In today's lecture, I'm going to be talking about microplastics.

在今天的讲座中，我将谈谈微塑料。

Microplastics are tiny pieces of plastic smaller than five millimetres in size.

微塑料是指小于五毫米的塑料碎片。

Recently there's been a greater awareness that there are large quantities of plastic waste – big and small – in the environment.

最近，人们越来越意识到，环境中存在着大量大大小小的塑料垃圾。

The amount of plastic waste in the oceans has received widespread attention, but far less is known about the effects of microplastics in freshwater and particularly in soil.

海洋中的塑料垃圾数量已引起广泛关注，但人们对淡水中，尤其是土壤中的微塑料的影响却知之甚少。

Microplastics can enter the environment via a number of different sources.

微塑料可通过多种不同途径进入环境。

Threads and microfibres detach from synthetic clothing every time they're put in a washing machine, and these find their way into the water system.

合成纤维衣物每次放进洗衣机后都会脱落线头和微纤维，这些都会进入水系统。

Other sources include big pieces of plastic waste that are already in the environment, and these break down into microscopic particles over a period of time.

其他途径包括已经存在于环境中的大块塑料废弃物，这些废弃物在一段时间后会分解成微小颗粒。

On a larger scale, factory waste is another route, as are tyres which wear down as cars, lorries and so on travel along road surfaces.

从更大的范围看，工厂废料是另外一种途径，汽车、卡车等在路面行驶时磨损的轮胎也是如此。

We already understand some of the impacts of microplastics from studies involving fish and other animals.

通过对鱼类和其他动物的研究，我们已经了解了微塑料的一些影响。

There is evidence that microplastics harm small creatures in a variety of ways, such as by damaging their mouths, or by impairing their ability to feed, for example when microplastics get lodged in their digestive system.

有证据表明，微塑料会以多种方式对小型生物造成伤害，例如损坏它们的口腔，或损害它们的进食能力，例如当微塑料卡在它们的消化系统中时。

Surprisingly perhaps, it is likely that humans consume microplastics, as these have been detected in a wide range of food and drink products, including bottled water, as well as in water that comes direct from the tap.

令人惊讶的是，人类很可能也会食用微塑料，因为在包括瓶装水在内的各种食品和饮料中以及在自来水中，都检测到了微塑料。

What's more, salt and many kinds of seafood have also been found to contain microplastics.

此外，盐和多种海产品也被发现含有微塑料。

However, it's important to underline that there is not yet conclusive proof that microplastics cause significant harm to people.

不过，需要强调的是，目前还没有确凿证据证明微塑料会对人体造成重大伤害。

In many countries, including here in the UK, there is legislation which prevents manufacturers from adding plastic microbeads to shower gels, facial cleansers and toothpaste.

包括英国在内的许多国家都立法禁止制造商在沐浴露、洁面乳和牙膏中添加塑料微珠。

It is very difficult to accurately estimate the total amount of microplastic particles in the soil as they can be hard to detect, but we do know they are carried in the air and deposited in the soil by rain.

要准确估计土壤中的微塑料颗粒总量非常困难，因为它们很难被检测到，但我们确实知道它们随空气传播，并通过降雨沉积在土壤中。

What's more, many of the fertilisers used by both farmers and gardeners contain microplastics.

此外，农民和园丁使用的许多肥料中都含有微塑料。

A team from the Anglia Ruskin University in Cambridge has carried out a study of the effects of microplastics on the digestive tracts of earthworms.

剑桥安格利亚鲁斯金大学的一个研究小组进行了一项关于微塑料对蚯蚓消化道影响的研究。

These worms, which live in topsoil, are an essential component of our agricultural system.

这些生活在表土中的蠕虫是我们农业系统的重要组成部分。

By feeding on soil, they mix nutrients into it, thereby making it more fertile.

它们以土壤为食，将养分混合到土壤中，从而使土壤更加肥沃。

The researchers set out to discover whether the introduction of microplastics into the soil – and the subsequent ingestion of these by earthworms – would impact soil quality and ultimately inhibit plant growth. The short answer was, yes, it did.

研究人员试图研究，在土壤中引入微塑料——以及蚯蚓随后摄入这些微塑料——是否会影响土壤质量，并最终抑制植物生长。简而言之：会。

After placing three different types of microplastic particles into the soil, they planted perennial rye grass.

将三种不同类型的微塑料颗粒放入土壤后，他们种植了多年生黑麦草。

The particles of microplastic, which included biodegradable PLA and conventional high-density polyethylene, or HDPE, were then ingested by the earthworms in the soil.

这些微塑料颗粒包括可生物降解的聚乳酸（PLA）和传统的高密度聚乙烯（HDPE），随后被土壤中的蚯蚓摄入。

The result was that the worms lost weight rapidly.

结果，蚯蚓的体重迅速下降。

What's more, a lower percentage than normal of the rye grass seeds germinated, and the researchers concluded that this was a direct result of the earthworms being unable to fulfil their normal role in making soil more fertile.

此外，黑麦草种子的发芽率也低于正常水平，研究人员得出结论，这是蚯蚓无法发挥其正常作用，使土壤更加肥沃的直接结果。

The team also discovered that there was an increase in the amount of acid found in the soil, and this was attributed mainly to the microplastic particles from conventional HDPE plastic.

研究小组还发现，土壤中的酸含量有所增加，这主要归因于传统高密度聚乙烯（HDPE）塑料中的微塑料颗粒。

The conclusions of the study make for very interesting reading – I've included the reference in the notes to give you at the end of this session.

这项研究的结论读起来非常有趣——我在本节课的课堂笔记中附上了这些参考文献。

To summarise, the authors proposed the idea that we need to regard soil as we would regard any other process in nature.

总而言之，作者提出的观点是，我们需要像看待自然界中的任何其他过程一样看待土壤。

This means we should accept the implications of soil being dependent on decaying and dead matter constantly being passed through the bodies of earthworms.

这意味着我们应该接受土壤依赖于蚯蚓体内不断传递的腐朽物质所带来的影响。

That is, when soil becomes impoverished by the presence of microplastics, not only ecosystems but also the whole of society are negatively impacted.

也就是说，当土壤因为微塑料的存在而变得贫瘠时，不仅生态系统，整个社会都会受到负面影响。