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MARINE ENVIRONMENTAL CHEMISTRY

MARINE ENVIRONMENTAL CHEMISTRY. Chap.2 marine oxygen-demanded organic pollution . conecept : 有机物质直接进入水体后,通过微生物的生物化学作用而分解为简单的无机物质二氧化碳和水,同时在分解过程中需要消耗水中的溶解氧;在缺氧条件下,该类污染物就发生腐败分解,恶化水质,所以称之为 需氧有机污染物 。 水中需氧有机物越多,耗氧也越多,水质也越差,表明水体污染越严重。 . Chap.2 marine oxygen-demanded organic pollution .

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MARINE ENVIRONMENTAL CHEMISTRY

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  1. MARINE ENVIRONMENTAL CHEMISTRY

  2. Chap.2 marine oxygen-demanded organic pollution • conecept: 有机物质直接进入水体后,通过微生物的生物化学作用而分解为简单的无机物质二氧化碳和水,同时在分解过程中需要消耗水中的溶解氧;在缺氧条件下,该类污染物就发生腐败分解,恶化水质,所以称之为需氧有机污染物。 • 水中需氧有机物越多,耗氧也越多,水质也越差,表明水体污染越严重。

  3. Chap.2 marine oxygen-demanded organic pollution 2.1 source and character 2.2 the index of oxygen-demanded organic pollution 2.3 consume and absorb of oxygen 2.4 analysis of examples

  4. 海洋中有机物的组成 海洋中有机物质分类 海洋需氧有机污染物的来源 一、来源 2.1 来源与污染特点

  5. 1. 海洋中有机物的组成 2.1 来源与污染特点

  6. 1. 海洋中有机物的组成 • 海洋中大量存在无生命的有机质,溶于海水中仅是其中一小部分; • 海水中约含有不到0.01%总盐量的溶解有机质,而大部分沉积于海洋沉积物中。 • 海水中有机质浓度一般为n~nx100微克碳/升,虽然浓度甚微,但其总量很大。

  7. 2.1 来源与污染特点 2. 海洋中有机物质分类 • 天然有机物质 • 人为污染的有机物质

  8. 2.1 来源与污染特点 天然有机物质 • 天然有机物质为浮游植物、浮游动物的分泌、排泄等代射产物和死亡生物分解碎屑降解、氧化、溶解产物,这些有机物质称为生源有机物。

  9. 2.1 来源与污染特点 人为污染的有机物质 • 随着工业的迅速发展,沿海城市的逐步扩大,人口的高度集中,生活水平的不断提高,各种污水排放量猛增。 • 因此,通过各种途径,直接和间接排入海洋中的有机物质成倍增加,造成港湾、河口和近岸海域有机物质污染的十分严重。

  10. 2.1 来源与污染特点 3. 海洋需氧有机污染物的来源 • 生活污水 • 工业废水 (如食品工业废水、造纸工业的废水) • 农业污水

  11. 2.1 来源与污染特点 二. 污染特点 • 生活污水和某些工业废水中所含的碳水化合物、蛋白质、脂肪和木质素等有机物质进入海洋后,其中一小部分可直接被摄取,大部分可在细菌和微生物作用下,在水中有氧下,需氧分解生成CO2,H2O和NO32-、PO43-等。

  12. 当排入水体的需氧有机物质数量有限时,也就是说没有超过水体的自净化作用的能力时,水中溶解氧交换补充及时,水体又可恢复到原有状态,有氧条件下有机物质分解产物不会造成水质进一步恶化。当排入水体的需氧有机物质数量有限时,也就是说没有超过水体的自净化作用的能力时,水中溶解氧交换补充及时,水体又可恢复到原有状态,有氧条件下有机物质分解产物不会造成水质进一步恶化。 • 因此,一般认为需氧有机物没有毒性,但氧化分解将消耗水中的溶解氧。

  13. 需氧有机物污染的主要危害: • 耗氧; • 影响水体的自净能力; • 在厌氧微生物作用下,有机物分解产生H2S、CH4、硫醇和氨等气体,使水质变臭; • 影响海洋生物甚至生态系统的正常活动。

  14. 2.1 来源与污染特点 降解方程式: • 水中有机物质氧化降解,可用以下反应式表示: • 水中有机物质氧化降解反应式: {CH2O}+ O2-→CO2 + H2O ({CH2O}代表有机物质) 2. 厌氧条件下: 2{CH2O}+SO42-+H+ —→2CO2+HS-+2H2O

  15. 淀粉氧化降解: 微生物 C6H10O5 + 6O2 → 6CO2 + 5H2O

  16. Chap.2 marine oxygen-demanded organic pollution 2.1 source and character 2.2 the index of oxygen-demanded organic pollution 2.3 consume and absorb of oxygen 2.4 analysis of examples

  17. 2.2 the index of marine oxygen-demanded pollution • BioChemical Oxygen Demand(BOD) • Chemical Oxygen Demand(COD) • Ultimate Oxygen Demand(UOD) • Theoretical Oxygen Demand(TOD)

  18. 2.2 the index of marine oxygen-demanded pollution Biochemical oxygen demand (BOD) • BOD test: the most commonest and most versatile measure of broad effect.

  19. 2.2 the index of marine oxygen-demanded pollution BioChemical Oxygen Demand(BOD) • definition: BioChemical Oxygen Demand(BOD),表示水中有机物质由微生物分解所需溶解氧的量。单位为mg-O2/l。 • 含义: 表示可氧化分解水体中所溶存的含碳有机物,也包括化学氧化法难以氧化的含N和P的有机物质。它在一定程度上可以反映水体中有机物质含量。

  20. 2.2 the index of marine oxygen-demanded pollution • If an organic compound gives the same oxygen demand for TOD, COD and BOD, it is readily oxidized and metalolized.

  21. 2.2 the index of marine oxygen-demanded pollution • Chemical oxygen demand (COD) : The amount of oxygen taken up when hot acid dichromate is used. • COD: often used because it is rapidly and can be used in short-term quality control. • For more resistant compounds, COD will be a fraction of TOD, and this depends on the efficiency of this method of oxidation.

  22. 2.2 the index of marine oxygen-demanded pollution • BOD depends on the following condition: • The particular blend of nutrients and other assessory factors in the basal medium. • The presence of natural inhibitors. • The condition and composition of microbial population present.

  23. 2.2 the index of marine oxygen-demanded pollution Calculation of BOD • The biochemical oxidation is belong to the first dynamic reaction,which can be shown as following equation: • dL/dt = k1 · L • 积分得Lt = L · e k1·t • L :总的BOD(mg/l); • Lt:t时刻的BOD(mg/l); • t :时间(d); • k1 : 耗氧常数(d-1) 

  24. 2.2 the index of marine oxygen-demanded pollution • 经过t时后,被微生物氧化分解的有机物量(Y): Y = L- Lt = L - L · e k1 ·t Y = L (1  e – k1·t) BOD5 = BODT·(1- e-K · t)

  25. 2.2 the index of marine oxygen-demanded pollution L、Lt、Y的关系

  26. 2.2 the index of marine oxygen-demanded pollution As an important index for assessment of water quality, normally 5 days at 20℃ is used; BOD520。This is the usual duration at a more suitable incubation temperature.

  27. 2.2 the index of marine oxygen-demanded pollution L、Lt、Y的关系

  28. 2.2 the index of marine oxygen-demanded pollution BOD5 = BODT·(1- e- K1·t) 说明: • 单位为mg/l; • (BOD520)中上标为温度(℃),下标为氧化分解的时间(d)。 • 在应用中,BOD520常简写为BOD5或BOD。 • BOD5是海水水质的重要指标。水体中BOD5高,表征水体中需氧有机物浓度高。

  29. 2.2 the index of marine oxygen-demanded pollution • Sometimes, We can use BOD measured in a time less than 5 days: BOD520=1.171×BOD230 (《海洋监测规范》)

  30. 2.2 the index of marine oxygen-demanded pollution The influence of temperature • 耗氧常数k除与有机物质种类、细菌微生物种类数量有关外,还与温度有关。K(T)= K(20)×〔1.047(T-20)〕 K(T)、K(20):分别代表T℃和20℃时耗氧常数。 • 此外,总的BOD与温度有关:LT = L20×〔1+0.02(T-20)〕 LT、L20:分别代表T℃和20℃总的BOD.

  31. 2.2 the index of marine oxygen-demanded pollution The quality standard of seawater (GB 3097-1997)

  32. 2.2 the index of marine oxygen-demanded pollution 例题1:某排污口污水水样,在20℃下测得BOD为208 mg/l,若K为0.1d-1,求BOD5值。 • 解: BOD5 = BODT·(1- e-K1t) = 208×(1 - e-0.15×5) = 110 mg/l 答:该生活污水BOD5值为110 mg/l 。

  33. 2. 实验室测得某工业废水BOD为750毫克/升,20℃时净化常数K1为0.20/天,计算BOD205,若K1降为0.10天,求BOD205。 解: BOD5 = BODT·(1- e-K1t) K1=0.2时,BOD5 = 750×(1- e-0.2×5) = 474 mg/l K1=0.1时,BOD5 = 750×(1- e-0.1×5) = 295 mg/l 答:当K1值分别为0.2和0.1/d时,水样BODT分别为474和295 mg/l。

  34. 2.2 the index of marine oxygen-demanded pollution 生化耗氧量(BOD)的优缺点 • 优点:在一定程度上可以反映水体中有机物质含量。 • 缺点:实验耗时长,不利于较快掌握水质污染情况;测定局限在实验室内进行,与天然水的差别较大。

  35. 2.2 the index of marine oxygen-demanded pollution • BioChemical Oxygen Demand(BOD) • Chemical Oxygen Demand(COD) • Ultimate Oxygen Demand(UOD) • Theoretical Oxygen Demand(TOD)

  36. 2.2 the index of marine oxygen-demanded pollution 2. Chemical Oxygen Demand) • 定义:化学耗氧量(mg/l),也称化学需氧量,化学耗氧量是用化学氧化剂(如重铬酸钾(CODcr)、高锰酸钾(CODMn))在一定条件下氧化水中有机污染物质所耗的氧量。 • CODCr:污水和河水的重要监测指标; CODMn:海水的监测指标。

  37. 2.2 the index of marine oxygen-demanded pollution The quality standard of seawater (GB 3097-1997)

  38. 2.2 the index of marine oxygen-demanded pollution • The method of BOD was often criticized but nevertheless it is still used widely by pollution chemist,why? • Because it gives a measure of biodegradability not only for substance that we have known, but also of complex waste we still de not know.

  39. 2.2 the index of marine oxygen-demanded pollution • No chemical oxidation gives a degree of oxygen demand for the range of components involved which even approximately equal that attained in biological systems.

  40. 2.2 the index of marine oxygen-demanded pollution • 由于复杂有机物或含氮有机物较难用化学方法氧化,所以当水体的COD和BOD5的关系未确定之前,仍不好用COD直接代替BOD5。

  41. 2.2 the index of marine oxygen-demanded pollution • BioChemical Oxygen Demand(BOD) • Chemical Oxygen Demand(COD) • Ultimate Oxygen Demand(UOD) • Theoretical Oxygen Demand(TOD)

  42. 2.2 the index of marine oxygen-demanded pollution 3. Ultimate Oxygen Demand • 定义:水中有机物质(包括含C和含N有机质)氧化的理论需氧量,即称之为极限需氧量(UOD),或长期需氧量。此时,水体中所有有机物质均被完全氧化生成CO2、H2O和NO3-。 • Equation for calculation of UOD: UOD = 2.67×org.-C + 4.57×(org.-N +NH3-N)+1.14×NO2-N

  43. 2.2 the index of marine oxygen-demanded pollution • BioChemical Oxygen Demand(BOD) • Chemical Oxygen Demand(COD) • Ultimate Oxygen Demand(UOD) • Theoretical Oxygen Demand(TOD)

  44. 2.2 the index of marine oxygen-demanded pollution 4. Theoretical Oxygen Demand • TOD: the theoretical oxygen demand is the chemical value for oxygen required for the theoretical conversion of all the component atoms of organic residues to carbon dioxides to their normal oxides. It is of no account which route for oxidation are possible or can be envisaged; the final product should be defined.

  45. 2.2 the index of marine oxygen-demanded pollution 4. Theoretical Theoretical Oxygen Demand • 测定方法:化学燃烧氧化法。 • 单位:mg-O2/l。 • 目前用燃烧法测定,TOD的结果相当于理论值的90~100%。

  46. 2.2 the index of marine oxygen-demanded pollution • TOD: the theoretical oxygen demand is the chemical value for oxygen required for the theoretical conversion of all the component atoms of organic residues to carbon dioxides to their normal oxides. It is of no account which route for oxidation are possible or can be envisaged; the final product should be defined.

  47. 2.2 the index of marine oxygen-demanded pollution Homework1: • 习题1、3、5、6、7、10、11。

  48. Thank you for your attention!

  49. 第二章 海洋需氧有机物污染 2.1 来源与污染特点2.2 需氧有机污染的指标2.3 溶解氧的收支平衡2.4 案例分析

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