尘埃量的增加一部分原因源于人类活动——比如，建筑，它属于直接原因，又如，为了耕种而将边际地块上的植物清除所造成的后果就属于间接原因。

Part of the increase stems from human activities—directly, in the case of construction, or indirectly, when it results from clearing vegetation from marginal land in order to farm it.

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射猎活动源于人类最初的蛮荒时代。

It originated in the beginning period of human beings.

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大部分的沙尘暴都源于长期干旱，并由于诸如过度放牧和伐木等人类活动而更加恶化。

Most dust storms are linked to long droughts, exacerbated by human activities like overgrazing and deforestation.

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