Search Results (9)

The Upper Cambrian–Lower Silurian sediments of the Baltic Basin represent organic-rich clastic and carbonate rocks that are a key exploration target for hydrocarbons in northern Pomerania, Poland. The source rocks contain an average total organic carbon (TOC) content of 4.1 wt% (range: 0.7–9.6 wt%). The organic matter is primarily in the early to mid-oil window; however, both more mature and overmature organic matter also occur (average Tmax: 445 °C; range: 427–488 °C; average Ro: 1.3%; range: 1.0%–1.8%). These organic-rich rocks were mostly deposited under dysoxic rather than anoxic conditions. Fossils of oxygen-dependent benthic fauna are widely distributed, even in the darkest (black shale) lithologies. Nevertheless, short intervals lacking benthic fossils indicate episodes of anoxic bottom-water conditions. The Furongian–Lower Llandovery source rocks exhibit a low sedimentation rate, ranging from 1 to 19 m/Ma. Geochemically, the organic matter is dominated by type II kerogen. Petrographically, the kerogen consists mainly of graptolites and algae. Due to the predominance of planktonic-origin fauna and thermal maturity, the kerogen is relatively hydrogen depleted (average Hydrogen Index, HI: 169 mg HC/g TOC; range: 1–340 mg HC/g TOC). The present day petroleum potential of these source rocks varies from fair to good and very good. Bitumen analysis revealed a dominance of kerogen components, with only minor admixtures of light and heavy oils. Full article

Improving the quality of oil-contaminated soils remains a critical challenge, and bioaugmentation using allochthonous bacteria offers promising perspectives. This study proposes a framework for exogenous bioaugmentation using a bacterial consortium, composed of strains from diverse climates, immobilized in alginate beads and combined with calcium peroxide as an oxygen-releasing compound. Two conditions were tested: freshly prepared beads (BA) and lyophilized beads (LA). Their performance was compared to natural attenuation (NA) and to landfarming coupled with bioaugmentation using a free autochthonous consortium. Hydrocarbon degradation was assessed through total petroleum hydrocarbon (TPH) and alkane depletion (GC-MS), microbial community dynamics (amplicon sequencing), and abundance of the alkB gene (qPCR). In three months, the BA treatment achieved a 44% TPH reduction, outperforming LA (34%) and NA (10% less than BA). However, LA induced a marked increase in alkB gene copies and microbial biomass at the end of the experiment, suggesting greater long-term potential. Dominant genera varied across treatments: Rhodococcus in NA, Gordonia in BA, and Pseudomonas in LA. In parallel, the autochthonous consortium achieved up to 80% oil degradation. This study demonstrates the viability of lyophilized microbial consortia in scalable, ready-to-use formulations and provides an operational methodology for exogenous bioaugmentation as a tool for the remediation of hydrocarbon-contaminated soils. Full article

The effectiveness of thermal treatment technologies for the remediation of soils contaminated with heavy hydrocarbons has been extensively documented in the scientific literature. In general, high-concentration crude-oil-contaminated soil is treated with high-temperature thermal desorption (HTTD) in order to achieve high remediation efficiency. However, this process has the unintended consequence of destroying soil fertility. Low-temperature thermal desorption (LTTD) represents an alternative approach that has been developed with the objective of remediating heavily crude-oil-contaminated soil in a more rapid and cost-effective manner while simultaneously enhancing soil fertility. The thermal desorption unit (TDU) was employed using both LTTD and HTTD, operating at 300 °C and 500 °C, respectively, with a 30 min residence time in the kiln. The concentration of total petroleum hydrocarbons (TPH) in both the LTTD- and HTTD-treated soils was found to be less than 1% by weight, thereby below regulatory standards. The environmental impacts of both processes were assessed using the OpenLCA software version 2.0. The HTTD process exhibited a total abiotic depletion potential (ADP) impact of 1.63 × 10⁻⁴ MJ and a global warming potential (GWP) of 414 kg CO₂-eq. In contrast, LTTD demonstrated lower impacts, with an ADP of 1.29 × 10⁻⁴ MJ and a GWP of 278 kg CO₂-eq. The transition from HTTD to LTTD resulted in a notable reduction in ADP by 20.5% and in GWP by 32.9%. The application of LTTD-treated soil coated with coke or carbonized residues has been demonstrated to serve as an effective soil amendment, with the capacity to sequester approximately 50% of organic hydrocarbon contaminants. The results of this study illustrate the potential of LTTD for not only economical and rapid soil remediation but also the enhancement of soil quality through beneficial reuse. Full article

To accelerate the depletion of total petroleum hydrocarbons, a hydrocarburoclastic ascomycetes, Lambertella sp. MUT 5852, was bioaugmented to dredged sediments co-composting with a lignocellulosic matrix. After only 28 days of incubation, a complete depletion of the contamination was observed. The 16S rDNA metabarcoding of the bacterial community and a predictive functional metagenomic analysis were adopted to evaluate potential bacterial degrading and detoxifying functions. A combination of toxicological assays on two eukaryotic models, the root tips of Vicia faba and the human intestinal epithelial Caco-2 cells, was adopted to assess the robustness of the process not only for the decontamination but also for the detoxification of the dredged sediments. Bacterial taxa, such as Kocuria and Sphingobacterium sps., resulted to be involved in both the decontamination and detoxification of the co-composting dredged sediments by potential activation of diverse oxidative processes. At the same time, the Kocuria sp. showed plant growth-promoting activity by the potential expression of the 1-aminocyclopropane-1-carboxylate deaminase activity, providing functional traits of interest for a technosol in terms of sustaining primary producer growth and development. Full article

Nowadays, soil contamination by total petroleum hydrocarbons is still one of the most widespread forms of contamination. Intervention technologies are consolidated; however, full-scale interventions turn out to be not sustainable. Sustainability is essential not only in terms of costs, but also in terms of restoration of the soil resilience. Bioremediation has the possibility to fill the gap of sustainability with proper knowledge. Bioremediation should be optimized by the exploitation of the recent “omic” approaches to the study of hydrocarburoclastic microbiomes. To reach the goal, an extensive and deep knowledge in the study of bacterial and fungal degradative pathways, their interactions within microbiomes and of microbiomes with the soil matrix has to be gained. “Omic” approaches permits to study both the culturable and the unculturable soil microbial communities active in degradation processes, offering the instruments to identify the key organisms responsible for soil contaminant depletion and restoration of soil resilience. Tools for the investigation of both microbial communities, their degradation pathways and their interaction, will be discussed, describing the dedicated genomic and metagenomic approaches, as well as the interpretative tools of the deriving data, that are exploitable for both optimizing bio-based approaches for the treatment of total petroleum hydrocarbon contaminated soils and for the correct scaling up of the technologies at the industrial scale. Full article

Two mycoremediation approaches for the depletion of the total petroleum hydrocarbons in dredged sediments were compared: co-composting with spent mushroom substrate (SMS) from Pleurotus ostreatus and bioaugmentation with Lambertella sp. MUT 5852, an ascomycetes autochthonous to the sediment, capable of utilizing diesel oil its sole carbon source. After 28 days of incubation, 99% depletion was observed in presence of Lambertella sp. MUT 5852. No total petroleum hydrocarbon depletion was observed in sediment co-composting with the SMS after 60 days of incubation. 16S rDNA metabarcoding of the bacterial community was performed to evaluate the potential synergism between fungi and bacteria in the bioremediation process. The functional metagenomic prediction approach indicated that the biodiversity of the bacterial genera potentially involved in the degradation of TPH was higher in sediment bioaugmented with Lambertella sp. MUT 5852, which resulted in being mandatory for TPH depletion. Mechanisms of co-substrate inhibition of the hydrocarburoclastic bacterial species, due to the bioavailable organic matter of the SMS, are suggested to be involved in the observed kinetics of TPH depletion, failing in the case of SMS and successful in the case of Lambertella sp. MUT 5852. Full article

The Baixo Alentejo Flysch Group (BAFG) is an important stratigraphic unit that covers over half of the South Portuguese Zone (SPZ) depositional area, and it is composed by three main tectono-stratigraphic units: the Mértola, Mira, and Brejeira formations. All of these formations contain significant thicknesses of black shales and have several wide areas with 0.81 wt.%, 0.91 wt.%, and 0.72 wt.% average total organic carbon (TOC) (respectively) and thermal maturation values within gas zones (overmature). This paper is considering new data from classical methods of organic geochemistry characterization, such as TOC, Rock–Eval pyrolysis, and organic petrography, to evaluate the unconventional petroleum system from the SPZ. A total of 53 samples were collected. From the stratigraphical point of view, TOC values seem to have a random distribution. The Rock–Eval parameters point out high thermal maturation compatible with gas window (overmature zone). The samples are dominated by gas-prone extremely hydrogen-depleted type III/IV kerogen, which no longer has the potential to generate and expel hydrocarbons. The petrographic analyses positioned the thermal evolution of these samples into the end of catagenesis to metagenesis (wet to dry gas zone), with values predominantly higher than 2 %Ro (dry gas zone). The presence of thermogenic hydrocarbon fluids characterized by previous papers indicate that the BAFG from SPZ represents a senile unconventional petroleum system, working nowadays basically as a gas reservoir. Full article

This work was aimed at evaluating the relative merits of bioaugmentation, biostimulation and surfactant-enhanced bioavailability of a desert soil contaminated by crude oil through biopile treatment. The results show that the desert soil required bioaugmentation and biostimulation for bioremediation of crude oil. The bioaugmented biopile system led to a total petroleum hydrocarbon (TPH) reduction of 77% over 156 days while the system with polyoxyethylene (20) sorbitan monooleate (Tween 80) gave a 56% decrease in TPH. The biostimulated system with indigenous micro-organisms gave 23% reduction in TPH. The control system gave 4% TPH reduction. The addition of Tween 80 led to a respiration rate that peaked in 48 days compared to 88 days for the bioaugmented system and respiration declined rapidly due to nitrogen depletion. The residual hydrocarbon in the biopile systems studied contained polyaromatics (PAH) in quantities that may be considered as hazardous. Nitrogen was found to be a limiting nutrient in desert soil bioremediation. Full article

Barrier islands of Northwest Florida were heavily oiled during the Deepwater Horizon spill, but less is known about the impacts to the shorelines of the associated estuaries. Shoreline sediment oiling was investigated at 18 sites within the Pensacola Bay, Florida system prior to impact, during peak oiling, and post-wellhead capping. Only two locations closest to the Gulf of Mexico had elevated levels of total petroleum hydrocarbons (TPH) and total polycyclic aromatic hydrocarbons (PAHs). These samples showed a clear weathered crude oil signature, pattern of depletion of C9 to C19 alkanes and C0 to C4 naphthalenes, and geochemical biomarker ratios in concordance with weathered Macondo crude oil. All other locations and sample times showed only trace petroleum contamination. The results of this study are consistent with available satellite imagery and visual shoreline survey data showing heavy shoreline oiling limited to sandy beaches near the entrance to Pensacola Bay and shorelines of Santa Rosa Island. Full article