1、G1 资源与循环要 点营养物资源 群落以形形色色的方式获得和损失营养物。机械风化、化学腐蚀，特别是碳酸化作用，都是重要的过程。矿物质在水中的简单溶解也使营养物从岩石和土壤中获得成为可能。在水流中水可能携带着营养物，给下流地区提供一个重要的资源。大气也提供营养物，特别是二氧化碳和氮。大气中其他营养物可能以湿降落（雨，雪和雾）和干降落（干燥期间的颗粒沉淀物）的方式回到群落。滞留营养物 G1 SOURCES AND CYCLESNutrients are gained and lost by communities in a variety of ways. Mechanical weatherin
2、g, chemical weathering, particularly carbonation, are important processes. Simple dissolution of minerals in water also makes nutrients available from rock and soil. Water may carry nutrients in watercourses providing an important source in downstream areas. Atmospheric gases provide nutrient source
3、s too, particularly carbon dioxide and nitrogen. Other nutrients from the atmosphere become available to communities as wetfall (rain, snow and fog) and dryfall (settling of particles during dry periods).Key NotesNutrient sources陆地群落营养物预算有机体吸收的特定营养物微粒可连续地循环，直到营养物最终损失，这是通过许多过程中的任一个过程把营养物从系统中除去。营养物释放可
4、直接到达空气或通过细菌作用（如甲烷）。对于许多元素来说，最重要的是丢失途径是在水流中。营养物损失的其他途径包括火灾、庄稼的收获和森林砍伐。A particular nutrient atom taken up by an organism may cycle continuously until eventually the nutrient will be lost through any one of a number of processes that remove nutrients from the system. Release may be direct to the atmos
5、phere or via bacterial action (as in the case of methane). For many elements, the most substantial pathway of loss is in streamflow. Other pathways of nutrient loss include fire, the harvesting of crops and deforestation.Nutrient budgets in terrestrial communities水生群落营养物预算水生 系统从水流中得到它们所需的大量营养物。在具有流出
6、口的溪流、河流和湖泊中，水流出是个重要因素。通常，无机营养物置换阶段与营养物固定在生物量中的时期是交替进行的。浮游生物在湖泊中的营养物循环中起关键作用。海洋含有温暖的表层水，生活着大多数的植物，还有冷的深层水（占总水容量的 90%）。表层水的营养物来源于两种方面：（ i） 深层水的上涌流（组成物预算的 95%以上），（ ii） 河流的输入。Aquatic systems obtain the bulk of their supply of nutrients from streamflow. In streams, rivers and lakes with a stream outflow,
7、 export in outgoing stream water is a major factor. Commonly, phases of fast inorganic nutrient displacement alternate with periods when the nutrient is locked in biomass. In lakes, plankton play a key role in nutrient cycling. Oceans contain warm suface waters, where most plant life is found and co
8、ld deep waters (which make up 90% of the total water volume). Nutrients in the suraface waters come from two sources: (i) upwelling from deep water (which comprise over 95% of the nutrient budget),and (ii) river input.Nutrient budgets in aquatic communities地球化学 地球上的化学元素库存在于各种圈层（ compartments）中：在岩石（岩
9、圈）和土壤水、溪流、湖泊或海洋（可组合构成水圈）中。在上述情况下，化学元素以无机形式存在。同时，生命有机体和已死亡及腐烂的有机物质是在含有有机元素的圈层里。研究在这些区域内发生的化学过程和圈层间元素的流动（通过生物过程产生了功能性的改变和影响），称为生物地球化学。化学元素形态与人体健康 The pools of chemical elements on earth exist in various compartments: in rocks (the lithosphere), and soil water, streams, lakes or oceans (whish, combined
10、, constitute the hydrosphere). In all these cases, the chemical elements exist in the inorganic form. In contrast, living organisms and dead and decaying organic matter are compartments which contain elements in the organic form. Studies of the chemical processes occurring within these compartments and the flux of elements between them (which are fundamentally altered and affected by biotic processes) is termed biogeochemistry.Geochemistry
