Tie Heng Sun

Plant-Microorganism Combined Remediation for Sediments Contaminated with Heavy Metals

In order to investigate the effects of four heavy metal tolerant microorganisms, Staphylococcus pasteuri (X1), Agrobacterium tumefaciens (X2), Penicillium chrysogenum (Z1) and Paecilomyces lavender (Z2), on heavy metals uptake by the heavy metal tolerance plant-maize and the cadmium hyperaccumulator plant-Beta vulgaris var. cicla L., a pot experiment with sediments was conducted. Through comparing the overall situations of four microorganisms’ role in enhancing maize and Beta vulgaris var. cicla L. to gather cadmium, lead, copper and zinc, plant biomasses, and enrichment characteristics, the combination of bacterium X2, fungus Z2 and these two plants can effectively repair these four heavy metals in sediments.

New Research Development on Heavy Metals’ Speciation in Soil

The bioavailability and environmental risk of heavy metals in soil depends greatly on their speciation, not total amounts. Different speciation analysis techniques of heavy metals in soil are reviewed and the speciation schemes are considered and discussed in some detail. The present problems remained in the field of environmental science and future trends of speciation analysis of heavy metals in soil are also briefly dealt with.

Impacts of pH and Electrolyte on Cadmium Desorption Characteristics in Contaminated Soil

In this paper, two kinds of different pollution degree soils denoted as L1 and L2 were used as test soils. Desorption experiment was carried out to study the impacts of pH and electrolyte on desorption characteristics of cadmium (Cd) in soils. The results showed that the variation trends of Cd desorption rates with increase in pH were similar. In other words, it decreased as pH increased. In acidic region, desorption rate of heavy metal Cd decreased rapidly as pH increased. When pH = 4, Cd desorption rate was largest; in neutral and alkaline regions (pH = 7-10), desorption rate of heavy metal Cd decreased slowly as pH increases. Cd desorption behavior was closely related to type and concentration of electrolyte. Under the same concentration, Cd desorption capabilities of three electrolytes in soils L1 and L2 could be expressed in following order: CaCl2> Ca (NO3)2> NaCl.

Enrichment Characteristics of Cadmium and Lead in Wheat at Different Growth Stages

In this paper, the soil simulation pot experiment was carried out. The self-made cadmium (Cd) and lead (Pb) compound contaminated soil was taken as the test soil, and wheat was taken as the test plant. The Cd and Pb concentrations in different parts of wheat under jointing stage, booting stage, flowering stage, and mature period were measured, and enrichment characteristics of wheat to Cd and Pb under different growth stages were analyzed. The results showed that Cd and Pb contents in wheat roots were the greatest, while the contents in nutritive organ seeds were the least. Sequence of Cd and Pb contents in various parts of wheat was: roots> stems & leaves> rice husks> seeds. Cd and Pb contents in various parts of wheat plant gradually grew in the entire growth period, which reached the maximum at mature stage. According to the transfer coefficient and enrichment factor analysis, ability of wheat roots to enrich heavy metals Cd and Pb was stronger than that of stems & leaves, rice husks and seeds. In the transfer process of heavy metals Cd and Pb from soil to root, the transfer ability sequence was Cd > Pb.

Impacts of Trace Elements Iron and Zinc on Phytoavailability of Heavy Metals Cadmium and Lead

In this paper, the soil simulation pot experiment was carried out to study the impacts of trace elements iron (Fe) and zinc (Zn) on availability of cadmium (Cd) and lead (Pb). The self-made Cd and Pb compound contaminated soil was taken as the test soil, and wheat was taken as the test plant. The results show that with the increase in Fe dosage, overground dry weight, root dry weight, and total dry weight of wheat gradually increase; the application of Zn reduces overground dry weight, root dry weight, and total dry weight of wheat. Meanwhile, wheat biomass under Cd and Pb combined pollution is smaller than that under single Cd pollution or single Pb pollution. The application of Fe fertilizer increases Cd absorption of various parts of wheat. In the single Cd pollution treatment, with the increase in Fe dosage, Cd concentrations in roots, stems and leaves of wheat will first be increased, then decreased; in Cd and Pb combined pollution treatment, with the increase in Fe, Cd concentrations in roots, stems and leaves of wheat will also be increased. The application of Fe promotes the Pb absorption of wheat. With the increase in Fe dosage, Pb concentrations in roots, stems and leaves of wheat will first be increased, then decreased slightly. Compared with Zn0, Cd concentrations of different parts of wheat after Zn1 and Zn2 treatment increase significantly. In addition, with the increase in Zn dosage, Cd concentrations of different parts of wheat will first increase, then decrease. Regardless of single Pb pollution treatment or Cd and Pb combined pollution treatment, Pb concentrations of different parts of wheat decrease as Zn dosage increases. Under different Fe and Zn levels, and when Cd and Pb coexist, Pb can promote Cd absorption of plant, but Cd inhibits Pb absorption of plant.

The Study of Heavy Metal Pollution Characteristics in Soil of Typical Urban-Industrial Wasteland

This study chooses the industrial wasteland after the relocation of a metal processing factory in Shenyang, Liaoning Province of China as the research object. Based on level three soil heavy metal quality standards of Soil Environment Quality Standard (GB15618-1995) in China, the pollution levels of four heavy metals (cadmium, lead, copper and zinc) in survey area are Cd> Cu> Zn> Pb; the Cd pollution is the most serious one, followed by Cu and Zn. The Pb content is low. Average comprehensive pollution index of Cd, Cu, Zn and Pb in soil of the wasteland is 17.33, which belong to Grade V severe pollution. The most polluted point is J-12, followed by J-11 and J-16. The land utilization risk assessment of the wasteland should be strengthened, and appropriate and necessary repair measures should be taken, such as planting accumulative or tolerant plants.

Research on the Arsenic and Cadmium-Fixing Effects of Ameliorant in Combined Contamination Soils

This article studied the effects of chemical fixation with magnesium oxide, calcium oxide, aluminum oxide, ferrous sulfate+calcium oxide in situ on Arsenic and Cadmium combined contamination soils. The results indicate: Four agents have well fixation effects, and the fixation effect of ferrous sulfate and calcium oxide mix- restoration is the best. However, it increases the leaching toxicity of Cadmium; Aluminum oxide also has a certain fixation effect on Arsenic, but it strengthens the leaching toxicity of Cadmium in acidity condition; the fixation in situ effects of magnesium oxide and calcium oxide on Arsenic and Cadmium combined contamination soils, which dramatically decreases the leaching toxicity of Arsenic and Cadmium and makes two pollution elements co-stabilized.

Performance of a Subsurface Wastewater Infiltration System (SWIS) Using a Novel Biosubstrate

Subsurface wastewater infiltration treatment system (SWIS) is a domestic wastewater treatment technology. While the traditional technology has a large floor area, long starting period and low pollutants removal rate. A new biosubstrate that can be applied in SWIS is studied, experiments about its characteristics were performed, and treatment effect was compared. The results show that the biosubstrate has high biological activity, with it, SWIS has shorter starting period, better pollutants removal rate and consequently needs less floor space.

Feasibility Study of Municipal Wastewater Treatment by a Subsurface Infiltration System in Northeast, China

From October 2009 to September 2010, this study focused on investigation the performance of a subsurface wastewater infiltration (SWI) system in treating domestic sewage, and evaluated the potential of the surface water pollution by using the SWI system. The results showed the removal efficiencies were relatively high: for biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), ammonia nitrogen (NH3-N) and total phosphorus (TP) were 95.0, 89.1, 98.1 87.6 and 98.4%, respectively. Meanwhile, the monitoring of a nearby stream characteristic indicated the SWI system could not decrease the receiving surface water quality.

Leaching Characteristics of Manganese and Iron from Artificial Soil

A leaching experiment was carried out over a period of 90 days to determine the manganese (Mn) and iron (Fe) leaching characteristics from artificial soils composed of sewage sludge and fly ash. The leachates of artificial soils were collected every 15 days and the concentration of manganese and iron in leachates of the artificial soil was measured. Results showed that the concentration of Fe and Mn in leachates of artificial soils got to a stable level by the end of the experiment. Moreover, plant Robina pseudoacacia and Amorpha fruticosa had different effect on the leachate Fe and Mn concentration. Robina pseudoacacia resulted in higher leachate Fe concentration, while Amorpha fruticosa resulted in higher Mn concentration. However, the leachate Fe and Mn concentrations from artificial soils was high, and it will also be transported to the surface and ground water. Therefore, some measures should be taken to reduce the concentration of heavy metals in the leachates before these artificial soils being applied on the ecological rehabilitation in mine spoil areas.