Plant-accelerated dissipation of phenanthrene and pyrene from water in the presence of a nonionic-surfactant

Plant-accelerated dissipation of phenanthrene and pyrene in water in the presence of a nonionic-surfactant (Brij35) was studied. The mechanisms involved were evaluated, based on the investigation of plant uptake of these compounds from water with Brij35. The presence of ryegrass (Lolium multiflorum Lam) clearly enhanced the dissipation of tested PAHs in water with 0-296 mg l(-1) Brij35. The first-order rate constants (K), calculated from the first-order kinetic models for these PAH degradation (all significant at P < 0.05, n=8), of phenanthrene and pyrene in the presence of ryegrass were 16.7-50% and 47.1-108% larger than those of plant-free treatments, whereas half-lives (T1/2) of the former were 14.3-33.4% and 32.0-52.0% smaller than the latter, respectively. However, the promotion of PAH dissipation by ryegrass was found to significantly decrease with increasing Brij35 concentrations. In the range of 0-296 mg l(-1), low concentrations (< or = 74.0 mg l(-1)) of Brij35 generally enhanced plant uptake and accumulation of phenanthrene and pyrene, based on the observed plant concentrations and accumulated amounts of these chemicals from water. In contrast, Brij35 at relatively high concentrations (> or = 148 mg l(-1)) markedly restricted plant uptake of these PAHs. Plant accumulation of phenanthrene and pyrene accounted for 6.21-35.0% and 7.66-24.3% of the dissipation enhancement of these compounds from planted versus unplanted water bodies. In addition, plant metabolism was speculated to be another major mechanism of plant-accelerated dissipation of these PAHs in water systems. Results obtained from this study provided some insight with regard to the feasibility of phytoremediation for PAH contaminated water bodies with coexisted contaminants of surfactants.     

The study of metal contamination in urban soils of Hong Kong using a GIS-based approach

The study of regional variations and the anthropogenic contamination by metals of soils is very important for environmental planning and monitoring in urban areas. An extensive survey was conducted in the highly urbanized Kowloon area (46.9 km(2)) of Hong Kong, using a systematic sampling strategy with a sampling density of 3-5 composite soil samples (0-15 cm) per km(2). Geochemical maps of 'total' metals (Cd, Cr, Cu, Ni, Pb and Zn) from strong acid extraction in the surface soils were produced based on geographical information system (GIS) technology. A significant spatial relationship was found for Ni, Cu, Pb and Zn in the soils using a GIS-based analysis, suggesting that these metal contaminants in the soils of the Kowloon area had common sources. Several hot-spot areas of metal contamination were identified from the composite metal geochemical map, mainly in the old industrial and residential areas. A further GIS analysis revealed that road junctions, major roads and industrial buildings were possible sources of heavy metals in the urban soils. The Pb isotope composition of the contaminated soils showed clear anthropogenic origins.     

Bioleaching of heavy metals from anaerobically digested sewage sludge using FeS2 as an energy source

The effect of using FeS2 as an energy source, on the bioleaching of heavy metals (Zn, Cr, Cu, Pb and Ni) and nutrients (nitrogen and phosphorus) from anaerobically digested sludge using isolated indigenous iron-oxidizing bacteria was investigated in this paper. Addition of FeS2 in the range of 0.5-4.0 g l(-1) accelerated the acidification of sludge and raised the oxidation-reduction potential of sludge medium with an inoculation of 15% (v/v) of active bacteria, thus resulting in an overall increase in metal dissolution efficiency. After 16 days of bioleaching at 28 degrees C and an initial pH of 3.0, up to 99% of Zn, 65% of Cr, 74% of Cu, 58% of Pb and 84% of Ni can be removed from the sludge. In contrast, only 94% of Zn, 12% of Cr, 21% of Cu, 32% of Pb and 38% of Ni were leached out in the control without inoculation of iron-oxidizing bacteria and the addition of FeS2. Less than 15% of nitrogen and 6% of phosphorous were lost after 16 days of bioleaching when using FeS2 as the energy source. Comparing to 39% and 45% loss respectively for these two nutrients when using FeSO4.7H2O as the energy source, FeS2 appears to be a more suitable energy source for preserving nutrients in sludge while removing heavy metals from sludge.     

The amplification refractory mutation system (ARMS): A rapid and direct prenatal diagnostic technique for β-thalassaemia in Singapore

β-Thalassaemia major patients have chronic anaemia and since 3–4 per cent of Singaporeans carry the β-gene, prenatal diagnosis is essential. We evaluated the amplification refractory mutation system (ARMS) technique as a routine test for prenatal diagnosis of β-major. Six mutations along the β-gene were studied—41–42 (-TCTT), IVSII #654 (C-T), 17β (A-T), – 28 TATA (A-G), IVSI #5 (G-C), and IVSI #1 (G-T). Our results indicate that prenatal diagnosis using these mutations can be offered to 90 per cent (35/39) of our Chinese couples and 54·6 per cent (12/22) of our Malay couples at risk. Confirmation of ARMS results was carried out using allele-specific oligonucleotide hybridization. Prenatal diagnosis using ARMS was successfully carried out in nine cases which included a set of triplets and twins. The triplets were diagnosed with the β-trait carrying the 41–42 mutation. The couple with twins possessed the #654 mutation and one twin was diagnosed with the β-trait and the other with #654 homozygosity. Genomic sequencing of the undefined mutations in the Chinese couples revealed rarer mutations at − 29 and an ATG-AGG base substitution at the initiation codon for translation. In the Malay couples, genomic sequencing detected mutations at codon 15 (TGG-TAG) and codon 26 (GAG-AAG). We conclude that ARMS with its direct detection of amplified products by gel electrophoresis provides an accurate, rapid, and simpler method for our β-thalassaemia prenatal diagnosis programme in Singapore.     

Aluminium and fluoride concentrations of three tea varieties growing at Lantau Island,Hong Kong

The present project aims to investigate aluminium (Al) and fluoride (F) contents in teas (Camellia sinensis (L.) O. Kuntze). Three different commercial tea varieties: Assam variety and two China sub-varieties, a large leafed variety and small leafed variety, were collected in two tea gardens of Lantau Island tea plantation of Hong Kong. In general, high concentrations of Al and F were accumulated in the mature leaves (15.3 and of 2.07 g kg^–1 respectively). Among the three varieties, the small leafed variety exhibited the highest Al and F contents followed by the large leafed variety whereas the Assam variety had the lowest Al and F concentrations in its tea bushes. Tea products from a plantation were also analysed and it was noted that black tea had higher Al and F concentrations than green tea. The amount of Al and F released into tea liquor was also tested and the results showed that higher concentrations of Al and F were released into tea liquor under repeated infusion method than continuous infusion method.     

渗滤湿地系统的工艺设计

本研究是以占地6公顷,日处理污水1400m~3的渗滤型芦苇湿地实验工程为依托,采用静态模拟与工程运转相结合的方法,着重对污水湿地处理系统BOD_5的生物降解模型进行研究,建立了确定Q值和K_T值的方法,提出了适于天津渗滤湿地系统的Q值和K_T值,为湿地系统设计提供了重要的科学依据.     

东南亚沿海生态旅游的趋势

当地居民的生活需求、保护生物多样性的必要性和娱乐旅游使得东南亚海岸资源压力不断增 加 .在这种情况下 , 沿海生态旅游会扮演越来越重要的角色 .这篇文章考察了泰国、菲律宾、 印度尼西亚、马来西亚和越南的沿海生态旅游的开发 .     

东南亚沿海生态旅游的趋势

当地居民的生活需求、保护生物多样性的必要性和娱乐旅游使得东南亚海岸资源压力不断增 加 .在这种情况下 , 沿海生态旅游会扮演越来越重要的角色 .这篇文章考察了泰国、菲律宾、 印度尼西亚、马来西亚和越南的沿海生态旅游的开发 .     

Degradation of azo dye Procion Red MX-5B by photocatalytic oxidation

The photocatalytic oxidation (PCO) of a monoazo dye Procion Red MX-5B under various physico-chemical conditions was investigated. Degradation of the dye by PCO was enhanced by augmentation in UV intensity, titanium dioxide and hydrogen peroxide concentrations but was inhibited by increase in initial dye concentration. The PCO process was affected by pH in a peculiar way. In the presence of 100 mg/l of TiO2 and the absence of H2O2, the highest reaction rate was observed when the initial pH was 10. With 500 mg/l of TiO2 and 10 mM of H2O2, the reaction was the fastest at initial pH of 3-5. The optimal conditions for the degradation of the dye, at an UV intensity of 17 mW/cm2, were determined to be: TiO2 concentration, 500 mg/l; initial H2O2 concentration, 10 mM; initial pH, 5.0. Monitoring of TOC loss showed that the dye was mineralized by 90% within 80 min under these conditions. Nevertheless, the persistence of a low level of TOC indicated that mineralization was not complete and dead-end product(s) which was (were) resistant to PCO might have accumulated.     

Soil and plant characteristics of landfill sites near Merseyside,England

An ecological survey of the plant and soil characteristics was carried out on three landfill sites near Merseyside, England. It was discovered that bare ground at two of the landfill areas had high levels of methane contained in the soil air (Sefton Meadows landfill: 6–8% at 35 cm and 16–35% at 65 cm below soil surface; Coalgate Lane landfill: 1–24% at 35 cm and 39–45% at 40 cm below soils surface), causing the appearance of dark grey reduced regions in the soil, a phenomenon similar to flooded soil. The wellvegetated areas at the two sites had lower levels of methane (under 7%).In areas relatively free of methane, the concentrations of mineralized N and NO₃ ^– had significant correlations with the dry weights of vegetation (r = 0.71 withp<0.01;r=0.61 withp<0.02 accordingly), indicating the necessity of applying available nitrogen fertilizer.