Introduction

Since 2000, with the increasingly prominent issue of soil pollution in China, soil environmental safety has attracted widespread attention from society. Based on the above reasons, the State Council issued the Soil Pollution Prevention and Control Action Plan (also known as the "Ten Measures") on May 31, 2016. The "Ten Measures for Soil Pollution Prevention and Control" have made a comprehensive strategic deployment for China's soil pollution prevention and control work in the coming period.

The "Ten Measures for Soil Pollution Prevention and Control" mentions "conducting soil pollution investigations and understanding the quality of soil environment", emphasizing the importance of soil testing as the foundation for soil pollution prevention and control work. There are many types of pollutants involved in soil, such as hydrocarbons, POPs, pesticide residues, and heavy metals. This issue will introduce the detection of these pollutants in soil.

Related testing knowledge

At present, China's standards for soil environment monitoring include the "Technical Specifications for Soil Environment Monitoring" (HJ/T 166-2004), which belongs to the environmental protection industry standards of the People's Republic of China.

General soil monitoring can be divided into monitoring of national regional soil background, farmland soil environment, construction project soil environment assessment, soil pollution accidents, and other types.

Monitoring projects are divided into routine projects, specific projects, and selected testing projects; The monitoring frequency corresponds to it.

Conventional project: In principle, it refers to the pollutants controlled as required by GB 15618 "Soil Environmental Quality Standards".

Specific project: Pollutants that are not required to be controlled in GB 15618 "Soil Environmental Quality Standards", but have been confirmed to accumulate in the soil, pose significant environmental hazards, have a wide range of impacts, and have strong toxicity based on the local environmental pollution situation, or substances that have serious adverse effects on the soil environment caused by pollution accidents. The specific project will be determined by each region.

Selection and testing items: generally include newly included soil properties indicators that accumulate less pollutants in the soil, soil properties indicators that have changed due to environmental pollution, and ecological environment indicators, which are selected and tested by each region.

Soil Monitoring Projects and Monitoring Frequency Table

Project category testing, project monitoring frequency

The basic items of routine projects include pH and cation exchange capacity, which should be sampled every 3 years after the summer or autumn harvest in farmland

Key projects include cadmium, chromium, mercury, arsenic, lead, copper, zinc, nickel, hexachlorocyclohexane, and DDT

Timely sampling of specific project (pollution accident) characteristic projects, and determining monitoring frequency based on the trend of pollutant changes

The selected testing items affect the yield. The total salt content, boron, fluoride, nitrogen, phosphorus, potassium, etc. of the project should be sampled every 3 years after the summer or autumn harvest of the farmland

Sewage irrigation project includes cyanide, hexavalent chromium, volatile phenols, alkylmercury, benzo [a] pyrene, organic matter, sulfides, petroleum, etc

POPs and highly toxic pesticides such as benzene, volatile halogenated hydrocarbons, organophosphorus pesticides, PCBs, PAHs, etc

Other projects include combined aluminum (acid rain area), selenium, vanadium, total rare earth oxide, molybdenum, iron, manganese, magnesium, calcium, sodium, aluminum, silicon, and specific radioactivity

Introduction to Testing Items

Project Name Testing Method

Organic matter soil testing - Part 6: Determination of soil organic matter

NY/T 1121.6-2006

Soil moisture content Determination of dry matter and moisture Weight method HJ 613-2011

PH Soil Testing Part 2: Determination of Soil pH

NY/T 1121.2-2006

Lead soil quality - Determination of lead and cadmium

Graphite furnace atomic absorption spectrophotometry GB/T 17141-1997

Cadmium Soil Quality - Determination of Lead and Cadmium

Graphite furnace atomic absorption spectrophotometry GB/T 17141-1997

Arsenic Soil Testing Part 11: Determination of Total Arsenic in Soil

NY/T 1121.11-2006

Chromium soil quality - Determination of total chromium - Flame atomic absorption spectrophotometric method

HJ 491-2009

Copper Soil Quality - Determination of Copper and Zinc

Flame atomic absorption spectrophotometry GB/T 17138-1997

Zinc Soil Quality - Determination of Copper and Zinc

Flame atomic absorption spectrophotometry GB/T 17138-1997

Nickel soil quality - Determination of nickel - Flame atomic absorption spectrophotometric method

GB/T 17139-1997

Hexavalent chromium Determination of hexavalent chromium Colorimetric method EPA 3060A-1996 (pretreatment)

EPA 7196A-1992 (Analysis)

Analysis of Water soluble Salt Content in Forest Soil with Total Salt Content (LY/T 1251-1999)

Determination of cation exchange capacity of forest soil by LY/T 1243-1999

Soil Environmental Quality Evaluation Standards for Cyanide Exhibition Land (Provisional)

HJ 350-2007 Appendix B Determination of Cyanide (CN -) in Soil

Isonicotinate pyrazolone colorimetric method

Radon concentration and soil

Surface radon release rate "Code for Indoor Environmental Pollution Control of Civil Building Engineering"

Appendix E of GB 50325-2010

Manganese "Modern Analysis Methods of Soil Elements" compiled by China Environmental Monitoring Station

Chapter 5, 5.7.1 Atomic Absorption Method

Mercury - Determination of Total Mercury, Total Arsenic, and Total Lead in Soil Quality - Atomic Fluorescence Method

Part 1: Determination of Total Mercury in Soil GB/T 22105.1-2008

Fluoride soil quality - Determination of fluoride

Ion selective electrode method GB/T 22104-2008

Cobalt: Modern Analytical Methods for Soil Elements, published by China Environmental Science Press

Chapter 5 5.3 Flame Atomic Absorption Method

Determination of Organophosphorus Pesticides in Organic Phosphorus Water and Soil by Gas Chromatography

GB/T 14552-2003 

Soil Environmental Quality Evaluation Standards for Organic Chlorine Exhibition Land (Provisional)

HJ 350-2007   Appendix G Determination of Organochlorine Pesticides in Soil

Gas chromatography method

Pre processing methods

Pre treatment of chromium in soil:

Accurately weigh 0.5g of the sample in a 50ml polytetrafluoroethylene crucible, wet it with water, add 10ml hydrochloric acid, and heat it at low temperature on an electric heating plate to preliminarily decompose the sample. When it evaporates to about 3ml, remove it and cool it slightly. Add 5ml nitric acid, 5ml hydrofluoric acid, and 3ml perchloric acid, cover it, and heat it at medium temperature on the electric heating plate for 1 hour. Then open the cover and continue heating at 150 degrees Celsius to remove silicon. When it is heated to emit thick white smoke of perchloric acid, cover it to fully decompose the black organic carbon compound. After the black organic matter on the crucible disappears, open the lid to drive away the white smoke and steam until the content becomes viscous. Add 3ml of nitric acid, 3ml of hydrofluoric acid, and 1ml of perchloric acid, repeat the above digestion process, remove and cool slightly, and add 3ml of hydrochloric acid solution to warm and dissolve the residue. Transfer the solution to a 50ml volumetric flask, add 5ml of ammonium chloride solution and cool to volume, shake well for testing. Simultaneously create a blank space.

Pre treatment of Zinc in Soil:

Accurately weigh 0.5g of the sample in a 100ml polytetrafluoroethylene crucible, wet it with water, add 10ml hydrochloric acid, and heat it at low temperature on an electric heating plate to preliminarily decompose the sample. When it evaporates to about 3ml, remove it and cool it slightly. Add 5ml nitric acid, 5ml hydrofluoric acid, and 3ml perchloric acid, cover it, and heat it at medium temperature on the electric heating plate for 1 hour. Then open the cover and continue heating at 150 degrees Celsius to remove silicon. When heated to a thick white smoke of perchloric acid, cover it to fully decompose the black organic carbon compound. After the black organic matter on the crucible disappears, open the lid to drive away the white smoke and steam until the content becomes viscous. Then add 3ml nitric acid, 3ml hydrofluoric acid, and 1ml perchloric acid, repeat the above digestion process. When the white smoke is almost completely emitted again and the content becomes viscous, remove it and cool it slightly. Rinse the lid and inner wall of the crucible with water, and add 1ml nitric acid solution to dissolve the residue warm. Transfer the solution to a 50ml volumetric flask, add 5ml of lanthanum nitrate solution to cool, then dilute with water and shake well for testing. Simultaneously create a blank space.

Pre treatment of organic phosphorus and organic chlorine in soil:

Take 5-20g of the sample, extract it by Soxhlet extraction/ultrasonic extraction, concentrate it to 1-2mL, purify and elute it by silica gel column/neutral alumina column, make up to 0.5-1ml, and wait for it to be loaded onto the machine.