Effect of humic deposit (leonardite) on degradation of semi-volatile and heavy hydrocarbons and soil quality in crude-oil-contaminated soil

In order to investigate the bioremedial potential of humic deposit (leonardite), the effects of the treatments of leonardite and a commercial bioaugmentation agent on the degradation of a variety of petroleum hydrocarbons (C13–C31) and soil enzyme activities (urease acid-alkaline phosphatase and dehydrogenase) were tested within a soil incubation experiment lasting 120 days. Experimentally crude-oil-contaminated soil (2.5%) was regulated to a C:N:P ratio (100:15:1; Oilcon), amended with 5% of leonardite and regulated to the same C:N:P ratio (Oilcon-L) or mixed with a commercial bioaugmentation product (Oilcon-B), respectively. In the short period of incubation (60 days), Oilcon and Oilcon-B treatments showed higher hydrocarbon degradations, whereas Oilcon-L showed higher hydrocarbon degradation over Oilcon and Oilcon-B treatments in the long-term (120 days). Applying contaminated soil with leonardite increased urease (LSD, 4.978, *P?<?0.05) and dehydrogenase (LSD, 0.660, *P?<?0.05) activities. However, acid and alkaline phosphatase activities showed no certain inclination between different treatments. Dehydrogenase seemed to be more related to hydrocarbon degradation process. Overall results showed that leonardite enhanced biodegradation of petroleum hydrocarbons and also stimulated soil ecological quality measured as soil enzyme activities.     

Preparation of ε-Caprolactone/Fe3O4 Magnetic Nanocomposite and Its Application to the Remazol Brilliant Violet 5R Dye Adsorption from Wastewaters by Using RSM

Journal of Polymers and the Environment - In this study, poly (ε-caprolactone)/Fe3O4 magnetic nanocomposite (PCL/Fe3O4 MNC) was synthesized by ring-opening polymerization. Then, PCL/Fe3O4 MNC...     

Evaluation of biosurfactants for crude oil contaminated soil washing

An evaluation of the ability of aqueous biosurfactant solutions (aescin, lecithin, rhamnolipid, saponin and tannin) for possible applications in washing crude oil contaminated soil was carried out. The biosurfactants behaviour in soil-water, water-oil and oil-soil systems (such as foaming, solubilization, sorption to soil, emulsification, surface and interfacial tension) was measured and compared with a well-known chemical surfactant (sodium dodecyl sulphate, SDS) at varying concentrations. Results showed that the biosurfactants were able to remove significant amount of crude oil from the contaminated soil at different solution concentrations for instance rhamnolipid and SDS removed up to 80% oil and lecithin about 42%. The performance of water alone in crude oil removal was equally as good as those of the other biosurfactants. Oil removal was due to mobilization, caused by the reduction of surface and interfacial tensions. Solubilization and emulsification effects in oil removal were negligible due to the low crude oil solubilization of 0.11%. Therefore, these studies suggest that knowledge of surfactants' behaviour across different systems is paramount before their use in the practical application of oil removal.     

Genotoxic effects of water pollution on two fish species living in Karasu River,Erzurum, Turkey

Karasu River, which is the only river in the Erzurum plain, is the source of the Euphrates River (Eastern Anatolia of Turkey). The river is in a serious environmental situation as a result of pollution by agricultural and industrial sewage and domestic discharges. The present study aims to evaluate genotoxic effects of toxic metals in chub, Leuciscus cephalus, and transcaucasian barb, Capoeta capoeta, collected from contaminated site of the Karasu River, in comparison with fish from an unpolluted reference site. Heavy metal concentrations in surface water of the river were determined. The condition factor (CF) was taken as a general biomarker of the health of the fish, and genotoxicity assays such as micronucleus (MN) and other nuclear abnormalities (NA) were carried out on the fish species studied. MN and NA such as kidney-shaped nucleus, notched nucleus, binucleated, lobed nucleus, and blebbed nucleus were assessed in peripheral blood erythrocytes, gill epithelial cells, and liver cells of the fish. A significant decrease in CF values associated with a significant elevation in MN and NA frequencies was observed in fish collected from the polluted sites compared with those from the reference site. Results of the current study show the significance of integrating a set of biomarkers to identify the effects of anthropogenic pollution. High concentrations of heavy metals have a potential genotoxic effects, and the toxicity is possibly related to industrial, agricultural, and domestic activities.     

A comparison of the efficiency of different surfactants for removal of crude oil from contaminated soils

This paper presents the results from study investigating the efficiency with which different surfactants remove crude oil from contaminated soil using a soil washing process. The surfactants studied were aqueous solutions of rhamnolipid, saponin and sodium dodecyl sulfate (SDS). The efficiency of surfactants' removal was quantified and then GC/MS analysis conducted to investigate the distribution of hydrocarbons remaining on the washed soil samples compared to those on a control. The results showed that SDS removed the most crude oil from soil, followed by rhamnolipid and then saponin. However, the different surfactants showed preferences in terms of which crude oil components they removed from the contaminated soil. SDS removed more of the aliphatics than aromatic hydrocarbons whereas saponin removed the aromatic hydrocarbon preferentially to the aliphatic hydrocarbons. Clearly these results provide important information for the selection of surfactants used to remove crude oil from contaminated soils.     

Evaluation of a fetus at risk for dihydropteridine reductase deficiency by direct mutation analysis using denaturing gradient gel electrophoresis

Dihydropteridine reductase (DHPR) is an enzyme involved in the recycling of tetrahydrobiopterin (BH₄), which is an obligate co-factor of the aromatic amino acid hydroxylases. DHPR deficiency is a rare, autosomal recessive disorder caused by mutations in the QDPR gene. DHPR-deficient patients are diagnosed by a lack of response to a low phenylalanine diet and by severe neurological symptoms. Final diagnosis is made by measurements of neurotransmitters and pterin metabolites in cerebrospinal fluid (CSF) and urine, in addition to DHPR enzyme activity, which can be assessed in whole red blood cells. Treatment of DHPR deficiency can be difficult and the outcome is not always satisfying, even if all treatment strategies are followed. Therefore prenatal diagnosis is of great importance in affected families. Prenatal diagnosis is possible by measuring DHPR activity in different cell types but this is time consuming. More than 25 different mutations have to date been identified in the QDPR gene and direct identification of a mutation in a fetus would be easy and rapid. We have developed a method based on denaturing gradient gel electrophoresis (DGGE) for the analysis of the QDPR gene. The method is useful for rapid and simultaneous scanning of all exons and flanking intronic sequences of the QDPR gene. We describe the first prenatal diagnosis conducted using this method. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of land conversion from native shrub to pistachio orchard on soil erodibility in an arid region

Land-use change through degrading natural vegetation for agricultural production adversely affects many of soil properties particularly organic carbon content of soils. The native shrub land and grassland of Gaziantep-Adiyaman plateau that is an important pistachio growing eco-region have been cleared to convert into pistachio orchard for the last 50 to 60 years. In this study, the effects of conversion of natural vegetation into agricultural uses on soil erodibility have been investigated. Soil samples were collected from surface of agricultural fields and adjacent natural vegetation areas, and samples were analyzed for some soil erodibility indices such as dispersion ratio (DR), erosion ratio (ER), structural stability index (SSI), Henin’s instability index (I _s ), and aggregate size distribution after wet sieving (AggSD). According to the statistical evaluation, these two areas were found as different from each other in terms of erosion indices except for I _s index (P < 0.001 for DR and ER or P < 0.01 for SSI). In addition, native shrub land and converted land to agriculture were found different in terms of AggSD in all aggregate size groups. As a contrary to expectations, correlation tests showed that there were no any interaction between soil organic carbon and measured erodibility indices in two areas. In addition, significant relationships were determined between measured variables and soil textural fractions as statistical. These obtaining findings were attributed to changing of textural component distribution and initial aggregate size distribution results from land-use change in the study area. Study results were explained about hierarchical aggregate formation mechanism.     

Crude oil contaminated soil washing in air sparging assisted stirred tank reactor using biosurfactants

This study investigated the removal of crude oil from soil using air sparging assisted stirred tank reactors. Two surfactants (rhamnolipid and sodium dodecyl sulfate, SDS) were tested and the effects of different parameters (i.e. temperature, surfactant concentrations, washing time, volume/mass ratio) were investigated under varying washing modes namely, stirring only, air sparging only and the combination of stirring and air sparging. The results showed that SDS removed more than 80% crude oil from non-weathered soil samples, whilst rhamnolipid showed similar oil removal at the third and fourth levels of the parameters tested. The oil removal ability of the seawater prepared solutions were better than those of the distilled water solutions at the first and second levels of temperature and concentration of surfactant solutions. This approach of soil washing was noted to be effective in reducing the amount of oil in soil. Therefore we suggested that a field scale test be conducted to assess the efficiency of these surfactants.     

Multi-criteria analysis for mapping of environmentally sensitive areas in a karst ecosystem

Environment, Development and Sustainability - Karst ecosystems are one of the ecologically sensitive areas most affected by the dramatic harmful effects of the desertification process due to their...     

Isolation and characterization of metal resistant-tolerant rhizosphere bacteria from the serpentine soils in Turkey

Despite the number of studies describing metal hyper-accumulating plants and their associated bacteria in various regions and countries, there is no information on rhizosphere microbial potential of the Turkish serpentine soils. This study aimed to explore the rhizosphere microbial diversity of Ni-resistant, hyper-accumulating plants grown on Ni-rich soils and their metal tolerance–resistance characteristics. One hundred ninety-one locations were visited to collect soil and plant samples from different serpentine regions of Western Turkey. Following bioavailable and total Ni analysis of collected samples, the seeds of the selected plants with higher Ni content were taken to the growth/germination test in a range of serpentine soils in a growth chamber condition. In order to investigate the rhizosphere microbial diversity, Isatis pinnatiloba and Alyssum dasycarpum which were able to germinate and grow well in the preliminary tests, were introduced to 6-month greenhouse experiment in the range of three serpentine soils with higher bioavailable Ni content. I. pinnatiloba had a better stimulatory effect on the rhizosphere microbial diversity. A total of 22 bacterial isolates were identified from different soil conditions in the end of experiment. Following microbial identification and confirmation tests, 11 isolates were found to be resistant and tolerant to the increasing concentrations of Ni, Pb, Cd and Zn in the range of 50–2,000 mg L^− 1, which was considerably higher than those indicated by earlier studies. The strains isolated and identified from the Turkish serpentine soils were the members of genera Arthrobacter, Bacillus, Microbacterium and Staphylococcus.