2020 Volume 68 Issue 6 Pages 546-551
The water quality in a river (water environment) is very important for human health and aquatic organisms. In 2015, the highly regarded Water Resources Management Strategy of Thailand was announced by The Ministry of Industry in Thailand. In this study, the water quality of the Ping river in Northern Thailand, including Chiang Mai and Lamphun provinces, was focused on and measured for three different seasons (summer, rainy, and winter seasons). Anions (F−, Cl−, NO2−, NO3−, and SO42−) and cations (Na+, Mg2+, Si4+, S6+, K+, and Ca2+) were qualified by an ion chromatograph and an inductively coupled plasma optical emission spectrometry, respectively. The concentration of anions and cations (except for Mg2+ and Ca2+) in the Ping river at upstream (countryside) locations were lower than that at downstream (closer main city) locations, which indicated that the fertilizers, industrial or household wastewaters had been flowing into the Ping river at downstream locations. Additionally, the concentration of anions and cations in the rainy season was higher than other seasons. The present results provide the water quality of the Ping river which was not yet reported officially by the Thailand government.
Thailand can be divided into four areas (the north, the central plains, the northeast, and the south). The north area is mainly surrounded by mountains, which serve as the origin of the Ping, Wang, Yom, and Nan rivers which merge to form the majestic Chao Phraya river. The Ping river is a major water supply for Chiang Mai in Northern Thailand. This river flows through Chiang Mai, Lamphun, Tak, Kamphaeng Phet, and Nakorn Sawan. The National Statistics Office of the Kingdom of Thailand reported that the economy and use of water resources from the Ping river ranked at the top compared to other rivers in Thailand, indicating that the Ping river is the most important for people’s daily lives and the economics in Thailand.1)
The increasing population demands for water through the growing commercial and industrial sectors are causes of the deterioration of water resources in Thailand.2–4) Additionally, human activities such as industry or agriculture along the river not only affect chemical or physical characteristics of the water, but also the aquatic organisms.5) Therefore, the Pollution Control Department (PCD) distributed the surface water quality standards that are classified into 5 classes to confirm the water’s environmental condition and preventing the deterioration of water quality in 1994. Thailand’s 48 major rivers were classified by the PCD. However, the present water quality conditions have been drastically influenced by changing environments and the land use over time or space.6) Therefore, the determination of the present water quality is important for preventing the further deterioration of water resources.
Moreover, some researchers reported on the relationship between the water quality in Thailand and health risks, aquatic organisms, or bioassessments with physicochemical factors (temperature, pH, electrical conductivity, turbidity, dissolved oxygen, biochemical oxygen demand, nitrates, phosphates, etc.).6–12) These results indicate that the water quality directly affects the human health or aquatic organisms in the water environment. In particular, the Ping river, known by the locals as “the lifeline of Chiang Mai,” have been utilized as a major source of drinking water by 8188 villages and 564160 households. However, the current conditions of this river are unswimmable, turbid, narrow, and depleted of fisheries resource etc.1) In addition, last year the Institute for Global Environmental Strategies reported that the concentration of some anions (F−, Cl−, and NO3−, etc.) were detected at levels over the standard quality in groundwater in Thailand.13) However, these ions were not determined for the present surface water quality in Thailand. Therefore, we have to determine the present surface water quality and share the results with the people living along the rivers for reasons regarding human health.
The objects of this study were to focus on the current water quality of the Ping river at different seasons and to determine the concentration of anions and cations in the Ping river.
Water sampling was conducted at different seasons (Aug. 24, 2018, Dec. 24, 2018, and Mar. 26, 2019). The water samples were collected from the middle of the bridge. Each 1000 mL of polyethylene bottle was briefly rinsed, three times, with river water before filling. Ping river water was collected at approximately 0.3–0.5 m depth from the surface. Sampling points are located upstream to downstream along the Ping river in Chiang Mai, Thailand. The map and information of the sampling points are shown in Fig. 1 and Tables 1, 2. From MP 1 to MP 15, areas are countryside in north Thailand. On the other hand, from MP 16 to MP 27, areas are closer to the main city in Chiang Mai and Lamphun. Moreover, the weather was cloudy and 30–40% chance of raining. The lowest and highest temperatures ranged between 22–25 and 31–35°C, respectively, on Aug. 21–24, 2018. The high pressure still covering Thailand caused continuous cool to cold weather over the upper country. The weather was cloudy and cold with no rain. The lowest and highest temperature were ranging between 10–12 and 28–30°C, respectively, on Dec. 21–24, 2018. Finally, the weather of the daytime was hot and sunny with the lowest and highest temperatures ranging between 18–21 and 36–38°C, respectively, on Mar. 24–26, 2019.
(I): Mountainous area, (II): Country side area, (III): Community, fish and longan farm areas.
| Code | Collecting point | Land use | Water flow rate (m3/s) | ||
|---|---|---|---|---|---|
| Aug. 24, 2018 | Dec. 24, 2018 | Mar. 26, 2019 | |||
| MP 1 | Chiang Dao Highway Division | Forest (Mountainous area) | 24.05 | 6.43 | 2.70 |
| MP 2 | Traisapavakarm Church Bridge | Forest (Mountainous area) | 24.05 | 6.43 | 2.70 |
| MP 3 | En-Sci Farm Bridge | Medium sized village with agricultural farm (Mountainous area) | 24.05 | 6.43 | 2.70 |
| MP 4 | Wat Intraram Bridge | Medium sized village with various agricultural farm such as corn farm, chilli farm, and indigenous vegetable farm (Mountainous area) | 55.33 | 14.19 | 7.14 |
| MP 5 | Ban Mae Ya School Bridge | Medium sized village with agricultural farm (Mountainous area) | 55.33 | 14.19 | 7.14 |
| MP 6 | Kaeng PanTao | Small sized village with agricultural farm (Mountainous area) | 55.33 | 14.19 | 7.14 |
| MP 7 | The Elephant Training Center Chiang Dao Bridge | Medium sized village with agricultural farm and elephant camp (Mountainous area) | 89.74 | 18.44 | 12.29 |
| MP 8 | Royal Ping Garden and Resort Bridge | Small sized village with agricultural farm and resort (Mountainous area) | 89.74 | 18.44 | 12.29 |
| MP 9 | Ban Pao Bridge | Medium sized village with agricultural farm (Mountainous area) | 89.74 | 18.44 | 12.29 |
| MP 10 | Cho Lae Bridge | Small sized village with agricultural farm (Mountainous area) | 89.74 | 18.44 | 12.29 |
| MP 11 | Wat Nong Ma jab Bridge | Medium sized village with agricultural farm such as flower farm (Lowland) | 149.57 | 25.71 | 14.80 |
| MP 12 | Road 3011 Bridge | Medium sized village with agricultural farm such as flower farm (Lowland) | 149.57 | 25.71 | 14.80 |
| MP 13 | Wat Suwannawat Bridge | Medium sized village with agricultural farm (Lowland) | 149.57 | 25.71 | 14.80 |
| MP 14 | Road 1260 Bridge | Medium sized village with agricultural farm (Lowland) | 149.57 | 25.71 | 14.80 |
| MP 15 | Road 121 Bridge | Large sized village (city) with agricultural farm and manufactural (Lowland) | 193.51 | 75.3 | 32.68 |
| MP 16 | Pa Tan Bridge | Large sized village (city) with agricultural farm and manufactural (Lowland) | 193.51 | 75.3 | 32.68 |
| MP 17 | Mahidol Bridge | Large sized village (city) with agricultural farm and manufactural (Lowland) | 193.51 | 75.3 | 32.68 |
| MP 18 | Road 121 Bridge | Large sized village (city) with agricultural farm and manufactural (Lowland) | 193.51 | 75.3 | 32.68 |
| MP 19 | Iron Bridge | Large sized village (city) with agricultural farm and manufactural (Lowland) | 167.32 | 60.24 | 26.15 |
| MP 20 | Wat Pa Duea Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 167.32 | 60.24 | 26.15 |
| MP 21 | Tha Khun Khong Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 167.32 | 60.24 | 26.15 |
| MP 22 | Ban Long Pu Mon Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 167.32 | 60.24 | 26.15 |
| MP 23 | Srivichai Anusorn Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 155.8 | 47.55 | 22.62 |
| MP 24 | Wat Intavichai Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 155.8 | 47.55 | 22.62 |
| MP 25 | San ma na Bridge | Medium sized village with agricultural farm and aquaculture in Ping river | 155.8 | 47.55 | 22.62 |
| MP 26 | Ban Reuan Bridge | Small sized village with agricultural farm especially for longan form | 131.24 | 41.35 | 18.05 |
| MP 27 | Ban Wang Ku Bridge | Small sized village with agricultural farm especially for longan form | 131.24 | 41.35 | 18.05 |
The population of small sized village, medium sized village, and large sized village is <6000, 6001–12000, and >12000, respectively.
| Code | Address | Detail of collecting point | Metres above sea level (MASL) | Location | |
|---|---|---|---|---|---|
| Latitude | Longitude | ||||
| MP 1 | Mueang Ngai, Chiang Dao, Chiang Mai | Roadside & Far from community (village) | 420.62 | 19.45577 | 98.99313 |
| MP 2 | Mueang Ngai, Chiang Dao, Chiang Mai | Roadside & closed to community (village) | 404.77 | 19.42244 | 98.9923 |
| MP 3 | Chiang Dao, Chiang Dao, Chiang Mai | Closed to lemon farm | 388.32 | 19.3876 | 98.97887 |
| MP 4 | Chiang Dao, Chiang Dao, Chiang Mai | Closed to community (village), Corn farm, chili farm, and indigenous vegetable farm | 388.01 | 19.36733 | 98.96874 |
| MP 5 | Mueang Na, Chiang Dao, Chiang Mai | Closed to constructing bridge | 375.82 | 19.32104 | 98.95868 |
| MP 6 | Mueang Na, Chiang Dao, Chiang Mai | Have a local food located on riverside | 394.41 | 19.28598 | 98.96851 |
| MP 7 | Inthakhin, Mae Taeng, Chiang Mai | Closed to elephant camp | 368.2 | 19.24861 | 98.97196 |
| MP 8 | 2 K.M. Chiangmai-Fang Rd., Ban Pao, Mae Taeng, Chiangmai | Closed to a popular resort (Royal ping garden and resort) | 355.09 | 19.21506 | 98.97196 |
| MP 9 | Inthakhin, Mae Taeng, Chiang Mai | Roadside & closed to community (village) | 345.64 | 19.18552 | 98.99149 |
| MP 10 | Cho Lae, Mae Taeng, Chiang Mai | Roadside & closed to community (village) | 340.46 | 19.14597 | 99.00738 |
| MP 11 | Mae Faek, San Sai, Chiang Mai | Roadside & closed to community (village) | 329.49 | 19.0766 | 98.95067 |
| MP 12 | Mae Faek, San Sai, Chiang Mai | Roadside & closed to community (village) | 323.09 | 19.00988 | 98.95972 |
| MP 13 | San Pong, Mae Rim, Chiang Mai | Roadside & closed to community (village) | 320.34 | 18.96747 | 98.96885 |
| MP 14 | Mueang Kaeo, Mae Rim, Chiang Mai | Roadside & closed to community (village) | 313.94 | 18.9173 | 98.96999 |
| MP 15 | San Phi Suea, Muang Chiang Mai, Chiang Mai | Roadside & closed to community (village) | 307.54 | 18.86657 | 98.97799 |
| MP 16 | Pa Tan, Muang Chiang Mai, Chiang Mai | Closed to community (village), Chiang Mai City The river contain a high amount of water hyacinth | 306.93 | 18.81017 | 99.00325 |
| MP 17 | Pa Daet, Muang Chiang Mai | Closed to community (village), Chiang Mai City | 305.4 | 18.76012 | 98.9972 |
| MP 18 | Pa Daet, Muang Chiang Mai, Chiang Mai | Closed to community (village), Chiang Mai City | 298.09 | 18.71956 | 98.98681 |
| MP 19 | Sop Mae Kha, Hang Dong, Chiang Mai | Closed to community (village), Chiang Mai City | 295.96 | 18.69068 | 98.98709 |
| MP 20 | Khua Mung, Saraphi, Chiang Mai | Fish farm in the river | 297.18 | 18.67968 | 98.98393 |
| MP 21 | Khun Khong, Hong Dong, Chiang Mai | Fish farm in the river | 296.26 | 18.65437 | 98.96153 |
| MP 22 | San Sai, Saraphi, Chiang Mai | Fish farm in the river | 294.44 | 18.61998 | 98.95441 |
| MP 23 | Rimping, Muang Lamphun, Lamphun | Fish farm in the river | 290.47 | 18.59908 | 98.9662 |
| MP 24 | Mae Ka, San Patong, Chiang Mai | Fish farm in the river | 288.64 | 18.5802 | 98.95343 |
| MP 25 | Tonthong, Muang Lamphun, Lamphun | Fish farm in the river | 287.43 | 18.5564 | 98.93572 |
| MP 26 | Tha Wang Phrao, San Patong, Chiang Mai | Closed to agricultural farm ex. Longan farm | 282.55 | 18.51069 | 98.87953 |
| MP 27 | Nam Dip, Pa Sang, Lamphun | Closed to agricultural farm ex. Longan farm | 276.15 | 18.4759 | 98.82272 |
In this study, water samples from each collecting point were stored in 50 mL of polyethylene bottles and kept at 5–7°C. We measured anions (F−, Cl−, NO2−, NO3−, and SO42−) and cations (Na+, Mg2+, Si4+, S6+, K+, and Ca2+) in the Ping river. A standard solution of anions (Anion mixed standard solution IV) was purchased from Kanto Chemical Co., Inc. (Tokyo, Japan). Standard solutions of Na+ (NaCl in water), Mg2+ (Mg(NO3)2 in 0.1 mol/L HNO3), Si4+ (Na2SiO3 in 0.2 mol/L Na2CO3), S6+ (Ammonium sulfate in water), K+ (KCl in water), and Ca2+ (CaCO3 in 0.1 mol/L HNO3) were obtained from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). The range of calibration curve of F−, Cl−, NO2−, NO3−, SO42−, Na+, Mg2+, Si4+, S6+, K+, and Ca2+ was 0–5, 0–10, 0–15, 0–30, 0–40, 0–20, 0–20, 0–20, 0–20, 0–20, and 0–20 mg/L, respectively. The correlation coefficient and relative standard deviation of these lines were over 0.996 and below 3.65%, respectively.
Anions were analyzed by a Dionex ICS-900 ion chromatograph (Thermo Fisher Inc., Japan). An IonPac AS12A column (4 × 2 mm, Thermo Fisher Inc.) was used for measurement. The regenerant and mobile phase composed of sulfuric acid (12.5 mmol/L) and sodium hydrogen carbonate (0.3 mol/L) + sodium carbonate (2.7 mmol/L), respectively. The flow rate and injection volume were 1.0 mL/min and 10 µL at ambient temperature, respectively. An AMMS 300 system was used as the micromembrane suppressor (4 mm, Thermo Fisher Inc.). Under our experimental conditions, elution times of F−, Cl−, NO2−, NO3−, and SO42− were 2.0, 2.9, 4.6, 5.9, and 8.4 min, respectively.
Cations were analyzed by an inductively coupled plasma optical emission spectrometry iCAP-7600 (Thermo Fisher Inc.).
March, May, and November in Thailand are the beginning of the summer, rainy, and winter seasons, respectively. The condition of the Ping river is quite different in these seasons. Therefore, we selected these days for collecting water samples.
The water pollution in Thailand is caused by urbanization, agricultural, and industrialization activities. The main pollutants were heavy metals, organic waste, and chemical substances, etc. In addition, the sewage system around the target area was as follows; mountainous areas (from MP 1 to 3) do not have any sewage system; an activated sludge process for a sewage system is adopted in the location from MP4 to 14 or from MP23 to 27 (the percentage of sewered population was approximately 50–70%); a simple wastewater treatment system, namely an activated sludge process and an aerated lagoon system, is adopted in the location from MP15 to 22. The National Environment Board in Thailand categorized surface water quality into 5 classes: 1 (very good), 2 (good), 3 (fair), 4 (poor), and 5 (very poor). The Ping River was classified as 3 (fair) and a previous study suggested a decrease in fecal coliform bacteria and suspended solids in the water quality.2) Therefore, the understanding of the current status of target materials was needed to solve the environmental water problems.14) In this study, we focused on concentrations of anions and cations in the Ping river.
The occurrence of anions (F−, Cl−, NO2−, NO3−, and SO42−) along the Ping river were shown in Fig. 2. In this study, the concentrations of anions in the Ping river from MP 1 to 15 (at the upstream area) tended to be lower, which indicated that there were no or only few contaminants in the surface water phase, because these areas were surrounded by deciduous forest and orchards. On the other hand, the MP 16 to 27 areas were closer to the main city in Chiang Mai and the concentration of anions tended to increase in these areas because the surrounding areas consisted of residents, agriculture, and aquaculture (fish farm and longan farm) areas, as well as some industrial factories. This suggests that the fertilizers and industrial or household wastewaters were contaminating the Ping river at downstream locations. Abovementioned, the sewage system is highly adopted in the location MP16 to 27. However, these sewage systems can not cover and perfectly perform the purification of wastewater in Chiang Mai and Lamphun areas. Thus, the wastewater included the fertilizers and industrial or household wastewaters directly flowed into Ping river. Similar trends were reported by a previous study.12)
The standard value of F− (below 1 mg/L) was established by the Coastal Water Quality Standard in Thailand, and a previous study reported that the concentration of F− was over the standard value in 2016. In this study, that of F− that was below 1 mg/L in all seasons.13) The standard values of Cl− as Cl2 (not more than 2000 mg/L) and NO3− (not more than 5 mg/L) were established by the Industrial Effluent Standard for Industrial Estate and Surface Water Quality, respectively. Cl− is an indicator for evaluating anthropogenic pollutants and is one of the major anions commonly found in wastewater. Cl− is usually included in wastewater from industries and municipalities, effluent wastewater from water softening, and agricultural runoff. Therefore, the concentration of Cl−, which was emitted by the human activity, increased in main city areas of Chiang Mai compared to countryside in north Thailand (winter and summer seasons). Additionally, the standard values of NO2− and SO42− were not established by government agencies in Thailand and therefore these data were valuable for understanding the present water quality in the Ping river.
Previous studies reported the flood effect on the water quality in the Ping river.10) This indicated that the inflow or outflow of water in the Ping river strongly affects the water quality. In this study, the water flow rate was in the order of summer season < winter season < rainy season (Table 1). In particular, the water flow rate in the rainy season in main city areas of Chiang Mai was approximately 200 m3/s. Therefore, the total amount of anions in the rainy season were higher compared to other seasons as a whole because each anion released from near the areas or soil flowed into the Ping river. Additionally, there is no sewage system or only few sewage systems in the mountainous areas, suggesting that the concentration of F−, Cl−, and NO3− were rarely higher in the location from MP1 to MP10 compared to other areas. However, through our research, the behaviors of the river water quality could not be explained in conjunction with the seasons. Therefore, we need to keep monitoring the water quality in the Ping river and investigating the environmental conditions of surrounding areas in detail to elucidate the factors for water pollutions.
Concentrations of Cations in the Ping RiverFigure 3 shows the occurrence of cations (Na+, Mg2+, Si4+, S6+, K+, and Ca2+) along the Ping river. Initially, the qualitative analysis of water samples from the Ping river was evaluated for a preliminary experiment in this study. Copper, nickel, manganese, zinc, cadmium, chromium, lead, mercury, and arsenic, of which the standard values were established by the Surface Water Quality, were not detected in our experiments (the limits of quantitation of manganese is less than 0.1 µg/L, copper, nickel, zinc, cadmium, chromium, or mercury is less than 1 µg/L, and lead and arsenic is less than 10 µg/L.) On the other hand, Na+, Mg2+, Si4+, S6+, K+, and Ca2+ were detected at different seasons in the Ping river. A previous study developed the measurement method (e.g. manganese etc.) for natural and waste water quality14) but there are no reports about measuring (or monitoring) these cations in the Ping river. Therefore, the monitoring of these detected cations was valuable for understanding the present water quality in the Ping river.
●: Rainy season (2018), 〇: Winter season (2018), 
: Summer season (2019).
The results demonstrated that the changes in the concentration of Na+, Si4+, S6+, and K+ were similar to the trends of anions. The concentrations from MP 1 to 15 areas tended to be lower, but those from MP16 to 27 areas were higher in this study. These results were also caused by the inflow of fertilizers and industrial or household wastewaters. However, the concentration behaviors of Mg2+ and Ca2+ were not consistent with that of other cations. Moreover, the concentrations of Mg2+ and Ca2+ from MP 3 to 10 areas in the summer season were higher than other seasons suggesting that an elevated level of Ca2+ and Mg2+ resulted from increased weathering caused by accelerated physical erosion of rocks, due to elevated climate-related mechanical forces characteristic of the sampling points of MP 1 to 15 in mountainous areas.15,16) Additionally, the water flow rate in rainy season was higher than that in the winter or summer seasons. Therefore, the total amount of cations in rainy season were greater than that in other seasons in this study.
In particular, the concentration of Na+ in the rainy season was drastically higher compared to other seasons. On the other hand, the concentration of other cations in rainy season was similar to other seasons in this study. It can be suggested here that in the rainy season, rains will remove a significant amount of the salts that accumulate in the soil such as sodium, and then flow into the river.15,16) Moreover, there is no or few sewage systems in the abovementioned mountainous areas, indicating that Ca2+ and Mg2+ inflowed directly into the river. However, the concentrations of each cation were quite different between each season in this study. Further investigations were needed to elucidate the factors for controlling the Ping river water quality.
In the present study, the water quality of the Ping river in Thailand at the summer, rainy, and winter seasons was investigated. The concentrations of anions and cations in river were detected, the concentration of them in the rainy season was higher than that in other seasons. These phenomena were due to the inflow of the fertilizers and industrial or household wastewaters in the Ping river at downstream (closer main city) locations. On the other hand, the concentrations of Mg2+ and Ca2+ in the Ping river was not changed from MP11 to 27. Therefore, we need to keep measuring or monitoring the water quality in the Ping river. In addition, our results in this study have not yet been reported by a government agency in Thailand. This fundamental data is valuable for the understanding of the conditions of the Ping river at different seasons and this will be useful for maintaining or improving the water environment in the future.
Authors would like to acknowledge a part of financial support from Cluster of Excellence on Biodiversity-based Economics and Society (B.BES-CMU), Chiang Mai University.
The authors declare no conflict of interest.
