Abrupt shift in the organic matter input to sediments in Lake Liangzi, a typical macrophyte-dominated shallow lake in Eastern China, and its response to anthropogenic impacts.

Understanding the historical variations in organic matter (OM) input to lake sediments and the possible mechanisms regulating this phenomenon is important for studying carbon cycling and burial in lake systems; however, this topic remains poorly addressed for macrophyte-dominated lakes. To bridge these gaps, we analyzed bulk OM and molecular geochemical proxies in a dated sediment core from Lake Liangzi, a typical submerged macrophyte-dominated lake in East China, to infer changes in OM input to sediments over the past 169 years due to the intensification of human activities in the catchment. A relatively primitive OM input pattern was observed in ca. 1841-1965, during which the lowest hydrogen index (HI), short-chain n-alkane abundance, and n-C17/n-C16 alkane indicated minimal input from phytoplankton, whereas the high Paq (proxy of aquatic macrophyte input) and long-chain n-alkane abundance suggested dominant and subordinate inputs from submerged and emergent macrophytes, respectively. OM input transitioned during ca. 1965-1993, with the highest Paq and lowest long-chain n-alkane abundance, indicating an increase of submerged macrophyte input and concurrent decline of emergent macrophyte input, probably caused by hydrological regulation practices and land reclamation in the 1960s, respectively. A further shift in OM input was observed since ca. 1993, characterized by the beginning of an increase in phytoplankton input, as indicated by the greater HI, short-chain n-alkane abundance, and n-C17/n-C16 alkane in sediments. Moreover, a lower Paq and higher abundance of long-chain n-alkanes indicated a decline in input from submerged macrophytes and an elevated input from terrestrial plants. The increase in αß-hopane abundance and homohopane index value indicated that petroleum-sourced OM was first introduced into the sediments. The causes of these OM input changes included nutrient influx associated with domestic and industrial discharge, aquaculture within the lake, and widespread deforestation and land clearance in the catchment.

Biodegradation of aliphatic and aromatic hydrocarbons by bacteria isolated from Bahregan area.

Environmental pollution with aromatic and aliphatic hydrocarbons caused by oil and petrochemical industries has very toxic and carcinogenic effects on living organisms and should be removed from the environment. In this research, after analyzing the oil sludge of the Bahregan area, it was found that most aliphatic paraffin compounds are related to octadecane, most liquid aliphatic compounds are related to hexadecane, and most aromatic compounds are related to naphthalene, phenanthrene, fluoranthene, and anthracene. Then, we investigated the ability of native bacteria from this area, such as Thalassospira, Chromohalobacter, and a bacterial consortium, to biodegrade the dominant aromatic and aliphatic hydrocarbons found in oil sludge. The results of Gas Chromatography-Mass Spectrometry analysis showed that among the tested hydrocarbon sources, Thalassospira can completely remove octadecane and hexadecane, and Chromohalobacter can reduce hexadecane from 15.9 to 9.9%. The bacterial consortium can completely remove octadecane and reduce hexadecane from 15.9 to 5.1%, toluene from 25.6 to 0.6%, and phenanthrene from 12.93 to 6%. According to the obtained results, the bacterial consortium effectively plays a role in the biodegradation of aromatic and aliphatic hydrocarbons, making it a viable solution for treating hydrocarbon pollutants in various environments.

Kerosene condenses in the trachea following inhalation.

PURPOSE: We have investigated the absorption dynamics of petroleum fuel components from the analytical results of autopsy samples. METHODS: Post-mortem samples of the severely burned case, including femoral blood, intratracheal contents (mucus) and intratracheal gas-phase samples were collected, and analysed by gas chromatography-mass spectrometer with head-space solid-phase microextraction. RESULTS: The composition of flammable substances in the tracheal gas phase differed slightly from that in mucus. CONCLUSION: High-boiling point components are retained in the trachea, whereas relatively lower-boiling point components are detected predominantly in the tracheal gas phase and blood.

Hydrocarbon markers for assessing the influence of human activities in the tropical semi-arid region (Acaraú River, state of Ceará, Brazil).

Coastal ecosystems are facing increasing anthropogenic stressors, including rapid urbanization rates and extensive fossil fuel usage. Nevertheless, the distribution of hydrocarbons in the Brazilian semi-arid region remains relatively uncharacterized. In this study, we analyzed ten surface sediment samples (0-2 cm) along the banks of the Acaraú River to assess the chronic contributions of aliphatic and aromatic hydrocarbons. The Acaraú River is a crucial riverine-estuarine area in the semi-arid region of Northeast Brazil. Ultrasound-assisted extraction and gas chromatograph coupled to a mass spectrometer were used to identify target compounds: 45 PAHs, 27 n-alkanes (C10-C38), and two isoprenoids. At most stations, the predominant grain size was sand, and the organic carbon content was less than 1%. The total n-alkanes concentration ranged from 14.1 to 170.0 µg g-1, while individual pristane and phytane concentrations ranged from not detected (nd) to 0.4 µg g-1 and nd to 0.7 µg g-1, respectively. These concentrations resemble those found in unpolluted sediments and are lower compared to samples from urbanized coastal areas. The total USEPA PAHs concentration varied from 157.8 to 1364 ng g-1, leading to the characterization of sediment samples as moderately polluted. Based on diagnostic ratios calculated from both alkane and PAH concentrations, the sediment samples were predominantly deriving from pyrolytic sources, with some contribution from petrogenic sources. The most abundant group was 5-ring PAHs (mean: 47.3 ± 36.7%), followed by 3-ring PAHs (mean: 17.9 ± 13.7%). This predominance indicates a pyrolytic origin of hydrocarbons in the Acaraú River. The concentrations reported here were representative of the level of background hydrocarbons in the region. Regarding the sediment quality assessment, BaP TPE calculated for the Acaraú River ranged from 13.2 to 1258.4 ng g-1 (mean: 409.3 ± 409.4 ng g-1). When considering site-specific sediment quality values for the coast of the state of Ceará, half of the stations are classified as strongly contaminated, and toxic effects are expected to occur (SQGq >0.25) for the ∑16 PAHs measured in the samples, especially due to dibenz [a,h]anthracene concentrations.

Cometabolic degradation mechanism and microbial network response of methanotrophic consortia to chlorinated hydrocarbon solvents.

The cometabolism mechanism of chlorinated hydrocarbon solvents (CHSs) in mixed consortia remains largely unknown. CHS biodegradation characteristics and microbial networks in methanotrophic consortia were studied for the first time. The results showed that all CHSs can efficiently be degraded via cometabolism with a maximum degradation rate of 4.8 mg/(h·gcell). Chloroalkane and chloroethylene were more easily degraded than chlorobenzenes by methanotrophic consortia, especially nonfully chlorinated aliphatic hydrocarbons, which were converted to Cl- with a production rate of 0.29-0.36 mg/(h·gcell). In addition, the microecological response results indicated that Methylocystaceae (49.0%), Methylomonas (65.3%) and Methylosarcina (41.9%) may be the major functional degraders in methanotrophic consortia. Furthermore, the results of the microbial correlation network suggested that interactive relationships constructed by type I methanotrophs and heterotrophs determined biodegradability. Additionally, PICRUSt analysis showed that CHSs could increase the relative abundance of CHS degradation genes and reduce the relative abundance of methane oxidation genes, which was in good agreement with the experimental results.

Guidelines for surfactant selection to treat petroleum hydrocarbon-contaminated soils.

The present study determined the most effective surfactants to remediate gasoline and diesel-contaminated soil integrating information from soil texture and soil organic matter. Different ranges for aliphatic and aromatic hydrocarbons (> C6-C8, > C8-C10, > C10-C12, > C12-C16, > C16-C21, and > C21-C35) in gasoline and diesel fuel were analyzed. This type of analysis has been investigated infrequently. Three types of soils (silty clay, silt loam, and loamy sand) and four surfactants (non-ionic: Brij 35 and Tween 80; anionic: SDBS and SDS) were used. The results indicated that the largest hydrocarbon desorption was 56% for silty clay soil (SDS), 59% for silt loam soil (SDBS), and 69% for loamy sand soil (SDS). Soils with large amounts of small particles showed the worst desorption efficiencies. Anionic surfactants removed more hydrocarbons than non-ionic surfactants. It was notable that preferential desorption on different hydrocarbon ranges was observed since aliphatic hydrocarbons and large ranges were the most recalcitrant compounds of gasoline and diesel fuel components. Unlike soil texture, natural organic matter concentration caused minor changes in the hydrocarbon removal rates. Based on these results, this study might be useful as a tool to select the most cost-effective surfactant knowing the soil texture and the size and chemical structure of the hydrocarbons present in a contaminated site.

n-Alkanes and n-Alkenes in Virgin Olive Oil from Calabria (South Italy): The Effects of Cultivar and Harvest Date.

n-Alkanes and n-alkenes are components of the unsaponifiable fraction of an olive oil. These were analysed by GC on-column analysis and are here proposed as an additional tool to certify the origin, authenticity, traceability and chemical quality of olive oil produced in the Reggio Calabria province (South Italy). Nine cultivars were studied: Cassanese, Coratina, Itrana, Leccino, Nociara, Ottobratica, Pendolino, Picholine and Sinopolese grown in the region of Calabria (South Italy). n-Alkanes in the range from 21 to 35 chain carbon atoms and alkenes in the range from 23:1 to 25:1 chain carbon atoms were found with the following elution order: heneicosane (C21), docosane (C22), tricosene (C23:1), tricosane (C23), tetracosene (C24:1), tetracosane (C24), pentacosene (C25:1), pentacosane (C25), hexacosane (C26), eptacosane (C27), octacosane (C28), nonacosane (C29), triacontane (C30), entriacontane (C31), dotriacontane (C32), tritriacontane (C33), tetratriacontane (C34), pentatriacontane (C35). The oil of all cultivars showed a decreasing trend in total n-alkane and n-alkene content, with the oil of Sinopolese showing the highest content, varying from 328.50 to 214.00 mg/kg. Odd-chain alkanes predominated over even-chain n-alkanes, and tricosane, tetracosane and pentacosane were the most represented alkanes. Cultivar and harvest date significantly influenced the n-alkane and n-alkene content. These findings can be useful to distinguish different olive cultivars and to decide the fruit harvest date for the oil of the Reggio Calabria province (South Italy). A daily quantity of 30 g of olive oil of the Sinoplese cv (the one with the highest n-alkane and n-alkene content) was found to be in accordance with the suggestions of the European Agency for the evaluation of medicinal products Committee for veterinary medicinal products and biogenic hydrocarbons intake for the human diet.

Discerning natural and anthropogenic organic matter inputs to salt marsh sediments of Ria Formosa lagoon (South Portugal).

Sedimentary organic matter (OM) origin and molecular composition provide useful information to understand carbon cycling in coastal wetlands. Core sediments from threors' Contributionse transects along Ria Formosa lagoon intertidal zone were analysed using analytical pyrolysis (Py-GC/MS) to determine composition, distribution and origin of sedimentary OM. The distribution of alkyl compounds (alkanes, alkanoic acids and alkan-2-ones), polycyclic aromatic hydrocarbons (PAHs), lignin-derived methoxyphenols, linear alkylbenzenes (LABs), steranes and hopanes indicated OM inputs to the intertidal environment from natural-autochthonous and allochthonous-as well as anthropogenic. Several n-alkane geochemical indices used to assess the distribution of main OM sources (terrestrial and marine) in the sediments indicate that algal and aquatic macrophyte derived OM inputs dominated over terrigenous plant sources. The lignin-derived methoxyphenol assemblage, dominated by vinylguaiacol and vinylsyringol derivatives in all sediments, points to large OM contribution from higher plants. The spatial distributions of PAHs (polyaromatic hydrocarbons) showed that most pollution sources were mixed sources including both pyrogenic and petrogenic. Low carbon preference indexes (CPI > 1) for n-alkanes, the presence of UCM (unresolved complex mixture) and the distribution of hopanes (C29-C36) and steranes (C27-C29) suggested localized petroleum-derived hydrocarbon inputs to the core sediments. Series of LABs were found in most sediment samples also pointing to domestic sewage anthropogenic contributions to the sediment OM.

Human health risk assessment of TPHs in brackish water prawn (Nematopalaemon hastatus, AURIVILLUS, 1898).

Edible aquatic brackish water shellfish (Nematopalaemon hastatus) obtained from the coastal waters of Ondo state, Nigeria was analyzed between 2017 and 2018 for the concentration of Total Petroleum Hydrocarbons (TPHs). TPHs level in the sampled species was measured using gas chromatography-flame ionization detector (GC/FID). Possible human health risks associated with the ingestion of the sampled species were determined by estimated dietary intake (EDI) and health risk index (HRI). The TPH level observed in the biota species (Nematopalaemon hastatus) varied across the period of study. The highest concentration was recorded in February (3401.55 mg/kg) while the lowest was recorded in April (1995.99 mg/kg). The TPH values of the analyzed fish species exceeded the threshold value of 50 mg/kg for fish. Petroleum aliphatic hydrocarbons attained higher concentration in n-Hentriacontane, n-Tridecane, n-Nonane, n-Tetradecane, n-Triacontane, n-Tetracosane and n-Octacosane with mean concentration values of (2242.02, 189.60, 40.90, 40.72, 25.79, 15.40 and 8.73 mg/kg) respectively. The EDI and HRI had their peak dose and index value (1.19 and 2.37) in February and lowest dose an index value (0.70 and 1.39) in April respectively. In addition, the HRI exceeded the safety limit of one (1). The findings from this study reveal a significant carcinogenic health risk connected with the consumption of the sea species. Thus, the species is therefore considered unfit and unsafe for consumption.

Oil contamination in surface sediment of Anzali Wetland in Iran is primarily even carbon number n-alkanes.

To determine the extent of oil contamination and biodegradation in Anzali Wetland of Iran, we examined aliphatic hydrocarbons in surface sediment of this area (n=20). Petroleum hydrocarbon levels (mean 1585 ± 1117; range 316 to 4358 µg g-1 dry weight) were similar in value to reports from other highly contaminated areas, such as New York Bight, Saudi and Kuwaiti coasts of the Persian Gulf, and Dubai shorelines. Even carbon homologs dominated distribution of n-alkanes in surface sediment of Anzali, which is rarely reported elsewhere. Multiple factors used in our study point to petrogenic source for n-alkanes in Anzali Wetland. Anzali receives multiple industrial and agricultural runoffs from the surrounding area. Shipping industry and oil industry are responsible for a major portion of pollutants entering Anzali. Municipal wastewater discharges are another source of Anzali pollution. To determine why even carbon number n-alkanes predominate in Anzali, we examined the following indices: existence of unresolved complex mixtures (UCM), ratio of UCM to resolved alkanes (RA), ratio of low-molecular weight to high-molecular weight molecules, presence of degraded oil residue, high-relative biodegradation, and the degree of hydrocarbon weathering in the surface sediment of the area. Our findings corroborate with such predominance.

Fingerprinting aliphatic hydrocarbon pollutants over agricultural lands surrounding Tehran oil refinery.

The analysis of aliphatic hydrocarbons, which are composed of n-alkanes as well as branched and cyclic alkanes, can be used to distinguish between the sources of hydrocarbon contamination. In this study, the concentration of aliphatic hydrocarbons, soil pH, and organic matter in agricultural soils located south of Tehran were monitored. Eighty-three soil samples were taken from two depth ranges of 0-30 and 30-60 cm. The results showed that aliphatic compounds ranged from 0.22-68.11 mg kg-1 at the top to 0.33-53.18 mg kg-1 at subsoil. The amount of hydrocarbons increases from the northern parts toward the south, and hydrocarbon pollutants originated from both petroleum and non-petroleum sources. Higher concentrations of aliphatic compounds in the southern parts indicated that, aside from the practice of irrigating with untreated wastewater, leakage from oil refinery storage tanks possibly contributed to soil pollution. The results also showed that several sources have polluted the agricultural soils. It is necessary to develop a new local pollution criterion as a diagnostic index that includes not only hydrocarbons but also other parameters such as heavy metal content in both soil and untreated wastewater, surface runoff, and other irrigation water resources to determine the exact origin of pollution.

Complete genome of Zhongshania aliphaticivorans SM-2(T), an aliphatic hydrocarbon-degrading bacterium isolated from tidal flat sediment.

Zhongshania aliphaticivorans SM-2(T), a degrader of aliphatic hydrocarbons, is a Gram-negative, rod-shaped, flagellated, facultatively aerobic bacterium. Here, we report the genome sequence of strain SM-2(T), which has a size of 4,204,359bp with 44 tRNAs, 9 rRNAs, and 3664 protein-coding genes. In addition, several genes encoding aliphatic hydrocarbon degraders (alkane 1-monooxygenase, haloalkane dehalogenase, and cytochrome P450) were detected in the genome shedding light on the function of pollutants degradation.

A comparison of the dechlorination mechanisms and Ni release styles of chloroalkane and chloroalkene removal using nickel/iron nanoparticles.

In this study, we compared the removal kinetics and Ni release styles of 1,1,1-trichloroethane (1,1,1-TCA), trichloroethylene (TCE), and tetrachloroethene (PCE) that result from the use of Ni/Fe nanoparticles in water. Compared to TCE and PCE, 1,1,1-TCA was more readily removed, and the concentration profiles of the three chlorinated aliphatic hydrocarbons (CAHs) during the reduction processes fit pseudo-first-order reaction rate models well. The surface area-normalized rate constants show that the 11% Ni Ni/Fe nanoparticles, which has the largest Brunauer-Emmett-Teller surface area, has the highest capacity for 1,1,1-TCA removal per unit surface area and that the 6% Ni sample was the best for removing TCE and PCE. The observed by-products suggested that hydrogenolysis was responsible for the dechlorination of CAHs in the presence of Ni/Fe nanoparticles. More Ni2+ was released during the degradation of 1,1,1-TCA than that of TCE and PCE because Ni will reduce the CAHs directly as a zerovalent metal does when hydrogen atoms in the Ni lattice are not sufficient due to the rapid incomplete dechlorination of 1,1,1-TCA. The different modes of adsorption of chloroalkane and chloroalkene onto the surfaces of Ni/Fe particles might play an important role in their dechlorination process.

Forensic investigation of aliphatic hydrocarbons in the sediments from selected mangrove ecosystems in the west coast of Peninsular Malaysia.

Peninsular Malaysia has gone through fast development during recent decades resulting in the release of large amounts of petroleum and its products into the environment. Aliphatic hydrocarbons are one of the major components of petroleum. Surface sediment samples were collected from five rivers along the west coast of Peninsular Malaysia and analyzed for aliphatic hydrocarbons. The total concentrations of C10 to C36 n-alkanes ranged from 27,945 to 254,463ng·g(-1)dry weight (dw). Evaluation of various n-alkane indices such as carbon preference index (CPI; 0.35 to 3.10) and average chain length (ACL; 26.74 to 29.23) of C25 to C33 n-alkanes indicated a predominance of petrogenic source n-alkanes in the lower parts of the Rivers, while biogenic origin n-alkanes from vascular plants are more predominant in the upper parts, especially in less polluted areas. Petrogenic sources of n-alkanes are predominantly heavy and degraded oil versus fresh oil inputs.

Anaerobic alkane biodegradation by cultures enriched from oil sands tailings ponds involves multiple species capable of fumarate addition.

A methanogenic short-chain alkane-degrading culture (SCADC) was enriched from oil sands tailings and transferred several times with a mixture of C6, C7, C8 and C10 n-alkanes as the predominant organic carbon source, plus 2-methylpentane, 3-methylpentane and methylcyclopentane as minor components. Cultures produced ∼40% of the maximum theoretical methane during 18 months incubation while depleting the n-alkanes, 2-methylpentane and methylcyclopentane. Substrate depletion correlated with detection of metabolites characteristic of fumarate activation of 2-methylpentane and methylcyclopentane, but not n-alkane metabolites. During active methanogenesis with the mixed alkanes, reverse-transcription PCR confirmed the expression of functional genes (assA and bssA) associated with hydrocarbon addition to fumarate. Pyrosequencing of 16S rRNA genes amplified during active alkane degradation revealed enrichment of Clostridia (particularly Peptococcaceae) and methanogenic Archaea (Methanosaetaceae and Methanomicrobiaceae). Methanogenic cultures transferred into medium containing sulphate produced sulphide, depleted n-alkanes and produced the corresponding succinylated alkane metabolites, but were slow to degrade 2-methylpentane and methylcyclopentane; these cultures were enriched in Deltaproteobacteria rather than Clostridia. 3-Methylpentane was not degraded by any cultures. Thus, nominally methanogenic oil sands tailings harbour dynamic and versatile hydrocarbon-degrading fermentative syntrophs and sulphate reducers capable of degrading n-, iso- and cyclo-alkanes by addition to fumarate.