Green environmental technologies and waste utilization

Environmental Science and Pollution Research -     

Effect of petroleum on decomposition of shrub–grass litters in soil in Northern Shaanxi of China

The impacts of petroleum contamination on the litter decomposition of shrub–grass land would directly influence nutrient cycling, and the stability and function of ecosystem. Ten common shrub and grass species from Yujiaping oil deposits were studied. Litters from these species were placed into litterbags and buried in petroleum-contaminated soil with 3 levels of contamination (slight, moderate and serious pollution with petroleum concentrations of 15, 30 and 45 g/kg, respectively). A decomposition experiment was then conducted in the lab to investigate the impacts of petroleum contamination on litter decomposition rates. Slight pollution did not inhibit the decomposition of any litters and significantly promoted the litter decomposition of Hippophae rhamnoides, Caragana korshinskii, Amorpha fruticosa, Ziziphus jujuba var. spinosa, Periploca sepium, Medicago sativa and Bothriochloa ischaemum. Moderate pollution significantly inhibited litter decomposition of M. sativa, Coronilla varia, Artemisia vestita and Trrifolium repens and significantly promoted the litter decomposition of C. korshinskii, Z. jujuba var. spinosa and P. sepium. Serious pollution significantly inhibited the litter decomposition of H. rhamnoides, A. fruticosa, B. ischaemum and A. vestita and significantly promoted the litter decomposition of Z. jujuba var. spinosa, P. sepium and M. sativa. In addition, the impacts of petroleum contamination did not exhibit a uniform increase or decrease as petroleum concentration increased. Inhibitory effects of petroleum on litter decomposition may hinder the substance cycling and result in the degradation of plant communities in contaminated areas.     

Analysis of volatile organic compounds released during food decaying processes

A number of volatile organic compounds (VOCs) including acetone, methyl ethyl ketone, toluene, ethylbenzene, m,p-xylene, styrene, and o- xylene released during food decaying processes were measured from three types of decaying food samples (Kimchi (KC), fresh fish (FF), and salted fish (SF)). To begin with, all the food samples were contained in a 100-mL throwaway syringe. These samples were then analyzed sequentially for up to a 14-day period. The patterns of VOC release contrasted sharply between two types of fish (FF and SF) and KC samples. A comparison of data in terms of total VOC showed that the mean values for the two fish types were in the similar magnitude with 280 ± 579 (FF) and 504 ± 1,089 ppmC (SF), while that for KC was much lower with 16.4 ± 7.6 ppmC. There were strong variations in VOC emission patterns during the food decaying processes between fishes and KC that are characterized most sensitively by such component as styrene. The overall results of this study indicate that concentration levels of the VOCs differed significantly between the food types and with the extent of decaying levels through time.     

Potential health risks of toxic heavy metals and nitrate via commonly consumed bivalve and vegetable species in Ho Chi Minh City,Vietnam

Environmental Science and Pollution Research - This study aimed to evaluate the health risks of cadmium (Cd), lead (Pb), inorganic arsenic (As), and nitrate exposure through the consumption of...     

Intercomparison of Satellite Remote Sensing‐Based Flood Inundation Mapping Techniques

The objective of this study was to determine the accuracy of five different digital image processing techniques to map flood inundation extent with Landsat 8–Operational Land Imager satellite imagery. The May 2016 flooding event in the Hempstead region of the Brazos River, Texas is used as a case study for this first comprehensive comparison of classification techniques of its kind. Five flood water classification techniques (i.e., supervised classification, unsupervised classification, delta‐cue change detection, Normalized Difference Water Index [NDWI], modified NDWI [MNDWI]) were implemented to characterize flooded regions. To identify flood water obscured by cloud cover, a digital elevation model (DEM)–based approach was employed. Classified floods were compared using an Advanced Fitness Index to a “reference flood map” created based on manual digitization, as well as other data sources, using the same satellite image. Supervised classification yielded the highest accuracy of 86.4%, while unsupervised, MNDWI, and NDWI closely followed at 79.6%, 77.3%, and 77.1%, respectively. Delta‐cue change detection yielded the lowest accuracy with 70.1%. Thus, supervised classification is recommended for flood water classification and inundation map generation under these settings. The DEM‐based approach used to identify cloud‐obscured flood water pixels was found reliable and easy to apply. It is therefore recommended for regions with relatively flat topography.     

Calculating of river water quality sampling frequency by the analytic hierarchy process (AHP)

River water quality sampling frequency is an important aspect of the river water quality monitoring network. A suitable sampling frequency for each station as well as for the whole network will provide a measure of the real water quality status for the water quality managers as well as the decision makers. The analytic hierarchy process (AHP) is an effective method for decision analysis and calculation of weighting factors based on multiple criteria to solve complicated problems. This study introduces a new procedure to design river water quality sampling frequency by applying the AHP. We introduce and combine weighting factors of variables with the relative weights of stations to select the sampling frequency for each station, monthly and yearly. The new procedure was applied for Jingmei and Xindian rivers, Taipei, Taiwan. The results showed that sampling frequency should be increased at high weighted stations while decreased at low weighted stations. In addition, a detailed monitoring plan for each station and each month could be scheduled from the output results. Finally, the study showed that the AHP is a suitable method to design a system for sampling frequency as it could combine multiple weights and multiple levels for stations and variables to calculate a final weight for stations, variables, and months.     

Persistence of white spot syndrome virus in shrimp ponds and surrounding areas after an outbreak

White Spot Syndrome Virus (WSSV) is the major and most serious pathogen in shrimp aquaculture industries. By using a sensitive PCR-based detection technique followed by sequencing multiple PCR products for confirmation, we address to the question of whether WSSV can persist in shrimp ponds and surrounding areas after an outbreak. The seawater samples were taken from two shrimp ponds and surrounding canals in a coastal area in northern Vietnam, Quang Ninh Province where the shrimps cultured in the two ponds had been killed due to a WSSV outbreak in April 2001 and the ponds were thereafter abandoned. A total of 480 seawater samples (30 samples each for July and December of 2001 and 2002) were subjected to WSSV genome detection. Although the detection rates of WSSV genome were generally gradually declined in seawater environments of both diseased shrimp ponds and surrounding canals, WSSV was still detected with rates of more than 10% in the diseased ponds and lower in surrounding canals in December 2002, 20 months after the WSSV outbreak.     

Activated carbon/Fe(3)O(4) nanoparticle composite: fabrication, methyl orange removal and regeneration by hydrogen peroxide

In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe₃O₄ nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe₃O₄ nanoparticles, were fabricated by a modified impregnation method using HNO₃ as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO₃ (powdered activated carbon modified by HNO₃) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe₃O₄ nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide.     

Occurrence of antimicrobials in animal manure-amended soils around the breeding farms: The case of the Saigon River (southern Vietnam)

The excessive use of antimicrobials in animal rearing and the associated environmental hazards have become a pressing issue. Animal agriculture is often viewed as a significant contributor to environmental degradation due to the residues of antimicrobials. It is a common practice to use livestock waste as a soil enhancer in farming. Despite some research into antimicrobials, there is room for more comprehensive data regarding these pollutants in animal farming environments. A handful of earlier studies have identified antimicrobials in animal waste. This research undertook the task of examining and evaluating soils amended with animal waste (from chickens, cows, and pigs) for the presence of seven specific antimicrobials. The antimicrobials under scrutiny included trimethoprim (TRI), ormethoprim (ORM), ofloxacin (OFL), norfloxacin (NOR), tetracycline (TET), chlortetracycline (CTE), and tylosin (TLS). Soil samples were collected from areas surrounding breeding farms located upstream of the Sai Gon River. These samples were then subjected to laboratory analysis, which involved solid-phase extraction using ultrasonic waves and the application of high-performance liquid chromatography-tandem mass spectrometry (LCMS/MS) to identify the antimicrobials. TRI, which had the highest average concentration (2.603–91.304 μg/kg), and OFL, with the second highest average concentration (1.815–15.832 μg/kg), were detected in all soil samples amended with manure. CTE, with the third highest average concentration, was found in soils amended with cow and pig waste (1.625–15.486 μg/kg). ORM and TE, with lower average concentrations (0.595–1.318 μ and 11.537–13.569 μg/kg, respectively), were only detected in soils amended with chicken waste, while NOR was only found in soils amended with cow waste. These findings indicate that the use of antimicrobials in animal farming can negatively impact the soil ecosystem. Consequently, these results can contribute to the creation of guidelines for monitoring antimicrobial residues in agricultural ecosystems.