Background technology
The current quickening along with industrial and agricultural development and urbanization process, the phenomenon of heavy-metal contaminated soil is commonplace in China some areas, particularly serious in some non-ferrous metal mining area and surrounding area, smeltery, wherein cadmium (Cd), plumbous (Pb), arsenic (As) are particularly serious, considerably beyond in GB15618-1995 " standard of soil environment quality " for ensureing that agriculture and forestry are produced and the soil critical value of plant normal growth.Now China is subject to approximately 2,500 ten thousand hectares of the agricultural land soils of heavy metal pollution, nearly 1,200 ten thousand tons, annual contaminated by heavy metals grain, and the direct economic loss causing exceedes 10,000,000,000 yuan.
In recent years, phytoremediation technology becomes main flow gradually in international and domestic improvement heavy metal pollution of soil field.Phytoremediation advantage mainly contains: be suitable for pollution factor extensive, be not only applicable to heavy metal, simultaneously doublely control organic contamination; From ecological view, be conducive to impurely restoration of the ecosystem, beautify the environment; Take solar energy as power, less investment, cost is low; Be difficult for causing secondary pollution.
In phytoremediation technology, selecting heavy metal super-enriched plant technology to carry out restoration of soil polluted by heavy metal is comparatively common a kind of technology.This technology remediation efficiency depends primarily on content and the phytomass of plant heavy metal of body.For plants enriched desirable super enriching plant, the tenor of its overground part should, than high hundred times even thousands of times of common plants, should have the higher speed of growth and larger biomass simultaneously.But regrettably, the biomass of most of super enriching plant of finding is at present generally less, thereby limit its application in contaminated soil is repaired.Adopt this technology longer repair time simultaneously, also limited to a certain extent the popularization of this technology.
At present, select energy-source plant aspect restoration of soil polluted by heavy metal, to have unique advantage, not only can, in administering soil pollution, obtain source benefit.Research shows, some energy-source plants have the ability of higher enrichment or tolerance heavy metal, can on heavy-metal contaminated soil, grow, and energy substance output is substantially unaffected simultaneously.Therefore choose applicable energy-source plant and carry out restoration of soil polluted by heavy metal, be not only conducive to heavy-metal contaminated soil and administer, and can advance the exploitation of new forms of energy, make contaminated land resource rationally be utilized simultaneously.But energy-source plant repairing heavy metal in soil pollutes and also exists growth cycle long, and repair time is of a specified duration, post processing difficulty, long-term planting reduces the total shortcoming of the plants such as soil fertility.Meanwhile, compared with hyperaccumulative plant, the ability of many energy-source plant enriching heavy metals is also lower.
Summary of the invention
(1) technical problem that will solve
For the deficiency of two Plants recovery techniques in prior art, the object of the invention is to propose to utilize castor-oil plant and ciliate desert-grass interplanting technique to repair the plant restoration method of the plumbous arsenic combined contamination soil of cadmium.
(2) technical scheme
A first aspect of the present invention is to provide a kind of plant restoration method of administering the plumbous arsenic combined contamination soil of cadmium, and it is as follows that the method comprising the steps of:
Step S1: choose cadmium concentration type castor-oil plant kind;
Step S2: control the acid-base value of the plumbous As polluted soil of cadmium, obtain the plumbous arsenic contaminated soil of cadmium of quinaldine acid basicity;
Step S3: cadmium concentration type castor-oil plant and ciliate desert-grass are planted to survival and growth in the plumbous arsenic contaminated soil of cadmium of quinaldine acid basicity with intercropping system, absorbed in a large number the cadmium in contaminated soil by the root system of castor-oil plant, and regularly gather in the crops ripe castor-oil plant, perform step S5;
Step S4: look the growing height of ciliate desert-grass, harvesting ciliate desert-grass top, absorbs the plumbous arsenic in contaminated soil in a large number by the grass roots system of ciliate desert-grass and the ciliate desert-grass top of harvesting, performs step S5; On described soil ground, retain a ciliate desert-grass section stubble, perform step S3;
Step S5: exclusive place is delivered to in the ripe castor-oil plant of results and ciliate desert-grass top and concentrate and do harmless treatment.
A second aspect of the present invention is to provide a kind of plant restoration method of administering cadmium pollution soil, and it is as follows that the method comprising the steps of:
Steps A 1: choose cadmium concentration type castor-oil plant kind;
Steps A 2: control the acid-base value of cadmium pollution soil, obtain the cadmium pollution soil of quinaldine acid basicity;
Steps A 3: cadmium concentration type cultivating castor-oil plant, to survival and growth in the cadmium pollution soil of quinaldine acid basicity, is regularly gathered in the crops to ripe castor-oil plant, by cadmium concentration type castor-oil plant, cadmium pollution soil is removed, decomposed;
Steps A 4: the ripe castor-oil plant of results is delivered to exclusive place and concentrate and do harmless treatment.
(3) beneficial effect
The present invention utilizes energy-source plant castor-oil plant to have certain cadmium ion ability, repairs deep soil, can establishing in large scale, beautify the environment and produce the feature of source benefit, and the plumbous arsenic enriching plant of cadmium ciliate desert-grass, have the advantages that the plumbous arsenic ion ability of enrichment arsenic is strong, cultivation technique is ripe, both combine the plumbous arsenic combined contamination soil of reparation cadmium, can reach higher remediation efficiency, and obtain source benefit.Provided by the invention in the plumbous As polluted soil of cadmium intercropping castor-oil plant and ciliate desert-grass, utilize castor-oil plant biomass larger, growth period is shorter and the enriched character of cadmium is absorbed to the cadmium in enrichment soil in a large number, utilize ciliate desert-grass to eliminate by harvesting overground part the method that the plumbous arsenic of cadmium in soil pollutes compared with plumbous arsenic short and that the super enriched character of plumbous arsenic is absorbed in enrichment soil in a large number growth period simultaneously, there is the not physicochemical property of spoiled soil, not high to the absorption enriching quantity of soil generation secondary pollution and the plumbous arsenic of cadmium, biological concentration coefficient is large and the plumbous arsenic migration of cadmium total amount is high, and there is higher economic benefit simultaneously, construction investment is few, operating cost is low, prevention soil and water loss, beautify the features such as landscape environment, be applicable to the improvement reparation of moderate and the plumbous As polluted soil of slight cadmium, its environmental benefit, Social benefit and economic benefit is obvious.
The specific embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.
One. first, introduce the ciliate desert-grass in the present invention:
Ciliate desert-grass is the super enriching plant that Chen Tongbin research team finds As the earliest in the world.Ciliate desert-grass not only shows as extremely strong patience ability and unique accumulation ability to As, and Pb is had to stronger patience effect and enrichment.Field investigation shows, ciliate desert-grass can be grown in slag that As content is 23400mg/kg and lead concentration up near the contaminated soil Pb-Zn tailings of 3368-3550mg/kg.Ciliate desert-grass has stronger arsenic patience, arsenic accumulation ability and arsenic absorption rate fast, and biological concentration coefficient in the soil of arsenic content < 1000mg/kg (in plant in certain content of beary metal and its root region soil the ratio of this content of beary metal) can reach 7-80.While growth the land reclamation in mining area that ciliate desert-grass is 4325-13254mg/kg at Pb content, the Pb content of ciliate desert-grass overground part has exceeded the requirement (1000mg/kg) of Pb super enriching plant, while ciliate desert-grass overground part Pb content is 1.4 times of underground part Pb content, illustrate that ciliate desert-grass has stronger accumulation ability and turn-over capacity (representing to transport coefficient, i.e. the ratio of this content of beary metal in plant shoot content of beary metal and its root) to Pb.Ciliate desert-grass overground part not only can enriched arsenic lead, and fast growth, biomass is large.But also there are some limiting factors in its popularization aspect: ciliate desert-grass growth needs shades, the growth conditions that moisturizing etc. are more harsh; Not strong to cadmium absorbability; Ciliate desert-grass root system is shallow not good to plough horizon bottom repairing effect; Can not directly bring economic interests etc.
Two. then, introduce the castor-oil plant in the present invention:
Castor-oil plant is " deep rooted plant ", belongs to annual or herbaceos perennial, is the oil crops that a kind of economic worth is higher, not high to environmental requirement, can survive the winter in south, and biomass is large, and heavy metal is had to stronger patience.Studies show that, castor-oil plant also has higher patience and accumulation ability to cadmium.Show after deliberation, for castor-oil plant, the cadmium of low concentration exposes and does not only suppress its growth, also castor-oil plant growth is produced to certain promotion.Castor-oil plant is in the time that Cadmium in Soil concentration for the treatment of is 40mg/kg, and it is maximum that the dry matter of the plant height of castor-oil plant and root, stem, leaf reaches.The Cd of castor-oil plant energy enrichment higher concentration in the time that soil Cd concentration is higher.Maximum when castor root ties up to Cadmium in Soil concentration for the treatment of and is 360mg/kg, reaches 4460mg/kg, and overground part leaf and stem reach maximum when cadmium concentration for the treatment of 320mg/kg and the 360mg/kg respectively to the accumulation of cadmium, and wherein stem reaches 137mg/kg to the maximum accumulation of cadmium.Therefore, castor-oil plant can be used for the improvement reparation of severe and slight cadmium pollution soil; Except absorption enriching quantity and biological concentration coefficient and transfer ratio to cadmium, biomass is also an important indicator evaluating phytoremediation cadmium pollution soil potential ability.Biomass is larger, illustrate within the isometric growth phase and identical concentration coefficient condition under, the amount of cadmium that this plant absorbs enrichment from soil is more, show under identical planting conditions, it is shorter that this plant makes cadmium pollution soil be reduced to the following time used of GB15618-1995 " standard of soil environment quality " regulation critical value.The biomass of castor-oil plant is larger, and its biomass is about 500~700g/ strain (dry weight).Castor-oil plant is significant for improving the reparation speed of cadmium pollution soil and reducing treatment cost, for the cadmium pollution of administering soil provides a kind of economic and practical plant restoration method.But while utilizing separately castor-oil plant repairing polluted soil at present, also exist it as not high in accumulation abilities such as plumbous arsenic to other heavy metals, the shortcoming such as repair time is long.
In sum, in view of ciliate desert-grass feature and growth conditions, and castor-oil plant and the ciliate desert-grass pluses and minuses while repairing separately, the present invention utilizes the advantage of ciliate desert-grass overground part, utilize the advantage of castor-oil plant, for the growth of ciliate desert-grass provides required growth conditions, adopt castor-oil plant-ciliate desert-grass united mode restoration of soil polluted by heavy metal, can highlight advantage, supplement each other.First, castor-oil plant has absorption selectivity from ciliate desert-grass to different heavy metals in soil, and both associatings can realize mutual supplement with each other's advantages, to process soil heavy metal combined pollution problem, in order to reduce the plumbous arsenic of cadmium in contaminated soil.Secondly, ciliate desert-grass is repaired thin solum, and the deep layer region that castor-oil plant can restoration of soil polluted by heavy metal, realizes interval complementary.The 3rd, castor-oil plant can be ciliate desert-grass and shades moisturizing to meet the ciliate desert-grass required environment of growing.
As Fig. 1 illustrates the flow chart of the plant restoration method of the plumbous arsenic combined contamination soil of improvement cadmium provided by the invention, the present invention by energy crop castor-oil plant by planting in the plumbous arsenic contaminated soil of cadmium with the mode of ciliate desert-grass intercropping, it is neutral controlling soil acidity or alkalinity, in the time that castor-oil plant grows to the maturity period, plant is removed from contaminated soil, thereby realized the object of removing the plumbous arsenic of pollutant in soil cadmium; The method absorbs the plumbous arsenic of cadmium in contaminated soil in a large number by castor-oil plant and ciliate desert-grass root system, and transfer them to the overground part organs such as cauline leaf, in the maturity period, castor-oil plant entirety comprised to the aerial part of root, stem, leaf, fruit part and ciliate desert-grass comprises that stem and leatherleaf remove from contaminated soil, and then transplant next batch of castor-oil plant, repeat afterwards said process.
Administer as shown in Figure 2 the flow chart of the plant restoration method of cadmium pollution soil, it is as follows that the method comprising the steps of: steps A 1: choose cadmium concentration type castor-oil plant kind; Steps A 2: control the acid-base value of cadmium pollution soil, obtain the cadmium pollution soil of quinaldine acid basicity; Steps A 3: cadmium concentration type cultivating castor-oil plant, to survival and growth in the cadmium pollution soil of quinaldine acid basicity, is regularly gathered in the crops to ripe castor-oil plant, by cadmium concentration type castor-oil plant, cadmium pollution soil is removed, decomposed; Steps A 4: the ripe castor-oil plant of results is delivered to exclusive place and concentrate and do harmless treatment.When described cadmium pollution soil is basic soil, be to basic soil mugineic acid material, in order to regulate the acid-base value of basic soil.Described acidic materials comprise one or more in b diammonium disodium edta salt, oxalic acid, citric acid.
Being subject to, in the plumbous arsenic contaminated soil of cadmium, directly sowing cadmium concentration type castor-oil plant kind, transplant ciliate desert-grass intercropping simultaneously.Utilize enriched character and the ciliate desert-grass enriched character to plumbous arsenic of castor-oil plant to cadmium, absorb in a large number the plumbous arsenic of cadmium in enrichment soil by root system, and it is upwards carried and transfers to overground part, remove the plumbous arsenic of cadmium in soil by harvesting overground part again, thereby complete improvement and the reparation to the plumbous As polluted soil of cadmium.
The present invention completes by following steps, the first relatively cadmium accumulation ability of 30 kinds of castor-oil plant kinds, and the cadmium concentration type kind of therefrom choosing establishing in large scale is used as repair materials.Secondly cadmium concentration type kind is planted and is subject in the plumbous arsenic contaminated soil of cadmium by the mode of direct sowing, and control soil acidity or alkalinity pH for neutral, the pH value that facts have proved control soil is 6.1~7.1 o'clock, cadmium amount maximum in its Root Absorption enrichment soil, wants mugineic acid material to be regulated for the soil of meta-alkalescence.The acidic materials of using comprise b diammonium disodium edta salt (EDTA), one or more in oxalic acid, citric acid; After cultivating castor-oil plant survives, when aerial part height is 60cm-100cm, transplant highly for 15cm-30cm ciliate desert-grass seedling and castor-oil plant carry out intercropping, according to the spacing in the rows plantation nonoculture castor-oil plant of 0.5m~1m, according to the spacing in the rows intercropping castor-oil plant of 0.2m~0.5m and ciliate desert-grass (as Fig. 5 illustrates); Water according to soil lack of water situation, make soil moisture content remain on 40~70% of field capacity; Gather in first when ciliate desert-grass grows into 60cm~80cm, in the time that ciliate desert-grass grows into 50cm~70cm, gather in once later; After each harvesting ciliate desert-grass aerial part, the height for the stubble left is 10cm~20cm; After castor-oil plant maturation, fruit biodiesel processed, stem stalk is for papermaking or building materials; The ciliate desert-grass overground part of each harvesting focuses on specially, and processing method is made innoxious landfill etc. after comprising burning or compression.
The invention will be further described by the following examples.
(1) cadmium concentration type castor-oil plant screening varieties:
Castor-oil plant to 30 kinds of different cultivars from America, Europe, Asia and African different regions carries out indoor pot experiment, to screen cadmium concentration type castor-oil plant kind (Fig. 3).Take low (2mg/kg) and moderate (5mg/kg) cadmium pollution soil as castor-oil plant growth substrate, record and analyzed castor-oil plant aerial part (stem, leaf and fruit) biomass and cadmium concentration.Consider the Cd content of biomass, cadmium content and the corresponding soil thereof of these 30 kinds of castor-oil plant kind aerial parts, Preliminary screening goes out 4 kinds of cadmium concentration type castor-oil plant kinds: Zibo-9, Zibo-6, Zibo-5 and Zibo-8 (Fig. 4), and according to the response of castor-oil plant biomass under low and moderate cadmium pollution soil condition as patience evaluation index, draw the cadmium patience of these four kinds of cadmium enrichment castor-oil plant kinds sequentially: Zibo-9 > Zibo-6 > Zibo-8 > Zibo-5.
(2) cadmium concentration type castor-oil plant is repaired pattern:
Certain heavy-metal contaminated soil pH value is 7.4, by adding b diammonium disodium edta salt that its pH is adjusted to 6.1-7.1.Cadmium content mean value is wherein 34mg/kg.The cadmium enrichment castor-oil plant kind Zibo-8 and the Zibo-5 that choose establishing in large scale are repair materials, are planted in Polluted Soil in the mode of pot experiment, and soil moisture content remains on 40~70% of field capacity.Grow after 2 months, Zibo-5 kind can not be survived, Zibo-8 kind energy normal growth.Get root and the aerial part (cauline leaf) of Zibo-8 kind and measure cadmium content analysis, be grown in the root of Zibo-8 kind and the cadmium content of aerial part adjusted after soil pH and be respectively 216mg/kg and 8.84mg/kg, be significantly higher than and be grown in the cadmium content of not adjusting the castor-oil plant underground and aboveground of the same race on pH soil, i.e. 205mg/kg and 1.84mg/kg.Therefore, Zibo-8 kind is not only applicable to slight cadmium pollution soil repairs, and is also applicable to severe cadmium pollution soil and repairs, and regulates the measure of soil pH can further improve its extraction effect to cadmium by adding acidic materials simultaneously.
(3) field castor-oil plant-ciliate desert-grass intercropping configuration mode
Certain heavy-metal contaminated soil pH value is 7.7, by adding b diammonium disodium edta salt that its pH is adjusted to 6.1-7.1.Cadmium content mean value is wherein 3.53mg/kg, and lead content mean value is wherein 274mg/kg, and arsenic content mean value is wherein 24mg/kg.The cadmium enrichment castor-oil plant kind Zibo-8 that chooses establishing in large scale is repair materials, after concentration type cultivating castor-oil plant survives, when aerial part height is 60-100cm, transplant highly for 15-30cm ciliate desert-grass seedling and castor-oil plant carry out intercropping (Fig. 3), according to the spacing in the rows plantation nonoculture castor-oil plant of 0.5~1m, according to spacing in the rows intercropping castor-oil plant and the ciliate desert-grass of 0.25~0.5m; Soil moisture content remains on 40~70% of field capacity.Grow after 4 months, gather in first its overground part of castor-oil plant, ciliate desert-grass is gathered in 2 times during this period, and harvested material send waste guaveyard security landfill.Measure by analysis, cadmium in ciliate desert-grass overground part, plumbous and arsenic content is respectively 4.1mg/kg, 83mg/kg and 324mg/kg, the cadmium of castor-oil plant stem, plumbous and arsenic content is respectively 3.17mg/kg, 14.59mg/kg and 2.47mg/kg, the cadmium of castor leaf, plumbous and arsenic content is respectively 20.31mg/kg, 38.46mg/kg and 26.14mg/kg, weigh 300kg and leaf dry weight 300kg according to every mu of castor-oil plant stem under Intercropping, ciliate desert-grass aerial part dry weight is that 100kg calculates, annual castor-oil plant results 2 times, ciliate desert-grass results 3 times, take every mu of intercropping mode can take away 15g cadmium from soil every year, 57g lead and 114g arsenic, can effectively take away the heavy metal contaminants in soil, obtain the effect of administering soil pollution.Output castor bean 400~500kg simultaneously, produces biodiesel 150kg left and right.
The above; be only the specific embodiment in the present invention, but protection scope of the present invention is not limited to this, any people who is familiar with this technology is in the disclosed technical scope of the present invention; can understand conversion or the replacement expected, all should be encompassed in of the present invention comprise scope within.