Impact of pH buffer capacity of sediment on dechlorination of atrazine using zero valent iron

This research investigated the role of the pH buffer capacity of sediment on the dechlorination of atrazine using zero valent iron (ZVI). The buffer capacity of the sediment was quantified by batch experiments and estimated to be 5.0 cmol OH(-) . pH(-1). The sediments were spiked with atrazine at 7.25-36.23 mg kg(-1) (6.21 x 10(-7)-3.09 x 10(-6) mol atrazine . g(-1) sediment) for the batch experiments. The buffer capacity of the sediment maintained the sediment suspension at neutral pH, thereby enabling continuous dechlorination until the buffer capacity of the sediment was depleted. The pseudo-first order dechlorination constants were estimated to be in the range of 1.19 x 10(-2)-7.04 x 10(-2) d(-1) for the atrazine-spiked sediments.     

Volatile pollutants emitted from selected liquid household products

BACKGROUND, AIM, AND SCOPE: To identify household products that may be potential sources of indoor air pollution, the chemical composition emitted from the products should be surveyed. Although this kind of survey has been conducted by certain research groups in Western Europe and the USA, there is still limited information in scientific literature. Moreover, chemical components and their proportions of household products are suspected to be different with different manufacturers. Consequently, the current study evaluated the emission composition for 42 liquid household products sold in Korea, focusing on five product classes (deodorizers, household cleaners, color removers, pesticides, and polishes). MATERIALS AND METHODS: The present study included two phase experiments. First, the chemical components and their proportions in household products were determined using a gas chromatograph and mass spectrometer system. For the 19 target compounds screened by the first phase of the experiment and other selection criteria, the second phase was done to identify their proportions in the purged-gas phase. RESULTS: The number of chemicals in the household products surveyed ranged from 9 to 113. Eight (product class of pesticides) to 17 (product class of cleaning products) compounds were detected in the purged-gas phase of each product class. Several compounds were identified in more than one product class. Six chemicals (acetone, ethanol, limonene, perchloroethylene (PCE), phenol, and 1-propanol) were identified in all five product classes. There were 13 analytes occurring with a frequency of more than 10% in the household products: limonene (76.2%), ethanol (71.4%), PCE (66.7%), phenol (40.5%), 1-propanol (35.7%), decane (33%), acetone (28.6%), toluene (19.0%), 2-butoxy ethanol (16.7%), o-xylene (16.7%), chlorobenzene (14.3%), ethylbenzene (11.9%), and hexane (11.9%). All of the 42 household products analyzed were found to contain one or more of the 19 compounds. DISCUSSION: The chemical composition varied broadly along with the product classes or product categories, and it was different from that reported in other studies abroad, although certain target chemicals were identified in both studies. This finding supports an assertion that chemical components emitted from household products may be different in different products and with different manufacturers. The chlorinated pollutants identified in the present study have not been reported to be components of cleaning products in papers published since the early 1990s. Limonene was identified as having the highest occurrence in the household products in the present study, although it was not detected in any of 67 household products sold in the U.S. CONCLUSIONS: The emission composition of selected household products was successfully examined by purge-and-trap analysis. Along with other exposure information such as use pattern of household products and the indoor climate, this composition data can be used to estimate personal exposure levels of building occupants. This exposure data can be employed to link environmental exposure to health risk. It is noteworthy that many liquid household products sold in Korea emitted several toxic aromatic and chlorinated organic compounds. Moreover, the current finding suggests that product types and manufacturers should be considered, when evaluating building occupants' exposure to chemical components emitted from household products. RECOMMENDATIONS AND PERSPECTIVES: The current findings can provide valuable information for the semiquantitative estimation of the population inhalation exposure to these compounds in indoor environments and for the selection of safer household products. However, although the chemical composition is known, the emissions of household products might include compounds formed during the use of the product or compounds not identified as ingredients by this study. Accordingly, further studies are required, and testing must be done to determine the actual composition being emitted. Similar to eco-labeling of shampoos, shower gels, and foam baths proposed by a previous study, eco-labeling of other household products is suggested.     

Review: Efficiently performing periodic elements with modern adsorption technologies for arsenic removal

Environmental Science and Pollution Research - Arsenic (As) toxicity is a global phenomenon, and it is continuously threatening human life. Arsenic remains in the Earth’s crust in the forms...     

Acute and chronic health risk assessment for inhalation and ingestion exposure in acrylic acid leak accidents

Environmental Science and Pollution Research - We established a hypothetical acrylic acid leak accident scenario, conducted a health risk assessment of local residents, and compared an actual...     

Roles of SO2 oxidation in new particle formation events

The oxidation of SO₂ is commonly regarded as a major driver for new particle formation (NPF) in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO₂ and observed long-term (duration > 3 hr) and short-term (duration <1.5 hr) NPF events at a semi-urban site in Toronto. Apparent NPF rates (J₃₀) showed a moderate correlation with the concentration of sulfuric acid ([H₂SO₄]) calculated from the measured mixing ratio of SO₂ in long-term NPF events and some short-term NPF events (Category I) (R² = 0.66). The exponent in the fitting line of J₃₀ ~ [H₂SO₄]ⁿ in these events was 1.6. It was also found that SO₂ mixing ratios varied a lot during long-term NPF events, leading to a significant variation of new particle counts. In the SO₂-unexplained short-term NPF events (Category II), analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO₂ probably made a negligible contribution to the growth of >10 nm new particles.     

Roles of SO2 oxidation in new particle formation events

The oxidation of SO₂ is commonly regarded as a major driver for new particle formation (NPF) in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO₂ and observed long-term (duration > 3 hr) and short-term (duration < 1.5 hr) NPF events at a semi-urban site in Toronto. Apparent NPF rates (J₃₀) showed a moderate correlation with the concentration of sulfuric acid ([H₂SO₄]) calculated from the measured mixing ratio of SO₂ in long-term NPF events and some short-term NPF events (Category I) (R² = 0.66). The exponent in the fitting line of J₃₀ ~ [H₂SO₄]ⁿ in these events was 1.6. It was also found that SO₂ mixing ratios varied a lot during long-term NPF events, leading to a significant variation of new particle counts. In the SO₂-unexplained short-term NPF events (Category II), analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO₂ probably made a negligible contribution to the growth of > 10 nm new particles.     

Human Enteric Viruses in Groundwater

Waterborne outbreaks of enteric viruses are a major public health concern. The present study has been carried out to assess the presence of enteric viruses responsible for human acute gastroenteritis (AGE) in groundwater intended for drinking and produce washing. In total, 62 samples from groundwater for drinking and produce washing collected from Dec 2007 to Dec 2008 in Seoul were tested for enteric viruses using conventional RT–PCR, ELISA, and real-time RT–PCR. Our results showed that enteric viruses were detected in 7 (8.8%) groundwater samples. Rotaviruses were detected in 3 (4.8%) of the samples by ELISA; human adenoviruses were detected in 2 (3.2%) of the samples by ELISA; and nested RT–PCR detected noroviruses in 2 (3.2%) of the samples. In one of the groundwater sample, the norovirus RNA was detected by conventional RT–PCR which was confirmed positive by real-time RT–PCR. Additionally, real-time RT–PCR successfully detected norovirus RNA in five out of 62 water samples (8.1%). The data demonstrate that real-time RT–PCR will be useful as a rapid and sensitive method for detecting norovirus in water samples. Phylogenetic analysis revealed that the noroviruses detected in two of the groundwater samples belonged to GII-4. These studies can provide important information for the prevalence of enteric viruses in Korean groundwater.