“黄金叶”

引子

If you’re looking for gold, don’t look down. Look up.

如果你在找金子，不要低头找了，抬头看。

In the good old days, gold miners could seek out ^1 visible specks of bling at the surface in order to find deeper, richer veins.These days, prospectors must examine samples of dirt for more minute traces suggestive of a hidden seam ^2 below. Analysing water from boreholes can also yield clues, but boreholes are scarce and new ones are costly and time-consuming to drill.

1. seam n.矿层；宝藏；线缝；缝隙。

以前的好日子里，矿工要找到储量丰富的金矿，只要找找地上有没有不灵不灵闪闪发光的东西就行了。近些年，人们就必须检测土壤样本才能发掘蛛丝马迹。或者分析钻孔中涌出来的水也能发现一些痕迹，然而钻孔稀少，打新的又耗钱耗时。

提出议题——”黄金叶“探测法

Trees offer an alternative that is finally bearing fruit ^1 in Australia. The idea has been around since the 1940s but, until now, never practical. Some trees have roots that reach deep underground, drawing up water ^2 and, along with it, tiny quantities of minerals that end up distributed throughout the tree. In this way, even lofty leaves bear^3 traces of what lies far beneath. The quantities are minuscule. In areas where there is no gold, leaves may have a background level of 0.15 parts per billion (ppb) of gold; on gold-rich sites that can rise to 4ppb.

2. bear fruit 结果
3. draw up 吸收
4. bear 熟词生义：vet.具有;承载

树木也提供了一种选择——澳大利亚有了成果。这个观点在上世纪四十年代就已经被讨论过，只是到现在，才有了操作可能。一些树木的根系已经深入到地下深层，吸取水分，也因此，微量的矿物质被吸收，然后分散遍布树木各处。这样一来，即便是高耸的树叶里，也隐含着地下深处的秘密。含量是很微小的。在没有金矿的地区，树叶的金含量水平是0.15ppb，含量丰富的地区可以达到4ppb.

解释“黄金叶“探测法

In theory, “biogeochemical” prospecting is a simple matter of collecting leaves from across a site and mapping ^1 mineral concentrations to reveal subterranean ^2 treasures. It is best applied to dry regions where plants seek out water with deep roots. Some even break down soil to extract mineral nutrients, thus increasing the amount of telltale ^3 minerals in their leaves. Gold is the obvious element to look for, but checking for elements that are associated with gold deposits^5, such as antimony and bismuth, can also be sensible.

1. map v.绘制···地图；在地图上标出；
   Map out vt.详细制定
2. subterranean adj. 隐藏的
3. telltail adj.泄密的
4. deposit n.沉积层

理论上，“生物地质化学”勘探法简单的说就是收集一处的树叶，然后绘制矿物浓度的分布来揭示隐藏的宝藏。在干旱地区，效果尤为显著。这些地方的植物为了汲取水分具有发达的根系。有些甚至打碎土壤来吸收矿物养分，因此提高了树叶中“泄密“矿物的含量。显而易见，金元素需要检测，不止于金元素，与黄金沉积层相关的物质，例如锑、铋，也可以探测到。

存在的困难

Sampling is harder than it sounds, though. Different trees accumulate gold in different ways, so exactly the same species must be sampled across each site for valid comparisons. Acacia is one of the trees of choice, but Australia has about 1,000 Acacia species, many of which look similar. To confuse matters further ^11, the degree to which elements accumulate in leaves varies with the seasons.

1. To confuse matters further

可是，取样要远比听起来困难。不同的树种以不同的方式聚集金元素。因此，必须在每一个地区对相同的树种进行采样，以便进行明显的对比。Acacia是被选中的树木之一，但是澳大利亚有大约1000种Acacia，有许多看起来还很相似。雪上加霜的是，聚集在树叶中的元素的量随着季节的变化而变化。

实际应用

In proof-of-principle studies over the last few years, Nathan Reid and his team at csiro, Australia’s national science agency, have shown that biogeochemical prospecting closely tallies ^1 with the surface and groundwater analyses. Inspired by these results, Marmota, an exploration firm, put the method to the test at its Aurora Tank site, 50km from the highly-productive Challenger mine in South Australia.

1. tally: vi.吻合 tally with

在过去几年的理论验证研究中，Nathan Reid和他的团队在澳大利亚的国家科学中心——Cairo，已经展示出来，生物地质化学探测方法与表层和地下水分析紧密吻合。受此鼓舞，Marmota，一个探测公司开始试用这种方法，在Aurora Tank，距离南澳大利亚高产出的Challenger 矿50公里。

Leaves collected immediately around a known deposit that lies beneath ten metres of rock contained traces of gold, validating the approach. Further samples were taken 40 metres apart around known deposits, and at wider spaces farther out. This turned up several anomalies^1, where gold seemed to be present but other tests had shown nothing. “The usual calcrete [surface sample] testing was saying ‘Don’t drill here’,” says Colin Rose, Marmota’s executive chairman, “but the tree sampling was saying ‘Drill here’.”

12. anomaly:n.【C】反常的事物

在已知矿层的周围收集起的树叶里发现了金子的痕迹，这证明了这种方法。这个矿层位于十米之厚的岩石下面。更远一点的样本取自距矿40米以外的地方，更广阔的区域。这就出现了一些异常的事情，检测起来似乎是有金子的，然而其他的测试都显示什么都没有。“普通表层样本好像在说‘不要在这里打井’”，Colin Rose，Marmota的执行官说：“但是树木样本却说‘就在这儿打’。”

Then came the pay-off. Drilling revealed a-metre-thick vein^1 with 27g of gold per tonne, more than 30 metres below the surface. A metre-thick inner layer held an impressive 105g per tonne. Five grams per tonne is considered high-grade.

13. vein: n.矿脉

接下来就有回报了。钻井发现了一米厚的矿脉，27克每吨的含量，深入表层30米。深层发现了含量高达105克每吨的矿，着实令人印象深刻。而5克每吨就已经被认为是高含量了。

Marmota is keen to explore further. In the outer sampling zone, the company found four anomalies in an area where only one potential seam had been identi- fied. They have yet to be drilled but plans are afoot^1 Prospecting with trees is starting to look less like a scientific curiosity and more like a golden opportunity.

14. afoot:adj.进行中的

Marmota倾向于进一步研究。在取样区域外围，这个公司在一个区域发现了四处异常，而只有一处被确认。这些地方还要被钻开，但是计划还在进行中。利用树木进行探测开始变得不像是科学发现，而更像是“黄金机会”了。