Concept: Land degradation
Understanding the factors that contribute to the degradation of bioactive compounds during microwave treatment is meaningful for the practical application of this novel technology. The influence of microwave power, energy density, temperature, pH value and the initial concentration of anthocyanin (Acys) on the degradation behavior of malvidin-3-glucoside (Mv-3-glu) and malvidin- 3,5- diglucoside (Mv-3,5-diglu) were investigated in this study. Results showed that the degradations of the both Acys were accelerated with the increase of power, microwave energy density, temperature, pH value and the initial concentration of Acys. The degradation process of the both Acys followed the first-order kinetics model (R2 > 0.94), whereas the relationship between Acys degradation and energy density fitted to the Logistic model well (R2 > 0.98). In addition, Mv-3-glu was more susceptible to the microwave treatment than Mv-3,5-diglu. Compared with the heating at 98 ºC ± 2 ºC water bath, the both Acys degraded more rapidly under microwave treatment at 100 ºC, indicating the occurrence of microwave effect. The results can provide a guide 20 for the scientific application of microwave treatment.
The white rot fungus Pleurotus ostreatus is able to completely remove the synthetic hormone 17α-ethinylestradiol (EE2, 200 μg in 20 mL) from a liquid complex or mineral medium in 3 or 14 days, respectively. Its efficiency has also been documented in the removal of estrogenic activity that correlated with the EE2 degradation. A set of in vitro experiments using various cellular and enzyme fractions has been performed and the results showed that EE2 was degraded by isolated laccase (about 90% within 24 h). The degradation was also tested with concentrated extracellular liquid where degradation reached 50% mainly due to the laccase activity; however, after a supplementation with H2O2 and Mn2+ residual manganese-dependent peroxidase activities (40 times lower than Lac) raised the degradation to 100%. Moreover, the intracellular fraction and also laccase-like activity associated with fungal mycelium were found to be efficient in the degradation too. As well, isolated microsomal proteins appeared to also be involved in the process. The degradation was completely suppressed in the presence of cytochrome P-450 inhibitors, piperonylbutoxide and carbon monoxide, indicating a role of this monooxygenase in the degradation process. Attention was also paid to monitoring of changes in the estrogenic activity during these particular in vitro experiments when mainly degradations related to ligninolytic enzymes were found to decrease the estrogenic activity with EE2 removal proportionally. Several novel metabolites of EE2 were detected using different chromatographic method with mass spectrometric techniques (LC-MS, GC-MS) including also [13C]-labeled substrates. The results document the involvement of various different simultaneous mechanisms in the EE2 degradation by P. ostreatus both the ligninolytic system and the eukaryotic machinery of cytochromes P-450.
- Environmental science and pollution research international
- Published almost 7 years ago
The biodegradability of nitrochlorinated (diuron and atrazine) and chlorophenoxy herbicides (2,4-D and MCPA) has been studied through several bioassays using different testing times and biomass/substrate ratios. A fast biodegradability test using unacclimated activated sludge yielded no biodegradation of the herbicides in 24 h. The inherent biodegradability test gave degradation percentages of around 20-30 % for the nitrochlorinated herbicides and almost complete removal of the chlorophenoxy compounds. Long-term biodegradability assays were performed using sequencing batch reactor (SBR) and sequencing batch membrane bioreactor (SB-MBR). Fixed concentrations of each herbicide below the corresponding EC50 value for activated sludge were used (30 mg L(-1) for diuron and atrazine and 50 mg L(-1) for 2,4-D and MCPA). No signs of herbicide degradation appeared before 35 days in the case of diuron and atrazine and 21 days for 2,4-D, whereas MCPA was partially degraded since the early stages. Around 25-36 % degradation of the nitrochlorinated herbicides and 53-77 % of the chlorophenoxy ones was achieved after 180 and 135 days, respectively, in SBR, whereas complete disappearance of 2,4-D was reached after 80 days in SB-MBR.
Pentachloronitrobenzene (PCNB) is a fungicide belonging to the organochlorine family and used extensively in agriculture for crop production. Many studies have implied that PCNB has become an environmental concern due to its widespread contamination in eco-systems. However, whether PCNB is bioaccumulated, degraded and phytotoxic in plants is poorly understood. In this study, several alfalfa (Medicago sativa) cultivars were grown in soil with PCNB to investigate their absorption and catabolism, including PCNB residues in the soil and PCNB-induced toxic responses in plants. Alfalfa plants varied widely in their ability to accumulate and degrade PCNB. The degradation rate of PCNB was 66.26-77.68% after alfalfa growth in the soils for 20 d, while the rates in the control (soil without alfalfa) were only 48.42%. Moreover, concentrations of PCNB residues in the rhizosphere soil were significantly higher than those in the non-rhizosphere soils. Alfalfa exposed to 10 mg kg(-1) PCNB showed inhibited growth and oxidative damage, but the effects of PCNB on the cultivars differed significantly, indicating that the alfalfa cultivars have different tolerance to PCNB. Activities of invertase (INV), urease (URE), polyphenol oxidase (PPO), alkaline phosphatase (ALP) and acid phosphatase (ACP) were assayed in the treated soils and showed that the enzyme activities were altered after PCNB exposure. The URE, PPO, ALP and ACP activities were increased in soil following the planting of alfalfa. The objective of the study was to analyze the potential of different cultivars of alfalfa to accumulate and degrade PCNB from the contaminated soil.
Thermoelectric figure-of-merits (ZT) are enhanced or degraded by crystal defects such as twins and excess atoms that are correlated with thermal conductivity (k) and carrier concentration (n). For Bi2Te3, it is unclear whether the crystal defects can enhance ZT without a degradation in the thermopower factor. In the present study, n-type Bi2Te3 nanowires (NWs) are electrochemically synthesized to have twin-free (TF) or twin-containing (TC) microstructures with a ZT of 0.10 and 0.08, respectively, at 300 K. The ZTs of TF and TC NWs remarkably increase up to 0.21 and 0.31, when heat-treatments cause n-reduction and twins induce phonon scattering, as follows: first, the enhancement of the Seebeck coefficient from -70 to -98 μV K(-1) for TF NWs and from -57 to -143 μV K(-1) for TC NWs, by virtue of n-reduction; secondly, twin-driven k-reduction from 1.9 to 1.4 W m(-1) K(-1) of TC NWs, while the k of TF NWs increases from 2.3 to 2.6 W m(-1) K(-1) due to the enhanced carrier mobility. The lattice thermal conductivities of TC NW are lowered from 1.1 to 0.8 W m(-1) K(-1) by phonon scattering at twins. Density functional theory calculations indicate that twins do not significantly influence the Seebeck coefficient of Bi2Te3. It is strongly recommended that twins be incorporated with an optimum carrier concentration to enhance the ZT of Bi2Te3.
Complete biodegradation of a newly-synthesized chemical in a wastewater treatment plant (WWTP) eliminates the potential for novel environmental pollutants. However, differences within- and between-WWTP microbial communities may alter expectations for biodegradation. WWTP communities can also serve as a source of unique consortia that, when enriched, can metabolize chemicals that tend to resist degradation, but are otherwise promising green alternatives. We tested the biodegradability of three ionic liquids (ILs): 1-octyl-3-methylpyridinium bromide (OMP), 1-butyl-3-methylpyridinium bromide (BMP) and 1-butyl-3-methylimidazolium chloride (BMIM). We performed tests using communities from two WWTPs at three time points. Site-specific and temporal variation both influenced community composition, which impacted the success of OMP biodegradability. Neither BMP nor BMIM degraded in any test, suggesting that these ILs are unlikely to be removed by traditional treatment. Following standard biodegradation assays, we enriched for three consortia that were capable of quickly degrading OMP, BMP and BMIM. Our results indicate WWTPs are not functionally redundant with regard to biodegradation of specific ionic liquids. However, consortia can be enriched to degrade chemicals that fail biodegradability assays. This information can be used to prepare pre-treatment procedures and prevent environmental release of novel pollutants.
Land degradation is a global problem that particularly impacts the poor rural inhabitants of low and middle-income countries. We improve upon existing literature by estimating the extent of rural populations in 2000 and 2010 globally on degrading and improving agricultural land, taking into account the role of market access, and analyzing the resulting impacts on poverty. Using a variety of spatially referenced datasets, we estimate that 1.33 billion people worldwide in 2000 were located on degrading agricultural land (DAL), of which 1.26 billion were in developing countries. Almost all the world’s 200 million people on remote DAL were in developing countries, which is about 6% of their rural population. There were also 1.54 billion rural people on improving agricultural land (IAL), with 1.34 billion in developing countries. We find that a lower share of people in 2000 on DAL, or a higher share on IAL, lowers significantly how much overall economic growth reduces poverty from 2000 to 2012 across 83 developing countries. As the population on DAL and IAL in developing countries grew by 13% and 15% respectively from 2000 to 2010, these changing spatial distributions of rural populations could impact significantly future poverty in developing countries.
The Aspergillus niger-derived prolyl endoprotease (AN-PEP) has previously been shown to degrade gluten in healthy subjects when added to an intragastrically infused meal. The current study investigated the efficacy of AN-PEP in a physiological meal setting. In this randomized placebo-controlled crossover study, 18 gluten-sensitive subjects consumed a porridge containing 0.5 g gluten together with two tablets either containing a high or low dose of AN-PEP, or placebo. Gastric and duodenal content was sampled over 180 minutes, and areas under the curve of gluten concentrations were calculated. The primary outcome, i.e. success rate of high dose AN-PEP defined as at least 50% gluten degradation compared to placebo in the duodenum, was achieved in 10 of 13 comparisons. In the stomach, gluten levels were reduced from 176.9 (median, interquartile range 73.5-357.8) to 22.0 (10.6-50.8, p = 0.001) in the high dose and to 25.4 μg × min/ml (16.4-43.7, p = 0.001) in the low dose. In the duodenum, gluten levels were reduced from 14.1 (8.3-124.7) in the placebo to 6.3 (3.5-19.8, p = 0.019) in the high dose and to 7.4 μg × min/ml in the low dose (3.8-12.0, p = 0.015). Thus even in a physiological meal setting, AN-PEP significantly degraded most gluten in the stomach before it entered the duodenum.
Mounting evidence suggests that natural microbial communities exhibit a high level of spatial organization at the micrometric scale that facilitate ecological interactions and support biogeochemical cycles. Microbial patterns are difficult to study definitively in natural environments due to complex biodiversity, observability and variable physicochemical factors. Here, we examine how trophic dependencies give rise to self-organized spatial patterns of a well-defined bacterial consortium grown on hydrated surfaces. The model consortium consisted of two Pseudomonas putida mutant strains that can fully degrade the aromatic hydrocarbon toluene. We demonstrated that obligate cooperation in toluene degradation (cooperative mutualism) favored convergence of 1:1 partner ratio and strong intermixing at the microscale (10-100 μm). In contrast, competition for benzoate, a compound degraded independently by both strains, led to distinct segregation patterns. Emergence of a persistent spatial pattern has been predicted for surface attached microbial activity in liquid films that mediate diffusive exchanges while permitting limited cell movement (colony expansion). This study of a simple microbial consortium offers mechanistic glimpses into the rules governing the assembly and functioning of complex sessile communities, and points to general principles of spatial organization with potential applications for natural and engineered microbial systems.
Mitigation strategies are crucial for desertification given that once degradation starts, other solutions are extremely expensive or unworkable. Prevention is key to handle this problem and solutions should be based on spotting and deactivating the stressors of the system. Following this topic, the Spanish Plan of Action to Combat Desertification (SPACD) created the basis for implementing two innovative approaches to evaluate the threat of land degradation in the country. This paper presents tools for preventing desertification in the form of a geomatic approach to enable the periodic assessments of the status and trends of land condition. Also System Dynamics modelling has been used to integrate bio-physical and socio-economic aspects of desertification to explain and analyse degradation in the main hot spots detected in Spain. The 2dRUE procedure was implemented to map the land-condition status by comparing potential land productivity according to water availability, the limiting factor in arid lands, with plant-biomass data. This assessment showed that 20% of the territory is degraded and an additional 1% is actively degrading. System Dynamics modelling was applied to study the five desertification landscapes identified by the SPACD. The risk analysis, implemented on these models, concluded that ‘Herbaceous crops affected by soil erosion’ is the landscape most at risk, while the Plackett-Burman sensitivity analysis used to rank the factors highlighted the supremacy of climatic factors above socioeconomic drivers.