Distribution, composition and risk assessment of hydrocarbon residue in surficial sediments of El-Dakhla, El-Kharga and El-Farafra oases, Egypt.

This work examined the polycyclic aromatic hydrocarbons (PAHs) and n-alkanes quantities, sources, and hazards in sediments collected from the Egyptian Western Desert Oases namely: Dakhla, Kharga and Farafra oases. The n-alkane (C9-C20) residue concentrations have ranged from 0.66 to 2417.91 µg/g recorded for the three Oases. On the other hand, the total n-alkane ranged from 448.54 µg/g to 8442.60 µg/g. Higher carbon preference index (CPI) values (> 1.0) proposed that the natural sources could be the main contributor to n-alkanes in the Oases sediment. GC-MS/MS (selected reaction monitoring (SRM) method) was used for the determination of the ΣPAHs concentrations in the studied sediments. The ΣPAHs concentrations (ng/g, dry weight) in the studied three Oases varied from 10.18 to 790.14, 10.55 to 667.72, and from 38.27 to 362.77 for the Kharga, Dakhla and Farafra Oases, respectively. The higher molecular weight PAHs were the most abundant compounds in the collected samples. Assessing potential ecological and human health issues highlighted serious dangers for living things and people. All the investigated PAHs had cancer risk values between 1.43 × 10-4 and 1.64 × 10-1, this finding suggests that PAHs in the samples under study pose a moderate risk of cancer. The main sources of PAHs in this study are biomass, natural gas, and gasoline/diesel burning emissions.

Insights about levels and source appointment of petroleum hydrocarbons in Brazilian semi-arid coastal: baseline status assessment for ocean decade targets.

The Ocean decade (2021-2030) for sustainable development proclaimed in 2017 by the UN, seeks to promote and conserve the sustainable use of oceans, seas, and marine resources. For this, the distribution of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and biomarkers, in sediments from the Fortaleza coastal zone (Mucuripe harbor (MH) and Inner Continental shelf (ICS)) were used to assess the impacts of anthropogenic activities in the area. The concentrations of total n-alkanes (Σ16 n-alkanes) in MH and ICS sediments varied from 35.9 to 94.9 and 17.9 to 197.3 µg g-1, respectively, while the isoprenoids phytane and pristane in MH and ICS sediments ranged from 0.1 to 1.69 ug g-1 and from 0.14 and 1.20 µg g-1, respectively. Most of the sediment samples presented carbon preference index (CPI) values close to unity, indicating that the area is submitted to petroleum-related sources. The concentrations of Σ16 PAHs in MH and ICS sediments varied from 87.0 to 562.0 and 98 to 288.0 ng g-1. This work presents the first investigation of the petroleum biomarkers hopanes and steranes in the Fortaleza coastal zone, in which ΣBiomarkers varied from 0.10 to 1.79 and 0.02 to 0.24 ug g-1 in MH and ICS sediments, respectively. The presence at stations of biomarkers also indicates petrogenic input. The diagnosis of the distribution of pollutants in the investigated zones of the Fortaleza coast suggests contamination from urban areas and oil spills and vessel traffic.

Assessment of contaminants in sand production from petroleum wells offshore Sabah.

Sand production remains a huge obstacle in many oil and gas fields around the world, but the hazards of contaminants riding on the produced sand are often not emphasised. Improper disposal of the sand could see the toxic leaching into the environment including the food chain, endangering all living organisms. The impending sand production from an oilfield offshore Sabah also suffers from the lack of hazards identification; hence, this study was conducted to assess the contaminant on the produced sand. Sand samples were collected from multiple wells in the area, with the contaminants extracted using n-hexane and subjected to chemical and thermal analyses. FTIR and GC-MS detected traces of harmful pollutants like naphthalene, amine substances, cyclohexanol, and short-chain alkanes. It was discovered that the volatile fraction of the contaminants was able to evaporate at 33 °C, while high energy was needed to remove 100% of the contaminants from the sand. Overall, the produced sand from the oilfield was unsafe and required treatment before it could be dumped or used.

Fingerprint analysis reveals sources of petroleum hydrocarbons in soils of different geographical oilfields of China and its ecological assessment.

The distribution and characteristics of petroleum in three different geographic oilfields in China: Shengli Oilfield (SL), Nanyang Oilfield (NY), and Yanchang Oilfield (YC) were investigated. The average concentration of the total petroleum hydrocarbons (TPHs) conformed to be in the following law: SL Oilfield > NY Oilfield > YC Oilfield. Fingerprint analysis on the petroleum contamination level and source was conducted by the geochemical indices of n-alkanes and PAHs, such as low to high molecular weight (LMW/HMW) hydrocarbons, n-alkanes/pristine or phytane (C17/ Pr, C18/Ph), and ratio of anthracene/ (anthracene + phenanthrene) [Ant/(Ant + Phe)]. Soils adjacent to working well oils indicated new petroleum input with higher ratio of low to high molecular weight (LMW/HMW) hydrocarbons. The oil contamination occurred in the grassland soils might result of rainfall runoff. Petroleum source, petroleum combustion source, and biomass combustion were dominant PAHs origination of soils collected from oil exploitation area, petrochemical-related sites, farmland and grassland, respectively. The suggestive petroleum control strategies were proposed in each oilfield soils. Ecological potential risk of PAHs was assessed according to the toxic equivalent quantity (TEQ) of seven carcinogenic PAHs. The results showed that high, medium, and low ecological risk presented in petro-related area, grassland soils, and farmland soils, respectively. High ecological risk was persistent in abandoned oil well areas over abandoned time of 15 years, and basically stable after 5 years. This study can provide a critical insight to ecological risk management and source control of the petroleum contamination.

Investigation of health risk assessment and odor pollution of volatile organic compounds from industrial activities in the Yangtze River Delta region, China.

To investigate composition characteristics and assess occupational health risks and odor pollution of volatile organic compounds (VOCs) from industrial activities in the Yangtze River Delta (YRD) region, China, one-year field measurements of VOCs were conducted simultaneously at an iron and steel industrial park (ISP), one chemical industrial park (CMP) and one petrochemical industrial park (PCP) from September, 2018 to August, 2019. The concentrations of VOCs were 80.2 ± 67.9 ppbv, 28.1 ± 27.2 ppbv and 144 ± 378 ppbv for ISP, CMP and PCP, respectively. Aromatics, alkanes and alkenes were the major components of VOCs at ISP, CMP and PCP, respectively. Moreover, the toluene to benzene ratios were 0.330 ± 0.302, 4.31 ± 6.48 and 1.84 ± 3.34, which generally showed the characteristics of combustion source for ISP, industrial activities for CMP and petrochemical industry for PCP, respectively. The hazard index values were 0.752 ± 0.438, 0.108 ± 0.248 and 0.090 ± 0.260 at ISP, CMP and PCP, which were generally lower than threshold limit value, suggesting a low noncarcinogenic risk for workers. Meanwhile, the 95th percentile LCR values of VOCs were 8.76 × 10-5, 1.15 × 10-5 and 1.00 × 10-5 at ISP, CMP and PCP, respectively, which were also under acceptable risk level, indicating a low carcinogenic risk. Benzene and 1,3-butadiene were main harmful substances for both noncarcinogenic and carcinogenic risks of VOCs. The odor levels of VOCs were 2.12 ± 4.21, 12.5 ± 28.7 and 1.01 ± 7.84 at ISP, CMP and PCP, respectively. Aromatics for ISP and sulfide compounds for CMP and PCP were primary pollutants for odor pollution. This work could improve the understanding of risk levels and odor characteristics of VOCs and benefit policy development on alleviating odor complaints and health risks for workers in YRD region, China.

Property Estimation of Per- and Polyfluoroalkyl Substances: A Comparative Assessment of Estimation Methods.

To accurately predict the environmental fate of per- and polyfluoroalkyl substances (PFAS), high-quality physicochemical property data are required. Because such data are often not available from experiments, assessment of the accuracy of existing property estimation models is essential. The quality of predicted physicochemical property data for a set of 25 PFAS was examined using COSMOtherm, EPI Suite, the estimation models accessible through the US Environmental Protection Agency's CompTox Chemicals Dashboard, and Linear Solvation Energy Relationships (LSERs) available through the UFZ-LSER Database. The results showed that COSMOtherm made the most accurate acid dissociation constant and air-water partition ratio estimates compared with literature data. The OPEn structure-activity/property Relationship App (OPERA; developed through the CompTox Chemicals Dashboard) estimates of vapor pressure and dry octanol-air partition ratios were the most accurate compared with other models of interest. Wet octanol-water partition ratios were comparably predicted by OPERA and EPI Suite, and the organic carbon soil coefficient and solubility were well predicted by OPERA and COSMOtherm. Acid dissociation of the perfluoroalkyl acids has a significant impact on their physicochemical properties, and corrections for ionization were included where applicable. Environ Toxicol Chem 2020;39:775-786. © 2020 SETAC.

Characteristics and health risk assessment of volatile organic compounds (VOCs) in restaurants in Shanghai.

Volatile organic compounds (VOCs) are important precursors of ozone and atmospheric particulates that have attracted extensive attention worldwide. Cooking emissions, the chemical characteristics of which vary dramatically due to different cooking styles, are a main source of ambient VOCs, especially in large cities. This research focused on the emission characteristics of VOCs from six types of restaurants in Shanghai: hot pot (HP), Sichuan cuisine (SC), Cantonese cuisine (CS), seafood (SF), Western fast food (WFF), and authentic Shanghai cuisine (ASC). It was found that HP, which discharged cooking fumes indoors, produced the highest mass concentration of VOCs (1900.2 ± 364.8 µg m-3), followed by SC (1403.7 ± 403.8 µg m-3), WFF (656.0 ± 156.9 µg m-3), SF (638.6 ± 145.1 µg m-3), CC (632.7 ± 127.7 µg m-3), and ASC (612.3 ± 51.3 µg m-3), the cooking fumes from which were collected by emission extraction stacks. Additionally, the VOC species from each cuisine were mainly low carbon substances. Alkanes were the major VOC pollutants from all six cuisines, accounting for 34.4-71.7%. The coefficient divergence values were 0.287-0.593, suggesting that there were differences between the cuisines in the present study. Ozone formation potential and secondary organic aerosol formation potential indicated that O-VOCs and aromatics were the largest contributors. Health risk assessment of VOCs via non-carcinogenic risk values (HQ) and carcinogenic risk values (RISK) indicated that frying, grilling, and stir-frying had relatively large impacts on human health. VOCs collected in emission extraction stacks were significantly higher risk compared with those in the indoor environment, but the RISK score of the HP restaurant was larger, second only to SC. The HQ and RISK values of 1,3-butadiene, acetaldehyde, and trichloroethylene in the HP restaurant all exceeded US EPA standards, indicating that long-term exposure in an HP restaurant would have a significant impact on human health and might carry a potential cancer risk.

Source tracing of n-alkanes in Songhua Lake, based on correspondence analysis and geochemical index.

This paper analyzes the source of n-alkanes in sediments spanning 63 years since 1943 from Songhua Lake, using the method of correspondence analysis and geochemical index. The area of Songhua Lake is 554 km2, and its ecological problems affect hundreds of thousands of people in the basin. The concentration of total n-alkanes (C13-C36) in the sediments ranged from 20.39 to 168.35 µg/g, averaged at 72.58 µg/g, indicating that the Songhua Lake has an ecological risk of n-alkanes and should be taken seriously and protected. The analysis of geochemical indexes, including main carbon distributions (MH), LMW/HMW ratio, Paq, average chain length and so on, shows the n-alkanes in the Songhua Lake sediments are mainly derived from modern higher terrestrial plants, followed by human activities, and a small part from aquatic vascular plants and algae. Moreover, the source and sedimentary history of n-alkanes in Songhua Lake were carried out by corresponding analysis. And the correspondence analysis could be a feasible and effective means of source tracing.

First Investigation of Seasonal Concentration Behaviors and Sources Assessment of Aliphatic Hydrocarbon in Waters and Sediments from Wadi El Bey, Tunisia.

The contents, composition profiles, and sources of aliphatic hydrocarbons were examined in surface sediment and water samples collected from Wadi El Bey, in Tunisia, during different year seasons in 14 stations receiving domestic effluent, industrial discharge, and agricultural drainage wastes. The target substances were analyzed by gas chromatography coupled with mass spectrometric detection (GC/MS). Total concentrations of n-alkanes (n-C14-n-C38) ranged from 0.08 ± 0.01 to 18.14 ± 0.1 µg/L in waters and 0.22 ± 0.04 to 31.9 ± 24.6 µg/g in sediments, while total aliphatic fraction ranged from 0.08 ± 0.01 to 196 ± 140 µg/L in waters and 0.22 ± 0.04 to 1977 ± 1219 µg/g in sediments, which means that almost all sites were affected by hydrocarbon contents in sediments exceeding the recommended limit (100 µg/g). Various diagnostic indices (ADIs) were used to identify the hydrocarbon sources, namely the concentration ratios of individual compounds (n-C17/pristane, n-C18/phytane, pristane/phytane, n-C29/n-C17, n-C31/n-C19) as well as cumulative quantities (Carbon Preference Index, natural n-alkanes ratio, terrigenous/aquatic compounds ratio, unresolved complex mixture percentage, low molecular weight vs. high molecular weight homologues, Alkane Proxy and Terrestrial Marine Discriminants). In general, these indexes indicated that the origin of aliphatic hydrocarbons affecting sediments and waters of Wadi El Bey were linked to both biogenic and petrogenic inputs, attesting the impact of plankton and terrestrial plants and of oil contamination, respectively. The average carbon chain length computation (ACL), used to further index the chemical environment, ranged from 25.5 to 31.1 in sediments and 47.9-116 in waters. This finding could depend on the severe disturbances suffered by the ecosystem as a consequence of heavy anthropogenic inputs. Petroleum contamination associated with high eutrophication rates in Wadi El Bey must be strictly controlled, due to possible harmful effects induced on ecosystem and humans.

Assessment of crude oil bioremediation potential of seawater and sediments from the shore of Lebanon in laboratory microcosms.

With the planned oil and gas exploration activities off the coast of Lebanon, the risk of shoreline contamination with crude oil spills has become a major concern. This study aimed at assessing the crude oil bioremediation potential of the chronically polluted Lebanese shores in light of the continuous discharge of nutrient-rich sewage into the Mediterranean Sea and the long-lasting absence of proper sewage treatment systems. It was anticipated that, with the high pollution levels of the coastline, background concentrations of nutrients would be sufficient to sustain high intrinsic biodegradation rates without human intervention. Biodegradation experiments were conducted using crude oil-spiked beach sediments and seawater under natural attenuation and biostimulation conditions. The experiments were conducted at 18 and 28 °C to account for seasonal variation in temperature, background nutrient levels, and microbial communities. The biodegradability of oil constituents - namely alkanes and polycyclic aromatic hydrocarbons (PAHs), was monitored over a 42-day period using gas chromatography-mass spectrometry (GC-MS). Under biostimulation conditions, significant enhancement in the overall biodegradation rates of alkanes and PAHs was observed in seawater at 18 and 28 °C, while little to no improvement was measured at both temperatures in sediments where background nutrient levels were sufficient to induce near maximum intrinsic biodegradation rates. Under both natural attenuation and biostimulation treatments, the increase in temperature increased the oil biodegradation rates in sediment and seawater microcosms. In both instances, the overall trend in the biodegradation of individual alkanes and PAHs suggested a typical decrease in biodegradation rates with the increase in carbon number/rings and alkyl groups.

A preliminary investigation of 942 organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam: Levels, potential sources, and risk assessment.

Of 942 organic micro-pollutants screened, 167 compounds were detected at least once in the atmosphere in some primitive waste processing sites and an urban area in northern Vietnam by using a polyurethane foam-based passive air sampling (PUF-PAS) method and an Automated Identification and Quantification System with a Database (AIQS-DB) for GC-MS. Total concentrations of organic pollutants were higher in samples collected from an urban area of Hanoi city (2300-2600 ng m-3) as compared with those from an end-of-life vehicle (ELV) dismantling area in Bac Giang (900-1700 ng m-3) and a waste recycling cooperative in Thai Nguyen (870-1300 ng m-3). Domestic chemicals (e.g., n-alkanes, phthalate ester plasticizers, and synthetic phenolic antioxidants) dominated the organic pollutant patterns in all the samples, especially in the urban area. Pesticides (e.g., permethrins, chlorpyrifos, and propiconazole) were found in the atmosphere around the ELV sites at more elevated concentrations than the other areas. Levels of polycyclic aromatic hydrocarbons and their derivatives in the Bac Giang and Thai Nguyen facilities were significantly higher than those measured in Hanoi urban houses, probably due to the waste processing activities. Daily intake doses of organic pollutants via inhalation were estimated for waste processing workers and urban residents. This study shall provide preliminary data on the environmental occurrence, potential emission sources, and effects of multiple classes of organic pollutants in urban and waste processing areas in northern Vietnam.

Ecotoxicity evaluation and human risk assessment of an agricultural polluted soil.

The present study aims to evaluate the nature and level of chemical pollution as well as the potential toxicity and ecotoxicity of an agricultural soil irrigated by the water of Litani River. Our findings showed that the soil was mainly contaminated by alkanes (hentriacontane, octadecane, hexadecane) and metal trace elements (nickel, vanadium, chromium, and manganese). Soil organic extracts showed high cytotoxicity against human hepatic (HepG2) and bronchial epithelial cells (Beas-2B). Soil ecotoxicity was revealed by seed germination inhibition of several plant species (wheat, clover, alfalfa, tall fescue, and ryegrass) ranging from 7 to 30% on the polluted soil compared to non-polluted one. In addition, significant decreases in telluric microbial biomasses (bacterial and fungal biomasses), quantified by phospholipid fatty acids (PLFA) analysis were observed in polluted soil compared to non-contaminated soils. The density of the arbuscular mycorrhizal fungal (AMF) spores isolated from the polluted soil was about 316 spores/100 g. Three main AMF species were identified as Funelliformis mosseae, Septoglomus constrictum, and Claroideoglomus lamellosum. Moreover, 16 indigenous plant species were inventoried with Silybum marianum L. as the dominant one. Plant biodiversity indices (Shannon, Simpson, Menhinick, and Margaleff) were lower than those found in other contaminated soils. Finally, it was found that all the present plant species on this polluted site were mycorrhized, suggesting a possible protection of these plants against encountered pollutants, and the possibility to use AMF-assisted phytoremediation to clean-up such a site.

Occurrence, source and ecological assessment of petroleum related hydrocarbons in intertidal marine sediments of the Bay of Fundy, New Brunswick, Canada.

Total petroleum hydrocarbons (TPH), n-alkanes, petroleum-related biomarkers of terpanes and steranes, and polycyclic aromatic hydrocarbons (PAHs) were analyzed in the intertidal sediments in the Bay of Fundy, Nova Scotia/New Brunswick, Canada. Sites close to the harbour and more densely populated areas had higher TPH levels than other pristine areas. n-Alkanes presented a typical single bell-shape in n-C16 to n-C35 range and an obvious odd to even carbon preference. Most sites had trace amounts of petroleum biomarkers. Abundant non-alkylated PAHs and lower amounts of alkylated PAHs represented the major input of the incomplete combustion of solid (e.g., coal, coke, biomass, and coal tar) and liquid fuels. The toxicity estimation for PAHs indicates that they did not have potential toxicity to benthic organisms at most sampling sites. However, possible to probable negative effects from the measured PAH concentrations were found for the two samples from Courtenay Bay and Saint Andrews.

Assessment of exposure to pesticides in rural workers in southern of Minas Gerais, Brazil.

The aim of the study was to assess of occupational exposure to pesticides in rural workers using genotoxicity test, bioindicators and clinical evaluation. Blood, urine and buccal samples from persons, rural workers exposed to a complex mixture of pesticides with organophosphates (n=94) and without organophosphates (n=94) were collected to compare the activities of cholinesterases, the levels of urinary dialkyl phosphates, genotoxicity data, from a cytome assay. Biomarkers were analysed by traditional/published methods Control group consisted of 50 other persons, non- occupationally exposed to pesticides from the city of Alfenas, Minas Gerais, Brazil. All subjects underwent a clinical evaluation. In the group exposed to organophosphates, the activity of acetylcholinesterase, butyrylcholinesterase and total cholinesterase was lower by 63.8%, 12.8%, and 14.8%, respectively, and 92.6% of the group had dialkyl phosphates present in their urine. The cytome assay was used to measure biomarkers of DNA damage (micronuclei and/or elimination of nuclear material by budding), cytokinetic defects (binucleated cells), and proliferative potential (basal cell) and/or cell death (condensed chromatin, karyorrhectic, pyknotic, and karyolytic cells). The group exposed to organophosphates showed significant changes in all these parameters compared to the control group and showed significant changes in budding, condensed chromatin and karyolytic cells compared with the group non-exposed to organophosphates. Data from the clinical evaluation showed significant changes in the central nervous, respiratory and auditory systems. The studied biomarkers are able to distinguish occupational and environmental exposure to pesticides and the data showed hazardous exposure to organophosphates and afforded valuable data to estimate the risk to cancer development.

Characterization and health risk assessment of PM2.5-bound organics inside and outside of Chinese smoking lounges.

PM2.5 samples were collected at six indoor public places that contained dedicated smoking lounges. Samples were taken in the smoking lounges, at two indoor locations outside of the lounges, and in outdoor air near the venues. Organic carbon (OC), elemental carbon (EC), and non-polar organic compounds including polycyclic aromatic hydrocarbons (PAHs), n-alkanes (n-C16 to n-C40), iso/anteiso-alkanes (C29 to C33), hopanes and phthalate esters (PAEs) were quantified. Average PM2.5 levels of 170.2 ± 85.9 µg/m3 in the lounges exceeded limits of 25 µg/m3 set by World Health Organization (WHO); these levels were 5.4 and 3.9 times higher than those indoors and outdoors, respectively. High ratios of OC to PM2.5, OC to EC, and PAHs diagnostic ratios in the lounges indicated contributions from environmental tobacco smoke (ETS). The maximum carbon number (Cmax) and carbon preference indices (CPI) for n-alkanes showed ETS transport from the enclosed lounges to nearby indoor non-smoking areas. Iso/anteiso-alkanes in the lounges were 876.5 ng/m3, ∼80 times higher than outdoor levels. 17α(H)-21ß(H),30-norhopane and 17α(H)-21ß(H),(22R)-homohopane were much higher in the lounges than outdoor air, but they cannot be directly attributed to ETS. Estimated carcinogenic risks of PAHs in the lounges exceeded the acceptable level of 10- 6.

Concentrations and inhalation risk assessment of short-chain polychlorinated paraffins in the urban air of Dalian, China.

The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m-3, with an average of 30.26 ng m-3 in 2010, and 65.30 to 91.00 ng m-3, with an average of 78.15 ng m-3 in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase. In 2010, 82.57-97.16% of the total SCCPs were found in the gas phase, except that in winter, where 63.11% of the total SCCPs were in the particulate phase; the air concentrations of SCCPs in gas phase were summer > autumn > spring > winter, which was positively correlated with the change of the average ambient temperature, while it was the contrary in particulate phase. In autumn, the gas phase and the total air concentration of SCCPs in 2016 were 2.57 times more than that in 2010, while the congener group patterns of SCCPs were similar. Spearman's rank correlation analysis between the concentrations of SCCPs with meteorological parameters was conducted. The gas-particle distribution was examined through the relationship of the logarithm of the gas-particle partition coefficient with that of the subcooled vapor pressure and the octanol-air partitioning coefficient of SCCPs. Results indicated that the absorption mechanisms contributed more to the partitioning process. The exposure risk of SCCPs was evaluated, which illustrated that the estimated exposure of SCCPs via the outdoor environment in Dalian did not exceed the health concern threshold of the European risk assessment.

Modern climate and vegetation variability recorded in organic compounds and carbon isotopic compositions in the Dianchi watershed.

The aliphatic hydrocarbons distribution and compound-specific characteristics of carbon isotopic compositions in the sediments from the small catchment (197 km(2)) of the Dianchi watershed were investigated for identification of modern climate and vegetation variations in the study area. Results show that a regular bimodal n-alkanes distribution ranged from nC16 to nC33, with strong dominance at nC17 for short-chain n-alkanes and nC31 for long-chain n-alkanes. Mass chromatogram of total fatty acids also indicates corresponding mixed contribution of algae, hydrophilous non-emergent (C4 plants) and terrestrial plants (C3 plants) to sedimentary organic matter (OM). At the depth of -24 to -25 cm (early 1970s), nC31/nC17 and terrestrial to aquatic ratio of hydrocarbons (TAR) values decrease, suggesting a shift of OM origins from C3 terrestrial plants to algae-derived C4 plants. The highest water stage in 1971 was found to be recorded in the particle size (<4 µm). For long-chain alkanes, the values of δ (13)Corg and δ (13)Cn-alkanes varied from -26.9 to -22.4 and -33.4 to -27.9 ‰, respectively. Population growth and economic development led to a demand for abundant habitable and cultivable land. Due to unreasonable land expansion, the primordial forest sporadically distributed. A mixture of C3 and C4 plants probably replaced C3 plants as the sources of OM in the past 10 years. The changes of land-use types and severe drought resulted in the excessive OM inputs to the watershed.

Arachidonic acid production by Mortierella alpina using raw crop materials.

BACKGROUND: Arachidonic acid (ARA) is one of the three essential fatty acids, and it is important for human body to keep healthy and is widely used. At present, expensive materials such as glucose and yeast extract are generally reported to be optimal for ARA production. A new cost-effective fermentation process including cheaper material for ARA production is of great significance. METHODS: Feasibility of using corn meal and powdered soybean for fungal growth and lipid accumulation was evaluated by means of single factor test. N-hexadecane concentration was optimized, and the effect of temperature on biomass and ARA content was examined. RESULTS: Mortierella alpina made better use of the aforementioned material as carbon and nitrogen sources for both hyphae growth and ARA production compared with glucose and yeast extract. Maximal levels of 10.9 g/L ARA and 26.1 g/L total lipids were obtained when 66 g/L corn meal, 54 g/L soybean meal and 6% (v/v) n-hexadecane were supplemented. A temperature-shift strategy involved three steps, namely, 30°C (3 days) - 25°C (4 days) - 20°C (4 days), which further improved ARA production by 24.7%. CONCLUSIONS: Several factors such as carbon and nitrogen sources, temperature and dissolved oxygen had great influence on biomass and microbial oil production. Mortierella alpina preferred corn and soybean meal compared with glucose and yeast extract, which would surely alleviate the high cost of ARA production. Based on this study, the new process is both low cost and practicable.

Allergic asthma exhaled breath metabolome: a challenge for comprehensive two-dimensional gas chromatography.

Allergic asthma represents an important public health issue, most common in the paediatric population, characterized by airway inflammation that may lead to changes in volatiles secreted via the lungs. Thus, exhaled breath has potential to be a matrix with relevant metabolomic information to characterize this disease. Progress in biochemistry, health sciences and related areas depends on instrumental advances, and a high throughput and sensitive equipment such as comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-ToFMS) was considered. GC×GC-ToFMS application in the analysis of the exhaled breath of 32 children with allergic asthma, from which 10 had also allergic rhinitis, and 27 control children allowed the identification of several hundreds of compounds belonging to different chemical families. Multivariate analysis, using Partial Least Squares-Discriminant Analysis in tandem with Monte Carlo Cross Validation was performed to assess the predictive power and to help the interpretation of recovered compounds possibly linked to oxidative stress, inflammation processes or other cellular processes that may characterize asthma. The results suggest that the model is robust, considering the high classification rate, sensitivity, and specificity. A pattern of six compounds belonging to the alkanes characterized the asthmatic population: nonane, 2,2,4,6,6-pentamethylheptane, decane, 3,6-dimethyldecane, dodecane, and tetradecane. To explore future clinical applications, and considering the future role of molecular-based methodologies, a compound set was established to rapid access of information from exhaled breath, reducing the time of data processing, and thus, becoming more expedite method for the clinical purposes.

Cumulative risk assessment of chemical exposures in urban environments.

We performed a cumulative risk assessment for people living in a hypothetical urban environment, called Urbania. The main aims of the study were to demonstrate how a cumulative risk assessment for a middle-sized European city can be performed and to identify the bottlenecks in terms of data availability and knowledge gaps. The assessment focused on five air pollutants (i.e., PM10, benzene, toluene, nonane and naphthalene) and six food pesticides (i.e., acetamiprid, carbendazim, chlorpyrifos, diazinon, imidacloprid and permethrin). Exposure predictions showed that PM10, benzene and naphthalene exposure frequently exceeded the standards, and that the indoor environment contributed more than the outdoor environment. Effect predictions showed that mixture and interaction effects were generally limited. However, model calculations indicated potential synergistic effects between naphthalene and benzene and between chlorpyrifos, diazinon and toluene. PM10 dominated the health impact expressed in Disability Adjusted Life Years (DALYs). We conclude that measures to reduce the health impact of environmental pollution should focus on the improvement of indoor air quality and the reduction of PM10 emissions. Cumulative risk assessment can be improved by (1) the development of person-oriented exposure models that can simulate the cumulative exposure history of individuals, (2) a better mechanistic understanding of the effects of cumulative stressors, and (3) the development of instruments to prioritize stressors for inclusion in cumulative risk assessments.