Analytical methods for conventional and emerging disinfection by-products in fresh-cut produce

The formation of toxic disinfection by-products (DBPs) is among the main concerns in the use of chlorine sanitizers for washing fresh and fresh-cut produce to minimize microbial cross-contamination. Even so, robust analytical methods for measuring various DBPs in produce have been lacking. This study has established two liquid-liquid extraction methods, followed by gas chromatography with electron capture detection, to measure 32 conventional and emerging DBPs in different produce types including lettuce, cabbage and strawberry. Good recoveries (50–130%) were achieved for most DBPs in the different produce. The method detection limits were in the range of 0.3–10 ng/g for trihalomethanes, haloacetic acids, nitrogenous DBPs, and other carbonaceous DBPs. Preliminary screening analysis indicated one-third of the target DBPs were found in unwashed produce, and washing with chlorine significantly promoted DBPs’ formation and concentrations in the produce. The developed analytical methods will be useful tools for future research on food DBPs

Heavy Metal Loading to Lake Lanier from Point Sources of Pollution and Urban Runoff

Proceedings of the 1997 Georgia Water Resources Conference, March 20-22, 1997, Athens, Georgia.An investigation into sources of heavy metal contamination in Lake Sydney Lanier has been carried out as part of the Clean Lakes Program. Previous studies have found evidence of trace metal contamination in the water column and sediments of the lake and its tributaries and in the tissues of fish. Currently, there is little quantitative data on point and non-point sources of toxic metals in the watershed. In this study, effluent samples from nine municipal and one industrial wastewater treatment plant and stormwater samples from three lake tributaries were analyzed for total recoverable mercury, arsenic, selenium, chromium, nickel, copper, zinc, cadmium, barium and lead. The most abundant metals were barium and zinc. Toxic metal loads due to stormwater runoff were always greater than those due to effluent discharges.Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602 with partial funding provided by the U.S. Department of Interior, Geological Survey, through the Georgia Water Research Institutes Authorization Act of 1990 (P.L. 101-397). The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of the University of Georgia or the U.S. Geological Survey or the conference sponsors

Study on correlation between fire fighting time and fire loss in urban building based on statistical data

In this paper, the correlation between fire fighting time and fire loss (burned area of urban building) based on fire statistical data in Jiangxi Province (China) from 2000 to 2010 was studied. The results showed the probability distribution of fire fighting time met lognormal distribution. In the probability density function, the expectation of the distribution represents the average level of fire fighting time. We found the average fighting time of warehouse and workshop fires were higher than the average level of whole building fires. In addition, the probability distribution of the burned area in each fire fighting time interval also followed power function, which was valid in the case of the fire fighting time within 4 hours. Furthermore, the absolute value of the exponent of the function is positively correlated with the small-scale fires and negatively with the large-scale fires. The value decreased with the increase of the fire fighting time, indicating that the fire control ability became poor with longer fire fighting time. Also, the fire control ability in residential waned fastest as the fighting time increased, and the ability in warehouse waned slowest. en fire fighting time and fire loss in urban building based on statistical dat

Experimental and Numerical Study on the Permeation Grouting Diffusion Mechanism considering Filtration Effects

Permeation grouting estimation is important for the design of grouting engineering. Filtration effects and rheological behavior play a key role in permeation grouting diffusion of cement-based grouts. To better understand the effect of filtration and grout rheological behavior on the grouting diffusion mechanism, one-dimensional permeation grout injections in sand columns under constant flow rate were performed by a self-developed experimental procedure. Experimental results showed that there were dramatic variations in rheological parameters and porosity along the diffusion distance. However, the rheological parameters changed slightly with time for each position. Based on the experimental results, a numerical model considering the filtration effect and grout rheological behavior was established to describe the mechanism of grout flow in porous media. In addition, numerical solutions from the proposed model are compared with the experimental results. The comparative results showed that the proposed numerical method can match the laboratory tests well. Finally, the effects of the grout flow velocity and the water/cement ratio of the grout on the diffusion mechanism are also discussed

Episode-Based Analysis of Size-Resolved Carbonaceous Aerosol Compositions in Wintertime of Xinxiang: Implication for the Haze Formation Processes in Central China

To provide a comprehensive understanding of carbonaceous aerosol and its role in the haze formation in the Central Plains Urban Agglomeration of China, size-segregated particulate matter samples (PM1, PM2.5 and PM10) were continually collected from 20 December 2017, to 17 January 2018, in Xinxiang, the third largest city of Henan province. The results showed that the mean mass concentrations of PM1, PM2.5 and PM10 were 63.20, 119.63 and 211.95 μg·m−3, respectively, and the organic carbon (OC) and elemental carbon (EC) were 11.37 (5.87), 19.24 (7.36), and 27.04 (10.27) μg·m−3, respectively. Four pollution episodes that were categorized by short evolution patterns (PE1 and PE3) and long evolution patterns (PE2 and PE4) were observed. Meteorological condition was attributed to haze episodes evolution pattern. Carbonaceous components contributed to PE1 and PE2 under drier condition through transportation and local combustion emission, while they were not main species in PE3 and PE4 for haze explosive growth under suitable RH, whatever for the short or long evolution pattern. The atmospheric self-cleaning processes were analyzed by a case study, which showed the wet scavenging effectively reduced the coarse particles with a removal rate of 73%, while it was not for the carbonaceous components in fine particles that is hydrophobic in nature. These results highlight that local primary emissions such as biomass combustion were the important sources for haze formation in Central China, especially in dry conditions

Reclamation-oriented spatiotemporal evolution of coastal wetland along Bohai Rim, China

Coastal wetlands are located in the ecotone of interaction between the land surface and sea, and anthropogenic activities extensively interfere with these wetlands through the reclamation of large tidal wetlands and destruction of the function of the ecosystems. In this study, we investigated the dynamic evolutionary characteristics of the Bohai Rim coastal area over the past 40 years using the Modified Normalized Difference Water Index, the fractal dimension, object-oriented classification, the land-use transfer trajectory, and regression analysis. Additionally, we quantified and monitored the evolution of reclamation and analyzed the correlation between reclamation and coastal wetlands based on 99 Landsat-2, -5, and -8 images (at 60 m and 30 m spatial resolution) over the period 1980-2019. The results are as follows. (1) The coastline of the Bohai Rim increased by 1 631.2 km from 1980 to 2019 with a zigzag variation. The artificial coastline increased by 2 946.1 km, whereas the natural coastline decreased by 90%. (2) The area of man-made wetlands increased by 3 736.9 km(2), the area of construction land increased by 1 008.4 km(2), and the natural wetland area decreased by 66%. The decrease of tidal flats is the main contributor to the decrease of natural wetland area (takes account for 91.1%). Coastal areas are affected by intense human disturbance, which was taken place across a large area of tidal flats and caused the landscape to fragment and be more heterogeneous. The coastal zone development activities were primarily concentrated in the southern Laizhou Bay, the Yellow River Delta, the Bohai Bay, the northern Liaodong Bay, and the Pulandian Bay. The solidified shorelines and increase in sea level have resulted in intertidal wetlands decreasing and impaired wetland ecology. (3) There is a good agreement between reclamation and the size of the coastal wetlands. Both land reclamation and the reduction in coastal wetland areas are significantly related to the population size, fishery output value, and urbanization rate. In summary, human activities, such as the construction of aquaculture ponds and salt pans, industrialization, and urbanization, are the primary forces that influence the environmental changes in the coastal region. This study is beneficial for establishing and improving the systems for the rational development and utilization of natural resources, and provides theoretical references for restoring wetland ecology and managing future reclamation activities in other coastal zone-related areas

Ecological Restoration of Degraded Supratidal Wetland Based on Microtopography Modification: a Case Study in the Yellow River Delta

In the past two decades, the supratidal wetland in the Yellow River Delta experienced severe saline-alkalization and vegetation degradation. Restoration with enclosure-freshwater release mode has prevailed since 2002. This method presented some positive effects, but need a massive freshwater supply. Furthermore, the subsequent formed singlePhragmites australisvegetation weakened the bird habitation function. In this study, we developed another restoration mode based on microtopography modification. The core idea of the mode is to enhance micro-habitat heterogeneity thus improve the water resource temporal-spatial distribution and shape more niches. An ecological restoration program was designed and implemented since May, 2015. The monitoring data from July, 2015 to December 2017 showed that, with no extra artificially drained freshwater released, the soil salinity decreased by 15.4% to 30.8%. The area of bare land decreased while that vegetation and water surface increased, resulting in relative even land cover composition, habitat heterogeneity increased and thus the bird biodiversity improved. This mode is more ecological and water cost-effective and is suitable to restore the degraded saline-alkalized supratidal wetlands. However, long-term comprehensive monitoring is essential to evaluate the restoration effect. Many detailed parameters for topography modification need further optimized