The symposium was held September 12, 2002 with 7 domestic speakers and about 182 participants in the NIAES conference hall.

Persistent organic pollutants (POPs) are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife. POPs circulate globally and can cause damage wherever they travel. The Stockholm Convention is a global treaty to protect human health and the environment from POPs.

In this symposium, seven domestic speakers briefly introduced the current status of environmental pollution by POPs to the participants. The participants also discussed with the speakers about how to prevent the pollution. Topics presented were as follows: 1) Ratification process of the Stockholm Convention by the Japanese government (K. Sawada, Pesticide Office, MAFF), 2) Dynamics of dioxins in agricultural lands (H. Eun, NIAES), 3) Ecotoxicology of organochlorine contaminants to amphibians (K. Kadokami, Kitakyushu Env. Sci. Inst.), 4) Accumulation and biological impacts of persistent toxic substances in aquatic organisms (H. Iwata, Ehime Univ.), 5) Technology development for POPs degradation (M. Hosomi, Tokyo Agri-Tech Univ.) 6) Microbial degradation of recalcitrant organic chemicals (N. Ogawa, NIAES), and 7) Hazardous chemicals and human health risk (J. Sekizawa, NIHS). In implementing the Convention, governments will take measures to eliminate or reduce the release of POPs into the environment. In this symposium, buried obsolete pesticides were estimated to be over 3,700 tons across Japan. It was also reported that pesticide treatment programs for these were underway, however grave the task.

The symposium was held September 13, 2002 with 3 domestic speakers and about 110 participants in the NIAES conference hall.

Due to the worldwide use of pesticides, there is a growing concern over the environmental contamination caused by their residues. The current methods such as gas chromatography and high-performance liquid chromatography have been successfully for analysis of many pesticides, however, they require a high-cost and skilled analysis, and involve time-consuming sample preparation steps. Therefore, there is a growing demand for more rapid and economical methods for determining pesticide residues, especially, in harvested crops before they reach market. Recently, ELISA (Enzyme-Linked Immunoabsorbent Assay) is being demonstrated as a suitable alternative to the traditional methods that can meet such demands.

In order to learn what is pesticide ELISA method, three speakers were invited to this workshop, and following three topics were presented: 1) Overview of ELISA method for residual pesticide analysis (E. Watanabe, NIAES), 2) Application of ELISA method for residual pesticide analysis in aquatic environment (H. Watanabe and Y. Kakegawa, Tokyo Agri-Tech. Univ.), and 3) Environmental ELISA method for beginners (Y. Ishii, NIAES).

In the second half of the meeting, topical "drin" issues (banned pesticides such as aldrin, dieldrin and endrin detected in cucumber plants in some prefectures) were also discussed, information were exchanged, and collection of old reports on this subject was decided. Widely used after 1954, drin pesticides were banned during the 1970s when they were found to cause cancer and possibly carry endocrine disrupters harmful to reproductive functions. However, they remain in the soil for decades.

It has increasingly been recognized that biogeochemical cycles are critical in maintaining the global environment, and that the human activities are disturbing the cycles at an alarming rate and extent. Prediction of the human impacts on global environment and the resultant changes in ecosystems and agriculture require quantitative understandings of the biogeochemical processes in ecosystems from plot to global scales. This workshop was held at NIAES on February 25 to review recent advances and future perspectives for observations, experimentation, and modeling of carbon and nitrogen cycling in terrestrial ecosystems.

Technologies are now available for studying the impacts of rising CO₂ concentration and/ or air temperature on intact ecosystems, and major scientific findings are being made with the manipulative experiments (K.Kobayashi & M.Yoshimoto, NIAES). Methane emission from rice paddies under elevated CO₂ concentrations has been studied with FACE (free-air CO₂ enrichment) in Japan and China. The Japanese results showed that CH₄ emission was stimulated by CO₂ enrichments (W.Cheng & K.Yagi, NIAES), whereas the Chinese results showed no difference between ambient and elevated CO₂ concentrations. The China FACE experiment has shown, however, that the CO₂ enrichment increased soil CO₂ concentration in winter wheat fields (X.Zheng, Chinese Academy of Sciences). While basic principles of isotopic fractionation are well-established for trace gas emission in anaerobic decomposition of organic matter, the fractionation signal could be modified due to differences in the structure of the microbial community, and the configuration of the gas transport pathway from the site of decomposition to the atmosphere (A.Sugimoto, Kyoto Univ.).

The DNDC (denitrification-decomposition) model has been used widely to estimate emission of trace gases from agricultural ecosystems, but a modification was necessary to simulate N₂O emission from Andosol, which is of volcanic-ash origin and a typical upland soil in Japan (T.Sawamoto, NIAES). Andosol was also problematic for the Rothamsted-Carbon model to simulate the soil organic carbon (SOC), whereas in other upland soils in Japan, the model simulated the long-term trend in SOC well (Y.Shirato, NIAES). A modification based on soil aluminum content improved the model simulation for Andosol substantially. It was found that seasonal change in hydrology rather than that in biological activities played a major role in nitrogen dynamics throughout a mini-watershed in a forest ecosystem in Japan (N.Ohte, Kyoto Univ.). The carbon cycling in terrestrial ecosystems was simulated with Sim-CYCLE model at the global scale, and the simulations of runoff and evapotranspiration were comparable to the observations at world's major river basins (A.Ito, Frontier Research System for Global Change).

The papers presented at this workshop showed collectively that models are improving in simulating the biogeochemical cycles under global change impacts, but that observations and experimentations are of critical importance to verify and improve the models further.

This seminar was held on February 26, 2003 with 8 speakers and about 260 participants in the NIAES meeting hall. In this seminar, the dynamic behavior of suspended solids (SS) was the focus, and the related recent topics were presented. Some environmental pollutants such as dioxins, heavy metal and phosphorus are absorbed with fine soil particles which are dispersed in water and run off into rivers and sea. First, with an emphasis on dioxins accumulated in rice paddy soils, the characteristics of effluent of SS from paddy fields and new methods to prevent SS effluence were presented. Secondly, the occurrence of SS associated with soil erosion and its effect on surrounding environments were presented. Thirdly, the behavior of SS through arable lands to rivers and sea and its effect on coastal environments were presented. In the discussion, the necessity to develop new methods to monitor the behavior of SS was stressed.

The fifth seminar on vegetation science was held at NIAES on 5 March 2003. The main title of the seminar was 'Ecological characteristics of agro-ecosystem habitats and network functions of rural landscapes in habitat preservation." The seminar comprised two agendas: the first, how to rearrange agricultural land use to increase habitats for the various plants and animals in agro-ecosystems, and the second, how to evaluate the function of rural landscapes as the network among habitats.

Seven speakers gave presentations, and their topics were: 1) the aim of this seminar (by Y. Ogawa, NIAES), 2) spatial distributions of environmental units in rural landscapes from the viewpoint of biological migration (by H. Moriyama, NIRE), 3) ecological features and conservation of aquatic organisms dependent on disturbances: case studies of frog and a threatened plant Ludwigia peploidae ssp. stipulacea (by K. Ohsawa, Japan University), 4) critical situations near extinction of Aster kantoensis a local plant endemic to flood plains and its conservation activities (by N. Kuramoto, Meiji University), 5) evaluation of biodiversity and conservation planning in wide areas using GIS (by H. Momose, NILIM), 6) restoration of landscape structures and network functions in rural areas (by K. Yamamoto, NIRE), 7) conservation and management of biodiversity using the fallow system in paddy fields (by T. Ohkuro, NIAES).

The highlight of the seminar was the general discussion in which the commentator from the rural management section of the MAFF explained the administrative efforts for improvement of the habitats in agricultural areas by remaking structures of farmland, such as the shapes of agricultural waterway and ridges of paddy fields. Some of scientists and NPO members emphasized that efforts for suppressing the abandonment of paddy fields should be placed more importance and a matter of urgency for keeping the habitats. More than 120 people participated in the seminar.