I. Elemental Geochemical Characteristics of Xiaoqing River Basin
Siaoqing River originates from Jinan Spring, starting from Muli Zhuang in the west and injecting into Laizhou Bay in the east, with a total length of 237 km, and a watershed area of 10,336 km2. Xiaoqing River Basin is an important economic development area in Shandong Province, with the industrial town of Zibo and the emerging industrial cities of Guangrao and Shengli Oilfield, complete industrial categories and township enterprises; A wide variety of crops, not only wheat, corn and cotton of all kinds, but also the reputation of the Yellow River, Mingshui rice, Zhangqiu onions and Shouguang vegetables, known throughout the country as the first northern tons of grain counties and cities - Huantai that is located in the south-central part of the work area. However, since the 1970s, with the basin Jinan, Zibo and Qilu Petrochemical and other cities and the rapid development of industrial and mining enterprises, industrial wastewater and domestic sewage discharges increased year by year, the entire drainage basin sewage discharges accounted for the annual average runoff into the sea of the Xiaoqing River 2/3 more, resulting in the deterioration of the water environment of the Xiaoqing River, the water body is seriously contaminated, the pollution of the water body so that the agricultural irrigation of water quality exceeded the standard in many places serious situation. Due to the lack of agricultural water, sewage irrigation area is expanding, sewage irrigation makes the soil Gr, Pb, Cu and other heavy metals and organic pollutants accumulation doubled, resulting in a serious decline in the quality of the soil environment, sewage irrigation area of the decline in the quality of agricultural and livestock products, the province's main sewage irrigation area of the province's main heavy metals in food crops exceeded the standard rate of 25%, according to statistics. In recent decades, the incidence of cancer, liver disease and fetal malformation along the polluted areas of the river increased significantly.
Therefore, it is of great significance to carry out the research on soil environmental quality along Xiaoqing River, to find out the pollution status of soil environment along Xiaoqing River, to carry out the evaluation of soil environmental quality, and to put forward the countermeasures and measures for soil improvement to improve the quality of agricultural products in the study area and to safeguard people's health.
The study area is from Jinan City in the west, east to the Bohai Sea estuary; from the north to the line of Qudie - Gaocheng County Town - Purehua Town, south to Zouping - Huantai. Jurisdiction of Jinan, Zibo, Dongying, Weifang and Binzhou five cities Zhangqiu, Jiyang, Zouping, Gaocheng, Boxing, Huantai, Guangrao and Shouguang 8 counties and cities.
(A) the geochemical content of elements in the Xiaoqing River Basin characteristics
1. Soil elemental statistical characteristics along the Xiaoqing River
Soil elemental content distribution along the Xiaoqing River is shown in Table 3-17, in the 25 analyzed elements and indicators, most of the outliers before and after the arithmetic mean value difference is small, only Cr, Hg, Mo, Se and S 5 mean value difference is large, Cr by 81.21 × 10.0%. Cr changed from 81.21×10 -6 to 72.44×10 -6, Hg changed from 52.8×10 -9 to 29.6×10 -9, Mo changed from 0.657×10 -6 to 0.589×10 -6, Se changed from 0.25×10 -6 to 0.20×10 -6, and S changed from 0.083% to 0.027%.
In terms of the coefficient of variation, 20 of the 25 indicators had a coefficient of variation of 0.5 or less, and the elements or indicators with a higher degree of data dispersion were S, Hg, Cr, Se, and Zn, whose original values of coefficients of variation were 5.74, 2.03, 0.79, 0.69, and 0.64, and the coefficients of variation of the 5 indicators were 0.30, 0.35 after the outliers were eliminated, 0.11, 0.25, and 0.25, and 0.27% for the 5 indicators, respectively, 0.11, 0.25, 0.16, all <0.4.
Table 3-17 Characteristic Parameters of Geochemical Content of Surface Soil Components in Xiaoqing River Basin
In terms of the distribution of elemental background values, the soil background in the area is basically close to that of the Lower Yellow River Basin in terms of the elements of As, Hg, Mo, SiO2, Al2 O3, TFe2 O3, and K2 O, while the elements of Na2 O, P, and B are slightly lower, while the elements of Na2 O, P, and B are slightly lower, while the elements of Na2 O, P, and B are slightly lower, P, B elements are slightly lower, while Cd, Co, Cr, Cu, F, Mn, Ni, Pb, V, Zn, N, S, Se, CaO, Mg are slightly higher than those in the lower Yellow River Basin soils; Co, Mn, Mo, Pb, Na2 O elements in the soils along Xiaoqing River are significantly lower than the average value of the soils in Shandong Province, of which Mo is only 0.1 times of that of the soils in Shandong Province, and the elements As, B, Cd, Cr, F B, Cd, Cr, F, Hg, Ni, Zn, Se, TFe2 O3, MgO, CaO and other elements are higher than the average value of soils in Shandong Province, of which CaO, Mg0, Cd elements are 2.56, 1.78, 1.79 times of the soils in Shandong Province, respectively, while Cu, Al2 O3, K2 O are basically equal to the average value of the soils in Shandong Province; the soil along the Xiaochenghe River has As, Hg, Mo, Se, Pb, Zn elements in the soil along Xiaoqing River are significantly lower than the average value of our soils, of which Hg, Mo is only 0.46, 0.3 times of our soils, Cd, Cr, F, Cu, Ni, MgO, CaO, Na2 O is higher than the average value of our soils, of which MgO, CaO are 1.84, 2.88 times of our soils, and the rest of the elements are basically close to the average value of our soils.
2. Distribution characteristics of soil elements in the upper, middle and lower reaches of the Xiaoqing River
Comparing the statistics of elemental contents of the surface soil in different sections of the upper, middle and lower reaches of the Xiaoqing River (Fig. 3-31), it can be found that, among the elements in the upper reaches of the river, the background values of F, Mn, Al2 O3, S, MgO and K2 O are lower than that in the middle and lower reaches of the river, and the background values of SiO2 and Na2 O were the highest in the upstream soil background values, while the other elements were higher than the downstream soil element background values and lower than the midstream soil element background values. The background values of As, B, Cu, Cd, Cr, Co, F, Hg, Mn, Ni, Pb, Zn, and Se in the midstream soil were higher than the background values of the upstream and downstream soils, among which Cd, Hg, and Se were 1.3, 1.6, and 1.4 times higher than the background values of the downstream soils, respectively, while SiO2 and Na2 O were lower than the background values of the upstream and downstream soils.
Figure 3-31 Soil element background values of upper, middle and lower reaches of Xiaoqing River
3. Distribution characteristics of soil elements in the south and north banks of Xiaoqing River
Comparing the statistics of soil element background values in the north and south banks of the Xiaoqing River, there is the following pattern as shown in Fig. 3-32, the background values of soil elements in the south bank of the Xiaoqing River, such as Hg, P, Pb, N, SiO2, and Na2 O, are slightly higher than that of soil elements in the north bank. The background values of Hg, P, Pb, N, SiO2 and Na2 O in the south bank soil were slightly higher than the background values of the north bank soil elements, of which Hg was 1.2 times of the background values of the north bank soil; As, B, Cd, Cr, F, Mn, Ni, Pb, Zn, Se and other elements and oxides were lower than the background values of the north bank soil elements, of which As, S, and CaO were 0.86, 0.88, and 0.81 times of the background values of the north bank soil, respectively.
Figure 3-32 Soil elemental background values on the south and north banks of Xiaoqing River
(II) Elemental profile characteristics
1. Distribution of elements in horizontal soil profiles along Xiaoqing River
Three horizontal profiles were laid out in the direction of Xiaoqing River vertically in Lixing District, Boxing County and Wangdao respectively, and the statistics of the three profiles showed that the distribution of elemental content varied considerably from one soil profile to another. The distribution of different soil profiles varies greatly, and there is also a significant difference between the two banks of Xiaoqing River in the same soil profile, see Table 3-18.
Table 3-18 Statistical table of elemental content of horizontal profiles of soils along Xiaoqing River
Continued Table
1) Lixing City profile starts from Wangsheren Town in the south, and reaches to Liujiajie in the north, with densely populated residential areas. The soil on the south bank of this profile is mainly distributed with tidal brown soil, while the north bank is dominated by tidal soil and salinized tidal soil. Statistics show that the content of soil elements As, Cr, F, Hg and Ni is significantly higher on the south bank than on the north bank, while Cd, Cu, Se and P are lower than on the north bank, and the content levels of the rest of the elements are relatively similar. However, the contents of heavy metal elements are all higher than the background value of soil in Xiaoqing River, which may cause a certain degree of pollution to the soil environment, which is related to the influence of human activities.
2) Boxing profile south from Qifeng Town north to Xifu Village in the west of Boxing County, the soil on the south bank is dominated by wet tidal soil subclasses, and the north bank is dominated by tidal soil. Statistics show that the distribution of heavy metal elements As, Cd, Cr, Cu, Hg, Pb and Zn in the soil on the north bank is significantly higher than that on the south bank, while the content of beneficial elements B, Mo, Se, N, S and CaO is significantly higher on the south bank than that on the north bank.
3) The Wangdao profile extends from Wolpu Township in the south to Guangbei Farm in the north, and the soil type is salinized tidal soil. The level of soil element content on the north bank is obviously lower than that on the south bank, in which the content of soil heavy metal elements As, Cd, Cr, Cu, Hg, Ni, Pb and Zn on the north bank is obviously lower than the content of the background value of Xiaoqing River, while the content on the south bank is slightly higher.
2. Distribution characteristics of vertical soil profile elements along Xiaoqing River
1) Distribution of vertical soil profile elements in Licheng. The soil texture of the profile was found in the field to be basically sandy clay in the upper layer and clay below 60 cm. Rust appeared in the deeper part. With the increase of depth, the organic matter content decreased, and the soil elements showed regular changes (Figure 3-33). The main components of soil, SiO2, MgO, K2 O, CaO, and Na2 O, did not change much with depth, and it was inferred that the composition of the original sediments was relatively stable, and the sedimentary rhythmites were not obviously stratified. The content of N, P, Cr, Hg, S, Se, Cd, Pb and other elements in the surface soil is abnormally high and decreases drastically from the surface to the depth of 80 (100) cm, especially the elements of N, P, Se, S, Hg. It is believed that the influence of human production activities on the soil plays a larger role, and it is presumed that the depth of influence is 100 cm. The content of elements such as TFe2 O3, Al2 O3, Mn, B, V, Co, etc. increases with the increase in depth and is enriched in the deeper part of the soil, the reason for which the soil may be that the surface layer of the loam becomes acidic, and the elements migrate to the bottom of the soil in the form of ionic compounds under the action of the epiphytic life, thus resulting in the elements being more enriched at the bottom. As, F, Ni, Cu, Zn, Mo and other elements content with the increase of depth is not obvious.
2) Distribution characteristics of elements in vertical profile of Boxing soil. The soil texture on the profile was found in the field with no obvious change, all of which were clay. With the increase of depth, a variety of elements showed regular changes (Figure 3-34). The main components of soil, SiO2 and Na2 O, changed slightly with depth, and were more stable in the 0-100 cm depth section, while increasing with depth from 100 cm; elements such as TFe2 O3, Al2 O3, MgO, K2 O, and V, Co, and Mn (which showed highly significant correlation with TFe2 O3 and Al2 O3), on the other hand, decreased with depth at 100 cm. Although loam-forming action can cause claying of surface soils and vertical changes in mineral composition, such a truncated change in mineral composition is obviously more closely related to the original sedimentary composition.Elements such as As, Cd, Cr, Hg, Ni, F, Cu, Pb, Zn, N, P, S, Se, etc. decrease with depth, and are abnormally enriched in the surface layer of the soils and decrease sharply from the surface to the depth of 60 cm, especially N, P, S and Se. There is a sharp decrease, especially in N, P, and Hg elements. This distribution is not only related to the stratification of the original sedimentary composition, but also related to the transport of surface biochemistry, adsorption and precipitation redistribution under the constraints of soil texture and organic matter content. Among them, N, P, Hg, and S were characterized by strong topsoil enrichment, which was obviously related to the pollution. elements such as C, B, and Mo did not change significantly with the increase of depth.
Figure 3-33 Distribution of elements in the calendar profile of soil along Xiaoqing River
3) Distribution characteristics of elements in the vertical profile of Wangdao soil. The soil type is dominated by salinized tidal soil. The soil texture on the profile was found in the field to be dominated by clay and sandy clay, with loose soil texture. The elemental content with depth showed obvious regularity (Figure 3-35): the content of soil main components SiO2 and Na2O increased with depth, TFe2O3, Al2O3, K2O, MgO, etc. were enriched in the surface layer of the soil, and tended to the background value after dropping sharply from 60 cm, which may be related to the composition of the soil clay/sand, and the content of the organic matter change. as, Cd, Cr, F, Hg, Ni, Cu, Pb, Zn, Mn, N, P, Se, S and other elements are enriched in the depth section from the surface to 60cm, and tend to the background value after decreasing sharply from 60cm, especially N, P, S, Cu, Pb, Zn elements. This distribution is on the one hand* related to the original sedimentary composition of the soil, and on the other hand* the strong enrichment characteristics of N, P, S, Cu, Pb, Zn and other elements caused by epigenetic effects are obviously affected by pollution.As element is obviously increased after a sharp decrease from the surface to 130cm, which may be related to the downward migration of As due to the experience of leaching effect.CaO is gradually increased from the surface to 60cm, enriched in the middle, and sharply increased from 60cm to the deep part. CaO gradually increased from the surface to 60cm, and was enriched in the middle, and decreased sharply from 60cm to the depth, which may be related to the use of mineral phosphorus fertilizer, etc. There was no significant change in B, Mo and other elements from the surface to the depth.
Figure 3-34 Distribution of elements in Boxing profile of soil along Xiaoqing River
Figure 3-35 Distribution of elements in Wangdao profile of soil along Xiaoqing River
(C) Combination of soil elements
1. Cluster analysis
Cluster analysis is a kind of multivariate statistical method, which is mainly used to recognize things with similarity and "cluster" them according to their different characteristics. Different characteristics to be "clustered", so that things in the same category have a high degree of homogeneity. The elemental categorization of background values by cluster analysis provides a more natural and objective description of the differences and connections between the background values of multiple samples. The principle of the cluster analysis method is to categorize the elements (or samples) by the degree of similarity between multiple samples, so that all elements within a class have a closer relationship with each other, while the interrelationship between the various classes is relatively distant. The degree of similarity between soil geochemical characteristics of multiple samples is usually expressed by certain indicators, based on the correlation coefficients between the geochemical characteristics. From these, cluster analysis results consistent with agrogeological interpretation are selected. By analyzing the spectrogram (correlation coefficient, Euclidean distance) of the clustering analysis of surface soil elements along Xiaoqing River, see Figure 3-36, the following elemental combinations exist for 25 elements:
Figure 3-36 Spectrogram of correlation coefficients of the clustering analysis of surface soil elements along Xiaocheng River
1) TFe2 O3, Al2 O3, Co, Ni, V;
2) Cd, Zn, Mo, Pb, Se;
3) F, Mn, As;
4) SiO2, Na2 O;
5) N, P;
6) Hg, P, Cr;
7) S.
2. Factor Analysis
Factor analysis is a method of analyzing a large amount of geological observation data and making a Factor analysis is a multivariate statistical analysis method to analyze and make a more reasonable explanation of a large amount of geological observation data, which can reflect the intricate relationship between many variables through the data method. Twenty-five elements reflecting the characteristics of the agro-geological background were selected for factor analysis of the soil along Xiaoqing River. According to the eigenroot percentage (variance contribution) and cumulative percentage of the eigenroots. Calculation results show that the percentage of variance contribution of the first 4 eigenvalues reaches 71.187%, and taking the first 4 eigenvalues has been able to extract more than 70% of the information of the changes of the original data, which is enough to explain the problem.
Calculating the initial factor loading matrix, and using the variance of the great orthogonal rotation to simplify the structure of the factor loading matrix, Table 3-19 for the rotated factor loading matrix. Table 3-19 shows the rotated factor loading matrix. From the table, it can be seen that the elements positively correlated with the first principal factor are As, Co, F, Mn, Ni, V, Al2 O3, TFe2 O3, K2 O, and negatively correlated with Na2 O; the elements positively correlated with the second principal factor are Cd, Cu, Hg, Mo, Pb, Zn, Se; the elements positively correlated with the third principal factor are S, CaO, and negatively correlated with SiO2; the elements positively correlated with the fourth principal factor are S, CaO, and negatively correlated with SiO2; the elements negatively correlated with SiO2; and the elements positively correlated with SiO2 are S, CaO. N, P, and Cr are positively correlated with the fourth principal factor.
Table 3-19 Factor loading matrix after rotation of surface soil along Xiaoqing River
Analysed by the principal factor score map (Figure 3-37), the combination of metal elements represented by principal factor 1 is prominent in the middle section of Xiaoqing River, which belongs to the jurisdiction of Boxing and Gaocheng counties, and the high value area distribution also occurs in the vicinity of Jinan. In addition, the distribution of high value areas also appeared around Jinan. Factor 2 represents Cd, Cu, Hg, Mo, Pb, Zn, and Se, which are important indicators of topsoil quality, and this factor is prominent in Jinan City, indicating that anthropogenic pollution in the city has a greater impact on the enrichment of these ions in the soil. Factor 3 indicates that the combination of S, SiO2, CaO elements can be considered as a characterization of soil geological factors, and its distribution is more consistent with the distribution of soil types within the Xiaoqing River coast. The main factor 4 represents the combination of N and P elements, which is prominent in the agriculturally developed areas in the middle section of Xiaoqing River, indicating that agricultural activities have a certain influence on the distribution of these elements.
Figure 3-37 Score of main factors along Xiaoqing River
Small Qing River Basin Environmental Pollution Status
Small Qing River Basin is an important industrial area in Shandong Province, including Jinan City, Jining City, and Zibo City, and other important large-scale industrial cities, and the main sources of pollution are fertilizer factories, plastic factories, iron and steel factories, oil refineries, heavy machinery factories, pharmaceutical factories, and power plants. etc. In recent years, with the rapid rise of township enterprises, small factories and mining enterprises, a wide range of types, throughout the major counties and townships. Due to the industrial emissions of three wastes is not good governance, to the environment has brought serious pollution and harm.
The sources of pollution in the area include: sewage wastewater, solid waste, municipal garbage and medical waste, as well as chemical fertilizers and pesticides. The big enterprises mainly include Shandong Chemical Plant, Jinan Yuxing Chemical General Factory, Jinan First Knitting Company, the Second Affiliated Hospital of Shanda University, Qilu Pharmaceutical Factory, Huangtai Power Plant, Jinan Daiyi Paper Manufacturing Third Factory and Jinan Chemical Fiber General Corporation and dozens of others.
The wastewater in the area mainly comes from urban sewage and industrial wastewater. The main pollutants in the wastewater are chloride, sulfate, chemical oxygen demand, fluoride, volatile phenols, ammonia nitrogen, cyanide, As, Pb, Cr, Cd, Hg. According to the information available in the industrial area of several key industrial sources of COD (Chemical Oxygen Demand) emissions statistics in Table 3-20.
Table 3-20 COD emission statistics of key industrial pollution sources in the area
Note: The source of the information is Jinan Environmental Protection Bureau, "Jinan Water Pollution Prevention and Control Plan".
The pollutants that produce the most slag and are relatively concentrated in the study area at present are mainly smelting slag, fly ash, slag, coal gangue and tailings. In Jinan, for example, solid waste disposal is a weak link in solid waste management, the main disposal method is currently incineration and landfill. Jinan solid waste storage in a variety of ways, the storage point is relatively decentralized, the storage of solid waste is mainly coal gangue, fly ash. Coal gangue is mainly stored in major coal companies; fly ash is mainly stored in Xiaoqinghe and Dasi dry ash field and other places. As most of the solid waste is well managed, it is not discharged into the environment.
From the point of view of the distribution of industries generating solid waste, the industries generating the largest amount of solid waste are smelting, thermoelectricity, extraction and chemical industry, which occupy more than 90% of the total amount, among which Jigang is the largest source of solid waste generation, with an average annual amount of 155.6×104 t.
Cr-containing wastes in Jinan are mainly generated by the Jinan Yuxing Chemical Plant, including Cr slag, Al sludge. As Cr slag contains the toxic component Cr6+, it has serious harm to the surrounding environment. The generation of fly ash is more concentrated, mainly distributed in the Huangtai Power Plant in Lixing District, and in 1998, the Huangtai Power Plant generated 57.5×104 t. The generation of steel slag is more concentrated, and is mainly distributed in the plant and the west of JISCO General Factory in Lixing District (Table 3-21).
Table 3-21 Solid Waste Key Generation Sources Generation Statistics
Note: The source of the information is Jinan Environmental Protection Bureau, Jinan City Water Pollution Prevention and Control Plan.
Municipal garbage mainly consists of several parts, including residents' living garbage, road sweeping garbage, commercial garbage and enterprises' and institutions' living garbage. According to the survey in 1998, Jinan City, the annual production of domestic garbage in the 55 × 104 t or so, living in the industrial area of the garbage accounted for nearly 1 / 6 of Jinan City, the rate of domestic garbage removal, treatment and disposal rate of 100%, harmless treatment reached 92.14%. Although the removal rate reached 100%, but not all harmless treatment, there is still part of the garbage without any treatment, in the various simple garbage dumps, or discharged to the suburbs of the countryside, causing pollution to the environment.
Because medical waste is toxic, bacterial and harmful, it is one of the main sources of pollution causing social cross-infection. Jinan daily production of medical waste 4269kg, medical waste of pathogenic bacteria is much higher than the living garbage and industrial waste, and the treatment of medical waste is mainly incineration and landfill, which will make the local atmospheric environment contaminated, increase the probability of disease transmission, spread, and exacerbate the pollution of groundwater quality of landfill sites. Therefore, it is necessary to strengthen the management, collection and treatment of medical waste.
In addition, agriculture in the upper reaches of Xiaoqing River is dominated by crops such as wheat, rice and corn. Agricultural fertilizers are mainly chemical fertilizers, supplemented by farmyard manure. In addition, the spraying of pesticides and the use of mulch film cause some pollution to the environment. The massive use of farmyard manure, chemical fertilizers and pesticides, most of which is absorbed by crops, and some of which seeps into the ground with precipitation and irrigation, polluting the groundwater body.
Three, soil environmental quality evaluation
(A) Evaluation factors and standards
Soil environmental quality evaluation to the national standard (GB 15618-1995) "soil environmental quality standards" as the evaluation criteria (Table 3-22). This standard only specifies the standards for 8 components or indicators, i.e., the upper limit content of different grades of 8 elements such as Cd, Hg, As, Cu, Pb, Cr, Zn and Ni. Therefore, the evaluation factor is selected for these 8 elements.
Table 3-22 Soil Environmental Quality Standards Unit: 10 -6
Continued
Note: ① Heavy metals (Cr is mainly trivalent) and As by elemental amount, applicable to cation exchange ＞ 5cmol (+) / kg, if ≤ 5cmol (+) / kg, the standard value of the table for half of the value. ② Hexachlorobenzene is the total of 4 isomers, and DDT is the total of 4 derivatives. ③The soil environmental quality standards for water and drought rotational cropping land, As using paddy field values, Cr using dry land values.
(II) Single-factor evaluation
1. Single-factor environmental quality grading statistics
The statistical results of single-factor environmental quality evaluation of heavy metal elements in the Xiaoqing River Basin are shown in Table 3-23. The results of single-factor soil environmental quality evaluation of mercury, arsenic, cadmium, lead, zinc, copper, chromium, nickel, etc., show that: the quality of the top layer of the surface soil within the investigation area of the Xiaoqing River is mainly in the category of Class Ⅰ and Ⅱ, while Class Ⅲ and Super Class Ⅲ are in the category of Ⅲ and Super Class Ⅲ, which are mainly in the category of Ⅲ and Ⅲ. At the same time, Class III and super Class III soil samples occupy a certain proportion, but the proportion is controlled within 3%. Among the single-factor indicators, Cu, Ni and Pb did not appear in the three indicators, and the number of Class I soil samples reached more than 90%. In the surface soil, Hg and Zn elements appeared in all 4 classes, of which the proportion of Class I exceeded 90%, and there were only 1 or 2 soil samples of Class III, the proportion of which did not exceed 1%. As and Cd also appeared in all 4 classes, of which there were soil samples of Class III, but the proportion of which did not exceed 1%, and the proportion of Class I soil was reduced, while the proportion of Class II was increased compared with that of Hg and Zn. Cd has the smallest proportion of class Ⅰ among all single-factor evaluation indexes, while the proportion of class 3 is the largest. The maximum number of soil samples with metal Cr element exceeding class III in this investigation area accounted for 0.6% of all samples. On the whole, the soil quality grade of Xiaoqing River Basin is still able to guarantee the safety of agricultural production at present.
2. Distribution characteristics of single-factor environmental quality grading
The environmental quality grading of As indicators is dominated by Class I soils, and Class II soils are mainly distributed in the middle reaches of Xiaoqing River Basin, concentrating in the area around Huashan Town, Sun Town, Fanjialin, Dingjiazhuang, Boxing County, and Dingzhuang Town in the form of islands, with the distribution area accounting for 5% of the total area. Although the overall quality is good, but note that the distribution area within Boxing County is large, and there is a tendency to connect with neighboring townships.
Cd indicators of the environmental quality level of the Ⅰ type of soil is dominated by the Ⅱ type of soil distribution in Jinan and the northeastern townships and Boxing, Gaoqing and Zouping counties, Ⅲ type of soil is mainly concentrated in the upper reaches of the Xiaoqing River in the city of Jinan, the Beiyuan Township area.
The environmental quality level of Cr indicators is mainly dominated by Class I soils, but at the same time Class III and super Class III soils are also distributed. Class Ⅱ soils are distributed in the upper reaches of Xiaoqing River near Jinan City as well as in the middle reaches of the watershed in areas such as Fanjialin, between Gaocheng East-Boxing County West and in the eastern part of Boxing County, while Class Ⅲ soils are mainly distributed in the urban area of Beiyuan Town and Zhaihaoshen, and the super Class Ⅲ soils are distributed only in the northern part of Beiyuan Town in Jinan City.
Copper indicators of environmental quality level Ⅱ soil is mainly distributed in the upper reaches of the Xiaoqing River in Jinan City and the northeastern region and the middle reaches of the eastern part of Boxing County, Boxing County, the territory of the only sporadic distribution of the island form.
Table 3-23 Statistical table of single factor evaluation of environmental quality of surface soil samples in the investigation area of Xiaoqing River
The environmental quality class of Hg indicator is mainly dominated by Class I soils, and although Class II and super Class III soils are also distributed, they are mainly concentrated in the urban area of Jinan City. In terms of distribution pattern, although Class Ⅲ soil is only distributed in Jinan city in the form of an island, the distribution range of Class Ⅱ soil in its periphery has a tendency to spread to the downstream, and therefore its development should be closely monitored in the future work.
Ni indicators of the environmental quality level to Ⅰ mainly, Ⅱ soil is mainly concentrated in the middle reaches of the Xiaoqing River, nickel Ⅱ soil distribution area is more dispersed, mainly in Huashan Town and Dingjiazhuang, Zhaohao Town North - Longhe and other areas.
Pb indicators of the environmental quality level of Ⅰ class soil is dominated by Ⅱ class soil is only distributed in the urban area of Jinan City and some of the surrounding townships and townships around the site. Class II soils are distributed in some settlements in Beiyuan Township, Yaojia Township, Wangsheren Township and Guodian Township.
The environmental quality level of Zn indicators is mainly dominated by Class I soils, but Class II and Class III soils are also distributed in the upper basin of Xiaoqing River. Class II soils are concentrated in the urban area of Jinan City and the areas around Beiyuan Town-Lokou, Yaojia Town-Beitantou and Guodian Town. Class III soils are distributed on both sides of the Xiaoqing River tributaries in the northwest of Guodian Town, suspected to be point pollution caused by the discharge of industrial wastewater from local factories.
3. Analysis of single-factor pollution indicators
Through the calculation of the single pollution index of each evaluation index and other indicators, it can reflect the impact of each indicator on the environmental quality in the evaluation area, so as to analyze the degree of impact of environmental pollution in the area. Commonly used pollution indicators include:
1) soil single pollution index. Individual pollution index index small pollution light, index large pollution is heavy. The formula is
Soil single pollution index = soil pollutant measured value / soil pollutant quality standards
2) soil pollutant accumulation index. Due to the large differences in the regional background of the soil, sometimes the cumulative soil pollution index can better reflect the degree of anthropogenic pollution of the soil. The formula for calculating the soil pollution accumulation index is as follows:
Soil Pollutant Accumulation Index = Measured Soil Pollutant / Pollutant Background Value
3) Soil Pollutant Sharing Rate. Soil pollutant burden rate can be evaluated to determine the main soil pollution project, pollutant burden rate from large to small order, pollutant primary and secondary also with this order.
Soil pollutant burden (%) = (soil pollution index / sum of pollution index) × 100%
4) soil pollution exceeds the times. Soil pollution exceeds the times is able to reflect the environmental status of the soil statistics.
Soil pollution exceeds the rate = (soil a pollutant measured value - a pollutant quality standards) / a pollutant quality standards
5) soil sample exceeds the rate. Soil sample exceeds the rate is also reflect the environmental status of the soil a statistical quantity.
Soil pollution samples exceeded the rate (%) = (total soil samples exceeded the total number of samples / total number of samples tested) × 100%
Calculation of the pollution index of the eight factors, and the results of its calculations are shown in Table 3-24. The results show that the soil index of the whole region is low, the pollution degree is very slight, the soil pollutants along Xiaoqing River are mainly As, Cd, Cr and Ni, and the order of pollution of heavy metal elements is as follows: Ni＞Cd＞As＞Cr＞Zn＞Cu＞Hg＞Pb. The exceeding multiples of pollutants of each single item are all <0, which indicates that the soil environmental quality of the whole region is good, and the scale of pollution is small, not enough to affect the whole region.
Table 3-24 Statistical Table of Surface Soil Pollution Index and Exceedance Rate in Xiaoqing River Basin
Note: Comparison standard is the upper limit value of secondary soil.
(C) Comprehensive Evaluation
1. Fuzzy Comprehensive Evaluation
The statistics of fuzzy judgment results of each region are shown in Table 3-25, and the data show that the soil in Xiaoqing River area is mainly of Class I and II, and there is no appearance of super Class III soil. The number of Class III soil samples is 10, accounting for <0.5%. The overall environmental quality is good.
Table 3-25 Statistical table of environmental quality of fuzzy comprehensive evaluation of surface soil samples in each investigation area
The distribution of soil comprehensive environmental quality grade is shown in Figure 3-38. It can be seen that most of the soils are Class I and Class II. This result seems to be different from the result of single factor evaluation, but it can be concluded that this is due to the fact that when we select the weights, it is based on the multiples of the factors exceeding the standard, and finally homogenized, and thus the result of fuzzy evaluation shows that the background of the soil environment in each region is good, even if some of the sections that have suffered from contamination, it is only in the lower stage, and the overall surface soil environment in each region is better. The overall surface soil environment of each region is superior.
Type I soils are mainly distributed along the north bank of Xiaoqing River in the areas of Yaowei-Gaoguanzhai Town-Weiqiao Town and Xiliuqiao-Wolubu-Yangkou, Type II soils are mainly distributed around Jinan City, the soils on the south bank of the upper reaches of the Xiaoqing River, and the area along the middle reaches of the Xiaoqing River, and Type III soils are mainly distributed in the area of Jinan City. soils are mainly distributed in the Jinan city area and the soil near individual townships' quarters.
Figure 3-38 Comprehensive environmental quality grade distribution of surface soil in Xiaoqing River Basin
2. Comprehensive Index Evaluation
The calculation of comprehensive index method is generally based on solving the pollution sub-index weights of the single factors, and different mathematical models are used for the calculation. The Nemero index method in the comprehensive index method is selected, which reflects the effect of each pollutant on the soil, and at the same time highlights the impact of high concentrations of pollutants on the quality of the soil environment, and is calculated as follows:
Research on the geological and geochemical environment of typical ecological zones of the northwestern plains of Shandong Province
The formula is as follows: P is the comprehensive pollution index; I=Ci/Si (measured/background value), and the background value is background value of the element in the soil along Xiaoqing River.
Figure 3-39 Evaluation map of Nemero index of soil environment in Xiaoqing River basin
The distribution of integrated pollution of heavy metals in soil of Xiaoqing River is shown in Figure 3-39, and the severely polluted area is mainly concentrated on the banks of Xiaoqing River in the area from Beiyuan Town to Huashan Town in urban area of Jinan City, and it is also sporadically distributed in the settlements such as Sihouzhang, Xixiangcun, and Nankou, etc., and the polluted area is importantly distributed in the areas of Lokou, Wangsheren Town, and Zhaihaoshen. Part of the townships and townships, lightly polluted areas are mainly concentrated in Qijia, Wangsheren Town - Zhengjia dock, Xinji - Qifeng Town, Caojiapo - Gaozhen Town - Boxing County - Longhe and Wangdao - Dingzhuang Town etc. Localized areas such as Sihou Zhang, Jiudu Town, Chengwai Liu and Xu Li are also slightly polluted by heavy metals.
From the above evaluation results, it can be seen that the region's soil is currently cleaner and less contaminated, but only Zhanhua's soil in the region is not currently contaminated, and other areas are contaminated to varying degrees. Analyze the scope of pollution distribution and the main factors of pollution in the region can be concluded as follows:
1) From the distribution pattern of pollution, pollution is mainly distributed in the form of points or islands, Yutai area pollution is concentrated in the northwest of Jining long ditch, Zhangqiu is concentrated in the northern part of Zhangqiu Baiyun Lake area, Shouguang is concentrated in the town of Wanggao - Tianliu, but the small clear river. Basin pollution distribution has developed to the surface, pollution is concentrated in the upstream Jinan City and the middle reaches of Boxing County range. The distribution of pollution areas in Xiaoqing River Basin is the largest, and the distribution pattern has been transitioned from point-like to face-like distribution, the expansion trend is faster, and it needs to be focused on monitoring in the future investigation.
2) From the location of the distribution of pollution, the distribution of pollution around the region shows a more uniform characteristics, that is, the higher pollution index of the region to a certain extent is the overlap of the location of the river or traffic roads. This phenomenon indicates that the pollution source if not timely detection and treatment of the chemical, its diffusion effect more quickly, the role of the scope of human activities with the expansion of the region and easier to expand, the role of the degree is also more intense.
3) From the analysis of the indicators causing pollution, there are differences in pollution sources around. The proportion of Cr pollution in Zhanhua area is larger, the contribution of Cd pollution in Yutai area is large, and Zhangqiu, Shouguang and Xiaoqing River Basin all have the largest Ni pollution index.
In summary, through the pollution evaluation found that the soil pollution in the evaluation area is relatively slight, suitable for the development of agricultural production, but at the same time, because there has been a localized pollution, and pollution has a tendency to further expand, so in the future work should be further carried out to investigate the sources of pollution and prevention of the focus of the study, in order to ensure the healthy development of eco-agriculture.