This is an executive summary report of the project "Present Situation of the Typical Eco-systems Destruction in China and Their Conservation, Restoration and Utilization". The project is a major project sponsored by the National Environmental Protection Agency of China during the Seventh-Fifve-Year-Plan (1986-1990) and is also the fire systematical, deep and large scale research project in regional eco-systems of China. In this paper, the background, guiding ideology, research tasks, technical routes, progress, main achievements and esisting problems of the project have been discussed separately. 

The variety, quantity and biomass of various aquatic organisms in Gucheng lake of Nanuing had been investigated from June 1987 to July 1988. The fish production and stocking mass of rearing fish in the lake have been approximately calculated. It is concluded that if the quantity of fish increases to the maximum allowance (1.8 million fish) of the lake, fish production can be increased from present 750 tonnes to 1600 tonnes. In addition, this study can also provide a series of useful data for scientific managemant of Gucheng lake. The feasible suggestions about the ra tional utilization and protection of the resources in the lake are also proposed.

According to practical conditions of the experimental unit, agricultural ecological engineering has been used to regulate properly inner system structure and adjust continuously ecological balance. A good cyclic system of "planting as a base, breeding as a centre, biogas as a link"is organized, which can facilitate harmonious development of eco-agricultural production, sustainable utilization of resources and realization of the least pollution environment and steady optimal productivity and eco-economic benefits.

The net primary productivity for grassland in Sichuan under different conditions and relevant solar energy utilization efficiency have been analyzed. The results indicate that when other conditions are optimal, the weight ed average of the net primary solar energy potential productivity (Yp) in the whole province, depending on the photosyn the tic active radiation (PAR), is 75. 88 t/ha/a; the net primary solar temperature potential productivity (Ypt), depending on PAR and temperature, is 44. 14t/ha/a; the net primary climtic potential productivity (Yptw) is 40. 26t/ha/a; the net primary productivity of the natural grassland (Yan) and the net primary productivity of the artificial grassland at present time (Yes) are 11. 26t/ha/a and 25. 15t/ha/a respectively. The solar energy utilization efficiencies of Rp, Rpt, Rptw, Ran and Ras corresponding to Yp, Ypt, Yptw, Yan and Yas are 4. 82%, 2. 86%, 2. 61%, 0. 71% and 1. 58% of PAR respectively.

On the basis of present economic, social and ecological conditions, development trend and existing problems in Tongbai county, 13 events in eco-environment of the county have been summarized by application of grey system theo ry. Two objects (need and feasibility) have been selected. In view of the 13 events, 46 coutermeasures have been proposed. By the method of grey sorting optimal decision, the plan of the county’ s ecological environment has been made. Thus the optimal decision for harnessing and protesting eco-environment of the county has been provided. 

Sandy-beach along river banks is an important land resources to be exploited. The situation of sandy-beach pear orchards in the past 16 years has been investigated. The results show that pear trees can adapt to the soil of sandy beach with high yield, and soil structure, fertility, water maintenance, temperature and local climatic conditions in the orchards could be improved Progressively. Meanwhile, significantly ecological and economic benefits can be achieved. The proposals for exploiting, utilizing and setting up a high efficient eco-economic system in sandy beachs have been proposed. 

Our country, having a large area of agricultural and foreaty land with a great amount of output, is much rich in the agricultural by-products as resources that may be comprehensively utilized at the boundless prospect. The approaches to their comprehensive utilization have been discussed, which include the uses of onion skins and peanut shells in the treatment of heavy metals in waste waters, some by-producta in use for manufacturing furfural, producing forages and cultivating edible mashrooms and the use of rice shells as raw materials to make water glass, activated carbon, and desirable alternatives of the fuel for power station that will be much beneficial to relax the tensikn of the ele.ctric energy demand in the third world.

Correlation and factor analysis of 20 samples in profiles of Sajang Nlack Soils have been conducted. The processes that contril accumulation of B, Mo and availability of Mn, Zn, Cu and Fe could be measured by the first two principle factors. Measures for regulating micronutrient supply to normal crop growth in Sajang Black Soils were also discussed.

Practical techniques of treating waste pulping liquid from small scale straw pulp mills, which have been conducted as the national major scientific and technical plans during the Seventh-Five-Year-Plan (1986-1990) have been briefly introduced. These practical techniques include; (1) simple recovering of alkali; (2) acidification of alkaline pulping waste liquid to get lighin and utilize it cmprehensively; (3) anaerobic digestion of lime straw pulp waste liquid; (4) recovery of alkali by electrodialysis process and (5) anaeribic digetion of the alkaline pulping waste liquid after lignin separated by acidification. It is suggested that the research on these practical techniques in produ’ctio scale should be continued and that two or three complete sets of practical technique of preventing and treating contamination for thousands of small-scale straw pulp mills should be developed. 

The ILWAS model has been used to simulate the acidification processes of Laohulin reservior in Nanjing city under three levels of acid deposition liad. Nomogeaphy has been adapted to establish the model of making pollution control decision between acid deposition load and surface water acidification rate.

In this study, kenaf has been retted in the middle paddy rice fields with abundant water source. The results indicate that retting kenaf in the rice fields can not only increase fibre extraction rate,fibre quality,following crop production (about 10-20%) and soil fertility, but also prevent and control the waste water pollution caused by floating water from retting kenaf. It is concluded that this process is the simple and feasible approach which could increase economic, environmental and social benefits simultaneously under present production situation in rural areas. 

Three forms of silver (Ag⁺, [Ag (S₂O₃)₂]^3-, AgBr) have been selected in the static experiment of purification of silver-bearing waste water from cinefilm processing factory by water hyacinth. The results indication that silver removal rates from SBWW within 24 hours were 0. 136, 0. 054 and 0. 030 for Ag⁺, [Ag (S₂O₃)₂]^3-and AgBr respectively. The purification rate relate mainly with detention time(t),original silver concentration,silver form,tempera ture and pH. In addition, the results of dynamic simulated experiment with [Ag (S₂O₃)₂]^3- indicate that the relationship between purification rate (R) and detention time (t) is R=Ae^R/t (B<0), Relationship between surface purification rate (Ps) and detention time (t) is Ps=At^R (B<0). 

Variety and content of the carcinogenic polycyclic aromatic hydrocarbons (PAHs) in the air, soils and vegetables near the indigenous coke ovens have been determined with gas chromatograph-mass spectrometry. Results showed that the content of BaP in the area with more indigenous coke ovens were 0. 024-0. 184μg/m3 in the air, 81. 2-151. 1μg/kg in soils and 8. 5-12. 0μg/kg in dry vegetables. On the basis of the results, the possible effects of indigenous coking on the nearby eco-environment have been analysed.

The increasing degradation of eco-environment is, to a great extent, caused by irrational utilization and exploitation of national resources and destructive production because of lacking scientific and technolgical sup port. Therefore, the advance of science and technology plays a decisive role in protecting and improving the eco-environments. On the basis of combination of economic development and environmental protection, environmental science researches should be carried out and appropriate techniques should be gradually developed in order to found a reliable base for relying on science and technology to protect and improve eco-environment.

It is quite evident that different eco - agriculture distributions bring about different economic benefits in eco- agricultural production. In the past four years, the distribution methods of basic model of eco - agriculture, pro grammed model of seeking and matching optimal strategic decision index, and modelof planned space have been applied in the eco - agricultural production of a farmer (Mr. Jiaqi Zhang) household in 1986, 1987 and 1988 respectively. The result showed that according to the basic model of eco- agriculture, the eco - agricultural production income of the household in 1986 was much high than that of 1985 during which farming was arranged in terms of traditionnal model (gross and net income increased by 39. 0% and 50. 2% respectively) (according to the programmed model of seeking and matching optimal strategic decision index, the household income in 1987 was higher than that of 1986 (gross arid net income increased by 148. 2% and 148. 7% respectively); and based on the method of planned space model, the household income in 1988 was higher than that of 1987 (gross and net income increased by 116. 6% and 120. 2% respectively). Therefore, it is concluded that the selection of distribution method is very important in eco -agrucultural production.