The distribution of molybdenum in the tissues of wild ducks

The Mo contents and the relations between Mo and Cu or Crcontents were investigated in the organs of Japanese wild ducks(spotbill duck, pintail, wigeon, scaup and tufted duck). Thehighest Mo content in kidney and liver of the dabbling duckswere more than 30 g g^-1 dry weight (g g^-1 d.wt.), though that of diving ducks were less than 11 gg^-1 d. wt. The contents were lower in the ducks migratingwithin Japan, Eurasia and North America than those in the birdsmigrating between Japan and Eurasia. The contents of liver inall species were more than 50 and less than 5 g g^-1 d.wt. for Cu and Cr, respectively. Significant correlations werefound between Mo and both elements in pintail and scaup, and Moand Cr in tufted duck. These results suggest that thecontamination of wild ducks reflects the reproductive area, andnot the collected area. Mo contents closely correlated with theCu and/or Cr contaminations.     

北京市汽车行驶工况和污染物排放系数调查研究

利用先进的技术和设备调查了北京市不同道路上的汽车行驶状况,基于这些调查数据进行了不同道路的汽车行驶工况解析,分别确定了用于北京市汽车排放污染物测定的一般道路行驶工况,快速路行驶工况,高速路行驶工况,城区综合道路行驶工况和综合道路行驶速度特征工况。     

Relationship between the riverine nitrate–nitrogen concentration and the land use in the Teshio River watershed, North Japan

The present research investigated the relationship between nitrate–nitrogen (NO₃–N) in river water and the land use/land cover (hereafter, land use) in the Teshio River watershed located in northern Hokkaido island to understand the effect of human activities such as agriculture, forestry, industry, and urbanization in the drainage basin on the river ecosystem quality and services. River water was sampled at nine points seasonally during a 2-year period and the nutrients concentration was measured. Land use profiles were estimated at two spatial scales, riparian and sub-catchment, for each sampling station. The spatial pattern of water quality in the Teshio River showed increased NO₃–N levels associated with agriculture and urban expansion, and forest reduction in the watershed. Land use at the riparian scale closely reflected that at the sub-catchment scale, which masked the unique riparian buffer effect on the river water condition. The increased agricultural and reduced forest area in the riparian zone, especially in the upper middle reach, could be a possible reason for a decline of ecosystem service for the provisioning of clean water and habitat for aquatic organisms. Measures towards sustainable and more nature-friendly agricultural management are necessary in the area to protect the Teshio River ecosystem and its ecosystem services.     

Abundance versus presence/absence data for modelling fish habitat preference with a genetic Takagi–Sugeno fuzzy system

This study compared the accuracy of fuzzy habitat preference models (FHPMs) and habitat preference curves (HPCs) obtained from the FHPMs in order to assess the effect of two types of data [log-transformed fish population density (LOG) and presence-absence (P/A) data] on the habitat preference evaluation of Japanese medaka (Oryzias latipes). Three independent data sets were prepared for each type of data. The results differed according to the data sets and the types of data used. The HPCs showed a similar trend, whilst the degrees of preference were different. The model accuracy also differed according to the data sets used. Although almost no statistical difference was observed, on average, the P/A-based models showed a better performance according to the threshold-independent performance measures, whilst the LOG-based models showed better performance in predicting absence of the fish. These results can be explained partly from the different shapes of HPCs. This case study of Japanese medaka demonstrated the effect of different types of data on habitat preference evaluation. Further studies should build on the present finding and evaluate the effects of data characteristics such as the size of data sets and the prevalence for better understanding and reliable assessment of the habitat for target species.     

Assessing the impact of the Japanese 2005 World Exposition Project on vascular plants' risk of extinction

The Red Data Book of Japanese Vascular Plants is based on their risk of extinction. In order to construct the list, 2000 taxa were evaluated using population data and rates of decline for approximately 4400 grids, each of approximately 100 km(2). This database can be used to estimate the impact of human activity on a threatened plant's risk of extinction. In order to evaluate extinction risks and apply the evaluation to conservation actions, the discount mean time to extinction is defined as a measure of extinction risk, where the present value of a species' persistence in the future decreases exponentially. The rate of decrease has to be much less than the rate of economic discounting, in order to realize intergenerational sustainability. Increases of the inverse, and logarithm, of the discount mean time to extinction are considered measures of the extinction risk. We applied these measures to an environmental impact assessment for the Japanese World Exposition that is to be held in 2005. Development will have a greater impact on threatened Salvia species than it will on star magnolia, Magnolia tomentosa, which has been conserved by changing the site plan.     

Interannual, seasonal, local and body size variations in reproduction of the prawn Penaeus (Marsupenaeus) japonicus (Crustacea: Decapoda: Penaeidae) in the Ariake Sea and Tachibana Bay, Japan

 The reproductive biology of female Penaeus japonicus Bate was investigated in the Ariake Sea and Tachibana Bay (located outside the Ariake Sea), Japan from 1994 to 1996. Interannual, seasonal, individual female body size and spatial influences on the incidence of spawning were examined. The proportion of inseminated females, increased with increasing body size up to 170 mm body length (BL) and decreased thereafter. The minimum size at maturity was similar between years; 130 to 140 mm BL. The minimum size of individuals with developing ovaries or spermatophores differed from that of ripe females by 20 to 25 mm. Spawning occurred in the central part of the Ariake Sea and Tachibana Bay but rarely in the inner part. P. japonicus had a clear reproductive cycle. Spawning started earlier and ended later, occurring from mid-May to mid-October, in the eastern central part of and outside of the Ariake Sea compared with the western central part, where spawning occurred from mid-June to mid-September. Spawning dynamics differed across seasons, body sizes and areas but not across years. The seasonal peak in the proportion of ripe females varied with body size. In small individuals (130 to 169 mm BL), no peak was observed, whereas in large individuals (>170 mm BL) the proportion of ripe individuals peaked in June. The proportion of ripe individuals increased with increasing body size and was high outside the Ariake Sea. Factors causing the variation in spawning dynamics are discussed. Received: 30 November 1998 / Accepted: 12 October 1999     

Human intake of PCDDs, PCDFs, and dioxin like PCBs in Japan, 2001 and 2002

PCDDs, PCDFs, and dioxin like PCBs (dioxin) surveillance results derived from regular environmental monitoring as well as other dioxin surveys by national and local governmental bodies in Japan were collected and analyzed. Several thousand data for air and soil in fiscal year 2001 (from 01/04/2001 to 31/03/2002) and 2002, water (from the sea, rivers and lakes), sediment (from the sea, rivers and lakes), ground water, aquatic organisms, purified water from water purification plants, raw water from water purification plants, human breast milk, and human blood in fiscal 2001, and total diet study (TDS) and various kinds of foodstuff in fiscal 1998-2002 were collected. Average human uptake of dioxin in Japan in fiscal 2001 was estimated at 1.68 pg-TEQ/kg-bw/day, while uptake in fiscal 2002 was estimated at 1.52 pg-TEQ/kg-bw/day. Diet accounted for more than 90% of the total intake. Contributions of inhalation and soil ingestion were relatively small. Age-group-specific contribution of various foodstuff to total dietary intake was also estimated. The estimates of intake through fish and shellfish accounted for approximately 45-70% of total dietary intake in each age group. Monte Carlo simulation was conducted, using the data of the air and soil concentrations in fiscal 2001 and the total diet study data in fiscal 1998-2001, in order to obtain information on the variability of dioxin intake; The estimated average, median, 5th percentile and 95th percentile of the intake distribution were 1.78, 1.69, 0.95 and 2.91 pg-TEQ/kg-bw/day, respectively. This study found that the average total intake estimates in Japan in both fiscal 2001 and 2002 were estimated to be below tolerable daily intake level (TDI) defined by the Ministry of Health, Labour and Welfare, Japan (i.e. 4 pg-TEQ/kg-bw/day). The 95th percentile of the dioxin intake distributions estimated with Monte Carlo simulation using the data of the air and soil concentrations in fiscal 2001 and TDS data in fiscal 1998-2001 was also below the Japanese TDI.     

Plutonium isotopes concentration in seawater and bottom sediment off the Pacific coast of Aomori sea area during 1991-2005

A radioactivity survey was launched in 1991 to determine the background levels of ^239+240Pu in the marine environment off a commercial spent nuclear fuel reprocessing plant before full operation of the facility. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratio in seawater and bottom sediment to identify the origins of Pu isotopes. The concentration of ^239+240Pu was almost uniform in surface water, decreasing slowly over time. Conversely, the ^239+240Pu concentration varied markedly in the bottom water and was dependent upon the sampling point, with higher concentrations of ^239+240Pu observed in the bottom water sample at sampling points having greater depth. The ²⁴⁰Pu/²³⁹Pu atom ratio in the seawater and sediment samples was higher than that of global fallout Pu, and comparable with the data in the other sea area around Japan which has likely been affected by close-in fallout Pu originating from the Pacific Proving Grounds. The ²⁴⁰Pu/²³⁹Pu atom ratio in bottom sediment samples decreased with sea depth. The land-originated Pu is not considered as the reason of the increasing ^239+240Pu concentration and also decreasing the ²⁴⁰Pu/²³⁹Pu atom ratio with sea depth, and further study is required to clarify it.