Fog as a Fresh-Water Resource: Overview and Perspectives

The collection of fog water is a simple and sustainable technology to obtain fresh water for afforestation, gardening, and as a drinking water source for human and animal consumption. In regions where fresh water is sparse and fog frequently occurs, it is feasible to set up a passive mesh system for fog water collection. The mesh is directly exposed to the atmosphere, and the foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m⁻² of mesh per day are typical of operational projects. The scope of this article is to review fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology.     

Structuring sustainability science

It is urgent in science and society to address climate change and other sustainability challenges such as biodiversity loss, deforestation, depletion of marine fish stocks, global ill-health, land degradation, land use change and water scarcity. Sustainability science (SS) is an attempt to bridge the natural and social sciences for seeking creative solutions to these complex challenges. In this article, we propose a research agenda that advances the methodological and theoretical understanding of what SS can be, how it can be pursued and what it can contribute. The key focus is on knowledge structuring. For that purpose, we designed a generic research platform organised as a three-dimensional matrix comprising three components: core themes (scientific understanding, sustainability goals, sustainability pathways); cross-cutting critical and problem-solving approaches; and any combination of the sustainability challenges above. As an example, we insert four sustainability challenges into the matrix (biodiversity loss, climate change, land use changes, water scarcity). Based on the matrix with the four challenges, we discuss three issues for advancing theory and methodology in SS: how new synergies across natural and social sciences can be created; how integrated theories for understanding and responding to complex sustainability issues can be developed; and how theories and concepts in economics, gender studies, geography, political science and sociology can be applied in SS. The generic research platform serves to structure and create new knowledge in SS and is a tool for exploring any set of sustainability challenges. The combined critical and problem-solving approach is essential.     

Nitrous oxide emissions respond differently to mineral and organic nitrogen sources in contrasting soil types

The use of various animal manures for nitrogen (N) fertilization is often viewed as a viable replacement for mineral N fertilizers. However, the impacts of amendment type on NO production may vary. In this study, NO emissions were measured for 2 yr on two soil types with contrasting texture and carbon (C) content under a cool, humid climate. Treatments consisted of a no-N control, calcium ammonium nitrate, poultry manure, liquid cattle manure, or liquid swine manure. The N sources were surface applied and immediately incorporated at 90 kg N ha before seeding of spring wheat ( L.). Cumulative NO-N emissions from the silty clay ranged from 2.2 to 8.3 kg ha yr and were slightly lower in the control than in the fertilized plots ( = 0.067). The 2-yr mean NO emission factors ranged from 2.0 to 4.4% of added N, with no difference among N sources. Emissions of NO from the sandy loam soil ranged from 0.3 to 2.2 kg NO-N ha yr, with higher emissions with organic than mineral N sources ( = 0.015) and the greatest emissions with poultry manure ( < 0.001). The NO emission factor from plots amended with poultry manure was 1.8%, more than double that of the other treatments (0.3-0.9%), likely because of its high C content. On the silty clay, the yield-based NO emissions (g NO-N kg grain yield N) were similar between treatments, whereas on the sandy loam, they were greatest when amended with poultry manure. Our findings suggest that, compared with mineral N sources, manure application only increases soil NO flux in soils with low C content.     

Tissue bioaccumulation patterns, xenobiotic biotransformation and steroid hormone levels in Atlantic salmon (Salmo salar) fed a diet containing perfluoroactane sulfonic or perfluorooctane carboxylic acids

In the present study, groups of juvenile Atlantic salmon (Salmo salar) were fed gelatine capsules containing fish-food spiked with PFOA or PFOS (0.2 mg kg⁻¹ fish) and solvent (methanol). The capsules were given at days 0, 3 and 6. Blood, liver and whole kidney samples were collected prior to exposure (no solvent control), and at days 2, 5, 8 and 14 after exposure (Note: that day 14 after exposure is equal to 7 d recovery period). We report on the differences in the tissue bioaccumulation patterns of PFOS and PFOA, in addition to tissue and compound differences in modulation pattern of biotransformation enzyme genes. We observed that the level of PFOS and PFOA increased in the blood, liver and kidney during the exposure period. Different PFOS and PFOA bioaccumulation patterns were observed in the kidney and liver during exposure- and after the recovery periods. Particularly, after the recovery period, PFOA levels in the kidney and liver tissues were almost at the control level. On the contrary, PFOS maintained an increase with tissue-specific differences, showing a higher bioaccumulation potential (also in the blood), compared with PFOA. While PFOS and PFOA produced an apparent time-dependent increase in kidney CYP3A, CYP1A1 and GST expression, similar effects were only temporary in the liver, significantly increasing at sampling day 2. PFOA and PFOS exposure resulted in significant decreases in plasma estrone, testosterone and cortisol levels at sampling day 2, and their effects differed with 17α-methyltestostrerone showing significant decrease by PFOA (also for cholesterol) and increase by PFOS. PFOA significantly increased estrone and testosterone, and no effects were observed for cortisol, 17α-methyltestosterone and cholesterol at sampling day 5. Overall, the changes in plasma steroid hormone levels parallel changes in CYP3A mRNA levels. Given that there are no known studies that have demonstrated such tissue differences in bioaccumulation patterns with associated differences in toxicological responses in any fish species or lower vertebrate, the present findings provide some potential insights and basis for a better understanding of the possible mechanisms of PFCs toxicity that need to be studied in more detail.     

Concentrations and diversity of microbes from four local bioaerosol emission sources in Finland

Microbial particles can readily be released into the air from different types of man-made sources such as waste operations. Microbiological emissions from different biological sources and their dispersion may be an issue of concern for area planning and for nearby residents. This study was designed to determine the concentrations and diversity of microbiological emissions from four different man-made source environments: waste center with composting windrows, sewage treatment plant, farming environment, and cattle manure spreading. Samples of airborne particles were collected onto polyvinyl chloride filters at three distances along the prevailing downwind direction, from each source environment during a period of approximately 1 week. These samples were analyzed for 13 species or assay groups of fungi, bacterial genus Streptomyces, and Gram-positive and -negative bacteria using quantitative polymerase chain reaction (PCR). Samples for determining the concentrations of viable fungi and bacteria were collected from all environments using a six-stage impactor. The results show that there were variations in the microbial diversity between the source environments. Specifically, composting was a major source for the fungal genera Aspergillus and Penicillium, particularly for Aspergillus fumigatus, and for the bacterial genus Streptomyces. Although the microbial concentrations in the sewage treatment plant area were significantly higher than those at 50 or 200 m distance from the plant area, in the farming environment or cattle manure spreading area, no significant difference was observed between different distances from the source. In summary, elevated concentrations of microbes that differ from background can only be detected within a few hundred meters from the source. This finding, reported earlier for culturable bacteria and fungi, could thus be confirmed using molecular methods that cover both culturable and nonculturable microbial material.     

Analysis of mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs) in soil by gas chromatography tandem mass spectrometry (GC-MS/MS)

Mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs, X = Br, Cl) are formed through combustion processes, and may be more toxic than their corresponding chlorinated and brominated analogues. With 4600 potential congeners, limited analytical standards, and complex environmental matrices, PXDD/PXDFs present a significant analytical challenge. Gas chromatography tandem mass spectrometry (GC-MS/MS) offers both selectivity and sensitivity through multiple reaction monitoring of unique transitions in a novel approach to PXDD/PXDF congener identification. Method validation was performed through analysis of soil samples obtained from a recycling plant fire. Of the PXDD/PXDFs examined, monobromo-dichlorodibenzofuran was the most prevalent, ranging in concentration from 8.6 ng g⁻¹ to 180 ng g⁻¹. Dibromo-dichlorodibenzo-p-dioxin, a compound of toxicological concern, ranged from 0.41 ng g⁻¹ to 10 ng g⁻¹. Concentrations of PXDD/PXDFs were between 6% and 10% that of the corresponding polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs), with the exception of dibromo-dichlorodibenzo-p-dioxin concentrations, which were 36% that of tetrachlorodibenzo-p-dioxins. Higher levels of polybrominated PXDD/PXDFs may indicate a significant bromine source was present during combustion.     

Use of a Continuous Nephelometer to Measure Personal Exposure to Particles During the U.S. Environmental Protection Agency Baltimore and Fresno Panel Studies

ABSTRACT

In population exposure studies, personal exposure to PM is typically measured as a 12- to 24-hr integrated mass concentration. To better understand short-term variation in personal PM exposure, continuous (1-min averaging time) nephelometers were worn by 15 participants as part of two U.S. Environmental Protection Agency (EPA) longitudinal PM exposure studies conducted in Baltimore County, MD, and Fresno, CA. Participants also wore iner-tial impactor samplers (24-hr integrated filter samples) and recorded their daily activities in 15-min intervals. In Baltimore, the nephelometers correlated well (R² = 0.66) with the PM₂₅ impactors. Time-series plots of personal nephelometer data showed each participant's PM exposure to consist of a series of peaks of relatively short duration. Activities corresponding to a significant instrument response included cooking, outdoor activities, transportation, laundry, cleaning, shopping, gardening, moving between microenvironments, and removing/putting on the instrument. On average, 63-66% of the daily PM exposure occurred indoors at home (about 2/3 of which occurred during waking hours), primarily due to the large amount of time spent in that location (an average of 7277%). Although not a reference method for measuring mass concentration, the nephelometer did help identify PM sources and the relative contribution of those sources to an individual's personal exposure.     

The Influence of Human Activity Patterns on Personal PM Exposure: A Comparative Analysis of Filter-Based and Continuous Particle Measurements

ABSTRACT

Particulate matter (PM) exposure data from the U.S. Environmental Protection Agency (EPA)-sponsored 1998 Baltimore and 1999 Fresno PM exposure studies were analyzed to identify important microenvironments and activities that may lead to increased particle exposure for select elderly (>65 years old) subjects. Integrated 24-hr filter-based PM_2.5 or PM₁₀ mass measurements [using Personal Environmental Monitors(PEMs)] included personal measurements, indoor and outdoor residential measurements, and measurements at a central indoor site and a community monitoring site. A subset of the participants in each study wore passive nephelometers that continuously measured (1-min averaging time) particles ranging in size from 0.1 to ~10 um. Significant activities and locations were identified by a statistical mixed model (p < 0.01) for each study population based on the measured PM_2.5 or PM₁₀ mass and time activity data. Elevated PM concentrations were associated with traveling (car or bus), commercial locations (store, office, mall, etc.), restaurants, and working.

The modeled results were compared to continuous PM concentrations determined by the nephelometers while participants were in these locations. Overall, the nephelometer data agreed within 6% of the modeled PM_2.5 results for the Baltimore participants and within ~20% for the Fresno participants (variability was due to zero drift associated with the nephelometer). The nephelom-eter did not agree as well with the PM₁₀ mass measurements, most likely because the nephelometer optimally responds to fine particles (0.3–2 um). Approximately one-half (54 ± 31%; mean ± standard deviation from both studies) of the average daily PM_2.5 exposure occurred inside residences, where the participants spent an average of 83 ± 10% of their time. These data also showed that a significant portion of PM_2.5 exposure occurred in locations where participants spent only 4–13% of their time.     

Genotoxicity of oxy-PAHs to Japanese medaka (Oryzias latipes) embryos assessed using the comet assay

Polycyclic aromatic hydrocarbons (PAHs) have long been recognized as important environmental toxicants. Despite a plethora of information on the fate and effects of parent PAHs, relatively little is known about the environmental fate and toxicity of ketone- and quinone-substituted PAH oxidation products (termed oxy-PAHs), particularly in the aquatic environment. This study begins to fill that gap using embryos of the Japanese medaka (Oryzias latipes) as a model species. The genotoxic potential of two environmentally relevant oxy-PAHs, acenaphthenequinone and 7,12-benz[a]anthracenquinone, was assessed using the comet assay. We found that both oxy-PAHs could cause significant increases in DNA damage after only 48 h of exposure at the lowest concentrations tested (5 μg/L). Comparisons of the genotoxic potential between these oxy-PAHs and their corresponding parent PAHs (acenaphthene and benz[a]anthracene) and a well-known mutagenic PAH, benzo[a]pyrene, indicated similar potencies among all five of these compounds, particularly after longer (7 day) exposures. This study demonstrates the mutagenic potential of oxy-PAHs to an in vivo fish embryo model and points out the need for further study of their environmental occurrence and biologic effects.