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The (239+240)Pu activities and (240)Pu/(239)Pu atom ratios in sediments of the northern South China Sea and its adjacent Pearl River Estuary were determined to examine the spatial and temporal variations of Pu inputs. We clarified that Pu in the study area is sourced from a combination of global fallout and close-in fallout from the Pacific Proving Grounds in the Marshall Islands where above-ground nuclear weapons testing was carried out during the period of 1952-1958. The latter source dominated the Pu input in the 1950s, as evidenced by elevated (240)Pu/(239)Pu atom ratios (>0.30) in a dated sediment core. Even after the 1950s, the Pacific Proving Grounds was still a dominant Pu source due to continuous transport of remobilized Pu from the Marshall Islands, about 4500 km away, along the North Equatorial Current followed by the transport of the Kuroshio current and its extension into the South China Sea through the Luzon Strait. Using a simple two end-member mixing model, we have quantified the contributions of Pu from the Pacific Proving Grounds to the northern South China Sea shelf and the Pearl River Estuary are 68% ± 1% and 30% ± 5%, respectively. This study also confirmed that there were no clear signals of Pu from the Fukushima Daiichi Nuclear Power Plant accident impacting the South China Sea.

Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal.

Escherichia coli producing the highly virulent, multidrug-resistant, CTX-M-15 extended-spectrum ␤-lactamase (ESBL), sequence type 131 (ST131), has emerged on three continents since the late 2000s. We described the molecular epidemiology, clinical features, and outcome of ESBL-producing E. coli bacteremia in Taiwan Independent risk factors predicting mortality at day 28 included malignancy, shock, and hospital-acquired bacteremia. In ESBLproducing E. coli bloodstream infections, the ST131 clone was not associated with health-care-associated risk factors, such as urinary catheter use or antibiotic exposure. Although highly virulent and multidrug resistant, the ST131 clone was not associated with higher mortality than non-ST131 clones. Between 2000 and 2006, Escherichia coli clone O25:H4-ST131, which produces CTX-M-15 extended-spectrum ␤-lactamase (ESBL), was identified on three continents and later found to be widespread in Europe, Australia, and the United States of America (6,11,13,17,19,22,24). The sequence type 131 (ST131) strain was associated with high, homogenous, extraintestinal virulence and multidrug resistance (6,11,13,17,19,22,24). Virulence gene analysis indicated that clone ST131 strains were more likely than non-ST131 strains to possess traT, iutA, iha, ompT, fimH, malX, fyuA, kpsM, or sat genes (6, 11, 13, 17, 19, 22, 24). Pulsotype analysis revealed that CTX-M-15 ST131 clones were usually approximately 85% similar (6,11,13,17,19,22,24).According to the published literature, most ST131 clones have been identified as a result of urine culture surveillance, and a few have been isolated from individuals with bacteremia. ST131 clones have been observed in the community, hospitals, and nursing homes (6,11,13,17,19,22,24) as well as in companion animals and poultry (23). In a French study, ST131 isolates were found in 7% of fecal E. coli isolates from independent healthy subjects and were unaccompanied by the CTX-M enzyme (14). However, several case reports have shown that ST131 clones can present in cases of severe infection, such as pyomyositis, emphysematous pyelonephritis, and other life-threatening infections (10,18,28). Only two cohorts with ST131 ESBL E. coli bacteremia have been reported in the literature. In these two ESBL E. coli bacteremia series, ST131 was found in 34% of isolates in the Netherlands (27) and 31.3% of isolates in Calgary, Canada (21). In Calgary's ESBL E. coli bacteremia cohort (21), ST131 isolates producing CTX-M-15 became predominant from 2005 to 2007 and were associated with community-onset infection and urosepsis. However, the detailed demographic features, clinical syndromes, and outcomes in these two cohorts of patients with ESBL E. coli bacteremia in clone ST131 are lacking. In previous risk factor analyses, ESBL E. coli infection was more closely associated with antibiotic use, comorbidity, and urinary catheter use than non-ESBL E. coli infection (2, 9, 15). We did not know whether ST131 clones were associated with the same risk factors as previous traditional ESBL E...

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[1] During a spring intermonsoon cruise in 2004, depth profiles of total and particulate 234 Th in the upper 100 m were collected at 36 stations in the southern South China Sea (SCS), covering a surface area of $1.0 Â 10 6 km 2 . Thorium-234 was sampled by using a modified small-volume MnO 2 co-precipitation technique, which allows mapping the 234 Th distribution with a high spatial resolution. A stratified structure of 234 Th/ 238 U disequilibria was generally observed in the upper 100 m water column, suggesting that the euphotic zone of the southern SCS in this season can be separated into two layers: an upper layer with low export production rates and a lower layer with high export production rates. At the same time, we observed extensive zones of 234 Th excess within the euphotic layer, which is possibly due to intense remineralization of particulate matter. Particulate organic carbon (POC) export was estimated from a three-dimensional steady state model of Th ratio on suspended particles. The POC export for this region varied from a low of À10.7 ± 1.5 mmolC m À2 d À1 to a high of 12.6 ± 1.1 mmolC m À2 d À1 , with an average of 3.8 ± 4.0 mmolC m À2 d À1 . A negative flux of POC export is interpreted as the result of lateral input of particulate matter from nearby waters. Regional patterns in POC export show enhanced fluxes along the western and southern boundaries of the study region, and a ''tongue'' of low export extending northwestward from $7°N 116°E to $10°N 111°E. This geographic distribution is consistent with the overall surface circulation pattern of the southern SCS in this season.

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