Greenland's icy mountains are not an obvious place to search for an archive of economic history, but a study just published in the Proceedings of the National Academy of Sciences shows that they provide one. Joseph McConnell of the Desert Research Institute, in Reno, Nevada, and (主題句）his colleagues have tracked economic activity in Europe and the Mediterranean地中海 over the centuries by measuring variations in the amount of lead in a core of Greenlandic ice. 

Lead is a good proxy (代用） for economic activity because it is a by-product of silvermaking 銀礦 (lead and silver often occur in the same ore, known as galena), and therefore of the money supply. Extracting silver from galena方鉛礦 involves boiling off the lead. Winds from Europe carried to Greenland enough lead pollution from this process for it to be preserved in the layers of snow that, compacted 插入語

Although the lead concentration in the core that Dr McConnell looked at shows many peaks and troughs, some overall patterns are clear. Emissions began to rise in around 1000BC. This corresponds to the spread of Phoenician traders and settlers from their home cities in the Levant into the western Mediterranean, and

The rise and fall of Rome is also visible. An increase in lead concentration coincided with Rome’s victories in the Punic wars, against Carthage, the largest Phoenician腓尼基人 colony, during in the third and second centuries BC （公元前 before christ）. This was followed by a fall during the civil strife of the first century BC, a rise again when Augustus abolished the Republic and brought the pax Romana of the Empire, and another fall during the third century AD, when the state was engulfed once more by civil war, and also suffered invasion from the east.

The decline (衰弱)in lead pollution was enhanced by Rome’s switch from the silver denarius 便士, which had been increasingly debased with copper, to a gold standard. Even allowing for that, though, the European dark ages, during which Spain was occupied by the Visigoths, are clearly visible in the record—as is the point when civilisation starts to return with the rise of the Frankish state that, under Charlemagne 查理曼大帝, became the “Holy Roman Empire”, and with the takeover of Spain by the Umayyad caliphate.

1科學家通過測量格陵蘭冰芯中鉛含量的變化，研究在歐洲和地中海地區近幾個世紀的經濟活動。

2公元前1000年左右，鉛排放量開始上升。與之對應，腓尼基商人及其殖民者 (開始) 從黎凡特鄉城向西地中海擴張，隨後他們在伊比利亞開採方鉛礦 。

3羅馬的興衰也由此可見。鉛濃度增加，恰逢羅馬在‘布匿戰爭’中大勝迦太基，隨後，濃度下降是由於公元前一世紀的內亂，而又再度崛起，因於‘奧古斯都’廢除了共和國，而帶來‘羅馬和平時代’的太平盛世，但，公元三世紀，濃度再一次下降，當時國家再次慘遭內戰以及東方的入侵。

4金本位制度讓鉛濃度降低 （後面扯了金本位制度的歷史）