Increase In Total Organic Carbon Research Articles

Poly(triacontamethylene triacontanedioate) as polyethylene analogue: Properties and enzymatic degradation

AbstractDiethyl triacontanedioate (CH3CH2O2C(CH2)28CO2CH2CH3) and triacontane‐ 1,30‐diol (HO(CH2)30OH) were prepared and condensed to synthesize poly(triacontamethylene triacontanedioate) (PTRM). The properties of (PTRM) were compared with those of commercial low density polyethylene (LDPE), and enzymatic degradation of the PTRM was investigated. PTRM showed not only high melting point of 113°C and a thermal stability comparable to LDPE. The elongation at break is low (about 5%) and the tensile strength is around 12.5 MPa, higher than that of LDPE. The small contact angles indicate that PTRM has good wettability compared with LDPE. The increase of total organic carbon by Rhizopus arrhizus lipase and the resulting change of surface morphology confirmed that PTRM is biodegradable.

Latest Paleocene benthic foraminiferal extinction and environmental changes at Tawanui, New Zealand

A major extinction of intermediate‐water (500–1000 m) benthic foraminiferal species coincided with a major decrease in δ13C (2.8‰) of terrestrial organic matter (n‐C29 alkane) and δ34S (20‰) of whole rock sulfide in a continuous siltstone sequence in the Tawanui Section (46°S paleolatitude) along the Akitio River, southeastern North Island, New Zealand, in the middle part of the uppermost Paleocene nannofossil zone (CP8). The benthic extinction (25% of species) occurred over ∼3 kyr at ∼55.5 Ma. Increases in kaolinite/illite and kaolinite/smectite ratios and in terrestrial organic carbon percentages started ∼3 kyr before the major benthic extinctions, lasted over ∼40 kyr, and probably reflect warmer climate and increased rainfall. The productivity of planktonic foraminifera and calcareous nannoplankton decreased ∼3 kyr prior to the major extinctions and recovered at the time of benthic extinctions. These events that started ∼3 kyr before the extinction can be best explained by warming, increased rainfall, reduced salinity of surface waters, and increased influence of warm saline deep water (WSDW). Benthic foraminiferal oxygen indices indicate a strong decrease in dissolved oxygen levels within the intermediate water from low oxic (1.5–3.0 mL/L O2) to suboxic (0.3–1.5 mL/L O2) conditions coinciding with the benthic extinctions. Increases in total organic carbon (TOC) and in the hydrocarbon‐generating potential of kerogen (measured as the hydrogen index (HI)) agree with the interpretation of decreased dissolved oxygen levels of the intermediate water. The lowest oxygen conditions lasted ∼40 kyr and coincided with a decrease in calcareous benthic foraminiferal productivity, highest TOC levels, and lowest δ13C of terrestrial organic carbon. Dominant formation of WSDW or sluggish intermediate‐water circulation caused by warming and high rainfall in high‐latitude areas most likely led to the ∼3‐kyr time lag between events on land and in surface waters preceeding the extinction and the development of dysaerobia in the sea, coinciding with the major benthic extinction and decrease in δ13C and δ34S in New Zealand. Global warming of deep and intermediate waters may have caused decomposition of methane hydrate in sediments, resulting in a strongly decreased δ13C of marine carbonates, promoting dysaerobia in the ocean, and warming global climate by increased methane concentrations in the atmosphere. Upwelling of WSDW, occurring soon after it became dominant in high‐latitude areas, is likely responsible for the recovery of normal salinity and the concomitant recovery of planktonic foraminifera and calcareous nannoplankton productivity in high‐latitude surface waters. Minor benthic foraminiferal extinctions (9% of species) occurred ∼40 kyr after the major extinctions, lasted ≤ ∼6 kyr, and coincided with the initiation of environmental recovery.

LEACHING ASPECTS OF OIL SLUDGE BIODEGRADATION IN SOIL1

Efficient disposal of waste oil sludges by biodegradation in soil (“land farming”) requires management practices that include fertilizer addition. The effect of such practices on soil leachate quality was studied in lysimeter columns containing 5 percent (wt/wt) hydrocarbon in a soil-sand mixture. Fertilizer was added in various formulations at a carbon:nitrogen and carbon:phosphorus ratio of 200:1 and 2640:1, respectively. As expected, undegraded hydrocarbons did not appear in the leachate, nor was phosphate eluted from the limed soil-sand mixture. A very moderate increase in total organic carbon of the leachate occurred due to hydrocarbon biodegradation. When nitrogen was applied as urea or as a urea-paraffin adduct, 23 and 19 percent of the added nitrogen were eluted in the leachate, respectively. No nitrogen appeared in the leachate when nitrogen was applied as urea formaldehyde. The above results and additional cited reports indicate that judiciously located and operated land-farming sites are not likely to endanger underground aquifers.

The Effect of Anaerobically Digested Sewage Sludge on Organic Fractions of Blount Silt Loam

AbstractLysimeters containing Blount silt loam (Aerie ochraqualf) were furrow irrigated with 298 metric tons/ha (as solids) of anaerobically digested sludge over the 6‐year period from May 1969 through April 1975. Soil organic carbon in the top 15 cm increased from 0.95 to 2.29% over this period. The greatest proportionate change among fractions of organic carbon was observed in the oil and grease fraction, which increased from 1.67 to 11.9% of the total soil organic carbon. No significant differences were observed between control and treated plots below the 30 cm level for any of the fractions except water‐extractable carbon. All organic fractions significantly increased with respect to control plots in leachate water sampled in 1975. Increases in total organic carbon due to sludge application were two‐ to threefold, from a minimum of 12.5 mg/liter in control plots to a maximum of 32.0 mg/liter in sludge‐treated plots. Carbohydrate carbon showed the greatest change among leachate‐water fractions, increasing from a high of 2.9 mg/liter for control plots to a high of 12.4 mg/liter for treated plots.