Characterizing Drought in Irrigated Agricultural Systems: The Surface Water Delivery Index (SWDI)

Quantifying surface water shortages in arid and semiarid agricultural regions is challenging because limited water supplies are distributed over long distances based on complex water management systems constrained by legal, economic, and social frameworks that evolve with time. In such regions, the water supply is often derived in a climate dramatically different from where the water is diverted to meet agricultural demand. The existing drought indices which rely on local climate do not portray the complexities of the economic and legal constraints on water delivery. Nor do these indices quantify the shortages that occur in drought. Therefore, this research proposes a methodological approach to define surface water shortages in irrigated agricultural systems using a newly developed index termed the Surface Water Delivery Index (SWDI). The SWDI can be used to uniformly quantify surface water deficits/shortages at the end of the irrigation season. Results from the SWDI clearly illustrate how water shortages in droughts identified by the existing indices (e.g., SPI and PDSI) vary strongly both within and between basins. Some surface water entities are much more prone to water shortages than other entities based both on their source of water supply and water right portfolios.     

Case study of landfill leachate recirculation using small-diameter vertical wells

A case study of landfill liquids addition using small diameter (5 cm) vertical wells is reported. More than 25,000 m³ of leachate was added via 134 vertical wells installed 3 m, 12 m, and 18 m deep over five years in a landfill in Florida, US. Liquids addition performance (flow rate per unit screen length per unit liquid head) ranged from 5.6 × 10^?8 to 3.6 × 10^?6 m³ s^?1 per m screen length per m liquid head. The estimated radial hydraulic conductivity ranged from 3.5 × 10^?6 to 4.2 × 10^?4 m s^?1. The extent of lateral moisture movement ranged from 8 to 10 m based on the responses of moisture sensors installed around vertical well clusters, and surface seeps were found to limit the achievable liquids addition rates, despite the use of concrete collars under a pressurized liquids addition scenario. The average moisture content before (51 samples) and after (272 samples) the recirculation experiments were 23% (wet weight basis) and 45% (wet weight basis), respectively, and biochemical methane potential measurements of excavated waste indicated significant (p < 0.025) decomposition.     

A comparison study on high-temperature water–gas shift reaction over Fe/Al/Cu and Fe/Al/Ni catalysts using simulated waste-derived synthesis gas

A comparative study on Fe/Al, Fe/Al/Cu, and Fe/Al/Ni catalysts in high-temperature water–gas shift reaction (HT–WGS) using simulated waste-derived synthesis gas has been carried out. The metal oxide (Cu and Ni) and aluminum incorporated Fe catalysts were designed to get highly active HT–WGS catalysts. Despite the high CO concentration in the simulated waste-derived synthesis gas, Fe/Al/Cu catalyst exhibited the highest CO conversion (84 %) and 100 % selectivity to CO₂ at a very high gas hourly space velocity (GHSV) of 40,057 h^?1. The outstanding catalytic performance is mainly due to easier reducibility, the synergy effect of Cu and Al, and the stability of the magnetite.     

A real-time monitoring and assessment method for calculation of total amounts of indoor air pollutants emitted in subway stations

Subway systems are considered as main public transportation facility in developed countries. Time spent by people in indoors, such as underground spaces, subway stations, and indoor buildings, has gradually increased in the recent past. Especially, operators or old persons who stay in indoor environments more than 15 hr per day usually influenced a greater extent by indoor air pollutants. Hence, regulations on indoor air pollutants are needed to ensure good health of people. Therefore, in this study, a new cumulative calculation method for the estimation of total amounts of indoor air pollutants emitted inside the subway station is proposed by taking cumulative amounts of indoor air pollutants based on integration concept. Minimum concentration of individual air pollutants which naturally exist in indoor space is referred as base concentration of air pollutants and can be found from the data collected. After subtracting the value of base concentration from data point of each data set of indoor air pollutant, the primary quantity of emitted air pollutant is calculated. After integration is carried out with these values, adding the base concentration to the integration quantity gives the total amount of indoor air pollutant emitted. Moreover, the values of new index for cumulative indoor air quality obtained for 1 day are calculated using the values of cumulative air quality index (CAI). Cumulative comprehensive indoor air quality index (CCIAI) is also proposed to compare the values of cumulative concentrations of indoor air pollutants. From the results, it is clear that the cumulative assessment approach of indoor air quality (IAQ) is useful for monitoring the values of total amounts of indoor air pollutants emitted, in case of exposure to indoor air pollutants for a long time. Also, the values of CCIAI are influenced more by the values of concentration of NO₂, which is released due to the use of air conditioners and combustion of the fuel. The results obtained in this study confirm that the proposed method can be applied to monitor total amounts of indoor air pollutants emitted, inside apartments and hospitals as well.

Implications: Nowadays, subway systems are considered as main public transportation facility in developed countries. Time spent by people in indoors, such as underground spaces, subway stations, and indoor buildings, has gradually increased in the recent past. Especially, operators or old persons who stay in the indoor environments more than 15 hr per day usually influenced a greater extent by indoor air pollutants. Hence, regulations on indoor air pollutants are needed to ensure good health of people. Therefore, this paper presents a new methodology for monitoring and assessing total amounts of indoor air pollutants emitted inside underground spaces and subway stations. A new methodology for the calculation of cumulative amounts of indoor air pollutants based on integration concept is proposed. The results suggest that the cumulative assessment approach of IAQ is useful for monitoring the values of total amounts of indoor air pollutants, if indoor air pollutants accumulated for a long time, especially NO₂ pollutants. The results obtained here confirm that the proposed method can be applied to monitor total amounts of indoor air pollutants emitted, inside apartments and hospitals as well.     

Risk assessment of particulate matter by considering time-activity-pattern and major microenvironments for preschool children living in Seoul,South Korea

Environmental Science and Pollution Research - Preschool children aged 3–6 years are vulnerable to exposed to particulate matter (“PM10” and “PM2.5”). It is required...     

Properties of alkali-activated systems with stone powder sludge

This article investigates the effects of stone powder sludge on the microstructure and strength development of alkali-activated fly ash and blast furnace slag mixes. Stone powder sludge produced from a crushed aggregate factory was used to replace fly ash and granulated blast furnace slag at replacement ratios of 0%, 10%, 20%, and 30% by mass. The unit weight and compressive strength of the samples were measured, and scanning electron microscopy/energy dispersive spectroscopy and X-ray diffraction (XRD) analyses were performed. The test results indicated that the compressive strength of alkali-activated blast furnace slag mixes using stone powder sludge was higher than that of the alkali-activated blast furnace slag control mix, but the compressive strength of alkali-activated fly ash mixes decreased with increasing replacement ratio of stone powder sludge. Microscopy results indicated that for alkaliactivated blast furnace slag samples, broken surfaces were more evident than for the alkali-activated fly ash samples. For all XRD diagrams, broad and diffuse peaks were observed around 2θ = 35° (d = 2.96–3.03 Å), implying amorphous or short-ordering structure phases.     

Toxicity potentials from waste cellular phones,and a waste management policy integrating consumer,corporate, and government responsibilities

Cellular phones have high environmental impact potentials because of their heavy metal content and current consumer attitudes toward purchasing new phones with higher functionality and neglecting to return waste phones into proper take-back systems. This study evaluates human health and ecological toxicity potentials from waste cellular phones; highlights consumer, corporate, and government responsibilities for effective waste management; and identifies key elements needed for an effective waste management strategy. The toxicity potentials are evaluated by using heavy metal content, respective characterization factors, and a pathway and impact model for heavy metals that considers end-of-life disposal in landfills or by incineration. Cancer potentials derive primarily from Pb and As; non-cancer potentials primarily from Cu and Pb; and ecotoxicity potentials primarily from Cu and Hg. These results are not completely in agreement with previous work in which leachability thresholds were the metric used to establish priority, thereby indicating the need for multiple or revised metrics. The triple bottom line of consumer, corporate, and government responsibilities is emphasized in terms of consumer attitudes, design for environment (DfE), and establishment and implementation of waste management systems including recycling streams, respectively. The key strategic elements for effective waste management include environmental taxation and a deposit-refund system to motivate consumer responsibility, which is linked and integrated with corporate and government responsibilities. The results of this study can contribute to DfE and waste management policy for cellular phones.     

Investigating the spatial distribution of phototrophic picoplankton in a tropical estuary

We sampled extensively (29 stations) at the Klang estuarine system over a 3-day scientific expedition. We measured physical and chemical variables (temperature, salinity, dissolved oxygen, total suspended solids, dissolved inorganic nutrients) and related them to the spatial distribution of phototrophic picoplankton (Ppico). Multivariate analysis of variance of the physicochemical variables showed the heterogeneity of the Klang estuarine system where the stations at each transect were significantly different (Rao’s F _{18, 36}?=?8.401, p?<?0.001). Correlation analyses also showed that variables related to Ppico abundance and growth were mutually exclusive. Distribution of Ppico was best explained by the physical mixing between freshwater and seawater whereas Ppico growth was correlated with temperature.     

Sorption and Biodegradation of Vapor-Phase Organic Compounds with Wastewater Sludge and Food Waste Compost

ABSTRACT

To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge.

The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation.     

Effects of adsorption onto silica sand particles on the hydrolysis of tetracycline antibiotics

Due to high usage of tetracycline antibiotics, concerns have been raised about their environmental fate. In this study, potential changes in the pseudo-first-order hydrolysis rate constants for three tetracyclines, tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC), were evaluated by measuring the rate constants in batch and column leaching experiments. The first-order hydrolysis rate constants were measured at pH 5, 7, and 9 using batch tests. The values were highest at pH 7 for all three tetracyclines (0.0030 ± 0.0004, 0.0042 ± 0.0001, and 0.0323 ± 0.0003 h(-1) for TC, OTC, and CTC, respectively), indicating relatively short environmental half-lives of tetracyclines. Interestingly, it was found that the rates of degradation of the parent tetracyclines were much faster when silica sand was present in a batch solution or when the solution was passed through a silica column. For example, the ratios of the first-order degradation rate constants obtained in the column experiments to those in batch experiments were 13.2, 2.1, and 2.0 for TC, OTC, and CTC at a volumetric flow rate of 0.08 mL h(-1), with an observed tendency for this ratio to increase with an increased flow rate. This indicates that the silica surface may serve as a catalyst for hydrolysis and that the actual environmental half-lives of tetracycline antibiotics could be shorter than those estimated from laboratory hydrolysis rate constants using the standard batch protocol. Furthermore, the toxicity of the column effluent containing hydrolysis metabolites was assessed using bioluminescence inhibition in Vibrio fischeri. It was estimated that the toxicity of the metabolites of CTC was lower than that of their parent compound, whereas the toxicity of metabolites of TC and OTC was as high as or higher than that of their parent compounds.