The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels

The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species.     

Formation of chlorinated phenols, dibenzo-p-dioxins, dibenzofurans, benzenes, benzoquinnones and perchloroethylenes from phenols in oxidative and copper (II) chloride-catalyzed thermal process

Formation of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and chlorinated phenols on CuCl(2) from unsubstituted phenol and three monochlorophenols was studied in a flow reactor over a temperature range of 100-425 degrees C. Heated nitrogen gas streams containing 8.0% oxygen were used as carrier gas. The 0.00024mol of unsubstituted phenol and 0.00039mol of each monochlorophenol were passed through a 1g and 1cm SiO(2) particle containing 0.5% (Cu by mass) CuCl(2). Chlorination preferentially occurred on ortho-(2, 6) and para-(4) positions. Chlorination increased up to 200 degrees C, and thereafter decreased as temperature increased. Chlorination of phenols plays an important role in the formation of the more chlorinated PCDD/Fs. Chlorinated benzenes are formed possibly from both chlorination of benzene and chlorodehydroxylation of phenols. Chlorinated phenols with ortho chlorine formed PCDD products, and major PCDD products were produced via loss of one chlorine. For PCDF formation, at least one unchlorinated ortho carbon was required.     

Ecological effects of imidacloprid on arthropod communities in and around a vegetable crop

To elucidate the ecological impacts of imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] on vegetable crops and their surrounding areas, arthropods on eggplant patches treated with this insecticide were monitored throughout two cultivation seasons, spring and autumn, and the results compared with those of control crops. Residues of imidacloprid in soil accounted for 4-8% of total applied, and concentrations outside the crop were always below 5 micro g/kg. Communities of the crop vegetation experienced significant density reductions, mostly of aphids, and had fewer species diversity during the first month. Those in the surrounding pasture were similarly affected though with less intensity, while non-target ground arthropods both inside and outside the crop only showed significant impacts in the two weeks after planting.     

Effects of driving conditions on diesel exhaust particulates

Four driving conditions were examined to characterize how speeds and loads of a medium-duty diesel engine affect resultant diesel exhaust particulates (DEPs) in terms of number concentrations (< or =400 nm), size distribution, persistent free radicals, elemental carbon (EC), and organic carbon (OC). At the medium engine load (60%), DEPs surged in number concentrations at around 40-70 nm, whereas DEPs from the full engine load (100%) showed a distinctive bimodal distribution with a large population of 30-50 nm and 100-400 nm. Under the full engine load, engine speeds insignificantly affected resultant DEP number concentrations. When the engine load decreased from 100% to the medium level (60%), DEPs of ultrafine size and 100-400 nm decreased at least 1.4 times (from 5.6 x 10(8) to 4 x 10(8) #/cm3) and more than 3 times (from 2.7 x 10(8) to 0.8 x 10(8) #/cm3), respectively. The same reduction in the engine load significantly decreased persistent free radicals in DEPs up to approximately 30 times (from 123 x 10(16) to 4 x 10(16) #spin/g). Decreasing the engine load from 100 to 60% also concurrently reduced both EC and OC in total DEPs around 2 times, from 27.3 to 13.9 mg/m3, and from 17.6 to 9.2 mg/m3, respectively. For DEPs smaller than 1 microm, under the full engine load, EC and OC consistently peaked at 170-330 nm under an engine speed of 1800 rpm or 94-170 nm under an engine speed of 3000 rpm, reflecting processes of nucleation, cluster-cluster agglomeration, and condensation. Decreasing the engine load from 100 to 60% reduced EC and OC in DEPs (smaller than 1 microm) at least 3 times (0.6 to 0.2 mg/m3) and 2 times (0.4 to 0.2 mg/m3), respectively. Taken together, decreasing the full engine load to a medium (60%) level effectively reduced the number concentrations (< or =400 nm), persistent free radicals, EC, and OC of total DEPs, as well as the concentration of EC and OC in ultrafine and accumulation-mode DEPs.     

Characterization of fuel gas products from the treatment of solid waste streams with a plasma arc torch

This work addresses the plasma treatment of two solid waste streams and production of fuel gases from the process. In this study, carpet waste and simulated solid wastes generated by a United States Air Force Basic Expeditionary Airfield Resources Base deployment were used. Waste was treated in a furnace fitted with a 100kW plasma arc torch. The off gas was analyzed to determine its composition. The product gas was composed primarily of carbon monoxide and hydrogen, with small amounts of methane, benzene and toluene also detected. These experiments demonstrate the feasibility of producing fuel gases by plasma treatment of the solid waste streams. While the thermal energy value of the fuel gas produced in these experiments was less than the energy input, a higher waste-to-fuel gas conversion efficiency is expected in full-scale application.     

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n?=?5,682, 18–96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 μg/L (95 % CI?=?1.57–1.62 μg/L) and 2.87 μg/dL (95 % CI?=?2.84–2.90 μg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n?=?3,165, BCL?=?1.87 μg/L, BLL?=?2.91 μg/dL) compared to people living more than 2 km away (n?=?2,517, BCL?=?1.31 μg/L, BLL?=?2.82 μg/dL; P?<?0.0001) and to the general population values reported in the literature.