4.1 Investigation and Monitoring on Key Industrial Wastewater Pollution Sources

According to the environmental statistics of 2005, the total amount of industrial wastewater of the Three Gorges Reservoir areas amounted to 574 million tons. Among them, the industrial wastewater from major downtown areas in Chongqing Municipality constituted the largest proportion of 549 million tons, taking up 95.6% of the total, and the amount from the Reservoir area of Hubei Province reached 25 million tons, taking up 4.4%. In the industrial wastewater, there were 77,100 tons of COD (chemical oxygen demand) and 5800 tons of ammonia nitrogen.

Table 4-1 The amount of industrial wastewater from the Three Gorges Reservoir areas

Area	Wastewater	COD	Ammonia nitrogen (10,000 t)
	(100 million t)	(10,000 t)
Hubei area	0.25	0.06	----
Chongqing area	5.49	7.65	0.58
Total	5.74	7.71	0.58

4.2 Investigation and Monitoring on Urban Sewage

Environmental data of 2005 showed that a total of 409 million tons of sewage were discharged in the Reservoir area. Among them, the discharge volume of the areas of Chongqing Municipality topped the list at 395 million tons, taking up 96.6% of the total, and the amount from Hubei area reached 14 million tons, accounting for 3.4%. In all the urban sewage, there were 92,600 tons of COD and 9400 tons of ammonia nitrogen.

Table 4-2  The Amount of urban sewage from the Three Gorges Reservoir areas

Area	Wastewater	COD	Ammonia nitrogen (10,000 t)
	(100 million t)	(10,000 t)
Hubei area	0.14	0.24	0.02
Chongqing area	3.95	9.02	0.92
Total	4.09	9.26	0.94

4.3 Monitoring of Pesticides and Chemical Fertilizers

In 2005, investigation results on the utilization of pesticides and chemical fertilizers in 156 towns and villages of 19 counties in the Reservoir area showed that the application of chemical fertilizers per unit area remained at high level and was still on the rise. Per unit application amount of pesticides increased at relatively large margin.

4.3.1 Chemical fertilizers

In 2005, calculated by the percentages of pure nitrogen, P₂O₅, and K₂O contained respectively in the three kinds of fertilizers, up to 88,400 tons chemical fertilizers were applied in 156 towns and villages of the Reservoir area, 58,500 tons of which were nitrogen fertilizer, 19,600 tons were phosphorus fertilizer and 10,300 tons of potash fertilizer. The total application of chemical fertilizers went down by 2.4% compared with that of the previous year. Among them, the application of nitrogen fertilizer cut by 3.6%, phosphorus fertilizer down by 3.2% and potash fertilizers up by 8.3%.

The fertilizers applied in the Reservoir area were still dominated by nitrogen ones. The ratio among consumed nitrogen fertilizer, phosphate fertilizer and potash fertilizer was 1:0.33:0.18, witnessing certain degree of improvement than in 2004. This indicated that fertilizer application ratio was developing in an appropriate way.

4.3.2 Pesticides

In 2005, a total of 541.05 tons pesticide equivalents were applied in 156 towns and villages of the Reservoir area including 257.64 tons of organic phosphorus pesticides, 136.45 tons of organic nitrogen, 48.55 tons of trifluorocypermethrin pesticides, 38.24 tons of herbicides and 60.17 tons of other pesticides. Compared with that of the previous year, the application of pesticide equivalents was 3.11 kg/ha, down by 4.6%.

The application percentage of organo-phosphorus pesticides dropped in the Reservoir area at 47.6% of the total, indicating further improvement of the pesticides application structure in the Reservoir Area.

4.4 Monitoring of Mobile Pollution Sources

There were nearly 130 shipping companies in the Reservoir area in 2005, no obvious change compared with that of 2004. There were more than 9,000 registered shipping vessels, less than that of 2004. The major underlying reason for the drop was the reduction of the amount of small ships and non-mechanically propelled boats while the number of big cargo ships increased.

4.4.1 Ship transportation

In 2005, the Three Gorges Dam permanent ship lock operated for accumulated 8,336 times passing through a total of 63,949 ship-times, which transported 1.88 million person-times and 32.91 million tons of cargo, which was 95.6%, 85.2%, 108.7% and 95.9% of the same period of 2004.  The lock of Gezhouba Dam had an operation of 16,966 times with 68,473 ships passing through bearing the passenger load of 1.69 million person-times and cargo load of 35.415 million tons, which was 110.7%, 90.9%, 110.5% and 116.4% of the same period of 2004 respectively.

In Chongqing Municipality, Fuling District and Wanzhou District of the Three Gorges Reservoir Area, large and medium-sized ports saw a passenger flow of 9.89 million person-times, 13.6% less than that of the same period of 2004 and a cargo flow of 36.51 million tons, up by 16.3% compared with that of the previous year. The main reason for the reduction of ship passengers was  the diversion of passengers due to the rapid increase of the capacity of air, railway and road that are must faster means of transportation.

4.4.2 Oil-containing wastewater from shipping vessels

Investigations on oil-polluted water from ships of the Reservoir areas in 2005 showed that, among the 483 ships, 96.9% had installed oil-water separator with the utilization rate of 86.3% and up-to-the-standard rate of 80.9%. The overall situation was similar to that of 2004.

In 2005, a total of 496,900 tons of oil-containing wastewater were discharged by ships in the Reservoir area, down by 6.2% than that of the previous year. Among them, 454,100 tons were treated with the treatment rate at 91.4%. A total of 400,100 tons discharged wastewater met the standard with the up-to-the-standard rate of 88.1%. In all the oil-containing wastewater, the discharge of petroleum reached 40.46 tons, cut by 8.0% compared with that of 2004. Of all kinds of shipping vessels, the oil pollutant discharged by cargo ships, passenger ships, tugboats, other ships and cruise ships were 33.06 tons, 5.78 tons, 0.87 ton, 0.66 ton and 0.09 ton respectively, accounting for 81.7%, 14.3%, 2.2%, 1.6% and 0.2% of the total respectively. Cargo ships remained as the dominant type of ship causing water pollution in the Reservoir waters.

4.4.3 Domestic wastewater from ships

In 2005, the findings of investigation on the discharge of domestic wastewater from the ships of the Reservoir area showed that the domestic sewage of the 6 of 30 ships under monitoring was treated and met discharging standard. While the sewage from the remaining 24 ships discharged into the waters without any treatment, the concentration of each pollutant obviously exceeded the standard with E.coli the worst.

According to estimate, the total amount of ship domestic wastewater of the Reservoir area was about 2.068 million tons in 2005, up by 9.0% compared with that of the previous year. However, only 36,000 tons of such wastewater went through treatment with the treatment rate of 1.7%. Most such wastewater directly discharged into the Reservoir. A total of 1,198.5 tons of domestic sewage pollutants had been discharged into the Reservoir area. Among them, 366.0 tons were SS, 287.5 tons were BOD₅, 483.9 tons were COD, 6.08 tons were total phosphorus and 55.0 tons of total nitrogen, taking up 30.5%, 24.0%, 40.4%, 0.5% and 4.6% of the total respectively. Among these pollutants, the top two were BOD₅ and COD.

Table 4-3 Discharge of oil-containing wastewater from shipping vessels in the Three Gorges Reservoir area

Ships		Oil-containing wastewater						Petroleum
Type	Amount	Discharge amount	Percent	Disposed amount	Treatment rate	Up-to-standard discharge amount	Up-to-standard rate	Discharge amount	Percent
		(10,000 t)	(%)	(10,000 t)	(%)	(10,000 t)	(%)	(t)	(%)
Cruise ship	52	1.33	2.7	1.33	100	1.29	97	0.09	0.2
Passenger ship	1872	15.31	30.8	13.94	91	11.84	85	5.78	14.3
Cargo ship	2830	23.35	46.9	20.79	89	17.71	85	33.06	81.7
Tugboat	381	7.14	14.4	6.96	97	6.92	99	0.87	2.2
Other ships	946	2.56	5.2	2.39	93	2.25	94	0.66	1.6
Total	6081	49.69	100	45.41	91	40.01	88	40.46	100

4.4.4 Garbage on ships

In 2005, seven garbage collection sites were set up in some ports of the Three Gorges Reservoir areas, equipped with six garbage collection ships. A total of 6,321 tons of garbage was collected throughout the year, up by 28.0% compared with that of 2004.

4.4.5 Ship pollution accidents 

In 2005, the Three Gorges Reservoir area saw 15 pollution accidents. Among them, 4 were very severe accidents, 5 were severe, 2 general and 4 light ones. They accounted for 26.7%, 33.3%, 13.3% and 26.7% of the total respectively. These pollution accidents had caused 11 ship sunk, 15 death with economic loss of 3.98 million yuan, similar to that of the previous year.