Compositions and source apportionments of atmospheric aerosol during Asian dust storm and local pollution in central Taiwan

A study has been carried out on water soluble ions, trace elements, as well as PM_2.5 and PM_2.5–10 elemental and organic carbon samples collected daily from Central Taiwan over a one year period in 2005. A source apportionment study was performed, employing a Gaussian trajectory transfer coefficient model (GTx) to the results from 141 sets of PM_2.5 and PM_2.5–10 samples. Two different types of PM₁₀ episodes, local pollution (LOP) and Asian dust storm (ADS) were observed in this study. The results revealed that relative high concentrations of secondary aerosols (NO₃⁻, SO₄²⁻ and NH₄⁺) and the elements Cu, Zn, Cd, Pb and As were observed in PM_2.5 during LOP periods. However, sea salt species (Na⁺ and Cl⁻) and crustal elements (e.g., Al, Fe, Mg, K, Ca and Ti) of PM_2.5–10 showed a sharp increase during ADS periods. Anthropogenic source metals, Cu, Zn, Cd, Pb and As, as well as coarse nitrate also increased with ADS episodes. Moreover, reconstruction of aerosol compositions revealed that soil of PM_2.5–10 elevated approximately 12–14% in ADS periods than LOP and Clear periods. A significantly high ratio of non-sea salt sulfate to elemental carbon (NSS-SO₄²⁻/EC) of PM_2.5–10 during ADS periods was associated with higher concentrations of non-sea-salt sulfates from the industrial regions of China. Source apportionment analysis showed that 39% of PM₁₀, 25% of PM_2.5, 50% of PM_2.5–10, 42% of sulfate and 30% of nitrate were attributable to the long range transport during ADS periods, respectively.     

Integrated application of the analytic hierarchy process and the geographic information system for flood risk assessment and flood plain management in Taiwan

Flooding is one of the major natural hazards in Taiwan, and most of the low-lying areas in Taiwan are flood-prone areas. In order to minimize loss of life and economic losses, a detailed and comprehensive decision-making tool is necessary for both flood control planning and emergency service operations. The objectives of this research were (i) to develop a hierarchical structure through the analytic hierarchy process (AHP) to provide preferred options for flood risk analysis, (ii) to map the relative flood risk using the geographic information system (GIS), and (iii) to integrate these two methodologies and apply them to one urban and one semi-rural area in central Taiwan. Fushin Township and the floodplain of Fazih River (1 km on either side of the channel) in Taichung City were selected for this study. In this paper, the flood risk is defined as the relative flood risk due to broken dikes or the failure of stormwater drainage systems. Seven factors were considered in relation to the failure of stormwater drainage, and five to that of broken dikes. Following well-defined procedures, flood maps were drawn based on the data collected from expert responses to a questionnaire, the field survey, satellite images, and documents from flood management agencies. The relative values of flood risk are presented using a 200-m grid for the two study areas. It is concluded that integration of AHP and GIS in flood risk assessment can provide useful detailed information for flood risk management, and the method can be easily applied to most areas in Taiwan where required data sets are readily available.     

Impact assessment of climatic and land-use changes on flood runoff in southeast Queensland

Abstract

Over the past century, land-use has changed in southeast Queensland, and when coupled with climatic change, the risk of flooding has increased. This research aims to examine impacts of climate and land-use changes on flood runoff in southeast Queensland, Australia. A rainfall–runoff model, RORB, was calibrated and validated using observed flood hydrographs for one rural and one urbanized catchment, for 1961–1990. The validated model was then used to generate flood hydrographs using projected rainfall based on two climate models: the Geophysical Fluid Dynamics Laboratory Climate Model 2.1 (GFDL CM2.1) and the Conformal-Cubic Atmospheric Model (CCAM), for 2016–2045. Projected daily rainfall for the two contrasting periods was used to derive adjustment factors for a given frequency of occurrence. Two land-use change scenarios were used to evaluate likely impacts. Based on the projected rainfall, the results showed that, in both catchments, future flood magnitudes are unlikely to increase for large flood events. Extreme land-use change would significantly impact flooding in the rural catchment, but not the urbanized catchment.

Editor Z.W. Kundzewicz; Associate editor Y. Gyasi-Agyei     

Location model analysis of flood relief facilities: a case study of the Fazih River floodplain,Taiwan

The continuously low efficiencies of flood relief service in responding to flooding disasters in Taiwan highlight a need for research. This service efficiency is negatively influenced by flood relief facility locations and their operational management structure. The Fazih River floodplain has been previously identified as a high-flood-risk area using an analytic hierarchy process. The purpose of this study is to use the location set covering problem and the maximal covering location problem to determine the number of relief facilities required and the maximum covering area of each facility for the case study area of the Fazih River floodplain. The findings showed that covering distances range from 3.0 to 6.6 km and the number of facilities required for improved service efficiency is between 1 and 4.

     

几种石油烃对斑马鱼的急性毒性效应研究

以斑马鱼(Brachydanio rerio)为受试生物,采用半静态实验法,考察了苯、甲苯、萘、菲和原油的水生生态毒性效应。研究表明,苯、甲苯、萘、菲和原油对斑马鱼的96h半致死浓度(Half lethal concentration,LC50)分别为49.24、75.17、33.95、36.71和59.71mg·L-1。根据鱼类毒性分级标准,5种试剂均属于中毒物质,毒性大小顺序为萘菲苯原油甲苯。在试验过程中中毒个体均出现身体失衡,无序游动,侧游仰游等症状。经过进一步的毒性机理分析得出,各物质的组成和分子结构不同,导致其在生物体内的转运和转化过程不尽相同,毒性大小各异。