Comprehensive evaluation of shallow groundwater pollution in the Hangjiahu Plain and its prevention

According to the surface water environmental quality standard (GB 3838-2002), the concentration of each pollutant component (mg L) specified in the water-like standard is as follows: total phosphorus, ; codcr，40；cr6+，；Total Lead,; nh4—n，。Except for the nitrate nitrogen content in Liangshui River, which is less than the standard of water (less than 10mg l), the concentrations of other pollutant components are greater than those of water standard, and the pollutant concentration value of river water in the dry season (April) is greater than that in the wet season (June), which is due to the abundant rainfall in the wet season diluting the pollutant concentration of the river water.

In order to determine the scope of pollution of the sewage river, two more wells were found at a distance from the river: Maying and Vineyard, of which Maying is in the southwest of the coal plant, 310m away from the coal plant, with a depth of about 150m, and the vineyard is also in the southwest of the coal plant, 580m away from the coal plant, and the well is about 50m deep, which has been mined for thirty or forty years. It can be seen from Table 4-2 that the COD and NH4-N variation of groundwater are basically the same, that is, the farther away from the river, the smaller the concentration value, and the COD and NH4-N of the coal plant well are much larger than those of Maying.

It should be noted that the well in the vineyard is mainly used for grape cultivation and irrigation, and its COD is higher than that of Maying, and NH4-N is even nearly twice as high as 1, which is related to the agricultural pollution and long mining history of the well. The high COD of coal plants is also related to the open-pit operation of coal plants. One thing is for sure, the Liangshui River is polluted with COD and NH4—N to and 3.

As for the other components: total phosphorus, the concentration of river water and groundwater are very small ( , consistent with the law of laboratory tests; Cr6+ and NO3—N, the concentration of river water is not high, and the groundwater is also very small.

Table 4-2 Concentration of characteristic pollution components in Liangshui River and each well Unit: mg L Table 4-3 Concentration table of conventional inorganic components in Liangshui River and each well Unit: mg L From Table 4-3, it can be seen that in the conventional cations, Mg2+ and Ca2+ are both groundwater greater than river water, while Na+ and K+ are river water greater than groundwater, and except for 1, the concentration of K+ in groundwater is shown to be smaller the farther away from the river.

The anion f- and the sum of the groundwater is greater than the river water (except 3), and the cl- shows that the coal plants near the river are both larger than the river water, and the concentration is higher the farther away from the river, and the cl- of the two wells in the distance is smaller than the river water. It is not clear from the variation law of Cl- that river water has an impact on groundwater, and there may be other Cl-** in groundwater.

Shallow groundwater refers to an aquifer within 60 meters below the surface.

Introduction: Shallow groundwater, shallow groundwater mainly refers to the relatively shallow burial, and the local atmospheric precipitation or surface water has a direct recharge relationship with the submerged or weakly confined water, mainly the aquifer within 60 meters below the surface. Due to its shallow burial and lack of deep rock filtration, the water is easily polluted by sewage discharged from factories and pesticides left on farmland, and drinking shallow contaminated groundwater can be harmful to health.

Water quality surveys. According to the results of the "Investigation and Evaluation of Groundwater Pollution in the North China Plain" implemented by the Institute of Hydroenvironment, Geology and Environment of the Chinese Academy of Geological Sciences, the comprehensive quality of shallow groundwater in the North China Plain is poor and the pollution is serious, and the unpolluted groundwater only accounts for the sampling points. The comprehensive quality of deep groundwater is slightly better than that of shallow groundwater, and the pollution is lighter.

Groundwater in a geological structure located in the first permeable layer above the first aquifer.

At present, in the evaluation of urban groundwater pollution, most of the evaluation of volatile phenol, cyanide, mercury, chromium, arsenic, (known as industrial pollutants), nitric acid, nitrous acid, and ammonia nitrogen (known as agricultural and domestic pollution) are mostly used. The indicators that are often used are: (1) Detection rate:

Detection rate (%) = total number of detection points Total number of monitoring points; (2) Over-standard rate: over-standard rate (%) = number of over-standard points and total number of detected points; (3) Exceeding the standard multiple: exceeding the standard multiple = exceeding the content of a substance at the purging point The drinking water quality standard of the substance; (4) Comprehensive pollution index:

The comprehensive pollution index is calculated using the following formula: p=n i=1ci COI, where: p is the comprehensive pollution index; CI COI is the pollution index of the substance; Ci is the measured content of substance I (M l); COI is the drinking water standard for substance I; i
……n is for pollution.