土壤衛(wèi)生一ppt課件(已修改)
2025-01-31 21:17 本頁面
【正文】 “Below that thin layer prising the delicate anism known as the soil is a pla as lifeless as the moon” Unless you are a farmer, you probably think of soil as dirt—something you don’t want on your hands, clothes, or carpet. You are acutely aware of your need for air and water, but you may be unaware that your life and that of other anisms depend on soil, especially the upper portion known as topsoil. The nutrients in the food we eat e from soil. To a large extent, all flesh is soil nutrients. Soil also provides you with wood, paper, cotton, and many other vital materials and helps purify the water you drink. As long as soil is held in place by vegetation, it stores water and releases it in a nourishing trickle instead of a devastating flood. Soil’s deposer anisms recycle the key chemicals we and most other forms of life need. Bacteria in soil depose degradable takes decades to hundreds of years in today’s pacted, oxygen deficient landfills. Soil is truly the base of life and civilization. Yet, since the beginning of agriculture, we have abused this vital, potentially renewable resource. Entire civilizations have collapsed because they mismanaged the topsoil that supported their populations. Today, we are abusing soil more than ever. Each of us must bee involved in protecting the lifegiving resource we call soil. In saving the soil, we save ourselves and other forms of life. 土壤衛(wèi)生 （一） 胡前勝 中山大學(xué)公共衛(wèi)生學(xué)院預(yù)防醫(yī)學(xué)系 一、土壤的組成、性質(zhì)及其衛(wèi)生學(xué)意義 二、土壤資源及其環(huán)境問題 三、土壤污染對(duì)人類健康的影響 四、土壤污染的防治 講授內(nèi)容： 一、土壤的組成、性質(zhì)及其衛(wèi)生學(xué)意義 一）土壤的定義 soil— 陸地表面具有肥力、能夠生長植物的疏松表層，由地殼表層的巖石經(jīng)過長期的風(fēng)化和生物學(xué)的作用形成的，其厚度一般在 2m左右。 成土母巖 成土母巖 長期風(fēng)化 生物學(xué)作用 土壤 二）土壤的物理特性 土壤的固相 土壤顆粒 土壤有機(jī)質(zhì) 土壤微生物 土壤的液相 土壤的氣相 ★ 土壤顆粒 soil particle—— 土壤的物質(zhì)基礎(chǔ) ◆ 主要來自巖石風(fēng)化后形成的礦物質(zhì)， 也有來源于動(dòng)植物以及有機(jī)無機(jī)結(jié)合的顆粒 ◆ 含量是土壤總重量的 80％～ 90％ ◆ 大小和排列狀態(tài)決定土壤的多種物理特性 孔隙率、透氣性、滲水性、容水性和土壤的毛細(xì)管現(xiàn)象 ◆ 粒級(jí) soil particle classification ◆ 土壤質(zhì)地 soil texture ◆ 粒級(jí) soil particle classification 根據(jù)土壤顆粒粒徑的大小可將土壤顆粒分為若干組 ◆ 土壤質(zhì)地 soil texture 土壤中各粒級(jí)所占的相對(duì)比例或重量百分?jǐn)?shù) 顆粒 土質(zhì) 孔隙 透氣性 排水性能 有機(jī)物分解 砂土 砂粒 疏松 大 好 強(qiáng) 快 壤土 粘土 細(xì)粘粒 粘重 小 差 弱 慢 ★ 土壤水分 soil water ◆ 土壤孔隙中的水分 ◆ 參與土壤中物質(zhì)轉(zhuǎn)化和動(dòng)植物的新陳代謝 雨雪水、灌溉水 大氣中的水汽、地下水 地下水層 土壤表層 濾過層 地下水位 —— 地下水層表面到地面的距離 地下水位 ↑→ 地面潮濕，形成沼澤 → 土壤中有機(jī)物的無機(jī)化 ↓ ◆ 滲水性 ——水分滲透過土壤的能力 ◇ 土壤顆粒 ↑→滲水 ↑→保持干燥 ◇ 滲水 ↑↑→地面的污染物滲入地下水 →不利于水源保護(hù) ◆ 容水量 ——一定容積的土壤中含有水分的量
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