4.1 Discharge of Industrial Wastewater

In 2006, environmental statistics showed that total wastewater discharge from industrial pollution sources of the reservoir area reached 628 million tons. 606 million tons of them were in the reservoir area in Chongqing Municipality and 22 million tons in the reservoir area in Hubei Province, accounting for 96.5% and 3.5% respectively. In all industrial effluent, the amount of COD (chemical oxygen demand) and ammonia nitrogen was 81,100 tons and 6400 tons respectively.

4.2 Discharge of Urban Sewage

In 2006, environmental statistics showed that total discharge of urban sewage of the reservoir area was 496 million tons, 480 million tons of them were in the reservoir area in Chongqing Municipality and 16 million tons in the reservoir area in Hubei Province, accounting for 96.8% and 3.2% respectively. In the discharged urban sewage, there were 102,700 tons of COD and 10,200 tons of ammonia nitrogen.

4.3 Pesticides and Fertilizers

In 2006, investigation results on the utilization of pesticides and chemical fertilizers in 150 towns of 19 districts or counties of the reservoir area showed that the application of chemical fertilizers was on the rise with no release of non-point pollution pressure imposed by fertilizers. There still existed the phenomenon of focusing on the application of nitrogen and phosphorus fertilizers but potash fertilizer. The total application amount of pesticide continued its increase with certain reduction of the amount of organic phosphorus and organic nitrogen pesticides.

4.3.1 Chemical Fertilizer

In 2006, a total of 154,600 tons (pure equivalent) of chemical fertilizers were applied in the reservoir area, up by 38.0% against that of 2004. 102,900 tons of them were nitrogen fertilizer, 36,000 tons phosphorus fertilizer and 15,300 tons potash fertilizer, accounting for 66.5%, 23.6% and 9.9% of the total application amount respectively. Per hectare application of chemical fertilizers was 817.4 kg.

The total loss of chemical fertilizers in the reservoir area reached 12,100 tons, down by 10.0% compared with that of 2004. Among them, 9000 tons were nitrogen fertilizer, 1500 tons phosphorus fertilizer, 400 tons potash fertilizer and 1200 tons compound fertilizer, accounting for 74.3%, 12.6%, 3.4% and 9.6% of the total loss respectively.

The application proportion of nitrogen, phosphorus and potash fertilizers in the reservoir area was 1: 0.35: 0.15 with dominance of nitrogen fertilizer and relatively lack of potash fertilizer, still indicating focusing on the application of nitrogen & phosphorus fertilizers but potash fertilizer in the region.

4.3.2 Pesticides

In 2006, total application of pesticides in the reservoir area was 655.47 tons (pure equivalent), up by 0.9% against that of 2004. Among them, 285.71 tons were organic phosphorus pesticide, 118.58 tons were organic nitrogen, 115.61 tons trifluorocypermethrin, 60.65 tons herbicide and 74.93 tons other pesticides, accounting for 43.6%, 18.1%, 17.6%, 9.3%, 11.4% of the total respectively. The application amount of organic phosphorus and nitrogen decreased by 12.2% and 23.9% respectively compared with that in 2004. And the application amount of trifluorocypermethrin and herbicide went up by 114.5% and 52.3% respectively. Per hectare pesticide application amount was 3.47 kg.

The total pesticide drain in the reservoir area was 47.98 tons, down by 7.4% than in 2004. Among them, 26.56 tons were organic phosphorus pesticide, 6.01 tons were organic nitrogen, 6.17 tons trifluorocypermethrin, 3.38 tons herbicide and 5.87 tons other pesticides, taking up 55.3%, 12.5%, 12.9%, 7.1% and 12.2% of the total respectively.

Judging from the application of pesticide, organic phosphorus pesticide had the biggest application amount, followed by organic nitrogen and trifluorocypermethrin pesticides, indicating widespread application of high-toxic pesticide in the reservoir area.

4.4 Monitoring of Mobile Pollution Sources

In 2006, there were almost 9,000 registered shipping vessels in the Three Gorges reservoir area, less than that of 2005. The total ship tonnage was more than 4 million tons with total power over 1.40 million kW, obviously more than that of 2005. Among various ships and boats, boats and old ships were phased out with the reduction of non-mechanically propelled boats and increase of mechanically propelled boats and big cargo ships, showing a trend of the development of bigger, environment-friendly, standardized and mechanically propelled ships.

4.4.1 Ship Transportation

In 2006, the Three Gorges Dam permanent ship lock operated for accumulated 8050 times, down by 3.4% compared with that of 2005. A total of 56,383 ship?times passed the gate with the transport of 1.62 million passenger?times and 5.71 million tons of cargo equivalent, down by 11.8%, 14.0% and 7.4% respectively than that of 2005. A total of 39.391 million tons of cargo passed the Dam, up by 19.7%. Ships passing the dam gate showed a continuous trend of bigger and standardized ones. The percentage of ship gate-passing times went down by 5.4 percentage points for 500-ton ships, decreased by 9.3 percentage points for 501-1000-ton ships but went up by 14.7 percentage points for over 1000-ton capacity ships compared with that of the last year.

In 2006, the annual cargo handling capacity of major ports of the reservoir area reached 43.70 million tons, up by 20% than in 2005. Annual passenger handling capacity was 8.367 million passenger*times with a decrease of 15.4%. The main reason for continuous reduction of ship passengers was the diversion of passengers due to the operation of expressway, especially Chongqing-Wanzhou Expressway. In comparison with fast and convenient expressway, railway and air transpiration, ship passenger transport is in disadvantageous position.

4.4.2 Oil-containing Wastewater from Ships

In 2006, the authority investigated 415 ships on the water pollution by oil-containing wastewater from the engine room and found that 67.0% of them met discharge standard. 97.8% of the ships had installed the oil-water separator and 85.7% of which operated smoothly. The normal up-to-the-standard rate of wastewater was 87.2%. The installation and use of oil-water separator in ships was similar to that of the last year with certain rise of meeting-the-standard rate.

In 2006, there were about 6740 ships in the reservoir area that generate oil-containing wastewater. It was estimated that the annual amount of oil-containing wastewater from these ships was about 470,800 tons with reduction by 5.2% than in 2005. 457,200 tons of them were treated, accounting for 97.1%. About 392,000 tons discharged wastewater could meet the standard, taking up 85.8%. The order of oil-containing water generation amount of the engine rooms of various ships was similar to that of 2005, i.e. 257,500 tons for cargo ships, 133,800 tons for passenger ships, 50,200 tons for tugboats, 22,400 tons for other ships, and 6,900 for tourist ships, accounting for 54.6%, 28.4%, 10.7%, 4.8% and 1.5% respectively of the total amount. The generated amount of oil-containing wastewater of tourist ships, passenger ships, tugboats and other ships reduced by 48.1%, 12.6%, 29.7% and 12.5% compared with that of 2005 with 10.3% rise for cargo ships.

In the discharged oil-containing wastewater, 28.02 tons were petroleum pollutant, down by 30.7% than that of 2005. Among various ships, the order of discharged amount of petroleum pollutant was the followings: 22.0 tons for cargo ships, 4.30 tons for passenger ships, 0.90 ton for other ships, 0.77 ton for tugboats, 0.05 ton for tourist ships, accounting for 78.6%, 15.3%, 3.2%, 2.7% and 0.2% of the total. The discharged amount of petroleum pollutants of tourist ships, cargo ships, passenger ships and tugboats decreased by 44.4%, 33.4%, 25.6% and 11.5% respectively compared with that of 2005. The discharged amount of petroleum pollutant of other ships went up by 36.4%. Cargo ships had most reduction in the discharge of petroleum pollutant but were still the key type of ship causing petroleum pollution in waters of the reservoir area.

In 2006, there was evident reduction of the amount of ship-born oil-containing wastewater and petroleum pollutants in the reservoir area. The main reason was the shift from two-way operation into one-way operation of the ship gate of the Three Gorges Dam during the construction completion period leading to dramatic decline of navigation capacity. In addition, 16-day continuous low water level of the Yangtze River in August caused big decrease of ship transportation. Moreover, the phasing out of some old ships and application of new energy-saving ships was one of the reasons of decrease of oil-containing wastewater from ships.

4.4.3 Domestic Sewage from Ships

In 2006, the authority investigated and monitoring the ship sewage of 31 ships navigating in the reservoir area. The sewage of 11 such ships met the discharge standards after treatment except individual item, indicating good effect of sewage treatment devices. But the utilization rate of these devices was relatively low. The sewage of other 20 ships was not treated and failed to meet discharge standard except individual item.

Based on investigation and monitoring results, the amount of various ships, passengers, crews, annual ship operation period and the proportion of the ship with different tonnage, it was estimated that the total ship sewage was about 3.32 million tons in 2006, an evident increase than in 2005. Among them, the sewage amount was 2.86 million tons for passenger ships and 460,000 tons for non-passenger ships.

In the discharged sewage, total amount of various water pollutants was about 1848.9 tons, including 787.5 tons SS (Suspended substances), 692.2 tons COD, 249.0 tons BOD₅ (biological oxygen demand), 103.0 tons TN and 17.2 tons TP, accounting for 42.6%, 37.4%, 13.5%, 5.6% and 0.9% respectively of the total. Among them, TP, SS and BOD₅ were major pollutants whose accumulated equivalent pollution load ratio was 77.3%.

4.4.4 Ship Garbage

In 2006, there were 6 garbage collection ships and 16 pollutant collection units in the reservoir area, 14 of them were ship garbage collection units, 1 was oil-containing wastewater collection unit and 2 units collecting both ship garbage and residual oil. A total of 7264.66 tons ship garbage were collected with an increase of 15% than in 2005. About 1,000 tons of oil-containing wastewater were collected with an obvious reduction against that of the last year.

In 2006, the authority visited 40 ships in the area to investigate the generation and disposal of ship garbage. From the investigation result, it was estimated that the total amount of ship garbage in the reservoir area was over 40,000 tons with only 18% being collected. Among them, about 34,000 tons of garbage came from passenger ships with domestic garbage in dominance. About 6000 tons garbage came from other ships, there may be production garbage apart from crew domestic garbage.

4.4.5 Ship Pollution Accidents

8 ship pollution accidents occurred in the reservoir area in 2006 without any big pollution accident. There were 10 ship transportation accidents in the year, 3 of which were very severe, 1 was severe, 2 were general and 4 small. These accidents led to the sink of 9 ships, 1 collision, 40 people falling into water with 22 rescued, 6 deaths and 12 missing. There was an evident decline of the amount of ship accidents, sunken ships, oil spill, pollution and direct economic loss compared with that of 2005.