Heavy metal contamination of soils and crops from auto traffic,sewage sludge,pig manure and chemical fertilizer

The present paper describes heavy metal contamination of soils and crops resulting from auto traffic, sewage sludge, pig manure and chemical fertilizers, in three separate experiments.The first experiment revealed that although the ADDT (average annual daily traffic) value of the Agricultural Area was lower, higher concentrations of Cu, Cd, Zn, Pb and Mn were obtained in soil when compared with the Commercial-Residential Area. Contaminations of trace metals from various source, e.g., chemical fertilizer, animal manure, night soil and pesticides of the nearby agricultural land were suspected.The second experiment compared the effects of adding a commercial fertilizer and digested sludge which contain substantial amounts of various trace metals to a sandy loam for growing Chinese radish. The results indicated that repeated applications of the fertilizer elevated the contents of various trace metals in the roots of Chinese radish. The phenomenon was further aggravated when digested sludge was also incorporated.The third experiment compared the contents of trace metals in the root and leaf tissues of tree seedlings (Acacia confusa) added with a single dose of the trace metalenriched fertilizer, and different portions of pig manure compost. It was revealed that the fertilizer-treated tree seedlings had a higher content of trace metals in the tissues than those amended with manure compost. Although the metal contents of soil increased as more manure compost was added, the contents in plant tissues did not increase correspondingly.     

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs.     

Optimization of micro-aeration intensity in acidogenic reactor of a two-phase anaerobic digester treating food waste

Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35 °C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21–27% and 38–64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH₄/g VS_added in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO₂ respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste.     

Individual and combined toxic effects of cypermethrin and chlorpyrifos on earthworm

Toxicities were assessed for a pyrethroid (cypermethrin) and an organophosphate insecticide (chlorpyrifos) individually and in combination. A series of tests were conducted on di erent responses (acute, chronic, behavioral) of earthworms of species Eisenia fetida andrei in the ecological risk assessment of these pesticides. The results showed that the toxicity of the mixture of cypermethrin and chlorpyrifos was significantly higher than either of these pesticides individually, especially on the earthworm’s chronic responses. At a concentration of 5 mg/kg, the mixture caused significant reductions on the growth and reproduction rates of earthworms, but did not cause any significant e ect when the individual was tested. The increase in toxicity of the pesticide mixture means that the use of toxicity data obtained exclusively from single-pesticide experiments may underestimate the ecological risk of pesticides that actually present in the field.     

Zinc and cadmium accumulation and tolerance in populations of Sedum alfredii

To investigate the variation of Zn and Cd accumulation and tolerance of Sedum alfredii (a newly reported Zn/Cd hyperaccumulator), field surveys and hydroponic experiments were conducted among three populations of this species: two originating from old Pb/Zn mines in Zhejiang (ZJ) and Hunan (HN) Provinces and one from a "clean" site in Guangdong (GD) Province, China. Under field conditions, up to 12,524 and 12,253 mg kg(-1) Zn, and 1400 and 97 mg kg(-1) Cd in shoots of ZJ and HN plants were recorded respectively. Under hydroponic conditions, ZJ and HN plants accumulated significantly higher Zn and Cd in their leaves and stems, and possessed significantly higher Zn and Cd tolerance than GD plants. Among the two contaminated populations, ZJ plants showed higher Cd tolerance and accumulation (in leaves) than HN plants. The present results indicate that significant differences in Zn and Cd accumulation and tolerance exist in populations of S. alfredii.     

A 3D aerosol and visibility information system for urban areas using remote sensing and GIS

Currently, the depiction of urban air quality at boundary layer scale uses modelled climatic and land cover data. However, such models are difficult to verify, and only low to moderate accuracy may be achieved due to the complexity of the input data required and the reliance on assumptions about dispersion patterns. The provision of comprehensive air quality data to urban residents in city districts, at a level of detail commensurate with other Location-Based Services (LBS) which are time- and place-sensitive, has therefore not been possible. A method for urban air quality monitoring over cities at boundary layer scale, other than by the use of air quality models is presented here. The system presented uses empirical Aerosol Optical Thickness (AOT) data in near-real time, combining AOT data from AERONET with aerosol vertical profiles computed from twice-daily MODIS satellite images at 500 m resolution, to give three dimensional (3D) air quality data over the urban landscape. There has been no previous attempt to project the horizontal spatial distribution of aerosols from satellite image pixels into a vertical dimension to give a spatially comprehensive three dimensional record of air quality. The paper describes the sources and accuracy of the AOT data input to the system as well as its storage and retrieval on a Geographic Information System (GIS) platform, to provide air quality and visibility information according to user query at any 3D geographical location, including individual buildings or building floor.     

Mathematical models for accurate prediction of atmospheric visibility with particular reference to the seasonal and environmental patterns in Hong Kong

Atmospheric visibility impairment has gained increasing concern as it is associated with the existence of a number of aerosols as well as common air pollutants and produces unfavorable conditions for observation, dispersion, and transportation. This study analyzed the atmospheric visibility data measured in urban and suburban Hong Kong (two selected stations) with respect to time-matched mass concentrations of common air pollutants including nitrogen dioxide (NO(2)), nitrogen monoxide (NO), respirable suspended particulates (PM(10)), sulfur dioxide (SO(2)), carbon monoxide (CO), and meteorological parameters including air temperature, relative humidity, and wind speed. No significant difference in atmospheric visibility was reported between the two measurement locations (p > or = 0.6, t test); and good atmospheric visibility was observed more frequently in summer and autumn than in winter and spring (p < 0.01, t test). It was also found that atmospheric visibility increased with temperature but decreased with the concentrations of SO(2), CO, PM(10), NO, and NO(2). The results showed that atmospheric visibility was season dependent and would have significant correlations with temperature, the mass concentrations of PM(10) and NO(2), and the air pollution index API (correlation coefficients mid R: R mid R: > or = 0.7, p < or = 0.0001, t test). Mathematical expressions catering to the seasonal variations of atmospheric visibility were thus proposed. By comparison, the proposed visibility prediction models were more accurate than some existing regional models. In addition to improving visibility prediction accuracy, this study would be useful for understanding the context of low atmospheric visibility, exploring possible remedial measures, and evaluating the impact of air pollution and atmospheric visibility impairment in this region.     

Sludge-grown algae for culturing aquatic organisms: Part II. Sludge-grown algae as feeds for aquatic organisms

This project investigated the feasibility of using sewage sludge to culture microalgae (Chlorella-HKBU) and their subsequent usage as feeds for rearing different organisms. Part II of the project evaluated the results of applying the sludge-grown algae to feedOreochromis mossambicus (fish),Macrobrachium hainenese (shrimp), andMoina macrocopa (cladocera). In general, the yields of the cultivated organisms were unsatisfactory when they were fed the sludge-grown algae directly. The body weights ofO. mossambicus andM. macrocopa dropped 21% and 37%, respectively, although there was a slight increase (4.4%) inM. hainenese. However, when feeding the algal-fed cladocerans to fish and shrimp, the body weights of the fish and shrimp were increased 7% and 11% accordingly. Protein contents of the cultivated organisms were comparable to the control diet, although they contained a rather high amount of heavy metals. When comparing absolute heavy metal contents in the cultivated organisms, the following order was observed: alga > cladocera > shrimp, fish > sludge extracts. Bioelimination of heavy metals may account for the decreasing heavy metal concentrations in higher trophic organisms.     

Reclamation of wastes contaminated by copper,lead, and zinc

Waste materials containing toxic levels of copper, lead, and zinc, such as mine and smelter wastes, present difficult conditions for the establishment of vegetation. This article reviews the many attempts which have been made to reclaim these wastes. Inert wastes from mining and quarrying operations, such as slate quarry waste and certain colliery shales, seem to be good materials for reclaiming wastes contaminated by copper, lead, and zinc. Organic wastes, such as sewage sludge and domestic refuse, may provide only a temporary visual improvement and stabilization of the toxic materials.Nontolerant plant materials may often be planted directly on modern waste materials, which are less toxic than they were in the past. However, tolerant plant materials are needed for revegetating waste materials produced by early and more primitive extraction methods.     

HUMAN BEHAVIOR AND RESPONSE TOWARDS STORM HAZARD IN WEST VANCOUVER,BRITISH COLUMBIA1

ABSTRACT: Human behavior and response towards storm hazard are examined in this study. One-hundred and twenty flood victims in West Vancouver, British Columbia, were administered a sentence completion test to ascertain how these victims behaved and responded to the flash flood of July 12, 1972. The sentence completion test consisted of 11 sentence stems. Seven of these dealt with the respondent's behavior toward the storm experience, and four with the issue of internal vs. external locus of control. Completions of the seven sentence stems at three time situations showed that West Vancouverites expressed the normal reactions of fear and anxiety before the storm; showed negative emotions during the storm; and displayed a feeling of mutual cooperation after the storm. Completions of the remaining four sentence stems revealed that West Vancouverites emphasized the importance of internal factors, viz., autonomy, drive and hard work, in controlling their lives. They recognized God as a benevolent - protective and almighty - powerful figure. Forty percent of the respondents did not believe in luck, while 8 percent regarded it as important in their lives. One might conclude that West Vancouverites could cope with natural hazardous threats better than those who rely on external factors in directing their lives.