Phytoremediation of Contaminated Chemical Plant Sites

[Objective] The aim was to research phytoremediation effects on soils with combined pollution. [Method] With simulation experiment, the test selected plants suitable for phytoremediation in soils polluted with Pb-Cd, PAHs, and Pb-Cd-PAHs,respectively and ryegrass was grown to explore phytoremediation on contaminated sites by adjusting bio-availability. [Result] After 70 d growing of ryegrass, the content of available Pb in contaminated soils was 375.26 mg/kg, the content of Cd was 4.9mg/kg after 90 d, and the content of B [a]P was 0.60 mg/kg after 100 d, which were all lower compared with soil limits. [Conclusion] Ryegrass is a suitable plant for phytoremediation.

Effects of mercury contaminated rice from typical chemical plant area in China on nitric oxide changes and c-fos expression of rats brain

China is one of countries with the highest mercury production in the world. The Guizhou Province in Southwestern China is currently one of the world's most important mercury production areas. In order to study the neurotoxicity of rice from Qingzhen Chemical Plant area and probe into the signal transduction molecular mechanism of injury in rat brain stimulation by mercury contaminated rice. The rats were exposed to mercury contaminated rice for 20 d. Both of the measurements of NO and NOS were processed according to the protocol of the kit. The effect of Hg contaminated rice on the expression of c-fos mRNA in rat brain and the expression of c-FOS protein in cortex, hippocampus were observed using reverse transcription polymerase chain reaction(RT-PCR) and immunocytochemical methods. The results showed the neural transmitter NO and NOS in brain were significantly change between exposure groups and control group; the mercury polluted rice induced significantly the expression of c-fos mRNA; the c-FOS positive cells in hippocampus and cortex of exposure groups were significant different from control group(p<0.01). It could be concluded that nitric oxide was involved in mercury contaminated rice induced immediate early gene c-fos expressions in the rat brain. Through food chain, local ecosystem and health of local people iave been deteriorated seriously by mercury. This serious situation will last a long period. In order to alleviate mercury pollution, more work needs to do.

A Novel Real-time Optimization Methodology for Chemical Plants

In this paper, a novel approach termed process goose queue (PGQ) is suggested to deal with real-time optimization (RTO) of chemical plants. Taking advantage of the ad-hoc structure of PGQ which imitates biologic nature of flying wild geese, a chemical plant optimization problem can be re-formulated as a combination of a multi-layer PGQ and a PGQ-Objective according to the relationship among process variables involved in the objective and constraints. Subsequently, chemical plant RTO solutions are converted into coordination issues among PGQs which could be dealt with in a novel way. Accordingly, theoretical definitions, adjustment rule and implementing procedures associated with the approach are explicitly introduced together with corresponding enabling algorithms. Finally, an exemplary chemical plant is employed to demonstrate the feasibility and validity of the contribution.

Agent Orange Chemical Plant Locations in the United States and Canada: Environmental and Human Health Impacts

During the Vietnam War, millions of liters of six tactical herbicides were sprayed on the southern Vietnam landscape to defoliate forests, to clear military perimeters and to destroy enemy food supplies. The environmental and human health impacts of spraying these herbicides, especially Agent Orange and those formulated with mixtures that included 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) which was contaminated with 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD) have been documented over the last 60 years. The dioxin TCDD clean-up efforts at former military bases and other Vietnam hotspots are ongoing. However, the lesser-told story was the environmental and human health impacts on the communities and chemical plant workers who manufactured Agent Orange and other herbicides that became contaminated with dioxin TCDD in the manufacturing processes at seven locations in the United States and one site in Canada. The pollution at these chemical plant sites, adjacent rivers and groundwater is well known within each affected state or province but not widely recognized beyond their localities. In this paper we assess the national long-term effects on land, groundwater and river resources where Agent Orange and other agricultural herbicides containing 2,4,5-T with unknown amounts of dioxin TCDD were manufactured, transported, and temporarily stored. The sites where residual tactical herbicides with contaminated by-products were applied to public lands or disposed of by military and civilian workers within the United States and Canada are identified. After 60 years, these communities are still paying the price for the U.S. Government, DOD and USDA decisions to provide and use agricultural herbicides as tactical chemical weapons during the Vietnam War (1962-1971). There have been human health issues associated with the chemical manufacture, transport, storage and disposal of these herbicides related to workers who moved these chemical weapons from United States and Canada to SE Asia. Most of these dioxin contaminated tactical herbicides were transported via railroads to ports at Mobile, Alabama and Gulfport, Mississippi. They were then loaded on ocean-going ships and transported via the Panama Canal for use during the Vietnam War. The objective of this study is to document the environmental and human consequences of the manufacture of tactical herbicides with dioxin TCDD and arsenic on the chemical plant, transportation, application, storage and disposal workers. The costs of cleanup of these North America chemical plant sites, transportation corridors, temporary and long-term storage areas, supply chain storage facilities with residual tactical herbicide, application, and disposal sites to date, is in the billions of dollars. Billions have been spent on hazardous waste incineration to destroy the dioxin TCDD or bury it in certified landfills. Government mandated environmental covenants are on titles of properties still contaminated with high levels of dioxin TCDD. If landowners attempt to rescind land use restrictions, many more billions of dollars will be needed to finish the environmental cleanup and restore natural resources. These cost estimates do not include the billions of dollars needed to treat the effects of dioxin TCDD exposure of U.S. and Canadian civilian workers who manufactured and handled these contaminated herbicides during the Vietnam War as well as address human health issues of their offspring.

Hexachlorobutadiene emissions from typical chemical plants

Hexachlorobutadiene(HCBD)was classed as a persistent organic pollutant under the Stockholm Convention in 2015.HCBD is mainly an unintentionally produced by-product of chlorinated hydrocarbon(e.g.,trichloroethylene and tetrachloroethylene)synthesis.Few studies of HCBD formation during chemical production processes have been performed,so HCBD emissions from these potentially important sources are not understood.In this study,HCBD concentrations in raw materials,intermediate products,products,and bottom residues from chemical plants producing chlorobenzene,trichloroethylene,and tetrachloroethylene were determined.The results indicated that HCBD is unintentionally produced at much higher concentrations in trichloroethylene and tetrachloroethylene plants than chlorobenzene plants.The sum of the HCBD concentrations in the samples from all of the trichloroethylene and tetrachloroethylene production stages in plant PC was 247000µg/mL,about three orders of magnitude higher than the concentrations in the tetrachloroethylene production samples(plant PB)and about six orders of magnitude higher than the concentrations in the chlorobenzene production samples(plant PA).The HCBD concentrations were highest in bottom residues from all of the plants.The concentrations in the bottom residue samples contributed 24%–99%of the total HCBD formed in the chemical production plants.The bottom residue,being hazardous waste,could be disposed of by incineration.The HCBD concentrations were much higher in intermediate products than raw materials,indicating that HCBD formed during production of the intended chemicals.The results indicate the concentrations of HCBD unintentionally produced in typical chemical plants and will be useful in developing protocols for controlling HCBD emissions to meet the Stockholm Convention requirements.

WEIFANG CHEMICALS PLANT

As a large, key enterprise in Weifang City and Shandong, the Weifang Chemicals Plant has developed an annual production capacity of 35.000 tons of caustic soda, 10,000 tons of polyvinyl chloride, 6,000 tons of polyethylene chloride, 15.000 tons of chlorine liquid. 10,000 tons of synthetic hydrochloric acid. 7.000 tons of etectride stone and 20.

Toxic Gas Put 161 Workers of Jilin Chemical Fiber Plant in Hospital

A news briefing held on May 13 by local government in Jilin city of Jilin province released that 161 workers got sick symptoms as a result of their contact with an unidentified gas emitting from Jilin Chemical Fiber Group Corp.

Global Change Effects on Plant Chemical Defenses against Insect Herbivores

This review focuses on individual effects of major global change factors, such as elevated CO2, O3, UV light and temperature, on plant secondary chemistry. These secondary metabolites are well-known for their role in plant defense against insect herbivory. Global change effects on secondary chemicals appear to be plant species-specifc and dependent on the chemical type. Even though plant chemical responses induced by these factors are highly variable, there seems to be some specificity in the response to different environmental stressors. For example, even though the production of phenolic compounds is enhanced by both elevated CO2 and UV light levels, the latter appears to primarily increase the concentrations of flavonoids. Likewise, specific phenolic metabolites seem to be induced by O3 but not by other factors, and an increase in volatile organic compounds has been particularly detected under elevated temperature. More information is needed regarding how global change factors influence inducibility of plant chemical defenses as well as how their indirect and direct effects impact insect performance and behavior, herbivory rates and pathogen attack. This knowledge is crucial to better understand how plants and their associated natural enemies will be affected in future changing environments.

Plant traits related to leaf decomposition processes in arid ecosystems of northern Patagonia

Aims Plants play an important role in ecosystem processes.Functional meaning of trait variation in wide environmental gradients is well known but is scarcely known across narrow gradients.We analyze the variation of morphological,physical and chemical traits of dom-inant plant species and the potential rates of dry mass loss and N release/immobilization during senesced leaf decomposition of these species across a narrow aridity gradient,and to identify indicative traits useful to set species functional groups sharing decomposition patterns.Methods We analyzed the variation of morphological,physical and chemical traits(specific leaf area,seed mass,N and soluble phenols in green and senesced leaves,plant height)in dominant plant species at 12 sites across an aridity gradient in northern Patagonia,Argentina.We collected senesced leaves of each plant species at each site and used them to estimate the poten-tial rates of dry mass loss and N release/immobilization from decomposing senesced leaves in a microcosm experiment.We analyzed the variation of plant traits and decomposition rates across the aridity gradient.We grouped plants species accord-ing to growth forms(perennial grasses,deciduous shrubs,ever-green shrubs)and different combinations of morpho-physical and chemical traits of green and senesced leaves and compared the potential rates of dry mass loss and N release/immobiliza-tion during leaf decomposition among these groups delimited by each grouping criteria.Important Findings Plant traits did not vary across the aridity gradient.The potential rate of dry mass loss was positively related to aridity,while the potential rate of N release/immobilization did not vary across the gradient.Grouping species by separately morpho-physical and chemical traits resulted in a large overlapping in mean values of decomposition rates among groups.In contrast,plant groupings based on growth forms and those including all morpho-physical and chemical traits of green or senesced leaves yielded groups with differentiated rates of decomposition processes.The two latter groupings clustered spe-cies from more than one growth form indicating some overlapping in the rates of decomposition processes among species of different growth forms.Among traits,N concentration in senesced leaves and plant height explained the highest variation in decomposition rates being positively related to potential rates of dry mass loss and N release/immobilization.We concluded that plant groupings based on morpho-physical and chemical traits of either green or senesced leaves may be more powerful to differentiate functional species groups sharing decomposition patterns than the growth form group-ing.Moreover,plant height and N concentration in senesced leaves may be considered relevant synthetic functional traits in relation to decomposition processes in narrow aridity gradients.

Generation of millimeter-wave sub-carrier optical pulse by using cascaded all-pass cavities

A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train is calculated, showing effective improvement by APC cascading. The extinction ratio is analyzed with different input pulses, different cavity reflectivities, and different cascading numbers. It is shown that the cascading does not introduce much effect on the extinction ratio. Two designs by using Gires-Tournois cavity and waveguide ring resonators are proposed to realize the cascaded APC.