Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Language
Publication year range
1.
Huan Jing Ke Xue ; 44(11): 6062-6070, 2023 Nov 08.
Article in Chinese | MEDLINE | ID: mdl-37973090

ABSTRACT

Elucidating the main sources and transformation process of nitrate for the prevention and control of groundwater nitrogen pollution and the development and utilization of groundwater resources has great significance. To explore the current situation and source of nitrate pollution in shallow groundwater around the Dianchi Lake, 73 shallow groundwater samples were collected in the rainy season in 2020(October) and dry season in 2021(April). Using the hydrochemistry and nitrogen and oxygen isotopes(δ15N-NO3- and δ18O-NO3-), the spatial distribution, source, and transformation process of nitrate in shallow groundwater were identified. The contribution of nitrogen from different sources to nitrate in shallow groundwater was quantitatively evaluated using the isotope mixing model(SIAR). The results showed that in nearly 40.5% of sampling points in the shallow groundwater in the dry season, ρ(NO3--N) exceeded the 20 mg·L-1 specified in the Class Ⅲ water quality standard for groundwater(GB/T 14848), and in more than 47.2% of sampling points in the rainy season, ρ (NO3--N) exceeded 20 mg·L-1. The analysis results of nitrogen and oxygen isotopes and SIAR model showed that soil organic nitrogen, chemical fertilizer nitrogen, and manure and sewage nitrogen were the main sources of nitrate in shallow groundwater; these nitrogen sources contributed 13.9%, 11.8%, and 66.5% to nitrate in shallow groundwater in the dry season and 33.7%, 31.1%, and 25.9% in the rainy season, respectively. However, the contribution rate of atmospheric nitrogen deposition was only 8.5%, which contributed little to the source of nitrate in shallow groundwater in the study area. Nitrification was the leading process of nitrate transformation in shallow groundwater in the dry season, denitrification was the dominant process in the rainy season, and denitrification was more noticeable in the rainy season than that in the dry season.

2.
Huan Jing Ke Xue ; 43(7): 3532-3542, 2022 Jul 08.
Article in Chinese | MEDLINE | ID: mdl-35791537

ABSTRACT

The extensive application of phosphorus fertilizers to croplands and the aggregation of towns and villages around plateau lakes has resulted in the continuous accumulation of phosphorus in the soil profile and the discharge of phosphorus pollutants, which causes phosphorus pollution in shallow groundwater around the lakes. The phosphorus entering the lake with shallow underground runoff in the region around the lake also affects the water quality safety of plateau lakes. The spatiotemporal differences in phosphorus concentrations in 452 shallow groundwater samples and the driving factors were analyzed by monitoring wells in croplands and residential areas around the eight lakes in Yunnan province during the rainy and dry seasons from 2019 to 2021. The results showed that seasonal changes and land use influenced phosphorus concentrations and their composition in shallow groundwater. The concentration of phosphorus in shallow groundwater in the rainy season was higher than that in the dry season, and it was also greater in cropland than that in residential areas. DTP was the dominant form of TP, accounting for 75%-81%, and DIP was the dominant form of DTP, accounting for 74%-80%. Nearly 30% of the samples around the eight lakes had TP concentrations exceeding the surface water Class Ⅲ standard (GB 3838); the exceeded rates of phosphorus in groundwater around the Erhai Lake (52%), Qiluhu Lake (45%), Xingyun Lake (42%), and Dianchi Lake (29%) were far higher than those of Yangzonghai Lake (16%), Fuxianhu Lake (13%), Chenghai Lake (6%), and Yilonghu Lake (5%). The key driving factors of phosphorus concentrations in shallow groundwater were water-soluble phosphorus (WEP), water content (MWC), soil organic matter (SOM), total nitrogen (TN), pH in the soil profile, and pH and groundwater level in the shallow groundwater (P<0.05). The increases in WEP, SOM, TN, and MWC in the soil and pH in groundwater significantly increased the concentrations of DIP and DTP in shallow groundwater, whereas the decrease in groundwater level significantly reduced the concentrations of DTP and DIP in the groundwater.


Subject(s)
Groundwater , Water Pollutants, Chemical , China , Lakes/chemistry , Nitrogen/analysis , Phosphorus/analysis , Soil , Water Pollutants, Chemical/analysis
3.
Huan Jing Ke Xue ; 43(6): 3027-3036, 2022 Jun 08.
Article in Chinese | MEDLINE | ID: mdl-35686772

ABSTRACT

Shallow groundwater around plateau lakes is one of the important sources of production and potable water. Shallow groundwater NO3--N pollution driven by factors such as surface nitrogen input load, rainfall, and irrigation is serious and threatens the water quality of plateau lakes. In order to identify the characteristics of nitrogen pollution and its driving factors in shallow groundwater, 463 shallow groundwater samples were collected from wells in farmland and residential areas around eight plateau lakes of Yunnan in the rainy and dry seasons in 2020 and 2021. The results showed that the average values of ρ(TN), ρ(NO3--N), ρ(ON), and ρ(NH4+-N) in shallow groundwater were 24.35, 15.15, 8.41, and 0.79 mg·L-1, respectively. Nearly 32% of the shallow groundwater samples around the eight lakes failed to meet the groundwater Class Ⅲ water quality requirements (GB/T 14848) of 20 mg·L-1 for NO3--N. Among them, the NO3--N concentration in the shallow groundwater around Erhai Lake, Qiluhu Lake, and Dianchi Lake had the highest rate of exceeding the standard, followed by that around Xingyunhu Lake, Yangzonghai Lake, Yilonghu Lake, Fuxianhu Lake, and Chenghai Lake as the smallest. Land use and seasonal changes affected the concentration and composition of various forms of nitrogen in shallow groundwater. The concentration of various forms of nitrogen in shallow groundwater in the farmland area was higher than that in the residential area. The nitrogen concentration in shallow groundwater in farmland was higher than that in residential areas. Except for NH4+-N, the concentration of various forms of nitrogen in shallow groundwater in the rainy season was higher than that in the dry season. NO3--N was the main nitrogen form in shallow groundwater; the fraction of TN was 57%-68%, and the fraction of ON was 27%-38%. The EC, DO, ORP, and T in shallow groundwater were the key factors reflecting or affecting the concentration of various forms of nitrogen in shallow groundwater, whereas soil factors had a weak impact on the concentration of various forms of nitrogen in shallow groundwater.


Subject(s)
Groundwater , Water Pollutants, Chemical , China , Environmental Monitoring/methods , Lakes , Nitrates/analysis , Nitrogen/analysis , Water Pollutants, Chemical/analysis , Water Quality
4.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-912861

ABSTRACT

Objective: To observe the clinical efficacy of acupuncture plus medicine in treating laryngopharyngeal reflux due to liver-qi stagnation and spleen deficiency. Methods: A total of 70 patients were divided into a control group and an observation group by the random number table method, with 35 cases in each group. Both groups were treated with conventional medications, and the observation group was treated with additional acupuncture therapy. The reflux symptom index (RSI) and reflux finding score (RFS) were evaluated. Esophageal motility indicators such as lower esophageal sphincter pressure (LESP) and upper esophageal sphincter pressure (UESP), and salivary pepsin level were measured. The clinical efficacy was also compared. Results: The total effective rate of the observation group was higher than that of the control group (P<0.05). After treatment, the RSI and RFS scores in both groups decreased significantly (all P<0.05), and the RSI and RFS scores in the observation group were significantly lower than those in the control group (both P<0.05). There were no significant changes in the LESP and UESP in the control group (both P>0.05), while LESP and UESP in the observation group increased significantly (both P<0.05), and higher than those in the control group (both P<0.05). The salivary pepsin levels in both groups decreased (both P<0.05), and the salivary pepsin level in the observation group was significantly lower than that in the control group (P<0.05). Conclusion: Acupuncture plus medicine can improve symptoms and signs in patients with laryngopharyngeal reflux due to liver-qi stagnation and spleen deficiency, and regulate esophageal motility and salivary pepsin level. Its efficacy is more significant compared with medicine alone.

SELECTION OF CITATIONS
SEARCH DETAIL
...