Showing papers by "Pedro J. J. Alvarez published in 2016"
TL;DR: Dissolved black carbon released from biochar decreased its ability to further generate ROS due to lower light absorption, which has significant implications on the environmental fate of dissolved BC and that of priority pollutants.
Abstract: Dissolved black carbon (BC) released from biochar can be one of the more photoactive components in the dissolved organic matter (DOM) pool. Dissolved BC was mainly composed of aliphatics and aromatics substituted by aromatic C-O and carboxyl/ester/quinone moieties as determined by solid-state nuclear magnetic resonance. It underwent 56% loss of absorbance at 254 nm, almost complete loss of fluorescence, and 30% mineralization during a 169 h simulated sunlight exposure. Photoreactions preferentially targeted aromatic and methyl moieties, generating CH2/CH/C and carboxyl/ester/quinone functional groups. During irradiation, dissolved BC generated reactive oxygen species (ROS) including singlet oxygen and superoxide. The apparent quantum yield of singlet oxygen was 4.07 ± 0.19%, 2-3 fold higher than many well-studied DOM. Carbonyl-containing structures other than aromatic ketones were involved in the singlet oxygen sensitization. The generation of superoxide apparently depended on electron transfer reactions mediated by silica minerals in dissolved BC, in which phenolic structures served as electron donors. Self-generated ROS played an important role in the phototransformation. Photobleaching of dissolved BC decreased its ability to further generate ROS due to lower light absorption. These findings have significant implications on the environmental fate of dissolved BC and that of priority pollutants.
221 citations
TL;DR: In this article, the authors review several common thermal treatment technologies for hydrocarbon-contaminated soils, assess their potential environmental impacts, and propose frameworks for sustainable and low-impact deployment based on a holistic consideration of energy and water requirements, ecosystem ecology, and soil science.
171 citations
TL;DR: It is suggested that polyvalent phages may be readily isolated from the environment by using different sequential hosts, and this approach should facilitate the study of their ecological significance as well as enable novel applications.
Abstract: Many studies on phage biology are based on isolation methods that may inadvertently select for narrow-host-range phages. Consequently, broad-host-range phages, whose ecological significance is largely unexplored, are consistently overlooked. To enhance research on such polyvalent phages, we developed two sequential multihost isolation methods and tested both culture-dependent and culture-independent phage libraries for broad infectivity. Lytic phages isolated from activated sludge were capable of interspecies or even interorder infectivity without a significant reduction in the efficiency of plating (0.45 to 1.15). Two polyvalent phages (PX1 of the Podoviridae family and PEf1 of the Siphoviridae family) were characterized in terms of adsorption rate (3.54 × 10(-10) to 8.53 × 10(-10) ml/min), latent time (40 to 55 min), and burst size (45 to 99 PFU/cell), using different hosts. These phages were enriched with a nonpathogenic host (Pseudomonas putida F1 or Escherichia coli K-12) and subsequently used to infect model problematic bacteria. By using a multiplicity of infection of 10 in bacterial challenge tests, >60% lethality was observed for Pseudomonas aeruginosa relative to uninfected controls. The corresponding lethality for Pseudomonas syringae was ∼ 50%. Overall, this work suggests that polyvalent phages may be readily isolated from the environment by using different sequential hosts, and this approach should facilitate the study of their ecological significance as well as enable novel applications.
95 citations
TL;DR: Nanotechnology enabled water treatment is a promising approach to enhance the effectiveness and efficiency of purifying water in many areas of the world as mentioned in this paper, and the unique material properties that emerge at the nano-scale enable solutions to treat pollutants in water for which existing technologies are inefficient or ineffective.
Abstract: Nanotechnology enabled water treatment is a promising approach to enhance the effectiveness and efficiency of purifying water in many areas of the world. Nanotechnology offers significant opportunities to revolutionize approaches towards drinking water treatment by enhancing the multifunctionality and versatility of treatment systems while reducing reliance on stoichiometric chemical addition (thus minimizing associated waste streams), shrinking large facilities with relatively long hydraulic contact times and minimizing energy intensive processes. The unique material properties that emerge at the nano-scale enable solutions to treat pollutants in water for which existing technologies are inefficient or ineffective. This perspective describes the rationale, opportunities and barriers for translating this nascent technology from promising bench-scale discoveries to full-scale commercialization and production of safe drinking water.
94 citations
TL;DR: The results suggest that soil pyrolysis could be a viable thermal treatment to quickly remediate soils impacted by weathered oil while improving soil fertility, potentially enhancing revegetation.
Abstract: Pyrolysis of contaminated soils at 420 °C converted recalcitrant heavy hydrocarbons into “char” (a carbonaceous material similar to petroleum coke) and enhanced soil fertility. Pyrolytic treatment reduced total petroleum hydrocarbons (TPH) to below regulatory standards (typically <1% by weight) within 3 h using only 40–60% of the energy required for incineration at 600–1200 °C. Formation of polycyclic aromatic hydrocarbons (PAHs) was not observed, with post-pyrolysis levels well below applicable standards. Plant growth studies showed a higher biomass production of Arabidopsis thaliana and Lactuca sativa (Simpson black-seeded lettuce) (80–900% heavier) in pyrolyzed soils than in contaminated or incinerated soils. Elemental analysis showed that pyrolyzed soils contained more carbon than incinerated soils (1.4–3.2% versus 0.3–0.4%). The stark color differences between pyrolyzed and incinerated soils suggest that the carbonaceous material produced via pyrolysis was dispersed in the form of a layer coating the...
77 citations
TL;DR: Wang et al. as discussed by the authors investigated the fate of nano-TiO 2 in two full scale WWTPs and their receiving streams in northern China (i.e., the Binhe and Minxin rivers, which flow to the Xiaohe River).
75 citations
TL;DR: Overall, QS stimulation through the addition of trace levels of such autoinducers might be a feasible approach to enhance MFC performance under high-salinity conditions.
60 citations
TL;DR: Large granules in R1 with intact extracellular polymeric substances (EPS) outer layer structure entrapped hydroxyapatite at center, which formed a core structure and further enhanced the stability of aerobic granules.
53 citations
TL;DR: This study evaluates the relationship between natural methane occurrence and three principal environmental factors (groundwater redox state, water type, and topography) using two pre-drill datasets of 132 samples from western Pennsylvania, Ohio, and West Virginia and 1417 samples from northeastern Pennsylvania to identify three factors, which offer strong predictive power regarding the natural occurrence of high methane concentrations.
Abstract: The recent boom in shale gas development in the Marcellus Shale has increased interest in the methods to distinguish between naturally occurring methane in groundwater and stray methane associated with drilling and production operations. This study evaluates the relationship between natural methane occurrence and three principal environmental factors (groundwater redox state, water type, and topography) using two pre-drill datasets of 132 samples from western Pennsylvania, Ohio, and West Virginia and 1417 samples from northeastern Pennsylvania. Higher natural methane concentrations in residential wells are strongly associated with reducing conditions characterized by low nitrate and low sulfate ([NO3- ] < 0.5 mg/L; [SO42- ] < 2.5 mg/L). However, no significant relationship exists between methane and iron [Fe(II)], which is traditionally considered an indicator of conditions that have progressed through iron reduction. As shown in previous studies, water type is significantly correlated with natural methane concentrations, where sodium (Na) -rich waters exhibit significantly higher (p<0.001) natural methane concentrations than calcium (Ca)-rich waters. For water wells exhibiting Na-rich waters and/or low nitrate and low sulfate conditions, valley locations are associated with higher methane concentrations than upland topography. Consequently, we identify three factors ("Low NO3- & SO42- " redox condition, Na-rich water type, and valley location), which, in combination, offer strong predictive power regarding the natural occurrence of high methane concentrations. Samples exhibiting these three factors have a median methane concentration of 10,000 µg/L. These heuristic relationships may facilitate the design of pre-drill monitoring programs and the subsequent evaluation of post-drill monitoring results to help distinguish between naturally occurring methane and methane originating from anthropogenic sources or migration pathways.
48 citations
TL;DR: The results show for the first time that the adsorptive interaction of π-donor aromatic compounds with carbon nanomaterials can be facilitated by N-doping.
Abstract: A large effort is being made to develop nanosorbents with tunable surface chemistry for enhanced adsorption affinity and selectivity toward target organic contaminants. Heteroatom N-doped multiwall carbon nanotubes (N-MCNT) were synthesized by chemical vapor deposition of pyridine and were further investigated for the adsorptive removal of several aromatic chemicals varying in electronic donor and acceptor ability from aqueous solutions using a batch technique. Compared with commercial nondoped multiwall carbon nanotubes (MCNT), N-MCNT had similar specific surface area, morphology, and pore-size distribution but more hydrophilic surfaces and more surface defects due to the doping of graphitic and pyridinic N atoms. N-MCNT exhibited enhanced adsorption (2–10 folds) for the π-donor chemicals (2-naphthol and 1-naphthalmine) at pH ∼6 but similar adsorption for the weak π-donor chemical (naphthalene) and even lower adsorption (up to a 2-fold change) for the π-acceptor chemical (1,3-dinitrobenzene). The enhance...
47 citations
TL;DR: It is demonstrated that fullerol can mediate the electron transfer from Rhodamine B dye to O2 under visible light irradiation, achieving simultaneous dye decolorization and •OH-induced degradation of 4-chlorophenol.
Abstract: Fullerenes and their derivatives are known to photosensitize the production of singlet oxygen (1O2), but their role in generating hydroxyl radical (•OH) under visible light has not been reported. Here, we demonstrate that fullerol can mediate the electron transfer from Rhodamine B dye to O2 under visible light irradiation, achieving simultaneous dye decolorization and •OH-induced degradation of 4-chlorophenol. The hydroxyl radical is proposed to be produced via a consecutive reduction of molecular oxygen by fullerol anion radical, which is formed through the electron transfer from the dye to the triplet state of fullerol. Mechanistic investigations using various probe reagents such as superoxide dismutase (superoxide quencher), t-butanol (•OH quencher), and coumarin (•OH probe) provided indirect evidence for the generation of •OH under visible light. Furthermore, spin trapping technique directly detected the oxidizing species such as •OH, HO2•, and 1O2 in the visible light irradiated solution of RhB/fulle...
TL;DR: Overall, higher-energy nanocrystals may exhibit greater propensity to adsorb to or react with biological protective barriers and/or background constituents, which passivates their reactivity and reduces their bioavailability and cytotoxicity.
Abstract: Responsible development of nanotechnology calls for improved understanding of how nanomaterial surface energy and reactivity affect potential toxicity. Here, we challenge the paradigm that cytotoxicity increases with nanoparticle reactivity. Higher-surface-energy {001}-faceted CdS nanorods (CdS-H) were less toxic to Saccharomyces cerevisiae than lower-energy ({101}-faceted) nanorods (CdS-L) of similar morphology, aggregate size, and charge. CdS-H adsorbed to the yeast’s cell wall to a greater extent than CdS-L, which decreased endocytosis and cytotoxicity. Higher uptake of CdS-L decreased cell viability and increased endoplasmatic reticulum stress despite lower release of toxic Cd2+ ions. Higher toxicity of CdS-L was confirmed with five different unicellular microorganisms. Overall, higher-energy nanocrystals may exhibit greater propensity to adsorb to or react with biological protective barriers and/or background constituents, which passivates their reactivity and reduces their bioavailability and cytoto...
TL;DR: A new mechanism via which graphene materials enhance oxidation of organic contaminants by metal oxides is reported, which may guide the development of novel metal oxide-graphene nanocomposites for contaminant removal.
TL;DR: In this article, the authors developed a regional temperature map showing that downhole temperatures in Bakken reservoir wells equal or exceed the upper known temperature limit for microbial life, suggesting souring had a geochemical origin.
Abstract: Hydrocarbon souring represents a significant safety and corrosion challenge to the oil and gas industry. H2S may originate from geochemical or biogenic sources, although its source is rarely discerned. Biocides are sometimes utilized during well operations to prevent or inhibit H2S generation. Here we develop a regional temperature map showing that downhole temperatures in Bakken reservoir wells equal or exceed the upper known temperature limit for microbial life. Attempts to extract microbial DNA from produced water yielded little to no detectable quantities. Stable isotope analysis yielded 34Sδ values from 4.4 to 9.8‰, suggesting souring had a geochemical origin. Under Bakken reservoir conditions, anhydrite can react with hydrocarbons to form H2S. Anhydrite present near the sour areas studied could be the underlying geochemical source creating this H2S. In cases of geochemical souring, reevaluation of the need for biocide addition may provide significant reductions in both operational costs and overall ...
TL;DR: In this paper, the authors showed that tin porphyrin loading on a silica substrate (SnP/silica) markedly accelerates the degradation of Microcystins (MCs) under visible light irradiation, despite a reduction of photosensitized singlet oxygen ( 1 O 2 ) production.
Abstract: This study demonstrates that tin porphyrin (SnP) loading on a silica substrate (SnP/silica) markedly accelerates the degradation of Microcystins (MCs) under visible light irradiation, despite a reduction of photosensitized singlet oxygen ( 1 O 2 ) production. A comparative study using Rose Bengal, SnP, and C 60 aminofullerene suggested that the MC-RR decay rate was directly proportional to the photosensitizing activity for triplet state-induced oxidation, while it exhibited poor correlation to singlet oxygenation efficiency. This implies that electron transfer from MC to the triplet state of SnP (facilitated by favorable MC sorption on silica) contributes to the photosensitized MC oxidation. Experiments to examine sensitizers for the one-electron oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) showed the superiority of SnP/silica for photo-initiated electron transfer as a possible MC oxidation route. This was corroborated by the negligible effects of reagents that quench or facilitate singlet oxygenation (e.g., azide ion, D 2 O) on the MC-RR degradation rate. Despite MC-RR removal below detection levels, residual toxicity (indicated by a significant decrease in protein phosphatase inhibition activity) was observed. Tandem mass spectrometric analysis suggests that this residual toxicity may be ascribed to byproducts resulting from addition of a single oxygen atom to the Adda moiety.
TL;DR: A group of international experts participated in a workshop organized by the Academy of Sciences of Nicaragua to review this ESIA and concluded that the ESIA does not meet international standards; essential information is lacking regarding the potential impacts on the lake, freshwater and marine environments, and biodiversity.
Abstract: The proposed interoceanic canal will connect the Caribbean Sea with the Pacific Ocean, traversing Lake Nicaragua, the major freshwater reservoir in Central America. If completed, the canal would be the largest infrastructure-related excavation project on Earth. In November 2015, the Nicaraguan government approved an environmental and social impact assessment (ESIA) for the canal. A group of international experts participated in a workshop organized by the Academy of Sciences of Nicaragua to review this ESIA. The group concluded that the ESIA does not meet international standards; essential information is lacking regarding the potential impacts on the lake, freshwater and marine environments, and biodiversity. The ESIA presents an inadequate assessment of natural hazards and socioeconomic disruptions. The panel recommends that work on the canal project be suspended until an appropriate ESIA is completed. The project should be resumed only if it is demonstrated to be economically feasible, environmentally acceptable, and socially beneficial.
TL;DR: This is the first field study to assess biodiesel/diesel blend (B20) behavior in groundwater and its effects on the biodegradation and plume length of priority groundwater pollutants.
TL;DR: In this article, the authors review the geological, technical, and legal contexts of groundwater in Texas and situate brackish groundwater within those constructs, and provide policy recommendations regarding use of the resource.
01 Jan 2016
TL;DR: In this article, the current state of brackish groundwater use and development in the United States is described, and a brief overview of the state of the water resources is given.
Abstract: This issue brief describes the current state of brackish groundwater use and development in the United States. Development of brackish groundwater, if carried out responsibly, can augment supplies and relieve growing stress on freshwater resources.
Patent•
15 Apr 2016
TL;DR: In this article, cyclodextrin compound therapeutics to reduce age-related non-bisretinoid lipofuscin in a patient having a buildup of same, said method comprising administering 2-hydroxypropyl-β-cyclodexxtrin, or its derivatives, or β-cyclodesxtrin or its derivative, or α-cycldextrin and its derivatives.
Abstract: Cyclodextrin compound therapeutics to reduce age-related non-bisretinoid lipofuscin in a patient having a buildup of same, said method comprising administering 2-hydroxypropyl-β-cyclodextrin, or its derivatives, or β-cyclodextrin or its derivatives, or α-cyclodextrin or its derivatives, or γ-cyclodextrin or its derivatives in an amount effective to reduce non-bisretinoid lipofuscin levels. The methods include treating and/or preventing aging of the skin, muscle and other tissues and organs, which may result in increased life-span or health-span.
Journal Article•
TL;DR: This method is faster (≤10 days) than most protocols to generate lipofuscin and assess its removal, which typically require 2 to 4 weeks or longer to complete.
Abstract: Lipofuscin is a brown-yellow, autofluorescent polymeric material that accumulates in a ceroid manner within postmitotic cells during aging. Lipofuscin accumulation impairs proteosome and lysosome pathways critical to cell health and homeostasis. Therefore, the ability to quickly generate lipofuscin in vitro, and identify drugs that mitigate the accumulation or clear lipofuscin would be of great benefit to aging research. Here, we present a platform to quickly create lipofuscin-loaded (but otherwise healthy) cells and screen drugs for efficacy in lipofuscin removal. The combination of leupeptin, iron (III) chloride and hydrogen peroxide generates significant amounts of lipofuscin within cells while eliminating the need for a 40% hyperoxic chamber. Alternative methods which load fibroblasts with “artificial” lipofuscin obtained via UV-peroxidation of mitochondrial fragments are much more labor-intensive. This method is faster (≤10 days) than most protocols to generate lipofuscin and assess its removal, which typically require 2 to 4 weeks or longer to complete.