WO2014094365A1 - Method for remediating soil polluted with lead-polychlorinated biphenyl compounds - Google Patents

Abstract

Disclosed is a method for remediating soil polluted with lead-polychlorinated biphenyl (Pb-PCBs) compounds, comprising: sterilizing Impatiens balsamina seeds with hydrogen peroxide and then spot-sowing in a seedling raising pot, transplanting into soil polluted with Pb and PCBs when the seeds have germinated and the young seedlings have grown to 5-8 cm, watering periodically to maintain an appropriate humidity, harvesting whole plants after growing for 120 days and handling properly, thereby completing a remediation cycle. The above operations are repeated until the content of Pb-PCBs in the soil is reduced to environmental safety standards. The present invention has the advantages of: Impatiens balsamina has strong adaptability and resistance to the cold and infertility, and seeds which are scattered on the ground can grow by themselves under appropriate humidity and heat conditions and can grow rapidly, facilitating cultivation and management; and compared to conventional polluted soil remediation methods, the remediation of soil polluted with Pb/PCBs compounds using the tolerant flower plant Impatiens balsamina has the characteristics of less investment, a low engineering workload, low technical requirements and no secondary pollution and the like, and the environment is beautified while the polluted soil is remediated.

Description

 Method for repairing lead-polychlorinated biphenyl composite contaminated soil Technical field

 The invention relates to a phytoremediation technology for heavy metal-persistent organic compound contaminated soil, in particular to a method for repairing lead-polychlorinated biphenyl composite contaminated soil.

Background technique

Due to mining, sewage irrigation and other heavy metal pollution in the soil is increasingly serious, according to the 2008 China Environmental Statistics Yearbook data, in the country's 1.4 million hectares of sewage irrigation area, the area affected by heavy metal pollution accounted for 64.8%, of which mild And moderate pollution area reached 87.0%, see Document 1: National Bureau of Statistics, Environmental Protection Administration. China Environmental Statistics Yearbook-2008 [M]. Beijing: China Statistics Press, 2008. With the rapid development of information technology, the upgrading of electronic products has accelerated, more and more electronic products have been eliminated, and heavy metals released into the environment when electronic waste is dismantled and recycled are becoming a new source of pollution. The soil in the e-waste dismantling area and the surrounding environment are polluted by severe heavy metals, and the concentration of Pb is as high as 110000 mg/kg. See Document 2: Leung A O W, Duzgoren-Aydin N S, Cheung K C, et al. Heavy Metals Concentrations of Surface Dust from e-Waste Recycling and Its Human Health Implications in Southeast China[J]. Environmental Science & Technology, 2008, 42(7): 2674-2680. The dismantling of e-waste will be accompanied by serious persistent organic pollution leakage. The PCBs of farmland soil in a main garbage dismantling area can be as high as 788μg/kg, forming a complex pollution of heavy metals and persistent organic matter. See Document 3: Chu Shaogang, Yang Chun, Xu Xiaozi, Liu Xiaoxing. Investigation on residual polychlorinated biphenyls (PCBs) in sediment and soil in typical polluted areas [J]. Chinese Environmental Science, 1995, 15(3): 199-203.

Excessive Pb in contaminated soil not only directly threatens human production environment and food safety, but also can be enriched in the human body through direct contact or food chain, resulting in chronic poisoning and excessive Pb content in blood. Excessive intake of Pb in the human body can damage the nervous system, hematopoietic organs and kidneys; loss of appetite, irritability, headache, insomnia, memory loss, muscle aches, anemia, etc., which can lead to shock or even death; Pb and its compounds can cause palpitations, It also has carcinogenic and mutagenic effects.

There are mainly physical, chemical and bioremediation techniques for the treatment of heavy metal contaminated soils. Common physical and chemical treatment methods include guest soil method, chemical leaching method, electric repair, chelation and plasma exchange method. These methods are fast and effective, but they have problems such as high technical difficulty, high cost, large amount of engineering, and easy secondary pollution. They are generally used in small-scale and short-term pollution-remediation processes. It is promoted in the remediation and treatment of polluted soil with large area and light pollution. Through agronomic regulation, regulating soil pH, moisture, oxidation-reduction potential, solidifying heavy metals in soil, and screening low-cumulative crops can reduce the absorption of heavy metals by crops and reduce the threat of heavy metals to human health. However, this method cannot fundamentally control heavy metal pollution in the soil.

Phytoremediation refers to the use of plants to transfer, contain or transform toxic and harmful pollutants in environmental media to make them harmless to the environment, so that the polluted environment can be repaired and treated. See Document 4: Cunningham SD, Shann JR, Crowley DR, Et al. Phytoremediation of contaminated water and soil. Phytoremediation of Soil and Water Contaminants [R]. USA: American Chemical Society, 1997, 2-17. Phytoremediation methods mainly include plant extraction, plant evaporation, plant degradation, plant stabilization, plant rhizosphere degradation and rhizosphere filtration, see Document 5: Cunningham SD, Ow DW. Promises and prospects of phytoremediation. Plant Physiology, 1996, 110 ( 3), 715-719; see Document 6: Flathman PE, Lanza GR. Phytoremediation current views on an emerging green technology [J]. Journal of Soil Contamination, 1998, 7(6), 415-432. Compared with the traditional repair technology, it has the characteristics of low cost, low cost and easy operation. While completing the treatment of contaminated soil, it also beautifies the environment and is easily accepted by the public. Screening out suitable restoration plants is the key to the whole technology. Plants that have been confirmed to have super-accumulative effects on Pb are Armeria martina , Thlaspi rotundifolium , Alyssum walfenianum , and white drums. Polycarpaea synandra , etc., see Document 7: Piechalak A, Tomaszewska B, Baralkiewicz D, Malecka A. Accumulation and detoxification of lead ions in legumes [J]. Phytochemistry, 2002, 60(2): 153-162. However, when Pb and POPs are combined, whether plants have a repair effect on heavy metals is relatively rare.

China is not only one of the countries with the most flower species in the world, but also the birthplace of flower cultivation in the world. The flower and plant resources are extremely rich. The screening of super-enriched plants in flower plants and their use in restoration research and practice has the following advantages: 1) The flower resources are quite rich and have great potential. This will give a solid foundation for the screening work; 2) At the same time as soil restoration, it can beautify the environment and kill two birds with one stone; 3) Flowers are ornamental plants, which will not enter the food chain and reduce the harm to the human body; 4) Many ornamental plants have certain economic value. After restoration, plant materials can be used as raw materials to improve repair output and reduce repair costs. 5) Humans have accumulated rich experience in variety breeding, flower cultivation and pest control in long-term production practice. See Document 8: Liu Jianu, Zhou Qixing, Sun Ting, Feasibility Study on Application of Flower Plants to Contaminated Soil Remediation [J]. Chinese Journal of Applied Ecology, 2006, 18 (7), 1617-1623. thus, It is completely feasible to screen plants from plants for repairing Pb under combined pollution conditions and for repairing practices.

technical problem

The object of the present invention is to provide a method for repairing lead-polychlorinated biphenyl-contaminated soil by using the flower plant Impatiens balsamina , which has low investment, small engineering quantity, and technology. The requirement is not high; and as a green in-situ remediation technology, the harvested plants are concentrated and will not cause secondary pollution; at the same time, the repair process will not only damage the soil ecological environment, but also help to improve the heavy metal Pb and Soil degradation and productivity caused by PCBs combined pollution, restore and improve its biodiversity.

Technical solution

 The technical solution of the invention:

 A method for repairing lead-polychlorinated biphenyl (Pb-PCBs) composite contaminated soil is as follows:

 1 Select full-bodied Impatiens seeds, sterilize them with 10wt% hydrogen peroxide for 10 minutes, rinse them with distilled water, and place them on the soil of the nursery pot to keep the soil moist;

 2 Planting 5-8 cm high-growth Impatiens seedlings into Pb-PCBs combined contaminated soil, watering 1-2 times a day to maintain soil water content in the field holding capacity of 60-80%;

 3 When the impatiens are matured, they are removed from the soil as a whole, and then the second impatiens are planted. The above operation is repeated until the content of Pb-PCBs in the soil drops to environmental safety standards.

The Impatiens is an annual herbaceous flower plant of the Impatiens genus Impatiens, with a plant height of 30-80 cm, bright colors and various colors, including white, purple and red, and flowers of several colors on the same plant. Its flower is like a flying phoenix, the head and tail are full, also known as the golden phoenix flower, with a single flap and two petals, the flower shape is beautiful; the flowering period of the balsam is from June to August, the knotted fruit, the hazelnut spindle, the white hair At the time of maturity, it is a fruit ring of 5 spirals; most of the seeds are spherical, black, and peach-like. After the seeds mature, the outer shell bursts by itself, and the seeds are popped and propagated.

 The impatiens harvested after the impatiens are matured can be sold as ornamental flowers or treated by centralized sanitary filling.

Beneficial effect

The invention has the advantages that the impatiens are strong in adaptability, cold-tolerant and tolerant to barrenness, and the seeds scattered on the ground can grow by themselves under suitable moist heat conditions, and grow rapidly, generally have few pests and diseases, and the cultivation and management are convenient, and experiments show that Impatiens has strong tolerance and Pb accumulation ability under Pb-PCBs combined pollution; PB-PCBs complex contaminated soil is repaired by planting Impatiens, which is compared with traditional physical and chemical methods for contaminating soil. It has the advantages of less investment, small amount of engineering and low technical requirements. Moreover, as a green in-situ remediation technology, the harvested plants are treated centrally without causing secondary pollution; at the same time, the repair process will not damage the soil ecological environment. It also helps to improve soil degradation and productivity degradation caused by heavy metal Pb-PCBs combined pollution, and restore and improve its biodiversity.

DRAWINGS

 The figure shows the distribution of the amount of accumulated Pb in the body of Impatiens balsamina in different pollution treatment groups.

BEST MODE FOR CARRYING OUT THE INVENTION

 Example:

 A method for repairing lead-polychlorinated biphenyl (Pb-PCBs) composite contaminated soil is as follows:

 1 Select full-bodied Impatiens seeds, sterilize them with 10wt% hydrogen peroxide for 10 minutes, rinse them with distilled water, and place them on the soil of the nursery pot to keep the soil moist;

 2 Planting 5-8 cm high-growth Impatiens seedlings into Pb-PCBs combined contaminated soil, watering 1-2 times a day to maintain soil water content in the field holding capacity of 60-80%;

 3 When the impatiens are matured, they are removed from the soil as a whole, and then the second impatiens are planted. The above operation is repeated until the content of Pb-PCBs in the soil drops to environmental safety standards.

 Greenhouse pot experiment of Pb-PCBs combined with Pb-PCBs combined with Pb

The pot experiment site was located in the greenhouse of TEDA College of Nankai University, and the clean soil was collected from Xianqiao District, Jieyang City, Guangdong Province. A total of 13 treatment groups were set up in this experiment, and each treatment was repeated 3 times. The concentration of Pb-PCBs added was 0-0 (CK), 300-0 (T1), 300-50 (T2), and 300-100 (T3). , 300-500 (T4), 600-0 (T5), 600-50 (T6), 600-100 (T7), 600-500 (T8), 1000-0 (T9), 1000-50 (T10), 1000-100 (T11), 1000-500 (T12), the concentration of pollutants added to each treatment group ρ _Pb × ρ _PCBs , Pb concentration unit is mg / kg, PCBs concentration unit is μg / kg, of which Pb is analytically pure Pb(NO) ₃ , PCBs are added in the form of a standard ratio of PCB18 and PCB28 of 1:1. 2kg per pot of soil, after adding pollutants, balance for 3 weeks for use. At the same time, carry out flower seedlings, select full-bodied Impatiens seeds, soak them in 10wt% hydrogen peroxide for 10 minutes, rinse them with distilled water, and place them on the seedling tray to keep the soil moist. After 15-20 days, the seedling height is 5-8, select The seedlings with the same growth were transferred into the above treatment pots, 3 per pot. Water is appropriately watered according to the soil moisture condition every day, so that the soil water content is often maintained at 60-80% of the field water holding capacity. In order to prevent the appearance of impatiens powdery mildew and affect the restoration effect of impatiens, the temperature of the greenhouse should not be too high and properly ventilated. When powdery mildew occurs, it can be sprayed with a 70% methyl thiophanate WP or carbendazim medicinal solution at 1000 times.

After 4 months of plant growth, the plants were harvested. The harvested samples were divided into roots, stems and leaves. They were rinsed with tap water, rinsed with distilled water, drained, and killed at 105 ° C for 20 minutes, then at 65 ° C. Dry to constant weight, weigh the dry weight and smash it for later use. The plant samples were digested with a 3:1 volume ratio of nitric acid-hydrogen peroxide, and the Pb content thereof was determined by an atomic absorption spectrophotometer.

The chart was made using Origin 8.0, and the results of all the machines were the average of 3 times of experimental data. The difference was significantly tested by SAS 9.1.3 (Duncan method), and the statistical significance was set to p < 0.05.

 The experimental results are as follows:

 The dry weight of each part of the Impatiens plant after 4 months of transplantation is shown in Table 1.

 Table 1 Dry weight of Impatiens plant in each treatment group

 Processing group  Impatiens underground part dry weight (g/pot)  Impatiens ground part dry weight (g/pot)  CK  3.45±0.77 ab  24.45±2.53 a  T1  1.30±0.79 f  13.95±4.71 cde  T2  3.82±0.41 a  22.00±1.36 ab  T3  2.83±0.54 bc  17.66±4.09 abc  T4  1.88±0.35 cdef  13.07±6.00 cde  T5  2.00±0.49 cdef  17.16±4.12 abcd  T6  1.95±0.38 cdef  14.84±2.04 bcde  T7  2.31±0.59 cde  18.10±4.42 abc  T8  1.30±0.35 f  10.12±2.53 de  T9  2.39±0.41 cde  18.85±6.33 abc  T10  1.42±0.32 ef  9.30±2.82 e  T11  1.64±0.68 def  13.49±4.10 cde  T12  2.55±0.29 bcd  14.44±0.15 cde

The experimental results showed that the total dry weight of Impatiens balsamina plants in all pollution treatment groups was smaller than that in the blank control group. When PCBs are combined with different concentrations of Pb, they exhibit different effects on the growth of Impatiens. Under the treatment of Pb pollution of 300mg/kg, the biomass of Pb-PCBs composite treatment group was higher than that of single Pb treatment group. The presence of PCBs promoted the growth of Impatiens, and the compound pollution treatment was performed when the concentration of PCBs was 50μg/kg. The maximum weight was significantly higher than that of the single Pb treatment group. As the concentration of PCBs increased, the dry weight of the aboveground and underground parts of Impatiens was reduced. Under the treatment of Pb pollution of 600mg/kg, PCBs promoted the growth of Impatiens when the concentration was 100μg/kg, while the other two groups inhibited the growth of Impatiens. There is a significant difference in dry weight from the above-ground and underground parts of the T8. Under the condition of Pb pollution of 1000mg/kg, the biomass of Pb-PCBs combined pollution treatment group was lower than that of single Pb treatment group. PCBs inhibited the growth of Impatiens, but with the increase of PCBs concentration, the underground of Impatiens Part of the dry weight is gradually increasing.

 The accumulation of Pb in different parts of Impatiens plants under different pollution treatments is shown in Table 2.

 Table 2 Cumulative amount of Pb in various parts of Impatiens balsamina under each treatment group (mg/kg)

 Processing group  Root Pb content  Stem Pb content  Leaf Pb content  CK  4.04±0.82 c  2.01±0.08 e  1.18±0.40 e  T1  154.31±38.96 bc  62.12±13.86 d  13.32±3.82 d  T2  138.26±24.4 bc  59.15±15.91 d  13.19±6.22 d  T3  171.34±66.15 bc  60.23±15.14 d  12.99±10.04 d  T4  161.42±56.73 bc  64.43±14.68 d  12.77±6.90 d  T5  261.42±58.30 b  132.67±29.75 c  25.05±9.25 cd  T6  266.95±69.96 b  128.43±9.80 c  40.57±1.59 bc  T7  270.55±66.83 b  131.94±12.88 c  32.71±13.47 c  T8  279.43±94.25 b  116.44±17.47 c  25.67±9.91 cd  T9  456.81±146.55 a  138.64±39.02 c  63.84±18.12 b  T10  522.39±147.17 a  198.84±37.62 ab  58.05±15.01 b  T11  559.77±119.42 a  222.66±21.19 a  115.75±22.74 a  T12  540.05±154.76 a  180.24±35.97 b  64.22±18.55 b

The results showed that the accumulation of Pb in the leaves of Impatiens was from root to stem > leaf, and the accumulation of Pb in various parts of Impatiens increased with the increase of Pb concentration in the treatment group. However, when the concentration of Pb treatment was the same, the accumulation of Pb in various parts of Impatiens showed different changes due to the different concentrations of PCBs. For the roots, when the Pb treatment concentration was 600mg/kg and 1000mg/kg, the Pb-PCBs combined pollution treatment of P. chinensis had higher Pb accumulation than the single Pb pollution treatment group, reaching the maximum value of 279.43 at T8 and T11, respectively. 559.77 mg/kg. For the stem, when the concentration of Pb was 1000mg/kg, the accumulation of Pb in Pb-PCBs combined pollution treatment group was significantly higher than that in the single Pb pollution treatment group, while the Pb treatment concentration was 600mg/kg. . For the leaf, the Pb accumulation of P. chinensis reached the maximum at the treatment concentration of PCBs of 100 μg/kg at Pb treatment concentration of 1000 mg/kg, which was significantly higher than that of other treatment groups.

The enrichment rate refers to the percentage of heavy metal enrichment in various parts of the plant as a percentage of the heavy metal enrichment of the whole plant. Under different pollution treatments, the enrichment rate of Pb in different parts of Impatiens was as shown in the attached figure. The figure shows that the enrichment rate of Pb in the roots of Impatiens balsamina in the combined pollution treatment group is generally larger than that in the corresponding single Pb treatment group, that is, PCBs promote the accumulation of Pb in the roots of Impatiens balsamina and reduce the transfer of Pb to the aboveground part. ratio.

Conclusion: Under the combined pollution of Pb-PCBs, Impatiens showed better tolerance and accumulation of Pb. Compared with the single Pb pollution treatment, Pb-PCBs combined pollution promoted the growth of Impatiens in low concentration Pb of 300mg/kg, inhibited the growth of Impatiens when the high concentration of Pb was 1000mg/kg, but promoted the phoenix The accumulation of Pb by P. sinensis; Pb-PCBs combined pollution promoted the accumulation of Pb in plant roots and reduced the damage of Pb in aboveground tissues. Therefore, the application of flower plant Impatiens to repair Pb in Pb-PCBs complex contaminated soil has good potential.

Embodiments of the invention

Industrial applicability

Under the condition of Pb-PCBs combined pollution, Impatiens showed better tolerance and accumulation of Pb. Compared with the single Pb pollution treatment, Pb-PCBs combined pollution promoted the growth of Impatiens in low concentration Pb of 300mg/kg, inhibited the growth of Impatiens when the high concentration of Pb was 1000mg/kg, but promoted the phoenix The accumulation of Pb by P. sinensis; Pb-PCBs combined pollution promoted the accumulation of Pb in plant roots and reduced the damage of Pb in aboveground tissues. Therefore, the application of flower plant Impatiens to repair Pb in Pb-PCBs complex contaminated soil has good potential.

Sequence table free content

Claims (3)

A method for repairing lead-polychlorinated biphenyl (Pb-PCBs) composite contaminated soil is characterized by the following steps: 1 Select full-bodied Impatiens seeds, sterilize them with 10wt% hydrogen peroxide for 10 minutes, rinse them with distilled water, and place them on the soil of the nursery pot to keep the soil moist; 2 Planting 5-8 cm high-growth Impatiens seedlings into Pb-PCBs combined contaminated soil, watering 1-2 times a day to maintain soil water content in the field holding capacity of 60-80%; 3 When the impatiens are matured, they are removed from the soil as a whole, and then the second impatiens are planted. The above operation is repeated until the content of Pb-PCBs in the soil drops to environmental safety standards. The method according to claim 1, wherein the impatiens are an annual herbaceous flower plant of the Impatiens genus Impatiens, and the plant height is 30 -80 cm, bright colors, various colors, including white, purple and red, the same plant can open several colors of flowers, the flowers are like flying phoenix, the head and tail are full, also known as the golden phoenix, with single and double petals The flower pattern is graceful; the flowering period of Impatiens is from June to August, the knotted fruit, the capsule is spindle-shaped, has white fur, and when it matures, it is split into five spiral fruit petals; the seeds are mostly spherical, black, and It is peach-like. After the seeds mature, the shell bursts on its own, and the seeds are popped and propagated. The method for compounding contaminated soil with compound lead-polychlorinated biphenyl (Pb-PCBs) according to claim 1, wherein the balsam flower harvested after the impatiens are matured can be sold as ornamental flowers or concentrated. Sanitary landfill treatment.

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