Tibet is often known as the water tower of Asia. This means that major rivers that run into many of the Southeast Asian countries emerge from Tibet. A water resource originating from Tibet shared by different downstream countries is used for irrigation, hydropower development, industry, and domestic use. An assessment of river quality is vital if one has to understand the role of the Tibetan Plateau as the origin of water resources in Southeast Asian countries. By assessing the river quality, it is also important to implement proper scientific research on the effects of mining on river quality and how to overcome such negative impacts on the river.
Based on several research findings, the rivers in Tibet are contaminated with heavy metals. The contamination of heavy metals has severely polluted the rivers and reduced the water quality. Natural processes and anthropogenic factors are considered the reasons for pollution. However, my presentation at the 4th Tibet Environment Conference was on mining as the main anthropogenic pollutants for river pollution in Tibet.
In a few research papers, it was written that mining has caused direct river pollution. However, many other research papers are there, that do not link river pollution directly to mining. For example, a paper titled Environmental impact of mining activities on the surface water quality in Tibet: Gyama Valley, published in June 2010, a paper reported that “The environment risk at the Gyamaxung chu source area where the measured contents correspond to geochemical background was zero”. The study further noted, “The great Gyama project is about to be launched in the valley despite lack of adequate understanding of the hydrogeochemistry of the heavy metals in this very sensitive environment and without environmental impacts being assessed.”
Gyamaxung chu is located south of Gyama Valley and it drains into the Lhasa River and finally merging into Yarlung Tsangpo. The locals in Lhasa city use the underground water of a well which is at the north bank of this river as the main source of drinking water therefore study warned that, the poor tailings and gangue piles of mine’ water can contaminate the groundwater through seepage in future and can risk to human health.
The river is an important natural resource. It is widely used for migration, transportation, navigation, irrigation, power generation, etc., and especially used for freshwater resources. As far as the Tibetan Plateau is concerned, the rivers start from here into other countries in South East Asia. Therefore, pollution created in the Tibetan Plateau will run into downstream countries. This contaminated river will destroy the ecosystem and pose a serious risk to the human health of the river basin. Toxic elements such as As and Cr are toxic because those elements cannot biodegrade and easily accumulate in water bodies and sediment. The physical and chemical parameters of water bodies that as pH and Eh can easily change with mining.
According to a paper titled, Heavy Metal Pollution and Environmental Risks in the Water of Rongna River Caused by Natural AMD around Tiegelongnan Copper Deposit, the river flowing through mining areas is more likely to get polluted with heavy metals. In their paper, they observed that the Rongma River which flows through the Tiegelongnan Copper Deposit gets polluted due to acid mine drainage formed in the middle of the ore body. This acid mine drainage that has polluted the river has caused serious ecological damage. For example, the disappearance of vegetation near the river and the formation of yellow froth in the river. Tiegelongnan Copper Deposit is located in the Oma (Ch: Wuma) township of Gerze County in Ngari prefecture with an estimated more than 11 million tons of copper ore reserve. After analyzing the source of heavy metals in Rongma River, it was noted that “the main pollution in the water was also Cu, Zn, Ni, Mn, and Cd, indicating that these heavy metals are mainly derived from AMD.
The acidic water produced in the mining area may be the main reason that the Rongna River is polluted by heavy metals.”They have identified the distribution of heavy metals in the Rongma River and they write before acid mine drainage entered into the river, the concentration of heavy metals in the upper reaches of the Rongna River (R1) was similar to that of the Bolong River. After acid mine drainage entered into the Rongma River, the concentration of heavy metals such as Cu, Zn, Mn, Pb, Cr, and Ni became 60.36, 5.23, 25.65, 3.00, 2.15 and 2.60 higher than Bolong River.
Based on research findings on Water quality in the Tibetan Plateau: Major ions and trace elements in rivers of the “Water Tower of Asia” published in August 2018, the minerals deposits such as copper ore and lead zinc ore near the Yarlung Tsangpo basin have polluted the Yarlung Tsangpo river. Chemicals such as Cd, Cr, Pb, and Zn in the YarlungTsanpo River were found three to ten times higher than other rivers in the Tibetan Plateau and the world. As the report noted river pollution in the Tibetan Plateau comes from anthropogenic sources, municipal waste from the plateau is another factor that has caused the river contamination by heavy metals. They further added that municipal waste has been directly thrown into the river without proper management for many decades. There is another paper titled Water Quality in the Tibetan Plateau: Metal Content Four Selected Rivers which also reported that there are no municipal waste treatment facilities in an area.
This study was carried out in April and May of 2006 on four rivers Salween, Mekong, Yangtze River, and YarlungTsangpo. The samples were collected and taken for analysis for Cu, Pb, Zn,Ag,Mo, Cd, Co, Cr, Ni, Li, Mn, Al, Fe, Mg, and Hg. In their analysis of the Salween River, they write that Tsenchu is a tributary of the Salween River and this river is a drinking water source and a domestic wastewater recipient for the town of Nakchu. Similarly, in their analysis of the Mekong River, they write “No municipal waste treatment facilities are available here. All liquid and solid wastes are ‘‘naturally’’ discarded directly into the rivers. The Dzachu and Ngomchu both serve as drinking water sources and as domestic wastewater recipients for the town”.
In the Yangtse River analysis of heavy metals concentration, they took the samples from different areas namely 20 to 33 sites, they mentioned that the concentration of copper at site 26 which is at Chunyido villages is found highest in the survey with a copper concentration of 14.6 mg/L even though the concentration of Aland Fe that is 0.5 to 1.7 mg/were found in high concentration as compared to other. However, they do not mention that the highest concentration of copper was detected due to its direct linkage with the Yulong copper mine with an estimation of 6.5 million tons of reserves in Chunyido village but they have mentioned that Samples 24, 25, and 26 and 27 were taken from the two creeks which is near to mining site and the sample26 which shows the highest level of copper is one among the four sample that was taken from creeks around the mining area.
As reported in a paper titled Water Quality in the Tibetan Plateau: Major Ions and Trace Elements in Rivers of the “Water Tower of Asia”, the source of river pollution from Hg and Ti in rivers is unclear but they write that those toxic elements are deposited with copper, lead, zinc, and other heavy metals sulfide ores. Those ores are generally developed near rivers. From this understanding, it tells that Hg and Ti pollution of rivers come from ores.
Conclusion
The river pollution in the Tibetan Plateau comes from mining. About many reports, some have evidence that shows mining has directly polluted the river yet on the other side, there are few other reports that do not link river pollution with mining but their reports suggest that due to the presence of mine sites in an area, river get contaminated with heavy metals. Another problem is the waste material treatment facilities. Maybe there are no adequate management facilities for municipal and domestic waste products, which have led to locals directly throwing their waste into the river. Therefore, it is necessary to build a proper waste management system in towns.