持續了將近15年之久，伴隨而來的作物歉收與飢荒可能導致了公元541年至543年，襲捲東羅馬帝國全境的查士丁尼瘟疫(Justinian plague)，最終導致歐陸人口的銳減。

"This new reconstruction of volcanic forcing will lead to improved climate model simulations through better quantification of the sensitivity of the climate system to volcanic influences during the past 2,500 years," noted Joe McConnell, Ph.D., a DRI research professor who developed the continuous-flow analysis system used to analyze the ice cores.

「透過更精確的定量過去2,500年間氣候系統受火山活動的影響程度，這項重建火山活動的全新結果可以改良氣候模型的模擬成效。」DRI的研究教授，Joe McConnell博士指出，他發展出用來分析冰芯的連續流動分析系統。

"As a result," McConnell added, "climate variability observed during more recent times can be put into a multi-millennial perspective -- including time periods such as the Roman Warm Period and the times of significant cultural change such as Great Migration Period of the 6th century in Europe."

「結果上而言，」McConnell補充，「我們應將最近觀測到的氣候變化納入數千年的尺度中，這段時期包括了像是羅馬溫暖期(Roman Warm Period)以及某些重大的文化變遷時期，如發生在6世紀時的歐洲民族大遷徙時期(Great Migration Period)。」

This reconciliation of ice-core records and other records of past environmental change will help define the role that large climatic perturbations may have had in the rise and fall of civilizations throughout human history.

化解冰芯紀錄與其他過去環境變遷的紀錄之間的不一致，有助於確立在人類歷史裡，強烈的氣候變動在文明的興衰中扮演何種角色。

"With new high-resolution records emerging from ice cores in Greenland and Antarctica, it will be possible to extend this reconstruction of volcanic forcing probably all the way back into the last Ice Age," said Sigl.

「有了來自格陵蘭與南極冰芯中的高解析紀錄，我們或許能重建遠至上次冰河期的火山作用。」Sigl說。

This research was largely funded by the U.S. National Science Foundation's Polar Program; with contributions from additional funding agencies and institutions in Belgium, Canada, China, Denmark, France, Germany, Iceland, Japan, Korea, The Netherlands, Sweden, Switzerland, and the United Kingdom.

此研究大部分由美國國家基金會的極地計畫資助，其他資金來源包括比利時、加拿大、中國、丹麥、法國、德國、冰島、日本、韓國、荷蘭、瑞典、瑞士及英國的資金補助機構與研究機構。

引用自：Desert Research Institute. "Volcanic eruptions that changed human history: Researchers find new evidence that large eruptions were responsible for cold temperature extremes recorded since early Roman times." ScienceDaily. ScienceDaily, 8 July 2015. 

海底熱泉為海洋中鐵的重要來源

原文網址：www.sciencedaily.com/releases/2015/07/150708133904.htm

Seafloor hot springs a significant source of iron in the oceans

海底熱泉為海洋中鐵的重要來源

At the bottom of the sea, volcanic and magmatic forces create hot springs that spew super-heated water into the deep sea. The hot, acidic water scours metals from Earth's crust, and the warm chemical-rich water from these remote geysers supports exotic deep-sea ecosystems.

在海底由火山與岩漿活動形成的熱泉會往深海噴出超高熱的泉水。在地底這些滾燙的酸性泉水會將地殼中的金屬沖刷出來，之後從那些人類難以抵達的噴泉噴出。這種富含礦物質的溫熱泉水支撐了噴泉附近的奇異深海生態系。

It had been widely thought the story stopped there. Metals such as iron and manganese were thought to quickly react and form particles that would either clump together or stick to other things, causing them to sink to the seafloor close to the source. But new research proves that the metals remain dissolved and follow deep-sea currents to provide a major source of iron to the world's oceans. The findings are published on the cover of Nature.

過去大都認為故事在此畫下句點。一般認為鐵與鎂這類的金屬會很快地發生化學反應而形成固體顆粒，之後聚集成團塊或是依附在別的東西上面，造成它們僅能沉降在來源附近的海床。然而新的研究顯示這些金屬可以維持在溶解態並且乘著深海洋流到達遠方，而成為全世界海洋中重要的鐵來源。此發現被刊登在《自然》( Nature)的封面。

"This proves that hydrothermal activity at the mid-ocean ridges impacts global ocean chemistry of important trace metals," said lead author Joseph Resing, a senior research scientist at the University of Washington's Joint Institute for the Study of the Atmosphere and Ocean, a partnership with the National Oceanic and Atmospheric Administration. "On longer timescales, it also impacts the productivity of the oceans."

「這證實了中洋脊的熱泉活動會影響全世界海洋的稀有金屬化學性質。」第一作者Joseph Resing說，他是華盛頓大學大氣海洋聯合研究中心(University of Washington's Joint Institute for the Study of the Atmosphere and Ocean)的高級研究員。此機構與美國國家海洋與大氣管理局(National Oceanic and Atmospheric Administration)有合作關係。「在長時間尺度下，這也會影響海洋的生產力。」

Metals, especially iron, are crucial to the growth of phytoplankton in the oceans. In many parts of the ocean iron controls the growth of marine life even though it is only present at concentrations of parts per trillion.

金屬，尤其是鐵，對於海洋中浮游植物的成長來說相當重要。在海洋的許多區域裡雖然鐵的濃度可能僅有一兆分之幾，但卻控制了當地海洋生物的繁盛與否。

Most of the iron in the ocean comes from dust blown off deserts, or from rivers that discharge into the sea. But recent research, some conducted by co-author Christopher German at Woods Hole Oceanographic Institution, hinted that iron might also be escaping from the volcanic ridge crest by exploiting some type of chemical trick to make the long-distance voyage.

海洋中大部分的鐵來自從沙漠吹至海上的沙塵，或是流入海洋的河流。然而最近的研究顯示(其中幾篇來自共同作者，伍茲霍爾海洋研究所(Woods Hole Oceanographic Institution)的Christopher German)，鐵或許能以某些化學戲法從火山洋脊頂端脫離出來，長途航行至遠方。

The new study, part of the U.S. National Science Foundation's GEOTRACES program, locates the "smoking gun" -- a plume of hydrothermal metals drawn westward by a slow-moving, deep-ocean current that carries these metals for decades to distant parts of the ocean.

此篇研究為美國國家科學基金會GEOTRACES計畫中的一部分，研究對象為「菸槍(smoking gun)」—其為一富含溶解金屬的熱液柱。往西方緩緩流動的深海洋流會拖曳此熱液柱，數十年來不斷地將其內的金屬帶至遠方的海洋。

A 57-day cruise in fall 2013 aboard the UW's research vessel, the Thomas G. Thompson, tracked water venting from the East Pacific Rise, a chain of underwater volcanoes west of Ecuador that is one of the most volcanically active places on Earth. The oceanographers followed the trail for more than 4,000 kilometers (2,500 miles) west across the South Pacific to Tahiti, using extremely sensitive tools to make measurements of the metals from the ocean''s surface to the seafloor.

在2013年秋天這趟57的航行中，華盛頓大學的研究船Thomas G. Thompson號追循著東太平洋隆起(East Pacific Rise)上的成串海底噴泉進行研究。東太平洋隆起為厄瓜多西方的海底火山鍊，是地球上火山活動最活躍的地方之一。這群海洋學家沿著南太平洋至大溪地這段長達4,000公里(2,500哩)的航線，利用極為靈敏的儀器來測量海洋表面至底層的金屬濃度。

While the aluminum eventually petered out, every station west of the ridge crest revealed evidence of hydrothermal manganese and, surprisingly, of iron, at about 2.5 kilometers (1.5 miles) depth.

測量結果顯示在洋脊頂峰以西每個測站的水深2.5公里(1.5哩)處，雖然鋁會逐漸消失，但都能測到來自熱泉的鎂，而且令人驚訝的，還有鐵。

"Every single day we were out there, we were surprised to see that the plume of dissolved iron was still present," Resing said. "We have never before documented dissolved iron carried so far in the ocean currents."

「在那裏的每一天我們都驚訝地看到含有溶解鐵的液柱依然存在，」Resing說。「我們先前從未記錄到溶解鐵能被洋流攜帶那麼長的一段距離。」

The finding is especially important for the Southern Ocean, circling Antarctica, where massive phytoplankton blooms are known to be limited by iron supplies, and where winds are less likely to carry iron-rich dust.

此發現對於環繞南極洲的南冰洋(Southern Ocean)來說特別重要，因為目前所知當地大規模浮游植物藻華的發生受限於鐵的供應，而那裏並沒有什麼機會能接收風帶來的沙塵。

Co-author Alessandro Tagliabue at the University of Liverpool, England, placed the results within an ocean model and found that phytoplankton growth in the Southern Ocean is supported by iron from deep-sea vents. Iron from vent systems thus helps sustain a major ecosystem that consumes carbon dioxide from the atmosphere. Much of this carbon is exported from the ocean surface to the deep sea, and in the Southern Ocean 15 to 30 percent of this carbon export is supported by hydrothermal iron.

共同作者英國利物浦大學的Alessandro Tagliabue將研究結果帶入海洋模型當中，發現南冰洋中浮游植物的生長的確有賴來自深海熱泉的鐵。從這些熱泉系統中釋放的鐵因此有助於支撐這個能夠吸收大氣二氧化碳的重要生態系。海洋吸收的二氧化碳大多數會從海洋表層被傳輸至深海，在南冰洋中這種傳輸方式有百分之15至30依靠熱泉系統產生的鐵來進行。

"To properly model the uptake of carbon dioxide by the Southern Ocean and to understand how this uptake impacts climate, you must account for this iron," Resing said.

「為了更正確地模擬南冰洋如何從大氣中汲取二氧化碳，以及瞭解這種吸收過程對氣候的影響，你必須將鐵納入考量。」Resing說。

Ongoing research by other collaborators will analyze additional water samples collected during the same cruise to figure out what allows the iron to be transported so far. Two leading theories are that it attaches to large organic molecules, similar to how iron clings to hemoglobin in our bloodstream, or that it separates into tiny nanoparticles that can remain suspended in the water for decades.

由其他協同人員進行的後續研究將會分析同樣從這趟航程中採集的水樣，以了解鐵為何可以被運送那麼長的距離。目前有兩個主要理論，其一認為鐵依附在大型有機分子上，就像鐵在我們的血液中攀附於血紅素而能到處流動；另一則認為它裂解成微小的奈米顆粒，此型態的鐵能夠在水中維持懸浮狀態數十年之久。

 引用自：University of Washington. "Seafloor hot springs a significant source of iron in the oceans." ScienceDaily. ScienceDaily, 8 July 2015.