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Endogenous contamination from the newly submerged sediment may have an impact on the water quality of the Danjiangkou Reservoir, the water source of the middle route of the South-to-North Water Diversion Project. In this study, in situ sediment samples were collected at different locations (Guojiashan (DJK1), Kongqueyuan (DJK2), Shijiagou (DJK3), Shiqiao Wharf (DJK4), and Songgang Wharf (DJK5) from the north to the south) of the Danjiangkou Reservoir and the upstream tributary using a columnar sediment sampler and statically cultured in laboratory, and the distribution and release of endogenous N and P from the sediment were investigated based on a double-membrane diffusion model. The results showed that the P contents in the main reservoir and the upstream tributary followed the order of inorganic phosphorus IP > organic phosphorus OP > calcium − phosphorus Ca − P > iron − phosphorus Fe − P > labile phosphorus LP . IP accounted for the largest proportion (47.10-59.70%) of total phosphorus (TP), while LP accounted for only a small proportion (0.10-0.90%) of TP. There is a significant difference in the spatial distribution of P at different sampling points, especially for the OP content (226.90 mg·kg-1) with a coefficient of variation of 26.90%. The contents of different forms of P and NH4+-N decreased from the upstream tributary to the main reservoir, which was mainly attributed to the land use type. In the vertical distribution, the contents of different forms of P in DJK4 and DJK5 decreased with the increase of sediment depth. The contents of NH4+-N and PO43--P in the sediment interstitial water of DJK4 and DJK5 were higher than those in the overlying water. In addition, the contents of NH4+-N and PO43--P were higher in DJK5 than that in DJK4. The static culture experiments showed that N and P were mainly released from the sediment-overlying water interface to the overlying water. The release rate of NH4+-N and PO43--P ranged from 13.08 mg·(m2·d)-1 to 21.39 mg·(m2·d)-1 and from 3.06 mg·(m2·d)-1 to 6.02 mg·(m2·d)-1, and the release amount calculated based on the double-membrane diffusion model was 1.17 × 10 3 t·a-1 and 0.53 × 10 3 t·a-1, respectively. Thus, endogenous contamination from the newly submerged land is an important factor affecting the water quality of the Danjiangkou Reservoir.

The effect of adding rice husk as an electron donor on the genetic and metabolic diversity of denitrifying communities in a long-term flooded constructed wetland (D1) was compared with the control group without external carbon source addition (D2). The underlying molecular mechanisms responsible for nitrate removal were quantified under different nitrate loading rates. The results showed that D1 achieved higher and more stable removal efficiencies for NO3−-N (90–97%) and total nitrogen (73–87%) under different nitrate loading rates, which were approximately 10 times higher than those of D2. This corresponded with much higher absolute abundances of bacterial and nitrogen functional genes in D1 than D2. Additionally, the vertical distribution of microbial communities in D1 and D2 showed significant differences. This pattern suggested that adding rice husk in flooded CWs had beneficial effects on the denitrifying community. Quantitative response relationships and network analysis indicated that denitrification was the dominant nitrogen removal pathway. Moreover, the present study indicated that using rice husk as an external carbon source could be conducive to completing the nitrification process, which was first confirmed at the molecular level. The present study indicated that using rice husk as an external carbon source can significantly enhance denitrification rates and thus improve nitrogen removal in CWs for wastewater treatment process.

Microbial denitrification is a main source of nitrous oxide (N2O) emissions which have strong greenhouse effect and destroy stratospheric ozone. Though the importance of sulfide driven chemoautotrophic denitrification has been recognized, its contribution to N2O emissions in nature remains elusive. We built up long-term sulfide-added microcosms with sediments from two freshwater lakes. Chemistry analysis confirmed sulfide could drive nitrate respiration in long term. N2O accumulated to over 1.5% of nitrate load in both microcosms after long-term sulfide addition, which was up to 12.9 times higher than N2O accumulation without sulfide addition. Metagenomes were extracted and sequenced during microcosm incubations. 16 S rRNA genes of Thiobacillus and Defluviimonas were gradually enriched. The nitric oxide reductase with c-type cytochromes as electron donors (cNorB) increased in abundance, while the nitric oxide reductase receiving electrons from quinols (qNorB) decreased in abundance. cnorB genes similar to Thiobacillus were enriched in both microcosms. In parallel, enrichment was observed for enzymes involved in sulfur oxidation, which supplied electrons to nitrate respiration, and enzymes involved in Calvin Cycle, which sustained autotrophic cell growth, implying the coupling relationship between carbon, nitrogen and sulfur cycling processes. Our results suggested sulfur pollution considerably increased N2O emissions in natural environments.

Increased nitrous oxide (N2O) in the atmosphere is of global concern. Biofiltration has been studied for gaseous nitrogen treatments in drinking water environments; however, the molecular mechanisms mediating N2O accumulation in denitrification biofilters have not been quantified. Five denitrification biofilters were developed in this study and all achieved high removal efficiencies for total nitrogen (TN: 72.4–92.7%), nitrate nitrogen (NO3−-N: 88.6–98.2%) and chemical oxygen demand (COD: 79.3–90.0%) across a low-temperature gradient (5–25 °C). Denitrification coupling with anaerobic ammonium oxidation (ANAMMOX) and dissimilatory nitrate reduction to ammonium (DNRA) processes yielded the presently robust treatment performance. Nitrite availability limited TN removal at 5–15 °C. Our findings indicate that temperature affected N2O accumulation indirectly by controlling the balance of nitrite versus N2O reductase carrying microorganisms. In addition, our results demonstrated that genetic association was an important index reflecting the relative intensity of N2O accumulation at low temperatures.

Heterotrophic denitrification is usually inhibited by insufficient carbon sources; however, the underlying mechanisms responsible for nitrous oxide (N 2 O) accumulation within denitrification at low carbon:nitrogen (C/N) ratios have not been quantified from a molecular level. In this study, five denitrification biofilters were developed and exhibited efficiency (total nitrogen: 18.5%–92.2%; nitrate nitrogen: 42.9%–99.5%; chemical oxygen demand: 50.5%–93.7%) in remediating micro-polluted water with C/N ratios ranging between 0.65 and 3.0. A combined analysis revealed that the coupling of anaerobic ammonium oxidation (ANAMMOX) and denitrification accounted for N 2 O accumulation in the biofilters, and the key drivers of the N 2 O accumulation rates were qnorB/nirK , nosZ/(narG + napA) , amx/(nirS + nirK) , narG/bacteria and qnorB/bacteria . Our study demonstrated that genetic association was indicative of microbial processes relative to nitrogen cycling and reflected N 2 O flux within denitrification biofilters at low C/N ratios.

Nitrogen removal through microorganisms is the most important pathway in constructed wetlands (CWs). In this review, we summarize the microbial coupling mechanisms of nitrogen removal, which are the common methods of nitrogen transformation. The electron pathways are shortened and consumption of oxygen and energy is reduced during the coupling of nitrogen transformation functional microorganisms. The highly efficient nitrogen removal mechanisms are cultivated from the design conditions in CWs, such as intermittent aeration and tidal flow. The coupling of microorganisms and substrates enhances nitrogen removal mainly by supplying electrons, and plants affect nitrogen transformation functional microorganisms by the release of oxygen and exudates from root systems as well as providing carriers for microbial attachment. In addition, inorganic elements such as Fe, S and H act as electron donors to drive the autotrophic denitrification process in CWs.

Effects of Cu(II) and Cr(III) ions on the binding of Al(III) onto Dissolved Organic Matter (DOM) exemplified by Suwannee River Humic Acid (SRHA) at pH 6.0 were quantified in this study using linear and log-transformed SRHA absorbance spectra acquired at varying Al(3+) concentrations and Cu(2+) or Cr(3+) levels. The competition between Al(3+) and Cu(2+)/Cr(3+) for the binding sites in DOM was ascertained by examining the intensity and shapes of the metal-specific differential spectra of DOM. The results indicated that the binding of Al(3+) onto SRHA is little influenced in the cases of in presence of 1.0 and 10.0 μM background Cr(3+) and in presence of 1.0 μM background Cu(2+), but it is significantly depressed in presence of 10.0 μM Cu(2+). Changes of the spectral slope of the log-transformed absorbance spectra in the 350-400 nm wavelength range (S350-400) were unambiguously correlated with the total amount of DOM-bound metals. The concentrations of Me-DOM complexes were determined using the NICA-Donnan Model. The results demonstrate that differential absorbance measurements provide quantitatively interpretable information concerning the nature and mechanisms of metal-DOM interactions and effects of metal cations competition on these processes.

A denitrification biofilter (DB), developed for the remediation of groundwater in this study, operated with increased removal efficiencies of total nitrogen (TN, 35.1–93.2%), nitrate ( N O 3 − – N , 61.6–97.7%), and chemical oxygen demand (COD, 43.2–82.4%) as hydraulic retention time (HRT) increased from 0.5 h to 4.0 h. Declined denitrification rates of N O 3 − – N (123.1–24.9 g/(m3 h)), N O 2 − – N (52.6–1.5 g/(m3 h)), NO (22.9–3.2 mg/(m3 h)) and N2O (64.8–11.1 g/(m3 h)), were observed with increased HRTs from 0.5 h to 4.0 h. Gene abundances (total bacterial 16S rRNA, anaerobic ammonium oxidation (anammox) bacterial 16S rRNA, archaeal 16S rRNA, narG, napA, nirK, nirS, qnorB and nosZ) were estimated and their relative importance in denitrification rates were quantified based on path analyses. As a result, the ratio (napA + narG)/(nirK + nirS), followed by nosZ/bacterial 16S rRNA were the main drivers for the transformation of N O 3 − – N and N O 2 − – N , while (napA + narG)/(nirK + nirS), followed by nosZ/narG dominated the accumulation of NO and N2O. In the content of environmental changes, this study suggests that gene associations integrating denitrification rates and recent environmental changes are valuable index reflecting variations in denitrification processes in groundwater restoration.

The present study investigated long-term treatment performance and nitrogen transformation mechanisms in tidal flow constructed wetlands (TFCWs) under 4, 8, and 12 °C temperature regimes. High and stable ammonium (NH4(+)-N) removal efficiency (93-96%) was achieved in our TFCWs, whereas nitrate (NO3(-)-N) was accumulated at different levels under different temperatures. Quantitative response relationships showed anammox/amoA, (narG+napA)/amoA, and (narG+napA)/bacteria were the respective key functional gene groups determining 4, 8, and 12 °C NO3(-)-N reduction. Pathway analysis revealed the contribution of these functional gene groups along a depth gradient. In addition, denitrification process increased, while anammox process decreased consistent with a rise in temperature from 4 to 12 °C. Furthermore, cold temperatures exhibited different effects on anammox and denitrification and their long-term acclimatization capacities changed with temperature.

Excessive nitrogen (N) loadings from human activities have led to increased eutrophication and associated water quality impacts in China's coastal wetlands. Denitrification accounts for significant reduction of inorganic N to nitrous oxide (N2O) or dinitrogen gas (N2), and thereby curtails harmful effects of N pollution in coastal and marine ecosystems. However, the molecular drivers and limiting steps of denitrification in coastal wetlands are not well understood. Here, we quantified the abundances of functional genes involved in N cycling and determined denitrification rates using 15N paring technique in the coastal wetland sediments of Bohai Economic Rim in eastern China. Denitrification accounting for 80.7 ± 12.6% of N removal was the dominant pathway for N removal in the coastal wetlands. In comparison, anaerobic ammonium oxidation (ANAMMOX) removed up to 36.9 ± 7.3% of inorganic N. Structural equation modeling analysis indicated that the effects of ammonium on denitrification potential were mainly mediated by the relative abundances of nosZ/nirS, nirS/(narG + napA) and amoA/nirK. Denitrification was limited by the relative strength of two steps, namely N2O reduction to N2 and nitrite (NO2−) reduction to nitric oxide (NO). Our results suggest that the relative abundances of functional genes which are more stable than sediment chemical compounds in the context of environmental changes are indictive of denitrification potential in coastal wetlands.

The present study explored the treatment performance and nitrogen removal pathways in a multimedia biofilter treating micro-polluted source water under hydraulic loading rate (HLR) constraints, ranging from 0.5 to 3.0 m3/m2 d. High and stable chemical oxygen demand (COD) (97.7–99.1%) and ammonium (NH4+-N) (76.3–90.9%) removal efficiency were simultaneously achieved. Results showed that an HLR exceeding 2.5 m3/m2 d was required to achieve complete denitrification without NO3−-N accumulation in the biofilter. Molecular biological analyses showed that nitrification and anaerobic ammonium oxidation were the dominant NH4+-N removal pathways in the biofilter. Quantitative analysis demonstrated that the key functional gene groups for NH4+-N transformation process rate were amoA/archaea, nxrA/archaea, and (nirS + nirK)/anammox. Furthermore, nxrA/archaea contributed the most to the NH4+-N transformation rate, followed by (nirS + nirK)/anammox, and amoA/archaea. The results support that archaea potentially play vital roles in the nitrogen removal pathways, and nitrogen transformation pathways are coupled at the molecular level (i.e., the functional gene level).

An adsorbent, volcanic rocks coated with α-Fe2O3 nanoparticles, was prepared and utilized for the removal of Cu(II) and Ni(II) ions from an aqueous solution. Characterization of the coated volcanic rocks indicated that the α-Fe2O3 nanoparticles were successfully and homogeneously distributed on the volcanic rocks, including penetration into rock pores. Batch experiments were conducted to investigate adsorption performance. The adsorption behavior of both ions was found to best fit a pseudo second-order model and Langmuir isotherm. The maximum adsorption capacities of Cu(II) and Ni(II) ions were 58.14 mg g−1 and 56.50 mg g−1 at 293 K, respectively, and increased with rising temperature. The loaded α-Fe2O3 nanoparticles onto volcanic rock significantly increased removal of Cu(II) and Ni(II) ions. The adsorption process was combined control of film diffusion and intra-particle diffusion. Adsorption thermodynamics indicated the adsorption process was spontaneous and occurred mainly through chemisorption. The results confirmed that the volcanic rocks coated with α-Fe2O3 nanoparticles acted as a high-efficiency and low-cost absorbent, and effectively removed Cu(II) and Ni(II) from wastewater.

The present study explored treatment performance and nitrogen removal mechanisms of a single-stage tidal flow constructed wetland (TFCW) under flooded time ranging from 12 to 48 h. The TFCW achieved high and stable COD (77–94%), NH 4 + –N (55–82%), and TN (60–84%) removal efficiencies simultaneously, without costly aeration. Quantitative response relationships between nitrogen transformation rates and nitrogen functional genes were established, and these relationships confirmed that, under the FT constraints, the anammox 16S rRNA was the key factor of the NH 4 + –N transformation rates, whereas, ( napA + narG ) was the key factor regulating the NO 3 − –N transformation rate. The analysis also revealed that the simultaneous nitrification, anammox, and denitrification (SNAD) process was the dominant nitrogen removal pathway in the TFCW.

The present study explored treatment performance and nitrogen removal mechanisms of a novel tidal flow constructed wetland (TF CW) under C/N ratios ranging from two to 12. High and stable COD (83-95%), [Formula: see text] (63-80%), and TN (50-82%) removal efficiency were simultaneously achieved in our single-stage TF CW without costly aeration. Results showed that a C/N ratio exceeding six was required to achieve complete denitrification without [Formula: see text] and [Formula: see text] accumulation in the system. Molecular biological analyses revealed aerobic ammonia oxidation was the dominant [Formula: see text] removal pathway when the C/N ratio was less than or equal to six. However, when the C/N ratio was greater than six, anammox was notably enhanced, resulting in another primary [Formula: see text] removal pathway, in addition to the aerobic ammonia oxidation. Quantitative response relationships between nitrogen transformation rates and nitrogen functional genes were established, and these relationships confirmed that different nitrogen transformation processes were coupled at the molecular level (functional genes), and collaboratively contributed to nitrogen removal in the TF CW. Specifically, [Formula: see text] transformation rates were collectively determined by amoA, nxrA, anammox, narG, nirS, nirK, and nosZ; and TN removal was influenced primarily by amoA and anammox.

The present study explored the distribution patterns of nitrogen micro-cycle genes and the underlying mechanisms responsible for nitrogen transformation at the molecular level (genes) in a biotrickling filter (biofilter). The biofilter achieved high removal efficiencies for ammonium (NH4(+)-N) (80-94%), whereas nitrate accumulated at different levels under a progressive NH4(+)-N load. Combined analyses revealed the anammox, nas, napA, narG, nirS, and nxrA genes were the dominant enriched genes in different treatment layers. The presence of simultaneous nitrification, ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were the primary factors accounted for the robust NH4(+)-N treatment performance. The presence of DNRA, nitrification, and denitrification was determined to be a pivotal pathway that contributed to the nitrate accumulation in the biofilter. The enrichment of functional genes at different depth gradients and the multi-path coupled cooperation at the functional gene level are conducive to achieving complete nitrogen removal.

The real-time polymerase chain reaction was used to quantitatively evaluate distribution patterns and nitrogen removal pathways of the amoA, nxrA, narG, napA, nirK, qnorB, nosZ, nas, and nifH genes and 16S rRNA in anaerobic ammonia oxidation bacteria in four multimedia constructed wetlands for rural wastewater treatment. The results indicated that the abundance of functional genes for nitrogen removal in the rhizosphere layer (0 to 30 cm), water distribution layer (30 to 50 cm), multime filler layer (50 to 130 cm), and catchment layer (130 to 170 cm) of the constructed wetlands were closely related. The rhizosphere layer was conducive to the absolute enrichment of dominant genes. The other three layers were favorable to the relative enrichment of rare genes.

An ultrasound-enhanced five-stage gradient elution system employing mixed solutions of Triton X-100 (TX100), sodium dodecyl benzenesulfonate (SBDS), and salt (abbr. MSTS) was used to elute super heavy oil from weathered soils. The use of ultrasound increased the elution of super heavy oil by 13–14% and improved first-stage dissolution and dispersion by 62%. However, the amount of super heavy oil dissolved or dispersed in the second through fifth elution stages was unchanged by the application of ultrasound. Saturated hydrocarbons were more quickly eluted in the first two stages. During the final three stages the order of elution for the four identified super heavy oil fractions was: asphaltenes > saturated hydrocarbons > aromatics > resins. A large number of elution stages aided in eluting markers containing a large number of C atoms in the absence of ultrasound. The elution at each stage was higher when ultrasound was employed, and ultrasound-enhanced elution is a potentially useful method for removing super heavy oil from weathered soils.

Ceramsite materials made from coal ash and modifiers such as sawdust, clinoptilolite, clay, and CaCO3 were prepared by pelletizing and high-temperature sintering to improve the adsorption to nitrogen and phosphorus. To incorporate Fe/C and Fe/Fe3C microelectrochemical cells, materials were also modified by the addition of metallic iron during the preparation process. Addition of more iron increased the Brunauer, Emmett, and Teller surface area and average pore diameter while decreasing the packing density and acid and alkali solubility. Examination using X-ray diffraction and X-ray fluorescence revealed that metallic iron modification also increased the abundance of Fe3C and FeC8 particles and electrochemical effects. Time required to reach adsorption equilibrium decreased with addition of iron. Ammonia nitrogen and phosphorus adsorption isotherms and kinetics for each ceramsite composition followed the Langmuir isotherm model in a similar second-order manner with respect to the amount of iron. R...

The multimedia biofilter achieved high and stable removal efficiencies for chemical oxygen demand (COD, 62–98%) and NH 4 + (68–98%) without costly aeration. Results revealed that lower CL (less than 13.9 g COD/m 3 d) and ACL (less than 2.8 g NH 4 + -N/m 3 d) or a C/N ratio exceeding five was required to reduce NO 3 − -N accumulation and NO/N 2 O emission. Integrated analyses indicated that the coupling of simultaneous nitrification, anammox and denitrification processes (SNAD) were the primary reason accounted for the enhanced NH 4 + -N treatment performance. NH 4 + -N removal pathways can be ranked as follows: nitrification ( amoA , archaeal) (54.6%) > partial denitrification ( nirS , nirK ) and anammox (37.8%) > anammox and partial denitrification ( narG , napA ) (12.6%). Specifically, NH 4 + -N removal was significantly inhibited by NO 2 − -N accumulation in the system (−21.6% inhibition). Results from stepwise regression analysis suggested that the NH 4 + removal rate was collectively controlled by amoA , archaeal, anammox, nirS , nirK , narG and napA .

A study was conducted of treatment performance and nitrogen transformation processes in a trickling filter (TF) used to treat micro-polluted source water under variable hydraulic loading rates (HLRs), ranging from 1.0 to 3.0 m(3)/m(2) d. The TF achieved high and stable COD (97.7-99.3%) and NH4(+)-N (67.3-92.7%) removal efficiencies. Nitrification and anaerobic ammonium oxidation were the dominant nitrogen removal processes in the TF. Path analysis indicated that amoA/anammox and amoA/(narG+napA) were the two key functional gene groups driving the major processes for NH4(+)-N and NO2(-)-N, respectively. The analysis also revealed that anammox/amoA and nxrA/(nirK+nirS) were the two key functional gene groups affecting processes associated with the NO3(-)-N transformation rate. The direct and indirect effect of functional gene groups further confirmed that nitrogen transformation processes are coupled at the molecular level, resulting in a mutual contribution to nitrogen removal in the TF.

An ultrasound-enhanced elution system employing water at a temperature of 70 degrees C was used to remedy weathered soils contaminated with severely biodegraded heavy oil (SBHO). The effect of varying the ultrasonic irradiation time from 0 to 1800 s on the elution of SBHO and three characteristic biomarkers (C(26-34) 17alpha 25-norhopanes, C(26-28) TAS, and C(27-29) MTAS) was analyzed using GC/MS, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Elution of the three biomarkers was closely related to the carbon number of the marker. C(26-34) 17alpha 25-norhopanes and C(26-28) TAS species with higher carbon numbers and C(27-29) MTAS species with lower carbon numbers were more readily eluted using sonication times of 1080-1800 s, while smaller TAS homologs were more readily eluted after sonication times of 0-360 s. SEM images of samples treated for longer periods revealed larger "bare patches" on the soil surface. The results of XRD and energy spectroscopy experiments indicated that ultrasound irradiation for 1080 s negatively affected the deposition of CaCO(3), but overall improved the mineral and chemical compositions of treated soils and removal of SBHO.

An ultrasound-enhanced elution system with Triton X-100 solution was used to remediate aging soils contaminated with super heavy oil. We used GC/MS, SEM, and X-ray diffraction (XRD) to analyze the effect of ultrasonic time (0-1800 s) on the elution of super heavy oil and its three characteristic biomarkers (C(26-34) 17alpha 25-norhopanes, C(26-28) triaromatic steroid [TAS], and C(27-29) methyl triaromatic steroid [MTAS]). The oil and biomarkers remaining in the treated soils followed similar second-order functions with increasing ultrasonication times. Biomarker elution was closely related to carbon numbers in the marker. For C(26-34) 17alpha 25-norhopanes, the smaller molecules were more readily eluted during 0-360 s ultrasound. This trend was reversed upon application of ultrasound during 1080-1800 s, with improved elution of larger molecules and elution followed a similar second-order function. For C(26-28) TAS, smaller molecules were more readily eluted but the elution of larger molecules followed a similar second-order function. For C(27-29) MTAS, elution of larger molecules was close to that of C(26-34) 17alpha 25-norhopanes. Results of SEM and XRD indicated that the mineral and chemical compositions of soils eluted at ultrasonication times of 1080-1800 s closely resembled clean soils.

An ultrasound-enhanced elution system using water at a temperature of 70 degrees C was employed to remove severely biodegraded heavy oil (SBHO) from weathered soil. The effect of varying the ultrasonic power density from 0 to 100 W L(-1) on the elution of SBHO and three characteristic biomarkers (C(26-34) 17alpha 25-norhopanes, C(26-28) triaromatic steroids (TAS), and C(27-29) methyl triaromatic steroids (MTAS) was analyzed using GC/MS, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The amount of SBHO and biomarkers present in the treated soils and eluent had significant negative correlation with increasing ultrasonic power density. Elution of the three biomarkers was closely related to the number of C atoms in the marker: C(26-34) 17alpha 25-norhopanes with more carbon numbers and MTAS homologs with less carbon numbers were more readily eluted at higher power densities. The smaller TAS species were more readily eluted at a power density of less than 60 W L(-1), while larger TAS species displayed improved elution at power densities greater than 60 W L(-1). SEM images of samples treated at higher power densities revealed a more compact SBHO accumulation layer at the water-soil interface. The results of XRD and energy spectroscopy experiments indicated that ultrasound at a power density of 20 W L(-1) was helpful for the formation and sedimentation of calcite, although this effect disappeared at higher power of greater than 60 W L(-1).

An ultrasound-enhanced elution system employing Triton X-100 solutions was used for remedying aging soils contaminated with super heavy oil. The effect of varying the ultrasonic power density on the elution of the oil and three characteristic biomarkers was analyzed using GC/MS and FTRS. The oil and biomarkers remaining in treated soils decreased as a similar first-order function of increasing ultrasonic power density. Elution of the three biomarkers in the absence of ultrasound was closely related to carbon numbers in the marker: smaller molecules were more readily eluted. This trend was reversed upon application of ultrasound at higher power densities, with improved elution of molecules containing a greater carbon numbers. The two ratios, both 22 S /(22 S + 22 R ) of C 26–34 17α 25-norhopanes and 20 S /(20 S + 20 R ) of C 26–28 triaromatic steroids, in treated soils decreased with increasing power density from 20 to 100 W L −1 . The results of SEM, FTRS, XRD, and energy spectroscopy experiments indicated that the mineral and chemical compositions of soils eluted at power densities greater than 60 W L −1 closely resembled clean soils.