Carbon, organic

Not only the quantity but also the quality of organic matter has been shown to influence bioavailability (Karickhoff et al., 1979). Sediment organic carbon provides a primary food source for benthic organisms. DeWitt et al. (1992) found that sediment pore water partitioning and toxicity of fluoranthene to the amphipod, Rheopyxinius abronius, were affected by sediment organic matter quality. 

FIGURE 14.4 EC size distribution measured inside a tunnel in southern California. The distribution corresponds to the primary particles emitted by automobiles. (Reprinted with permission from Venkataraman, C. and Friedlander, S. K. Size distributions of polycyclic hydrocarbons and elemental carbon. 1. Sampling, measurement methods and source characterization. Environ. Sci. Technol. 28. Copyright 1994 American Chemical Society.) 

2K2Cr207 + 8H2SO4 + 30--- 2K2SO4 + 20r2(S04)g + 8H2O + 3OO2 

2FeS04(NH4)2 SO4. I2H2O + H2SO4 + O Action of diphenylamine indicator 

C6H5N-C6H4C6H4N-C6H5 diphenyl benzidine (violet) 

FeS04(NH4)2 SO4.6H2O, in water. Add 25 ml of concentrated H2SO4 and dilute to one litre. 

Diphenylamine indicator-. Dissolve 0.5 g of diphenylamine in a mixture of 100 ml cone, sulphuric acid and 20 ml distilled water, and store in a coloured bottle. 

---

The commercialization by Kureha Chemical Co. of Japan of a new, highly attrition-resistant, activated-carbon adsorbent as Beaded Activated Carbon (BAC) allowed development of a process employing fluidized-bed adsorption and moving-bed desorption for removal of volatile organic carbon compounds from air. The process has been marketed as GASTAK in Japan and as PURASIV HR (91) in the United States, and is now marketed as SOLD ACS by Daikin Industries, Ltd. 

Several methods have been developed to estimate the oxygen demand in waste water treatment systems. Commonly used laboratory methods are biochemical oxygen demand (BOD), chemical oxygen demand (COD), total oxygen demand (TOD), total organic carbon (TOC), and theoretical oxygen demand (ThOD). 

Chemical composition data for CPM and FPM for a variety of locations are summarized in Table 5. These data illustrate several important points. First, the distributions of the PM q between CPM and FPM vary from about 0.4 to 0.7. Second, the ratio of PM q to TSP varies from 0.58 to 0.79. In general, both this ratio and the ratio of FPM to PM q tend to be higher at mral sites, but Bermuda, because of the large influence of sea salt in the CPM, is an exception. Sulfate (SO ), carbon (as organic carbon, OC, and elemental carbon, EC), and nitrate (NO3 ) compounds generally account for 70—80% of the FPM. In the eastern United States, compounds are the dominant species, although very Httie is emitted directiy into the atmosphere. Thus... 

The proposed mechanism by which chlorinated dioxins and furans form has shifted from one of incomplete destmction of the waste to one of low temperature, downstream formation on fly ash particles (33). Two mechanisms are proposed, a de novo synthesis, in which PCDD and PCDF are formed from organic carbon sources and Cl in the presence of metal catalysts, and a more direct synthesis from chlorinated organic precursors, again involving heterogeneous catalysis. Bench-scale tests suggest that the optimum temperature for PCDD and PCDF formation in the presence of fly ash is roughly 300°C. 

Although httie or no reduction in total organic carbon occurs during ozonation, partially oxidized polar compounds (containing, COOH,... 

Fig. 3. pH Dependence of total organic carbon (TOC) decay during the photooxidation of a landfill leachate using H2O2/uv. Initial TOC concentration,... 

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

Because many studies have shown a direct relationship between pesticide sorption and organic carbon content of sod, attempts have been made to develop a universal sorption coefficient based on sorption of the pesticide to sod organic carbon (44). Sorption based on sod organic carbon is expressed as C, where is pesticide sorbed per unit mass sod organic carbon, and C is pesticide solution concentration after equdibration. If. is the fraction of organic carbon, can be obtained from i in the equation. Assumptions in the use of this approach include... 

Indirect methods of estimating sorption have been used when actual measurement of sorption isotherm is impossible (44). For instance, sorption coefficients have been estimated from soil organic carbon and a specific surface of soil, and from semiempidcal equations using pesticide properties. 

Cychc carbonates result from polyols by transesterification using organic carbonates (115). Thus sorbitol and diphenylcarbonate in the presence of dibutyl tin oxide at 140—150°C form sorbitol tricarbonate in quantitative yield (116). 

It is important to identify volatile organic carbon (VOC) and the presence of specific priority poUutants, ia additioa to the total organic content. The... 

Table 3. Oxygen Demand and Organic Carbon of Industrial Wastewaters...

Recent air pollution regulations limit the amount of volatile organic carbon (VOC) that can be discharged from wastewater treatment plants. Benzene is a particular case in which air emission controls are required if the concentration of benzene in the influent wastewater exceeds 10 mg/L. 

Organic Carbon. The total organic carbon (TOC) in a water sample is determined by injecting a microliter sample into a heated, packed tube in a stream of oxygen. The water is vapori2ed and carbon is converted to carbon dioxide, which is detected with a nondispersive infrared analy2er. 

HAZVVOPER Hazardous waste operators TOC Total organic carbon... 

---