Assessment of pumped mercury vapour adsorption tubes as passive samplers using a micro-exposure chamber

Mercury vapour adsorption tubes manufactured for pumped sampling and analysis have been evaluated for their performance as passive samplers. This has been done by exposing these tubes in a novel micro-exposure chamber. The uptake rates of these tubes have been found to be low (approximately 0.215 ml min(-1)) as compared to bespoke passive samplers for mercury vapour (typically in excess of 50 ml min(-1)). The measured uptake rates were shown to vary significantly between tubes and this was attributed to the variability in the air-sorbent interface and the proportion of the cross sectional area removed by the crimp in the quartz tubes used to secure the sorbent material. As a result of this variability the uptake rate of each tube must be determined using the micro-exposure chamber prior to deployment. Results have shown that the uptake rate determined in the micro-exposure chamber is invariant of concentration, and therefore these uptakes rates may be determined at a high mercury vapour concentration for many tubes at once in less than one hour. The uptake rate of the adsorption tubes under these conditions may be determined with a precision of 5%. Measurements made on a limited field trial in indoor and outdoor ambient air have shown that these tubes give results in acceptable agreement with more traditional pumped sampling methods, although longer sampling periods are required in order to reduce the uncertainty of the measurement, which is currently approximately 30%.     

Attribution of aerosol light absorption to black carbon and volatile aerosols

We investigated the contribution of volatile aerosols in light-absorption measurement by three filter-based optical instruments [aethalometer, continuous light-absorption photometer (CLAP), and continuous soot monitoring system (COSMOS)] at Gosan Climate Observatory (GCO) from February to June 2012. The aerosol absorption coefficient (σ _abs) and the equivalent black carbon (BC) mass concentration (M _BC) measured by the aethalometer and CLAP showed good agreement with a difference of 9 %, which is likely due to the instrumental uncertainty. However, σ _abs and M _BC measured by the COSMOS with a heated inlet were found to be approximately 44 and 49 % lower than those measured by the aethalometer and CLAP under ambient conditions, respectively. This difference can be attributed to the light absorption by the volatile aerosols coexisting with the BC. Even considering inherent observational uncertainty, it suggests that approximately 35–40 % difference in the σ _abs and M _BC can be contributed by volatile aerosols. Increase in the difference of M _BC measured by the aethalometer and COSMOS with the increasing thermal organic carbon (OC) measured by Sunset OC/EC analyzer further suggests that the filter-based optical instruments without the use of a heater are likely to enhance the value of σ _abs and M _BC, because this sample air may contain both BC and volatile aerosols.     

Environmental quality of Korean coasts as determined by modified Shannon–Wiener evenness proportion

The coast of the Korean peninsula experiences a range of human impacts, including pollution, shipping, reclamation, and aquaculture, that have motivated numerous local studies of macrobenthic organisms. In this paper, 1,492 subtidal stations were compiled from 23 studies (areas) to evaluate environmental quality on a broader scale. A common index in biomonitoring, Shannon–Wiener evenness proportion (SEP), could not incorporate azoic or single-species samples. This shortcoming was overcome by developing an inverse function of SEP (ISEP), which was positively correlated with independent measures of water quality available for nine sites and was not biased by the size of the sampling unit. Additionally, at Shihwa Dike, where samples were collected before and after reinstating a tidal connection with the ocean, ISEP values improved over time, as expected. Thus, it is now possible to assign Korean subtidal sites to seven ISEP “grades” and to use their values and trends to guide coastal management.     

Indoor air quality assessment in child care and medical facilities in Korea

In order to characterize the status of indoor air pollution in some important facilities, a list of key criteria pollutants [particulate matter (PM(10)), carbon dioxide (CO(2)), carbon monoxide (CO), formaldehyde (HCHO), and bioaerosol] was measured from a total of 91 randomly selected sites in 18 different cities, Korea (February 2006 to December 2009). The target facilities include 43 child care facilities, 38 medical facilities, 6 elementary schools, and 4 postnatal care centers. The results showed that some air pollutants (e.g., CO and HCHO) did not exceed the recommended guideline [e.g., the Korean indoor air standard (KIAS) values of 10 ppm and 100 ppb, respectively]. However, concentration of PM(10), CO(2), and bioaerosol occasionally exceeded their respective guidelines (e.g., seven, three, and two cases). Discrete seasonalities were observed from indoor pollutants because of varying ventilation practice (e.g., summer time dominance of PM(10), HCHO, and bioaerosol or winter dominance of CO(2) and CO). However, as the concentrations of the indoor pollutants were scarcely above the recommended guideline level, more diversified approaches are desirable to diagnose the status of indoor pollution and to provide a realistic strategy for the improvement of IAQ.     

Use of continuous monitoring to assess stream nitrate flux and transformation patterns

Delivery of nitrogen from farmed fields to the stream network is an ongoing water quality issue in central North America and other parts of the world. Although fertilization and other farming practices have been refined to produce environmental improvements, stemming loss of nitrogen, especially in the soluble nitrate form, is a problem that has seemingly defied solution. The Iowa Nutrient Reduction Strategy is a policy initiative designed to implement conservation and other farm management practices to produce reductions in nitrate loading. The strategy does not focus on how the streams themselves may or may not be processing nitrogen and reducing downstream loading. We used continuous high-frequency nitrate and discharge monitoring over 3 years at two sites separated by 18 km in a low-order, agricultural stream in eastern Iowa to estimate how nitrogen is processed, and whether or not these processes are reducing downstream loading. We conclude that the upstream to downstream nitrate concentration decline between the two sites was not driven by denitrification. These data also show that nitrate concentrations are closely coupled to discharge during periods of adequate moisture, but decoupling of concentration from discharge occurs during dry periods. This decoupling is a possible indicator of in-stream nitrate processing. Finally, nitrate concentrations are likely diluted by water sourced from non-row crop land covers in the lower reaches of the watershed.     

Rapid in situ assessment for predicting soil quality using an algae-soaked disc seeding assay

The soil quality of remediated land is altered and this land consequently exerts unexpected biological effects on terrestrial organisms. Therefore, field evaluation of such land should be conducted using biological indicators. Algae are a promising new biological indicator since they are a food source for organisms in higher soil trophic levels and easily sampled from the soil. Field evaluation of soil characteristics is preferred to be testing in laboratory conditions because many biological effects cannot be duplicated during laboratory evaluations. Herein, we describe a convenient and rapid algae-soaked disc seeding assay for assessing soil quality in the field based on soil algae. The collection of algae is easy and rapid and the method predicts the short-term quality of contaminated, remediated, and amended farm and paddy soils. The algae-soaked disc seeding assay is yet to be extensively evaluated, and the method cannot be applied to loamy sand soil in in situ evaluations. The algae-soaked disc seeding assay is recommended for prediction of soil quality in in situ evaluations because it reflects all variations in the environment. The algae-soaked disc seeding assay will help to develop management strategies for in situ evaluation.     

Mussel watch program for organic contaminants along the Korean coast, 2001–2007

The level and extent of organic contaminants along the Korean coast were estimated through the mussel watch program, established in 2001. Mussels and oysters were collected at 20 sites along the Korean coast in 2001 and at 25 sites from 2002 to 2007. The mussel tissues were analyzed for PCBs, organochlorine presticides, PAHs, BTs, and PCDD/Fs. PCBs, PAHs, BTs, and PCDD/Fs were ubiquitous contaminants along the Korean coast, showing mean detection frequencies of more than 95% over 7 years. The concentrations of organic contaminants in mussels along the Korean coast were relatively low or moderate compared with foreign studies. Concentrations of DDTs, PCBs, and PCDD/Fs were below the action or maximum levels for humans established by USFDA and EU. Elevated concentrations above the 85th percentile were found for PCBs, PAHs, BTs, and PCDD/Fs at sites near industrial complexes or big harbors, for HCHs at sites near non-industrial complexes, and for DDTs at sites near both non-industrial and industrial complexes. Using two nonparametric tests to assess temporal trends, the Spearman test revealed that BTs and PCDD/Fs had significant decreasing trends at four sites (Gwangyang Bay, Cheonsu Bay, Garorym Bay, and the Incheon coast) and at six sites (Hupo coast, Guryongpo coast, eastern part of Geojedo, Gunsan coast, Garorym Bay, and Asan Bay), respectively.     

Analysis of spatial and seasonal distributions of MODIS aerosol optical properties and ground-based measurements of mass concentrations in the Yellow Sea region in 2009

Satellite-retrieved data on aerosol optical depth (AOD) and Ångström exponent (AE) using a moderate resolution imaging spectrometer (MODIS) were used to analyze large-scale distributions of atmospheric aerosols in East Asia. AOD was relatively high in March (0.44?±?0.25) and low in September (0.24?±?0.21) in the East Asian region in 2009. Sandstorms originating from the deserts and dry areas in northern China and Mongolia were transported on a massive scale during the springtime, thus contributing to the high AOD in East Asia. However, whereas PM10 with diameters ≤10 μm was the highest in February at Anmyon, Cheongwon, and Ulleung, located leeward about halfway through the Korean Peninsula, AOD rose to its highest in May. The growth of hygroscopic aerosols attendant on increases in relative humidity prior to the Asian monsoon season contributed to a high AOD level in May. AE typically appears at high levels (1.30?±?0.37) in August due to anthropogenic aerosols originating from the industrial areas in eastern China, while AOD stays low in summer due to the removal process caused by rainfall. The linear correlation coefficients of the MODIS AOD and ground-based mass concentrations of PM10 at Anmyon, Cheongwon, and Ulleung were measured at 0.4~0.6. Four cases (6 days) of mineral dustfall from sandstorms and six cases (12 days) of anthropogenically polluted particles were observed in the central area of the Korean Peninsula in 2009. PM10 mass concentrations increased at both Anmyon and Cheongwon in the cases of mineral dustfall and anthropogenically polluted particles. Cases of dustfall from sandstorms and anthropogenic polluted particles, with increasing PM10 mass concentrations, showed higher AOD values in the Yellow Sea region.     

Comparison of arsenic uptake ability of barnyard grass and rice species for arsenic phytoremediation

In this research, the relative performance in arsenic (As) remediation was evaluated among some barnyard grass and rice species under hydroponic conditions. To this end, four barnyard grass varieties and two rice species were selected and tested for their remediation potential of arsenic. The plants were grown for 2 weeks in As-rich solutions up to 10 mg As L^?1 to measure their tolerance to As and their uptake capabilities. Among the varieties of plants tested in all treatment types, BR-29 rice absorbed the highest amount of As in the root, while Nipponbare translocated the maximum amount of As in the shoot. Himetainubie barnyard grass produced the highest biomass, irrespective of the quantity of As in the solution. In all As-treated solutions, the maximum uptake of As was found in BR-29 followed by Choto shama and Himetainubie. In contrast, while the bioaccumulation factor was found to be the highest in Nipponbare followed by BR-29 and Himetainubie. The results suggest that both Choto shama and Himetainubie barnyard grass varieties should exhibit a great potential for As removal, while BR-29 and Nipponbare rice species are the best option for arsenic phytoremediation.