Biofuels from Microalgae Li, Yanqun; Horsman, Mark; Wu, Nan ...
Biotechnology progress,
July/August 2008, Letnik:
24, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Microalgae are a diverse group of prokaryotic and eukaryotic photosynthetic microorganisms that grow rapidly due to their simple structure. They can potentially be employed for the production of ...biofuels in an economically effective and environmentally sustainable manner. Microalgae have been investigated for the production of a number of different biofuels including biodiesel, bio‐oil, bio‐syngas, and bio‐hydrogen. The production of these biofuels can be coupled with flue gas CO2 mitigation, wastewater treatment, and the production of high‐value chemicals. Microalgal farming can also be carried out with seawater using marine microalgal species as the producers. Developments in microalgal cultivation and downstream processing (e.g., harvesting, drying, and thermochemical processing) are expected to further enhance the cost‐effectiveness of the biofuel from microalgae strategy.
•We developed a method for the determination of phthalates, parabens and BP3 in urine.•The method was successfully validated according to the total error approach.•The LOQs obtained ranged from 0.30 ...to 1.23ng/ml depending on the analytes.•Different enzymatic treatments allowed the determination of phase-II metabolites.•Phthalates metabolites were detected in most human urine samples analyzed.
Phthalates, parabens and 2-hydroxy-4-methoxybenzophenone or benzophone-3 are thought to act as endocrine disrupting chemicals, being able to disrupt the endocrine balance and therefore able to lead to some hormonal diseases. Numerous large-scale biomonitoring studies have detected the biomarkers of these compounds in more than 75% of the general population. To assess the exposure to these chemicals, we developed an analytical method based on a Solid Phase Extraction (SPE) prior to ultra high pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous measurement of seven phthalate metabolites (monobenzyl phthalate, mono-n-butyl phthalate, mono-iso-butyl phthalate, mono-2-ethylhexyl phthalate, mono-2-ethyl-5-hydroxyhexyl phthalate, mono-2-ethyl-5-oxohexyl phthalate, monoethyl phthalate), four parabens (methyl paraben, ethyl paraben, n-propyl paraben, n-butyl parabens) and benzophenone-3 in human urine. The distinction between unconjugated, glucuro- and sulfoconjugated forms was achieved using different enzymatic hydrolyses. The whole procedure was validated according to the total error approach, and was demonstrated to be linear (regression coefficient ranging from 0.987 to 0.998) and accurate (inter and intra assay precision <17.71%, relative bias <5.87%) in the dosing range of concentrations. The limits of quantification (LOQs) obtained ranged between 0.30 and 1.23ng/ml depending on the analyte. The reliability of the method was proven in passing successfully the German External Quality Assessment Scheme (G-EQUAS). Moreover, the urine from 25 volunteers were analyzed for the determination of glucuro-, sulfo- and free species separately. Phthalate metabolites, parabens and benzophenone-3 were positively detected in almost all urine samples, with detection rates ranging from 40 to 100%. Levels measured ranged from <LOQ to 2207ng/ml varying widely depending on the compound and the individual. In our small participating population, most of the phthalate metabolites were excreted predominately as glucuroconjugated forms while parabens and benzophenone-3 were detected as glucuro- and sulfoconjugated species in variable proportions according to the target compound.
Strong earthquakes at active ocean margins can remobilize vast amounts of surficial slope sediments and dynamically strengthen the margin sequences. Current process understanding is obtained from ...resulting event deposits and low‐resolution shear strength data, respectively. Here we directly target a site offshore Japan where both processes are expected to initiate, that is, at the uppermost part (15 cm) of a sedimentary slope sequence. Based on a novel application of short‐lived radionuclide data, we identified, dated, and quantified centimeter‐scale gaps related to surficial remobilization. Temporal correlation to the three largest regional earthquakes attest triggering by strong earthquakes (Mw >8). Also, extremely elevated shear strength values suggest a strong influence of seismic strengthening on shallow sediments. We show that despite enhanced slope stability by seismic strengthening, earthquake‐induced sediment transport can occur through surficial remobilization, which has large implications for the assessment of turbidite paleoseismology and carbon cycling at active margins.
Plain Language Summary
During strong earthquakes, large amounts of sediment are stripped from ocean slopes and transported into the deeper basin. The resulting event deposits can provide information on the recurrence of past earthquakes, which is crucial for seismic hazard assessment. To unravel the information stored within this archive, it is important to understand the effect of earthquakes on surficial slope sediments where the removal of sediment is supposed to take place. We discovered—for the first time—several centimeter‐scale gaps in a slope sequence offshore Japan, which can be linked to the largest regional earthquakes. Also, we found that seismic shaking can strengthen and stabilize a slope, therefore reducing the probability for large landslides and associated destructive tsunamis. This study shows that strong earthquakes can both stabilize and remobilize young sediments at ocean slopes.
Key Points
Slope stratigraphy reveals direct impact of strong earthquakes on young sediments of the active margin offshore Japan
Remobilization of surficial slope sediments at site occurs during Mw 8+ earthquakes, allowing turbidite paleoseismology in terminal basins
Seismic strengthening is most effective on uppermost sediments, progressively reducing submarine landslide potential
•A method was successfully validated for the determination of major cannabinoids in plant material.•It was then applied to 213 samples seized in CBD shops.•Half of the products were exceeding the ...legal threshold of 0.2% THC + THC-A.•Large discrepancies were observed between labeled and measured CBD concentration.•Large discrepancies were observed for a same same strain sold in various CBD shop.
Nowadays, (−)-cannabidiol (CBD) is gaining popularity for the treatment of various problems and can be found easily in many stores in Belgium. However, such product must comply with the law: if the total tetrahydrocannabinol (THC) content (−)-Δ9-tetrahydrocannabinol + (−)-Δ9-tetrahydrocannabinolic acid A (THC-A) is higher than 0.2%, it is considered as narcotic by the Belgian legislation. In this context, we have developed a method to quantify major cannabinoids (THC, THC-A, CBD, cannabidiolic acid, cannabigerolic acid, cannabigerol and cannabinol) in plant material.
After drying, a liquid-liquid extraction was performed on plant materials, followed by dilutions. Extracts were analyzed by ultra-high-performance liquid chromatography combined with a photodiode array detector. Mobile phases consisted of methanol and 0.1% formic acid in water applied in a 16-minute gradient mode. After validating the method, it was applied to 213 samples seized by the police in CBD shops.
The method fulfilled the criteria in terms of specificity, calibration curve, precision, trueness and dosing range. Total THC content ranged from 0.14 to 1.17% (median 0.38%) with 110 samples exceeding the Belgian legal threshold of 0.2%. The amounts measured in the samples varied greatly, some were 6 times below the amount labelled on the packaging, others showed a concentration 4 times higher than stated on the package. Same strain also showed concentration differences from shop to shop.
Our method was successfully validated and applied to samples seized in CBD shops. Half of the products exceeded the Belgian legal threshold. THC and CBD concentrations discrepancies showed that products sold in CBD shops are not pharmaceutical grade.
GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into ...their neutral counterparts. Conversely, HPLC permits the determination of the original composition of plant cannabinoids by direct analysis. Several HPLC methods have been described in the literature, but most of them failed to separate efficiently all the cannabinoids or were not validated according to general guidelines. By use of an innovative methodology for modelling chromatographic responses, a simple and accurate HPLC/DAD method was developed for the quantification of major neutral and acidic cannabinoids present in cannabis plant material: Δ9-tetrahydrocannabinol (THC), THC acid (THCA), cannabidiol (CBD), CBD acid (CBDA), cannabigerol (CBG), CBG acid (CBGA) and cannabinol (CBN). Δ8-Tetrahydrocannabinol (Δ8-THC) was determined qualitatively. Following the practice of design of experiments, predictive multilinear models were developed and used in order to find optimal chromatographic analytical conditions. The method was validated following an approach using accuracy profiles based on β-expectation tolerance intervals for the total error measurement, and assessing the measurements uncertainty. This analytical method can be used for diverse applications, e.g. plant phenotype determination, evaluation of psychoactive potency and control of material quality.
Bisphenol A, triclosan and 4-nonylphenol are among the endocrine disruptors which are widely used in daily products. In this study, we reported total urinary levels of bisphenol A, triclosan and ...4-nonylphenol, in order to evaluate the baseline contamination of a general population in Belgium. Bisphenol A and triclosan were detected in respectively 97.7% and 74.6% of the samples examined demonstrating that the general Belgian population is extensively exposed to both chemicals. On the other hand, 4-nonylphenol was not detected in any urine samples analyzed, suggesting either low exposure, inadequate biomarker, or that urine is an inappropriate biological matrix for assessing exposure to nonylphenol commercial mixtures. Geometric mean concentration was determined for bisphenol A at 2.55μg/l and for triclosan at 2.70μg/l. No significant difference was observed between levels and gender for both bisphenol A and triclosan. When classified by age, the 20–39year group showed the highest triclosan levels, while all age groups seemed to be similarly exposed to bisphenol A. Both bisphenol A and triclosan urinary levels were not correlated with creatinine excretion in our healthy population, questioning the relevance of the creatinine adjustment in reporting these chemical levels. Bisphenol A levels in urine of people living in the same home and collected on the same time were fairly correlated, confirming the assumption that dietary intake would be the primary route of exposure. Triclosan urinary levels were not correlated with bisphenol A levels.
► We measured bisphenol A, triclosan and nonylphenol in a general Belgian population. ► BPA and triclosan were detected respectively in 97.7% and 74.6% of the urine samples. ► 4-Nonylphenol was not detected in any urine samples. ► We did not find any correlation between BPA levels and gender or age. ► We found higher triclosan level for participants aged between 20 and 39years old.
Nitrogen isotopes are an important tool for evaluating past biogeochemical cycling from the paleoceanographic record. However, bulk sedimentary nitrogen isotope ratios, which can be determined ...routinely and at minimal cost, may be altered during burial and early sedimentary diagenesis, particularly outside of continental margin settings. The causes and detailed mechanisms of isotopic alteration are still under investigation. Case studies of the Mediterranean and South China Seas underscore the complexities of investigating isotopic alteration. In an effort to evaluate the evidence for alteration of the sedimentary N isotopic signal and try to quantify the net effect, we have compiled and compared data demonstrating alteration from the published literature. A >100 point comparison of sediment trap and surface sedimentary nitrogen isotope values demonstrates that, at sites located off of the continental margins, an increase in sediment 15N/14N occurs during early burial, likely at the seafloor. The extent of isotopic alteration appears to be a function of water depth. Depth‐related differences in oxygen exposure time at the seafloor are likely the dominant control on the extent of N isotopic alteration. Moreover, the compiled data suggest that the degree of alteration is likely to be uniform through time at most sites so that bulk sedimentary isotope records likely provide a good means for evaluating relative changes in the global N cycle.
Key Points
Use of sedimentary nitrogen isotopes is examined
On average, sediment 15N/14N increases approx. 2 per mil during early burial
Isotopic alteration scales with water depth
Subaqueous paleoseismic studies used soft sediment deformation structures (SSDS) to discern the shaking strength of past earthquakes, as the deformation degree of SSDS related to Kelvin Helmholtz ...Instability evolves from disturbed lamination and folds to intraclast breccia with higher peak ground accelerations (PGA). We lack comparative studies of different sediment types with SSDS related to earthquakes from different seismogenic sources to comprehend how these factors modulate earthquake‐induced deformation. Here, we compile sediment records with seven earthquake‐triggered SSDS from 10 lakes with organic‐, carbonate‐, siliciclastic‐, and diatom‐rich sediment from three subduction zones and one collisional setting. We target basin sequences with slope angles <0.65° to reduce the influence of gravitational downslope stress. We find that even minimal increases in slope angle, maximal 1°, lead to higher deformation degrees and, for some earthquakes, SSDS are only present at >0.65°. Fine‐grained clastics enhance sediment susceptibility to deformation, whereas abundant diatoms reduce it, demonstrating the influence of composition. Deformation correlates best with PGA and the vicinity of the earthquakes, suggesting that high frequency shaking promotes deformation. In addition, deformation only occurs above a minimum magnitude dependent on sediment composition, and higher deformation degrees in our studied basin sedimentary sequences only above Mw 4.9 for all sediment types, suggesting that sufficient duration of shaking—magnitude correlates with duration—is essential for SSDS development. We advise taking multiple cores on gentle slopes to study SSDS—additional to basin cores—to resolve small magnitude local earthquakes and relative differences in frequency content of past events.
Plain Language Summary
Earthquakes can deform sediment and store information on the shaking strength of past earthquakes within these structures. Therefore, studying deformation records can help society to understand the recurrence and magnitude of past earthquakes. To successfully apply this method, we need to understand exactly how seismic shaking interacts with the sediment on the lake floor. However, we lack studies investigating how sediment composition modulates deformation or which characteristics of an earthquake control deformation. To fill this knowledge gap, we compare the deformation records of 10 lakes with different sediment types caused by earthquakes with different shaking characteristics. Our data show that high concentrations of fine mineral grains within the sediment can ease earthquake‐triggered deformation, whereas abundant diatoms—a type of algae—makes sediment more resistant. Furthermore, we propose that mainly the high frequency component of seismic waves and sufficient duration of the earthquake are critical to deform sediment. We claim that deformations are a valuable addition to other sedimentological records of past earthquakes as they can resolve relative differences between the shaking characteristics of past earthquakes.
Key Points
Sediment composition modulates sediment sensitivity to deformation as fine‐grained sediment increases and diatoms decrease sensitivity
Aside from strong seismic shaking, sufficient high frequency content and duration of seismic waves are a prerequisite for deformation
For paleoseismology, we advise taking multiple cores on gentle slopes to study deformations and in the flat basin to study event deposits
Lacustrine alkenones are increasingly reported in freshwater lakes worldwide, which makes them a very promising proxy to reconstruct past continental temperatures. However, a more systematic ...understanding of ecological preferences of freshwater alkenone-producers at global scale is lacking, which limits our understanding of alkenones as a proxy in lakes. Here we investigated 56 Swiss freshwater lakes and report Group 1 alkenones in 33 of them. In twelve of the lakes containing alkenones, a mixed Group 1/Group 2 alkenone signature was detected. We used a random forest (RF) model to investigate the influence of 15 environmental variables on alkenone occurrence in Swiss lakes and found sodium (Na + ) concentration and mean annual air temperature (MAAT) to be the most important variables. We also trained a RF model on a database that included Swiss lakes and all freshwater lakes worldwide, which were previously investigated for alkenone presence. Water depth appeared as the most important variable followed by MAAT and Na + , sulfate and potassium concentrations. This is very similar to results found for freshwater and saline lakes, which suggests that Group 1 and Group 2 alkenone occurrence could be controlled by the same variables in freshwater lakes. For each tested variable, we defined the optimal range(s) for the presence of alkenones in freshwater lakes. The similarity of the results for the Swiss and global models suggests that the environmental parameters controlling the occurrence of freshwater alkenone producers could be homogenous worldwide.
Lake sediments constitute natural archives of past environmental changes. Historically, research has focused mainly on generating regional climate records, but records of human impacts caused by land ...use and exploitation of freshwater resources are now attracting scientific and management interests. Long-term environmental records are useful to establish ecosystem reference conditions, enabling comparisons with current environments and potentially allowing future trajectories to be more tightly constrained. Here we review the timing and onset of human disturbance in and around inland water ecosystems as revealed through sedimentary archives from around the world. Palaeolimnology provides access to a wealth of information reflecting early human activities and their corresponding aquatic ecological shifts. First human impacts on aquatic systems and their watersheds are highly variable in time and space. Landscape disturbance often constitutes the first anthropogenic signal in palaeolimnological records. While the effects of humans at the landscape level are relatively easily demonstrated, the earliest signals of human-induced changes in the structure and functioning of aquatic ecosystems need very careful investigation using multiple proxies. Additional studies will improve our understanding of linkages between human settlements, their exploitation of land and water resources, and the downstream effects on continental waters.
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