1. Scope of Application of Technical Specifications

Monitoring of national regional soil background, farmland soil environment, soil environment assessment of construction projects, soil pollution accidents, etc

2. Terms and definitions

2.1. Soil: the loose material with fertility continuously covering the earth's land surface, which is a historical natural body that changes with climate, biology, parent material, terrain and time factors

2.2. Soil environment: The earth environment is composed of the lithosphere, hydrosphere, pedosphere, biosphere and atmosphere. The soil is located in the center of the system, which is not only the product of the interaction of the spheres, but also the hub of the material cycle and energy exchange of the spheres. The internal or external soil conditions affected by natural and human activities are called soil environment

2.3. Soil background: the original chemical composition and element content level of the soil in the region, which is rarely affected by human activities and is not or is not obviously polluted and destroyed by modern industry

3. Point distribution method

3.1. Simple random

3.1.1. The monitoring unit shall be divided into grids, and each grid shall be numbered. After determining the number of samples at the sampling point, samples of the specified number of samples shall be randomly selected. The grid number corresponding to the sample number is the sampling point.

3.1.2. Random number can be obtained by rolling dice, drawing lots and checking the random number table.

3.2. Block random

3.2.1. According to the collected data, if there are obvious types of soil in the monitoring area, the area can be divided into several blocks. The pollutants in each block are uniform and the differences between blocks are obvious.

3.3. System random

3.3.1. Divide the monitoring area into several parts with equal area (grid division), and arrange a sampling point in each grid, which is called system random distribution. If the content of soil pollutants in the area changes greatly, the representativeness of the samples collected by the system with random distribution is better than that of the samples collected by the simple random distribution.

4. Sample collection

4.1. Three stages

4.1.1. Early sampling

According to the background data and site investigation results, a certain number of samples are collected for analysis and determination, which is used to preliminarily verify the spatial differentiation of pollutants and judge the degree of soil pollution, to provide a basis for the development of monitoring plans (selection of point distribution methods and determination of monitoring items and sample quantity). The previous sampling can be conducted at the same time as the site investigation.

4.1.2. Formal sampling

Implement on-site sampling according to the monitoring plan

4.1.3. Supplementary sampling

After formal sampling and testing, additional sampling points shall be added for supplementary sampling if it is found that the arranged sampling points do not meet the requirements of the overall design.

4.2. Regional environmental background soil sampling

4.2.1. Sampling

Surface samples or soil profiles can be taken at sampling points. Generally, topsoil is monitored and collected at a depth of 0-20cm,

For monitoring with special requirements (soil background, environmental assessment, pollution accident, etc.), if necessary, select some sampling points to collect profile samples.

4.2.2. Field selection

The natural landscape of the sampling point should meet the requirements of the soil environmental background value study

It shall be selected at the place with obvious soil type characteristics, relatively flat and stable terrain and good vegetation;

The sampling point shall be at least 300 m away from the railway and highway

4.3. Farmland soil sampling

4.3.1. Monitoring unit

(1) Air pollution type soil monitoring unit;

(2) Irrigation water pollution monitoring unit;

(3) Solid waste pile contaminated soil monitoring unit;

(4) Agricultural solid waste contaminated soil monitoring unit;

(5) Monitoring unit for soil contaminated by agricultural chemicals;

(6) Comprehensive pollution type soil monitoring unit (pollutants mainly come from above two ways).

4.3.2. Point distribution

1. Air pollution type soil monitoring unit and solid waste pile pollution type soil monitoring unit:

Arrange points radially with the pollution source as the center, and appropriately increase sampling points in the dominant wind direction and the runoff direction of surface water

2. Irrigation water pollution monitoring unit, agricultural solid waste contaminated soil monitoring unit, agricultural chemical substances contaminated soil monitoring unit: uniformly distributed

3. Irrigation water pollution monitoring unit: the sampling points shall be distributed in a strip manner according to the flow direction, and the sampling points shall be gradually sparse from the sewage inlet

4. Comprehensive pollution type soil monitoring unit: comprehensive radial, uniform and zonal point distribution method

4.3.3. Sample collection

(1) Diagonal method: applicable to sewage irrigated farmland soil. The diagonal is divided into 5 equal parts, and the equal points are taken as sampling points;

(2) Plum blossom point method: it is applicable to the plot with small area, flat terrain, relatively uniform soil composition and pollution degree, and about 5 points are set;

(3) Chessboard method: it is suitable for medium area, flat terrain and uneven soil plots, with about 10 points; The soil polluted by sludge, garbage and other solid wastes shall be divided into more than 20 points;

(4) Snake method: It is suitable for large area, uneven soil and uneven terrain. There are about 15 sub points, which are mostly used for agricultural contaminated soil.

4.4. Monitoring sampling for soil environment assessment of the construction project

4.4.1. There shall be at least 5 sampling points for every 100 hectares of land, and the total number of sampling points shall not be less than 5. Among them, small construction projects shall have 1 sampling point for columnar samples, large and medium-sized construction projects shall have at least 3 sampling points for columnar samples, and mega construction projects or construction projects sensitive to soil environmental impacts shall have at least 5 sampling points for columnar samples

4.4.2. Non mechanical interference soil

The sampling depth of topsoil is 0-20cm; The sampling depth of each column sample is 100cm, and three soil samples are taken: surface sample (0-20cm), middle sample (20-60cm), and deep sample (60-100cm).

4.4.3. Mechanical interference soil

4.5. Urban soil sampling

4.5.1. The upper layer (0-30 cm) may be the backfill or the part greatly affected by human activities,

4.5.2. The lower layer (30-60 cm) is the part with relatively small human impact

4.6. Soil sampling for pollution accident monitoring

4.6.1. Solid pollutant scattering pollution type

Collect 5 cm soil samples on the surface after cleaning, and the number of sampling points shall not be less than 3

4.6.2. Liquid rollover pollution type

When pollutants flow to the low-lying area, they penetrate into the depth direction and diffuse laterally to both sides. Each point is sampled layer by layer. The sample points at the accident point are dense, the sampling depth is deep, and the sample points far away from the accident point are sparse, and the sampling depth is shallow. At least 5 sampling points

5. Sample preparation

5.1. Requirements for sample preparation workshop

5.1.1 Air drying room and sample grinding room are set separately.

5.1.2 The air drying room faces south (prevent direct sunlight on soil samples), and is well ventilated, clean, dust-free, and free of volatile chemicals.

5.2. Sample preparation tools and containers

5.2.1. Soil sample (＞ 500g)

5.3. Sample preparation procedure

5.3.1. Air drying

Place the soil sample in the air drying tray in the air drying room, spread it into a thin layer of 2~3 cm, timely crush and turn it over, and pick out the crushed stone, gravel, and plant debris

5.3.2. Rough grinding of samples

5.3.3. Fine grinding sample

5.3.4. Sample subpackage

The samples after grinding and mixing shall be put into sample bags or bottles respectively, and the soil labels shall be filled in duplicate, one in the bottle or bag, and one outside the bottle or bag

5.3.5. Precautions

During sample preparation, the soil label and soil shall always be placed together. It is strictly prohibited to mix them. The name and code of the sample shall remain unchanged

The sample preparation tool shall be wiped (washed) clean after each sample is processed to prevent cross contamination;

The above sample preparation is not required for the analysis of volatile, semi volatile organic compounds or extractable organic compounds, and fresh samples are used for sample pretreatment according to specific methods.

6. Sample preservation

6.1. Classified storage according to sample name, number and particle size

6.2. Preservation of fresh samples

6.2.1. The soil samples that need fresh samples for the test items shall be stored in a sealed polyethylene or glass container under 4 ℃ and away from light after collection, and the samples shall be filled with containers

6.3. Reserved samples

6.3.1. Reserved samples are stored in the sample library

6.4. Analyze the remaining samples after use

6.4.1. The remaining samples after analysis and use shall also be handed over to the sample library for storage after all the measured data are reported

6.5. Storage time

6.5.1. The remaining samples after analysis are generally retained for half a year, and the reserved samples are generally retained for 2 years.

6.5.2. Special, rare, arbitrated and disputed samples shall generally be kept permanently.

6.6. Requirements for sample library

6.6.1. Keep dry, ventilated, free from direct sunlight and pollution; The samples shall be cleaned regularly to prevent mildew, rat damage and label falling off.

6.6.2. The warehousing, receiving and cleaning of samples shall be recorded.

6.7. Storage conditions and time of fresh samples

7. Soil analysis and determination

7.1. Soil color

7.1.1. The color can be measured by using the Munsell color card

7.1.2. Soil color triangle table can also be used for description

7.2. Analysis method

7.2.1. The first method: standard method (arbitration method), according to the analysis method selected in the soil environmental quality standard

7.2.2. The second method: the method specified or recommended by the authority.

7.2.3. The third method: according to the actual situation of each place, the equivalent method shall be selected, but the standard sample verification or comparison test shall be carried out, and the detection limit, accuracy and precision shall not be lower than the level required by the corresponding general method or the requirements for accurate quantification of the object to be measured.

7.3. Soil monitoring items

7.3.1. Regular items: once every 3 years; Sampling of farmland after summer or autumn harvest

Basic items: pH, cation exchange capacity

Key projects: cadmium, chromium, mercury, arsenic, lead, copper, zinc, nickel, BHC, DDT

7.3.2. Specific items (pollution accidents)

Characteristic items: timely sampling, and monitoring frequency shall be determined according to pollutant change trend

7.3.3. Selected survey items

Once every 3 years, the farmland shall be sampled after summer or autumn harvest

8. Soil monitoring error

8.1. Sampling error (SE)

8.2. Sample preparation error (PE)

8.3. Analysis error (AE)

8.4. Total error (TE)

8.4.1. TE=SE＋PE＋AE

9. Soil environment quality assessment

9.1 The assessment of soil environmental quality involves assessment factors, standards and models.

9.2. The number of evaluation factors and the type of project depend on the purpose of monitoring and the actual economic and technical conditions.

9.3. The evaluation standard usually adopts the national soil environmental quality standard, regional soil background value or departmental (professional) soil quality standard.

9.4. The assessment model usually uses the pollution index method or its related assessment methods.

9.5. Evaluation of pollution index and exceeding standard rate (multiple)

9.5.1. Single soil pollution index=measured value of soil pollutants/quality standard of soil pollutants

9.5.2. Cumulative index of soil pollution=measured value of soil pollutants/background value of pollutants

9.5.3. Sharing rate of soil pollutants (%)=(a certain pollution index of soil/sum of all pollution indexes) × 100%

9.5.4 Excess multiple of soil pollution=(measured value of a pollutant in soil - quality standard of a pollutant)/quality standard of a pollutant

9.5.5 Exceedance rate of soil pollution samples (%)=(total number of soil samples exceeding the standard/total number of monitoring samples) × 100%

10. Quality assurance and quality control

10.1. Quality control of sampling and sample preparation

10.2. Laboratory quality control

10.2.1. Precision control

20% parallel samples shall be made for each batch of samples and each item for analysis; When there are less than 5 samples, the number of parallel samples shall not be less than 1

Measurement method: clear code parallel sample compiled by the analyst, or code parallel sample compiled by the quality controller at the sampling site or laboratory

Qualification requirements: the error of parallel double sample measurement results is within the allowable error range

10.2.2. Accuracy control

Use of reference materials or quality control samples

Determination of spiked recovery

Standard addition rate: 10%~20% samples are randomly selected from a batch of samples for standard addition recovery determination

Scaling amount: The spiking amount depends on the content of the tested component. Add 0.5~1.0 times of the content of the tested component if the content is high, and add 2~3 times of the content of the tested component if the content is low. However, the total amount of the tested component after spiking shall not exceed the upper limit of the method.

Qualification requirements: The spiked recovery rate shall be within the allowable range of spiked recovery rate.

10.2.3. Quality Control Chart

10.2.4. Soil standard sample