Organochlorine pesticides and polychlorinated biphenyls in soils surrounding the Tanggu Chemical Industrial District of Tianjin, China

The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1–12,549 μg?kg^?1 (average, 965 μg?kg^?1), n.d.–2,033 μg?kg^?1 (average, 88.4 μg?kg^?1), n.d.–1,924 μg?kg^?1 (average, 349 μg?kg^?1), and n.d.–373 μg?kg^?1 (average, 46.2 μg?kg^?1), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.     

The Bechtel Confined Zone dispersion Process for FGD Retrofit Situations Proof-of-Concept Tests

The Bechtel Confined Zone Dispersion (CZD) process for FGD retrofit situations was tested at two sites: one at a level of 5 MWe; the other at 70 MWe. The CZD process involves injecting a finely atomized slurry of hydrated lime into a straight run of duct between a boiler's air heater and its electrostatic precipitator (ESP). The effect of process variables on SO₂ removal and ESP performance was investigated for dolomitic/calcitic lime. Removals of SO₂ in excess of 50 percent were achieved for either lime type at the 5 MWe site. A very short duct length limited injection rate at the 70 MWe site, limiting sulfur removals to a maximum of 30 percent. SO₂ removal data for both sites were successfully correlated on a common basis. ESP performance was not fully acceptable during lime injection at both sites, but it is felt that optimization of ESP operations should eliminate this problem. Additional testing is recommended to further explore ESP performance and to optimize lime injection parameters. The results obtained to date continue to indicate that the CZD process is an attractive and economical candidate for FGD retrofit situations.     

Mitigation of nutrient losses via surface runoff from rice cropping systems with alternate wetting and drying irrigation and site-specific nutrient management practices

Resource-conserving irrigation and fertilizer management practices have been developed for rice systems which may help address water quality concerns by reducing N and P losses via surface runoff. Field experiments under three treatments, i.e., farmers’ conventional practice (FCP), alternate wetting and drying (AWD), and AWD integrated with site-specific nutrient management (AWD + SSNM) were carried out during two rice seasons at two sites in the southwest Yangtze River delta region. Across site years, results indicated that under AWD irrigation (i.e., AWD and AWD + SSNM), water inputs were reduced by 13.4?~?27.5 % and surface runoff was reduced by 30.2?~?36.7 % compared to FCP. When AWD was implemented alone, total N and P loss masses via surface runoff were reduced by 23.3?~?30.4 % and 26.9?~?31.7 %, respectively, compared to FCP. However, nutrient concentrations of surface runoff did not decrease under AWD alone. Under AWD + SSNM, total N and P loss masses via surface runoff were reduced to a greater extent than AWD alone (39.4?~?47.6 % and 46.1?~?48.3 % compared to FCP, respectively), while fertilizer inputs and N surpluses significantly decreased and rice grain yields increased relative to FCP. Therefore, by more closely matching nutrient supply with crop demand and reducing both surface runoff and nutrient concentrations of surface runoff, our results demonstrate that integration of AWD and SSNM practices can mitigate N and P losses via surface runoff from rice fields while maintaining high yields.     

One way to reduce the NOX Emission of biodiesels: The increase of cetane number

Compared to conventional diesel fuels, biodiesels normally have lower smoke and particulate matter, while higher nitrogen oxides (NO_X) emissions. In our study, an attempt was made to reduce the NO_X emissions of biodiesels by increasing the cetane numbers (CNs). Three kinds of biodiesels with extremely high CNs (70.1, 76.9, 80.9, respectively) were developed. Their main physical and chemical properties were tested. With a two-cylinder direct injection diesel engine, their emission performances were experimentally investigated. The results indicate that, CN, freezing point, as well as viscosity of biodiesels are linearly increased with the increase of carbon number. The NO_X emission for biodiesels with high CNs is lower than that of conventional diesel fuels. High CN promotes smoke formation as well while lower smoke emissions are still obtained for biodiesels when certain oxygen contents are present. That is, the smoke/NO_X tradeoff is broken. Besides, as fuel CN is elevated, NO_X for biodiesels decreases but smoke and carbon monoxide emissions are increased.     

Novel Renewable Polyols Based on Limonene for Rigid Polyurethane Foams

Novel renewable polyols based on limonene were synthesized using thiol-ene “click” chemistry. These limonene based polyols were structurally characterized using wet methods (hydroxyl number, acid value and viscosity), gel permeation chromatography and spectroscopic methods. The results indicated that high yield of polyols from limonene based materials can be obtained using thiol-ene reaction. These limonene based polyols were used successfully for preparation of rigid polyurethane foams. These foams had regular shape cells and uniform cell size distribution. Thermal studies on these foams indicated that foams were thermally stable up to 250 °C. The glass transition temperature of the foams was higher than 200 °C. These rigid polyurethane foams had high compressive strength and the highest compressive strength of 195 kPa was observed. These foams have good physical–mechanical characteristics and could be suitable for all the applications of rigid polyurethane foams such as thermal insulation of freezers, storage tanks for the chemical and food industries, and packing materials for food industries.     

Faecal pollution loads in the wastewater effluents and receiving water bodies: a potential threat to the health of Sedibeng and Soshanguve communities,South Africa

The discharge of untreated or inadequately treated effluents has been identified among the activities responsible for the spread of a wide range of potentially infectious agents. The aim of this study was to determine whether inadequate treatment of wastewater and the faecal pollution load of effluents and receiving water bodies in Sedibeng District and Soshanguve peri-urban area of the Tshwane Metropolitan Municipality could be a potential threat to the health of the surrounding communities. Variations in the counts of faecal indicator bacteria and pathogenic microorganisms and compliance of the effluents and receiving water bodies with South African and World Health Organization standards were assessed between August 2011 and May 2012 using culture-based methods and molecular techniques. The overall quality of effluents did not comply with the South African special standard of no risk for unrestricted irrigation (zero?Escherichia coli/100 ml). The quality of the receiving water bodies did not comply with South African regulatory limits set for domestic purposes (zero?E.?coli/100 ml, <30 faecal enterococci/100 ml and <1 somatic coliphages/100 ml), for full contact recreation (<20 somatic coliphages/100 ml) and aquaculture (<10?E.?coli/100 ml) and WHO standards for full and intermediate contact recreational use (<1?E.?coli/100 ml and <40 faecal enterococci/100 ml, respectively). The PCR results revealed the prevalence of pathogenic microorganisms; between 0 and 60 % of samples tested positive for Salmonella Typhimurium and Shigella dysenteriae, and between 20 and 60 % of samples tested positive for Vibrio cholerae. These findings demonstrated that potential health risks might be associated with the use of the target river waters for domestic, recreational and irrigation purposes. This study calls for a prompt intervention to improve wastewater management.     

Increasing extremes of heat and drought associated with recent severe wildfires in southern Greece

Mountains of the northern Mediterranean basin face two major threats under global change. Aridity and available fuel are both expected to increase because of climatic and land-use changes, increasing fire danger. There may already be signs of such effects in the case of the Pinus nigra and Abies cephalonica forests on Mt. Taygetos (southern Greece). We reconstructed climate (mid- to late-fire-season drought) using tree-rings for the last 150 years and compared it with the mountain’s fire history reconstructed from P. nigra fire scars. Seven, out of the ten, large fires Mt. Taygetos experienced were associated with below-normal precipitation (P) or above-normal maximum temperature (T _max). The largest fires occurred in late summer of 1879, 1944, 1998, and 2007. However, only the recent fires (1998 and 2007) had both low P and high T _max, also confirmed from long-term meteorological data. The synergy between climate and fuel availability may explain the very high intensity of 1998 and 2007 fires that burned mostly as stand-replacing crown fires. The other two large fire events (1879 and 1944) most likely occurred under reduced availability in burning fuel and were related to above-normal T _max. Our findings are among the first based on long-term and site-specific empirical data to support the prediction that Mediterranean mountainous areas will face a very large threat from wildfires in the twenty-first century, if socioeconomic changes leading to land abandonment and thus burning fuel accumulation are combined with the drought intensification projected for the region under global warming.     

Bacterial communities in urban aerosols collected with wetted-wall cyclonic samplers and seasonal fluctuations of live and culturable airborne bacteria

Airborne transmission of bacterial pathogens from point sources (e.g., ranches, dairy waste treatment facilities) to areas of food production (farms) has been suspected. Determining the incidence, transport and viability of extremely low levels of pathogens require collection of high volumes of air and characterization of live bacteria from aerosols. We monitored the numbers of culturable bacteria in urban aerosols on 21 separate days during a 9 month period using high volume cyclonic samplers at an elevation of 6 m above ground level. Culturable bacteria in aerosols fluctuated from 3 CFU to 6 million CFU/L of air per hour and correlated significantly with changes in seasonal temperatures, but not with humidity or wind speed. Concentrations of viable bacteria determined by fluorescence staining and flow cytometry correlated significantly with culturable bacteria. Members of the phylum Proteobacteria constituted 98% of the bacterial community, which was characterized using 16S rRNA gene sequencing using DNA from aerosols. Aquabacterium sp., previously characterized from aquatic environments, represented 63% of all clones and the second most common were Burkholderia sp; these are ubiquitous in nature and some are potential human pathogens. Whole genome amplification prior to sequencing resulted in a substantial decrease in species diversity compared to characterizing culturable bacteria sorted by flow cytometry based on scatter signals. Although 27 isolated colonies were characterized, we were able to culture 38% of bacteria characterized by sequencing. The whole genome amplification method amplified DNA preferentially from Phyllobacterium myrsinacearum, a minor member of the bacterial communities, whereas Variovorax paradoxus dominated the cultured organisms.