Absence Of Sunlight Research Articles

Metagenomic analysis of basal ice from an Alaskan glacier

BackgroundGlaciers cover ~ 10% of land but are among the least explored environments on Earth. The basal portion of glaciers often harbors unique aquatic microbial ecosystems in the absence of sunlight, and knowledge on the microbial community structures and their metabolic potential is very limited. Here, we provide insights into the microbial lifestyle present at the base of the Matanuska Glacier, Alaska.ResultsDNA and RNA were extracted from samples of the Matanuska Glacier basal ice. Using Illumina MiSeq and HiSeq sequencing, we investigated the microbial diversity with the metagenomic shotgun reads and 16S ribosomal RNA data. We further assembled 9 partial and draft bacterial genomes from the metagenomic assembly, and identified key metabolic pathways such as sulfur oxidation and nitrification. Collectively, our analyses suggest a prevalence of lithotrophic and heterotrophic metabolisms in the subglacial microbiome.ConclusionOur results present the first metagenomic assembly and bacterial draft genomes for a subglacial environment. These results extend our understanding of the chemical and biological processes in subglacial environments critically influenced by global climate change.

Effect of photo-biodegradation and biodegradation on the biogeochemical cycling of dissolved organic matter across diverse surface water bodies.

The objective of this research was to quantify the temporal variation of dissolved organic matter (DOM) in five distinct waterbodies in watersheds with diverse types of land use and land cover in the presence and absence of sunlight. The water bodies were an agricultural pond, a lake in a forested watershed, a man-made reservoir, an estuary, and a bay. Two sets of samples were prepared by dispensing unfiltered samples into filtered samples in 1:10 ratio (V/V). The first set was exposed to sunlight (10 hr per day for 30 days) for examining the combined effect of photo-biodegradation, while the second set was stored in dark for examining biodegradation alone. Spectroscopic measurements in tandem with multivariate statistics were used to interpret DOM lability and composition. The results suggest that the agricultural pond behaved differently compared to other study locations during degradation experiments due to the presence of higher amount of microbial humic-like and protein-like components derived from microbial/anthropogenic sources. For all samples, a larger decrease in dissolved organic carbon (DOC) concentration (10.12% ± 9.81% for photo-biodegradation and 6.65% ± 2.83% for biodegradation) and rapid transformation of DOM components (i.e., terrestrial humic-like components into microbial humic and protein-like components) were observed during photo-biodegradation experiments. Results suggest that sunlight facilitated DOM biodegradation, resulting in simpler recalcitrant molecules regardless of original composition. Overall, it was found that combined effects of light and bacteria are more efficient than bacterial effects alone in remineralizing and altering DOM, which highlights the crucial importance of sunlight in transforming aquatic DOM.

A life cycle assessment of Agaricus bisporus mushroom production in the USA

PurposeStakeholders across the food product supply chain are increasingly interested in understanding the environmental effects of food production. Mushrooms are a unique food crop, grown in the absence of sunlight and in climate controlled environments. Few life cycle assessment (LCA) studies have been conducted previously on mushrooms and none in the USA. This study assesses the cradle-to-gate life cycle environmental impacts of mushroom production in the USA from cultivation to harvest and preparation for bulk packaging.MethodsThis process-based LCA uses primary data from mushroom producers to define the foreground system. Primary data for operations were collected from compost and mushroom producers in the USA, representing approximately one third of US mushroom production. Secondary data were collected from life cycle inventory databases and other published resources to define background systems and process emissions from the foreground system. The study uses a functional unit of 1 kg mushrooms and applies the Institute of Environmental Sciences (CML) impact analysis method, supplemented with additional impact categories for energy use, freshwater use, and 20 and 100-year global warming potentials (GWPs) with and without carbon-climate feedback.Results and discussionResults show that GWP100 impacts range from 2.13 to 2.95 kg CO2e/kg of mushroom product, slightly lower than previous mushroom LCAs conducted for Australian and Spanish production systems. Electricity and fossil fuels were the most impactful inputs, not just for GWP, but most other impact categories as well, followed by compost materials, compost emissions, and transportation. Transport of peat, a key input to the mushroom production substrate, and compost materials contributed to 60 and 36% of the total transportation impacts, respectively. The co-product generated by the system, spent mushroom substrate (SMS), was handled using the displacement method. SMS generated very small credits to the system, less than 1% in every impact category.ConclusionsRecommendations to improve the commercial mushroom production process include reducing electricity and fossil fuel use through on-site renewable energy generation. This recommendation is primarily relevant to mushroom producers in the Eastern region of the USA, where the electricity grid is the most coal and fossil fuel-intensive. Future work should contextualize the results of this study in the context of nutrition, meal, or diet-level assessments to enable informed food choices.

HYBRID GRIDS ANALYSIS WITH RENEWABLE ENERGY AND THERMAL ENERGY FOR STREET LIGHT -A CASE STUDY

This paper presents a techno-economic assessment for a unique Isolated Hybrid Power System (IHPS) design which could be used for remote areas isolated from the grid which also has the capability of being operated as a smart the hybrid energy system considering solar and wind energy sources for the purpose of street lighting. Solar-Wind Street light is an intelligent, small scale, and off grid LED lighting system. The modelling design and simulations were based on Simulations conducted using the Data collected and HOMER Energy Planning and Design software tools. Its components are solar panel, wind generator system (PVC blowers), Dynamo, LDRs, battery, LED light, charge controller. The energy stored in battery during day time due to solar panel, get extracted by LEDs during the night time (because LDRs get activated due to absence of sun light). Wind also charges the batteries due to wind which is used for glowing street light. The advantage of this idea is to avoid daily running cost and make the system purely off-grid. In this prototype, we have used 12V DC system to supply energy to the lights.

Development of nanostructured photocatalytic coatings for anti-bioadhesion and self-cleaning of residual bacterial cells

In this work, nanostructured oxide coatings with photocatalytic activity were prepared by anodization, Zn acetate (ZnAc) modification and/or annealing, enabling high-performance anti-bioadhesion and self-cleaning of residual bacterial cells and biofilm upon sunlight irradiation and/or H2O2 treatment. The morphology, surface roughness, composition and semiconducting properties of the nano-coatings were characterized by atomic force microscopy, Raman spectroscopy and ultraviolet (UV)-visible diffuse reflectance spectroscopy. The anti-adhesion of the coatings to P. aeruginosa bacteria was measured by a confocal laser scanning microscope, and their electrochemical stability was evaluated by open-circuit potential and linear polarization resistance measurements in a chloride solution. The results demonstrate that, compared to the prepared anodized, annealed and 1-time ZnAc modified nano-coatings, the 2-time ZnAc modified nano-coating containing photocatalytic ZnFe2O4 achieves the best anti-bioadhesion performance and self-cleaning of residual bacterial cells and biofilm, while maintaining a high electrochemical stability. The nano-coating achieves 99.6% of anti-bioadhesion under sunlight irradiation relative to bare steel. The treatment of 1 h UV irradiation and 0.02 mM H2O2 allows 99.3% of removal of bacterial cells and biofilm plaques which are formed in the absence of sunlight. The high-performance anti-bioadhesion of the nano-coating is attributed to production of a high concentration of O2− induced by photocatalytic activity of the ZnFe2O4 component contained in the coating. Under combined UV irradiation and the addition of H2O2, the •OH is produced due to the photocatalytic reaction of H2O2 with O2− or photo-electrons on the coating. The periodic H2O2 treatment provides a promising strategy to re-store the nanostructure of the prepared coatings, and sustain their high performance for anti-bioadhesion.

The experimental new hybrid solar dryer and hot water storage system of thin layer coffee bean dehumidification

The thin layer coffee beans dehumidification and hot water storage were investigated in solar greenhouse dryer simultaneously. The thermal energy was stored for use in the absence of sunlight. The conditions were studied the flow rate of water circulating, model of installation for solar collector assistance, the area ratio of product dehumidification to solar hot water producing (Ad:Ac), flow pattern of water circulation and capacity tank of water circulating in the system. The experiments were found the flow pattern of water circulation within the force flow 0.20 kg/s-mˆ2, tray products temperature (45 deg. C) at (Ad:Ac) 1:1, capacity tank of water circulating (60 L). The thermal energy can be used and stored in the form of hot water and reused at a time without sunlight as well. The initial coffee beans moisture content was dropped from 55 to below 12 (%w.b.) in 12 h drying time. The optimum of mathematical equations for thin layer coffee beans drying based on Midilli mathematical model i.e. (MR = a exp(-ktˆn) – bt); k = 0.03838, n = 1.56771, a = 1.03046, b = −0.00477, R2 = 0.9896, RMSE = 0.0420. Moreover, the effective moisture diffusivity coefficient of 9.754 × 10ˆ-11 mˆ2/s.

CFD modeling and optimization of a latent heat storage unit for running a solar assisted single effect Li-Br absorption chiller using multi-objective genetic algorithm

In this paper, the feasibility of a solar absorption refrigeration system to be powered by a latent heat storage (LHS) unit is investigated for a representative building. A single effect absorption chiller, utilizing Li-Br and water as working fluids is thermodynamically simulated. Then, the simulation of the latent heat storage unit is performed by applying finite difference method and the results were validated by the researches in the literature. Then, the geometry of a phase change material (PCM) based LHS system was optimized using multi-objective Genetic Algorithm for simultaneously minimizing the charging time, and maximizing the discharging time. Since the paper considers conflicting objectives, a Pareto front is presented that can be used for obtaining the optimum geometry according to the environmental conditions and working hours of the absorption system. As an illustrative example, the designed heat storage system was shown to be able to drive the 72kW generator of an absorption system, for at least 10h of operation in the discharging mode with the absence of sunlight. Therefore, it is possible to run absorption chillers under low-load operation conditions using the solar energy if the appropriate storage unit, such as what is introduced here, is used.

A physiologically based pharmacokinetic model of vitamin D.

Despite the plethora of studies discussing the benefits of vitamin D on physiological functioning, few mathematical models of vitamin D predict the response of the body on low-concentration supplementation of vitamin D under sunlight-restricted conditions. This study developed a physiologically based pharmacokinetic (PBPK) model utilizing published human data on the metabolic cascade of orally derived, low-concentration (placebo, 5 μg and 10 μg) supplementation of vitamin D over the course of 28 days in the absence of sunlight. Vitamin D and its metabolites are highly lipophilic and binding assays of these compounds in serum may not account for binding by lipids and additional proteins. To compensate for the additional bound amounts, this study allowed the effective adipose-plasma partition coefficient to vary dynamically with the concentration of each compound in serum utilizing the Hill equation for binding. Through incorporating the optimized parameters with the adipose partition coefficient adaptation to the PBPK model, this study was able to fit serum concentration data for circulating vitamin D at all three supplementation concentrations within confidence intervals of the data. Copyright © 2017 John Wiley & Sons, Ltd.

Enhanced intestinal absorption of curcumin in Caco-2 cell monolayer using mucoadhesive nanostructured lipid carriers.

This study aimed to compare the intestinal permeation of curcumin-loaded polymer coated nanostructured lipid carriers (NLCs) and uncoated NLCs using the Caco-2 cell model. The uncoated NLCs were prepared using a warm microemulsion technique, while polymer-coated NLCs were prepared with the same method but were followed by coating particle surface with polyethylene glycol (PEG) 400 or polyvinyl alcohol (PVA). After lyophilization, all formulations possessed a mean size of <400nm with a zeta potential of ∼-30mV and a high entrapment efficacy up to 90%. All NLCs formulation showed significantly improvement in curcumin water solubility, more than 60-folds as compared to curcumin dispersion. In addition, they could protect curcumin from degradation in basic pH, 90% curcumin remaining after 6h incubation in culture medium. In vitro permeation studies revealed that PEG-NLCs and PVA-NLCs provided significantly higher apparent permeation coefficient (Papp ) value than uncoated NLCs. Moreover, after 6months storage at 4 °C in the absence of sunlight, the physical, and chemical stabilities of the lyophilized curcumin-loaded polymer coated NLCs and uncoated NLCs could be maintained, i.e., the mean particle size and the amount of curcumin showed no significant changes (p>0.05) compared to those freshly prepared formulations. Considered overall, polymer coated NLCs are an important strategy to improve the oral bioavailability of curcumin. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 734-741, 2018.

Physiological Parameters of Pigs Raised with and without Environmental Enrichment

Ethical and commercial issues are associated with animal welfare in pig farming, in that sense, the objective of this work was to evaluate physiological and blood parameters in addition to weight gain in pigs raised with and without sunlight and environmental enrichment (EE), as well as to correlate physiological and environmental parameters as welfare indicators. Twenty-four pigs distributed in a randomized block design with a 2 × 2 factorial arrangement were used. Blocks were represented by shifts (morning and afternoon), and factors by the presence or absence of EE and sunlight. Blood and environmental parameters of thermal comfort, in addition to weight gain, were registered. Physiological parameters showed to be shift dependent (p &lt; 0.05), with the afternoon shift being superior when compared to the morning shift, thus indicating climate influence. Weight gain showed significant interactions (p &lt; 0.05) in the presence and absence of sunlight and EE in the stalls. Temperature correlated positively with the physiological parameters. Moisture showed negative correlations with physiological parameters. The packed cell volume was lower (p &lt; 0.05) in the presence of EE. The EE provides physiological well-being and weight gain for pigs in the nursery stage, especially when sunlight was absent in the stalls.

Solar Photocatalytic Degradation of Methylene Blue by ZnO Nanoparticles.

The scalable and economical synthesis approach of ZnO has always been demanded, since it is very useful material in the degradation of hazardous dyes. Herein, a scalable synthesis approach for ZnO nanoparticles by precipitating the precursors such as zinc sulphate heptahydrate and ammonium hydroxide has been proposed. Calcinations at suitable temperatures can improve crystalline nature of materials. Therefore as-synthesized ZnO nanoparticles were calcinated at different temperatures 400 °C, 650 °C, 900 °C, 1150 °C, and subsequently their physical and morphological properties were characterized. The TEM analysis revealed the morphology, whereas XRD and SAED confirmed the purity and crystalline nature of ZnO. Moreover, photo catalytic degradation/adsorption results for methylene blue dye of lower (2.5 ppm) and higher concentrations (5 ppm) in the presence and absence of sunlight and ZnO nanoparticles are also reported. Addition of ZnO nanoparticles to methylene blue resulted in enhanced rate of photo degradation in the presence of sunlight. The complete photodegradation of 2.5 and 5 ppm methylene blue in sunlight occurred in 90 min and 165 min, respectively in presence of ZnO nanoparticles. In general many photocatalytic degradation studies had been reported using an artificial light source; however in the present work direct sunlight has been utilized.

Solar still with latent heat energy storage: A review

The requirement of fresh water is growing exponentially in industrial as well as domestic sector, resulting in more pollution of natural water resources and creating a scarcity of drinking water. Additionally, the number of arid and desert regions on the world map which already face the shortage of rainfalls and ground water. The problem is substantially increased as most of the water bodies like rivers, lakes are saline and brackish which are not suitable for drinking purpose. In recent past, solar desalination has been found to be a sustainable and economical way of generating the fresh water to cater the need of drinking water at large. Much technological advancement in the field of solar stills has been made which can ably produce a large quantity of fresh water depending on the availability of solar radiation. Various desalination schemes have been utilized to utilise water from such available resources to convert the available water in to the drinkable water. Additionally, attention has also been put on developing efficient solar still with latent heat based thermal energy storage systems which can work in the absence of sunlight as well. In the present paper, a short review on solar stills utilizing latent heat storage has been presented. The present study covers the design specifications, efficiency, along with the comparative analysis of solar stills with latent heat storage system, investigated in the last decade. A discussion on the future research outlook in the area of solar stills with latent heat storage has also been given, so as to make it more economically viable for generating sustainable potable water.

Designing a wireless sensor with ultra-capacitor and PV microcell for smart building energy management

Building owners face a number of challenges, as they search for ways to reduce energy consumption, lower operating costs, and manage modern technology and systems. A research group from Aerospace School of Madrid has addressed these aims by developing a real-time building management system that consists of a plurality of transmitter nodes, a central controller, and a user interface. Monitoring, control, and actuation systems lack reliable and cost effective data logging and measuring devices of energy parameters in buildings. In this paper, a new concept of wireless sensors is recommended, powered by PV microcells and electric double layer capacitors. With these power sources, the sensor can send data every minute without being affected by the absence of sunlight. The feasibility of such a sensor was studied empirically and the findings are reported in this paper.

Determination of optimal conditions for electrodeposition of Tin(II) in the presence of Alizarin Red S.

A detailed physicochemical properties of aqueous solutions of alizarin red S − tin (II) chloride, has been thoroughly investigated by extensively exploring the effect of pH, concentration and temperature on the optimal conditions for the formation of tin (II)-alizarin red S (ARS-Sn II) complex. UV-Vis spectra, electrical conductivity and pH method were also used to characterize the final product. The stoichiometry of the reaction complex formation was determined via different referential methods. It was observed that, the reaction complex was formed when the concentrations were smaller than a certain limit (10−5 M). Adjusting the pH of the reaction (typically from 3.7 to 6.0) also resulted in the formation of the complex. The formed complex was highly stable in dark conditions (absence of sunlight) and at ambient temperature. Without the use of additives and by employing the investigated optimal conditions (i.e. pH: 5.0, i: 6 mA/cm2, t: 5 min, C: 0.1 M, d: 1.273 × 10−4 cm), electrodeposition of tin (II) was demonstrated to be successful.

Development of simultaneous partial nitrification, anammox and denitrification (SNAD) in a non-aerated SBR

The objective of this work was to develop simultaneous partial nitrification, anammox and denitrification (SNAD) process in a twenty liter non-aerated sequencing batch reactor (SBR). Flocculent type activated sludge sourced from a tannery common effluent treatment plant was used as seed biomass. The SBR was operated for 161 days in 23 cycles with initial feed concentrations of NH4-N and COD as 250 ± 14.9 mg l−1 and 250 ± 4.6 mg l−1, respectively. The process was developed in a non-mixing condition in a dark room with no temperature control, but the temperature in SBR varied between 30 °C and 36 °C. The average HRT was 10.5 d with SBR cycle time of 7 d. The last three cycles gave the best average removals of NH4-N (94%), COD (92%) and TN (82%). The conversion ratio Y(NO2-N+ NO3-N)/(NH4-N) during the last 10 cycles remained below 0.11, confirming a stable SNAD process. Maximum specific substrate (NH4-N, COD and TN) utilization rates of SNAD biomass were determined as 185 mg NH4-N g−1 MLVSS d−1, 153 mg COD g−1 MLVSS d−1 and 172 mg N g−1 MLVSS d−1. These results contribute towards the application of SNAD process in shallow anoxic ponds/tanks/ditches in the absence of sunlight.

Behavior of Atrazine and Its Degradation Products Deethylatrazine and Deisopropylatrazine in Oxisol Samples

This work investigates the behavior of atrazine (AT) and its degradation products deethylatrazine (DEA) and deisopropylatrazine (DIA) in oxisol samples. The study was carried out at different depths of maize culture soil under no-till management for up to 180 days. Additionally, controlled laboratory experiments were performed in open flasks in the absence of sunlight or in closed flasks at 4 °C. Higher AT dissipation occurred in the in the field as compared with the samples evaluated under controlled conditions, which indicated that environmental conditions might degrade AT. Interestingly, DEA and DIA levels were low, which suggested that leaching and runoff processes, formation of other degradation products, or even AT mineralization took place. Residual AT, DEA, and DIA were detected in the oxisol samples after 180 days depending on the initial amount of AT in the soil. This study has shown that straw plays a relevant role in AT retention and significantly contributes to DEA and DIA formation. At 180 days, straw samples contained AT concentrations near 100 μg kg−1 and concentrations of the more leachable DEA and DIA close to 50 μg kg−1 even under the influence of sunlight and rainfall. A preliminary analysis of natural water samples near the investigated region showed that DEA and DIA were absent and that AT concentrations were high, which pointed to the need for more detailed evaluation.

Human-Associated Bacteroides spp. and Human Polyomaviruses as Microbial Source Tracking Markers in Hawaii.

This study represents an in-depth characterization of microbial source tracking (MST) markers in Hawaii. The distribution and concentrations of HF183TaqMan and HPyV markers in human and animal fecal samples and in wastewater, coupled with decay data obtained from sunlight-exposed and unexposed microcosms, support the concurrent application of HF183TaqMan and HPyV markers for sewage contamination detection in Hawaii waters. Both markers are more conservative and more specific markers of sewage than fecal indicator bacteria (enterococci and Escherichia coli). Analysis of HF183TaqMan (or newer derivatives) is recommended for inclusion in future epidemiological studies concerned with beach water quality, while better concentration techniques are needed for HPyV. Such epidemiological studies can be used to develop new recreational water quality criteria, which will provide direct information on the absence or presence of sewage contamination in water samples as well as reliable measurements of the risk of waterborne disease transmission to swimmers.

Arsenic concentrations and species in three hydrothermal vent worms, Ridgeia piscesae, Paralvinella sulficola and Paralvinella palmiformis

Hydrothermal vents are surficial expressions of subsurface geological and hydrological processes. Fluids emitting from active vents are chemically distinct from bottom seawater, and are enriched in dissolved metals and metalloids, including arsenic. Vent organisms accumulate arsenic but the arsenic speciation in these non-photosynthetic organisms is largely unknown. Here, arsenic concentrations and chemical species were measured in three deep sea hydrothermal vent worms (Ridgeia piscesae, Paralvinella sulfincola and Paralvinella palmiformis ) from the Juan de Fuca Ridge in the Northwest pacific. R. piscesae has similar arsenic concentrations (3.8–35µgg−1) to shallow water polychaetes while P. sulfincola and P. palmiformis have significantly higher arsenic concentrations (420–1417 and 125–321µgg−1 respectively). R. piscesae contains appreciable quantities of inorganic arsenic (36±14%), monomethyl arsenic (2±2%), dimethyl arsenic (34±21%), an unknown methyl arsenical (7±16%), OSO3-arsenosugar (5±9%), TETRA (4±5%), ThioPO4/ThioDMAE (1±2%) and an unknown thio-arsenical (12±14%). These results suggests that host and symbionts are either involved in the methylation of arsenic, or are bathed in fluids enriched in methylated arsenic as a result of free-living microbial activity. The host carrying out methylation, however, cannot be ruled out. In contrast, 96–97% of the arsenic in P. sulfincola and P. palmiformis is inorganic arsenic, likely the result of arsenic precipitation within and upon the mucus they ingest while feeding. While all worms have oxo- and thio arsenosugars (2–30%), Paralvinella also have small amounts of arsenobetaine (<0.001–0.21%). The presence of arsenosugars, arsenobetaine and other minor arsenic species in the absence of photosynthesising algae/bacteria indicates that they may be formed by vent animals in the absence of sunlight, but at this time their formation cannot be explained.

E-Street Zone-Automatic Streetlight based on the Movement of Vehicles

Objective: This study report smart street lights in national highways which can reduce the consumption of electricity. Methods: Two types of energy sources viz., solar AC from TNEB were used to conduct the present study. A solar pannel is placed on top of each street light which genrates electricity in the day time and also the AC supply from TNEB will be availed during night time sytem. The electricity availed from the TNEB will be used only when solar power inadequate. Thus a hybrid network is used in this project. Findings: Every Street light can be integrated with an IR sensor which detects the movements of vehicles. When the sensor detects the vehicles, the street light glows with full efficiency and when there is no movement it glows with 10% efficiency. By adapting this system, the electricity consumption can be efficiently reduced. Around 20-30% of electricity can be reduced by using this system. A solar panel is being installed in this set up, so that it charges in the presence of sun light and it uses the charge effectively in the absence of sun light. The electricity supply from TNEB is also availed so that in case of bad weather conditions, when solar panels not work, uninterrupted power supply is given to street lights. A hybrid set up is being established in which both the solar power and AC from TNEB is given. Street light utilises solar power as it can and if it is not sufficient it avails AC from TNEB. Applications/Improvements: This set up can be enhanced further by placing approximation sensor for detecting the failed street light and sending SMS to the control department via GSM for appropriate action. This setup can be applied in national highways and accident free zones. It reduces the consumption of electricity.

Influence of UVB radiation on the lethal and sublethal toxicity of dispersed crude oil to planktonic copepod nauplii

Toxic effects of petroleum to marine zooplankton have been generally investigated using dissolved petroleum hydrocarbons and in the absence of sunlight. In this study, we determined the influence of natural ultraviolet B (UVB) radiation on the lethal and sublethal toxicity of dispersed crude oil to naupliar stages of the planktonic copepods Acartia tonsa, Temora turbinata and Pseudodiaptomus pelagicus. Low concentrations of dispersed crude oil (1 μL L−1) caused a significant reduction in survival, growth and swimming activity of copepod nauplii after 48 h of exposure. UVB radiation increased toxicity of dispersed crude oil by 1.3–3.8 times, depending on the experiment and measured variables. Ingestion of crude oil droplets may increase photoenhanced toxicity of crude oil to copepod nauplii by enhancing photosensitization. Photoenhanced sublethal toxicity was significantly higher when T. turbinata nauplii were exposed to dispersant-treated oil than crude oil alone, suggesting that chemical dispersion of crude oil may promote photoenhanced toxicity to marine zooplankton. Our results demonstrate that acute exposure to concentrations of dispersed crude oil and dispersant (Corexit 9500) commonly found in the sea after oil spills are highly toxic to copepod nauplii and that natural levels of UVB radiation substantially increase the toxicity of crude oil to these planktonic organisms. Overall, this study emphasizes the importance of considering sunlight in petroleum toxicological studies and models to better estimate the impact of crude oil spills on marine zooplankton.