What is the pollution situation of Minjiang River?

In 2003, the proportion of water quality in Minjiang River Basin reached or exceeded Grade III was 85.5%, which was 8 percentage points lower than that in 2002. In 2004, the proportion of water quality reaching or better than Grade III was 83% (the water environmental function compliance rate was 84.3%, the same below), which was 2.5 percentage points lower than that in 2003. Among them, the compliance rates of Class III water quality in Shaxi, Futunxi, Jianxi, Nanping and Fuzhou sections of the main stream are 665,438 0.5% (665,438 0.5%), 865,438 0.3% (965,438 0.7%) and 96.4%(96.4%) respectively. See figure 1 for the change of the proportion of I-III water quality in Minjiang River Basin in recent years, and figure 2 for the proportion of various water quality in 2004.

The main environmental problems in the basin are as follows:

1. Agricultural non-point source pollution is prominent, and livestock breeding has become the main pollution source.

The rapid development of livestock and poultry breeding has caused serious pollution in some river sections and has become the main pollution source in the basin. According to statistics, in 2003, the COD (chemical oxygen demand) emission of livestock and poultry breeding in Minjiang River Basin accounted for 62.5% of the total COD emission of industrial, domestic and livestock wastewater, and ammonia nitrogen accounted for 63.0%.

Over-dense cage culture in some river sections has also polluted water bodies. According to statistics, in 2003, the inland aquaculture output of Fuzhou, Sanming and Nanping reached 23 1, 1 1,000 tons, and the aquaculture area reached 38,800 hectares. Contaminants such as metabolites of aquaculture, residual bait, pesticides for cleaning and disinfection in ponds, and drugs for preventing and treating aquatic diseases enter the water body, which makes the water quality of some river sections decline.

A large number of chemical fertilizers and pesticides have caused non-point source pollution. According to statistics, in 2003, Fuzhou, Sanming and Nanping * * * applied nitrogen fertilizer164,900 tons, phosphorus fertilizer 56,700 tons, and pesticide 2 1300 tons, of which about 20% of nitrogen fertilizer and 10% of phosphorus fertilizer were lost.

2. The construction of environmental protection infrastructure lags behind, and the domestic pollution is still serious.

The domestic pollution load has exceeded the industrial pollution load. In 2003, the urban domestic sewage discharge in the whole basin was 277 million tons, and the ratio to industrial sewage discharge increased from 0.86: 1 in 2000 to 1: 1, and the ratio of COD and ammonia nitrogen discharge to industrial discharge reached 2.5: 1 and 3.4: 68 respectively.

Domestic sewage treatment capacity is insufficient. Although 10 sewage treatment plants have been built in Fuzhou, Sanming, Nanping and other places, with a designed treatment capacity of 545,000 tons/day, the actual treatment capacity is only 355,000 tons/day, and the sewage treatment rate is only 35.9%. The sewage treatment plants failed to meet the discharge standards stably, resulting in secondary pollution.

The harmless treatment rate of domestic garbage is low. The phenomenon of dumping and stacking garbage without treatment is still common. The leachate of the completed municipal waste treatment plant exceeds the standard. The pilot project of harmless treatment of township waste did not achieve the expected results.

3. Industrial structural pollution has not been fundamentally solved, and some enterprises have rebounded.

Unreasonable industrial structure and layout are the important factors that cause the deterioration of water environment in local reaches of the basin. Shaxi reach is the most concentrated industrial area in Minjiang River basin, with dense pollution sources along the way, receiving a large number of livestock and poultry breeding, domestic and industrial wastewater, and becoming the most polluted reach in the basin.

Industrial development has increased the total discharge of pollutants. Minjiang River Basin is a relatively concentrated and rapidly developing area in our province. In 2003, the chemical oxygen demand and ammonia nitrogen emitted by industrial enterprises in the basin accounted for 48.2% and 49.8% of the total emissions respectively. Because the overall progress of industrial structure adjustment in the river basin lags behind the needs of water pollution prevention and control, the structural pollution problem has not been fundamentally solved, and there is a trend of aggravation in some places.

Some enterprises have seen a rebound in pollution. Due to backward process equipment and low technical level, some enterprises' pollution control facilities failed to operate normally and stably, and pollutants could not be discharged stably. Although a special campaign to strictly investigate environmental violations has been launched for four consecutive years, and a number of illegal sewage disposal enterprises have been severely investigated, some enterprises still have illegal phenomena such as stopping treatment facilities without authorization, installing concealed pipes, and stealing and leaking. Sudden pollution accidents occur from time to time, endangering the safety of water environment in the basin.

4. Unreasonable cascade development has changed the natural attributes of the basin, and its impact on the ecological environment has become increasingly prominent.

According to statistics, there are 29 large and medium-sized hydropower stations in Minjiang River Basin, and there are a large number of small hydropower stations developed in disorder. Excessive and unreasonable hydropower development has turned natural rapids into artificial lakes, slowed down river flow, reduced self-purification ability, deposited pollutants, deteriorated water quality, aggravated eutrophication in the reservoir area and bred a large number of water hyacinths. Most hydropower stations can't guarantee the necessary minimum discharge flow as required, and the downstream ecological environment water can't be guaranteed, which destroys the normal aquatic ecosystem.

Since 2003, due to the rare continuous drought and lack of rain in history, the rainfall in the basin has decreased by about 40% compared with normal years, objectively resulting in a significant decrease in water quantity and a decline in water purification capacity in the Minjiang River basin. Due to the lack of unified allocation and management of water resources in river basins and power stations at all levels, power stations at all levels have long impounded river water, which has aggravated the unreasonable time-history distribution of river water, and even cut off the river under dams of individual power stations for a long time, further deteriorating the water quality of rivers.

5. Ecological destruction in some areas has caused soil erosion and river siltation.

Although the forest coverage rate is high, the forest structure is not reasonable and the ecological function is restricted. Precipitation is unevenly distributed in time and space, which is prone to drought, flood, soil erosion and geological disasters. Mineral development, capital construction and engineering construction have caused different degrees of vegetation destruction and soil erosion. In some places, management is weak, and domestic garbage and construction garbage are dumped at will, resulting in river siltation and water environment pollution.

The "green devil" endangers the river.

When it comes to water hyacinth, people are no strangers. This perennial floating herb grows in slow-flowing waters such as rivers and lakes and is native to South America. In 1960s, China introduced it as pig feed. With the development of feed industry and the change of pig-raising methods, water hyacinth gradually lost its use value and was not harvested. The water hyacinth has spread in many places in southern China, which has become a major disaster that destroys the ecological environment and is listed as one of the top ten harmful weeds in the world.