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Meng L.,Sichuan Agricultural University | Meng L.,Key Laboratory of Soil Environment Protection of Sichuan Province | Zhang S.,Sichuan Agricultural University | Zhang S.,Key Laboratory of Soil Environment Protection of Sichuan Province | And 6 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2015

In order to remove the excess zinc in the soil and ensure the security of soil quality, batch soil washing experiments were conducted to investigate the Zn removal efficiencies by four types of biologic materials (Rumex patientia, Herba Loophatheri, Blassika kapestris and Pterocarya stenoptera) under the conditions of different concentrations, pH values and contact time. The results showed that Zn removal efficiencies significantly increased with increasing concentrations of biologic materials at 25 ℃ and 200 r·min-1 rotational speed of constant temperature oscillator. The removal efficiencies gradually reduced with increasing pH, and showed small change with contact time increment. The maximum removal efficiencies for zinc were 48.33%, 33.69%, 49.82% and 49.32%, respectively, with 4% eluent at pH 5.0 and a reaction time of 2 h. ©, 2015, Science Press. All right reserved.


Luo R.Y.,Key Laboratory of Soil Environment Protection of Sichuan Province | Luo R.Y.,Sichuan Agricultural University | Zhang S.R.,Key Laboratory of Soil Environment Protection of Sichuan Province | Zhang S.R.,Sichuan Agricultural University | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Nitrogen (N) is one of the most important element in plant growth and an important part of the global ecosystem substances circulation. Organic N is both the main form of soil N and pool of mineral N. Soil organic N plays an important role in soil fertility, N cycling and environmental protection. Usually, the concentration and distribution of soil organic N mainly affected by soil types, soil level, rhizospheric environment, fertility and farming conditions, etc, and the chemical forms and status of soil organic N is the important factor affecting the availability of soil N. Currently, researchers have focused more on effect of different land use systems on changes of soil organic N fractions, dissolved organic N, particulate organic N and microbial biomass N, as well as effect of different fertilization and irrigation approaches on concentrations and composition of organic N fractions by using the Bremner's method to separate soil organic N fractions. Combined with filed investigation, five types of soil samples in the lower reaches of Heihe river wetland were collected, and the organic N fractions were studied using the Bremner's method, the results showed that acidolysable N was the dominant fraction of organic N in all the soil samples (0—50 cm soil layer), and the proportion of acidolysable N to total N was from 71.04% to 81.79%. The concentrations of acidolysable N, non-acidolysable N and acidolysable N fractions (ammonia N, amino acid N, amino sugar N) of Peat soil, Boggy soil, Meadow soil, Subalpine meadow soil decreased, but increased in the Aeolian sandy soil generally with soil depth in the profile. Furthermore, the proportions of acidolysable N and acidolysable N fractions (ammonia N, amino acid N, amino sugar N) to total N of all the soil samples generally decreased with soil depth in the profile distribution, while the proportion of non-acidolysable N to total N generally increased with soil depth in the profile distribution. The concentration of acidolysable unknown N and the proportion to total N of all the soil samples did not show any specific characteristics. In addition, in the same soil layer (0—30 cm), the concentrations of acidolysable N fractions and the proportions to total N varied as the followings: amino acid N > ammonia N > unknown N > amino sugar N; However, in 30—50 cm soil layer, the concentrations of acidolysable N fractions and the proportions to total N of the soil did not show any typic characteristics. Besides, the soil organic N fractions in the surface soil (0—10 cm) changed obviously along with the soil desiccation and desertification in the lower reaches of the Heihe River wetland, and the soil ammonia N of soil was the most sensitive one to the ecological environment factors. © 2015, Ecological Society of China. All rights reserved.


Chen Q.S.,Sichuan Agricultural University | Chen Q.S.,Key laboratory of Soil Environment Protection of Sichuan Province | Li T.,Sichuan Agricultural University | Li T.,Key laboratory of Soil Environment Protection of Sichuan Province | And 6 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

Urban-rural fringe is a special zone that evolved from the suburbanization accompanying intensified land use changes from agricultural to non-agricultural land. Nitrogen in the soil of urban-rural fringe is an important nitrogen source and sink for urban and suburban ecosystems. The nitrogen content changes not only affect greenhouse gas emissions, but also threaten plant nitrogen supply and water ecosystems. However, in suburb urbanization, the proportion of non-agricultural land, construction land, and road land exhibited a successive increase. Currently, the mechanism of spatial distribution of soil nitrogen, caused by an increase in non-agricultural land, remains unclear. In the present study, the 3S platform was used to investigate the spatial distribution of soil nitrogen and its influencing factors in the urban-rural fringe of the western suburbs of Chengdu. Results showed that the average contents of soil total nitrogen (STN), nitrate (NO3 --N), and ammonium (NH4 +-N) were (1.46±0.06) g/kg, (50.04±3.59) and (6.72±0.53) mg/kg, respectively. In the investigated region, average content of soil nitrogen gradually increased from the inner to the outer suburbs. The STN and NO3 --N distribution in the inner suburbs were higher than those of the northern and southern areas. High STN(>1.5 g/kg) and soil NO3 --N(> 62.2 mg/kg) values presented mass distribution in the eastern suburbs. In addition, NH4 +-N in soil gradually increased from the northwest or southeast to the center, and the high values(> 8.5 mg/kg) presented irregular piece distribution in the eastern suburbs. Analysis of variance (ANOVA) showed that the difference of STN, NO3-N, and NH4 +-N contents were significant under different land use patterns (P < 0.01). The STN content in vegetable fields was the highest (> 1.8 g/kg), followed by rape fields, gardens, and woodland (1.5-1.8 g/kg). Garlic fields and idle land were relatively moderate (1.0-1.5 g/kg), and residential land and urban green land were relatively low (< 1.0 g/kg). NO3 --N content was ranked as residential land > vegetable field > garlic field > garden > rape field > idle field > woodland > urban green land. NH4 +-N content was ranked as vegetable field > woodland > garden > rape field > garlic field > residential land > idle field > urban green land. Correlation analysis indicated that average STN content and building density (BD) showed a negative linear correlation (P <0.05), and similar linear correlation was also observed between STN and road density (RD) (P < 0.05). NO3 --N content in soil and road density showed a negative correlation (P = 0.001). However, the correlation was not significant between NO3 --N and the building density (P = 0.217) after being analyzed using different curve models. NH4 +-N content and building density showed a significant negative linear correlation (P = 0.001), and a significant exponential correlation existed in NH4 +-N content and the road density (P = 0.021). Therefore, a significant effect on the development of urban distribution of soil nitrogen was observed, that was potentially strengthened by increasing road lengths and building areas. It can be suggested that the monitoring and management of soil nitrogen should be enhanced, and the cycling of soil nitrogen, atmospheric nitrogen, and water nitrogen should be investigated in future studies. © 2016, Ecological Society of China. All rights reserved.


Luo Y.,Key Laboratory of Soil Environment Protection of Sichuan Province | Luo Y.,Sichuan Agricultural University | Zhang S.R.,Key Laboratory of Soil Environment Protection of Sichuan Province | Zhang S.R.,Sichuan Agricultural University | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Heavy metal pollution in soil is a compelling global problem. Particularly, cadmium as a non-essential element negatively affects human health by way of food chain, even at low concentrations. In recent years, Cd concentrations in soils have dramatically increased with the development of industrial and agricultural and rural urbanization. Therefore, cleanup of Cd contaminated soils is emergent and imperative. Phytoremediation of heavy metal-contaminated soils has received increasing attention for its environmental benefits. However, phytoremediation efficiency was largely restricted by the bioavailability of heavy metal. Therefore, chelant-assisted phytoextraction has been proposed an alternative. In the phytoextraction process, roots contact with the toxic metal irons and plants usually adapt to the environment stress by changing their root morphology, and thus directly affect the physiological metabolic activity of the roots. However, there was little information dealing with the toxicity and mechanisms behind Cd tolerance concerning the roots under the chelant treatments. The objectives of the present study were to investigate the effects of biodegradable chelants on the root morphology and physiological-biochemical responses of hybridus L. root to cadmium stress. The soils in pot experiments were contaminated artificially with the Cd concentrations of 10 and 100 mg/ kg soil, respectively. 0.52 g nitrogen, 0.40 g phosphorus (P2O5) and 0.36 g potassium (K2 O) were applied in every pot as a base fertilizer. After the soils were incubated for 4 weeks, four uniform A.hybridus seedlings (5—6 cm high with 3—4 fronds) were transplanted into each pot. Four replicates were run for each treatment and the experiment was arranged in a completely randomized design. Chelants assisted phytoextraction, EDDS and NTA, were added on the 65th and 75th day of transplanting at a concentration of 0 (Control), 1 and 2 mmol/ kg. Finally, plant samples for evaluating root morphology, root biomass, the activities of peroxidase (POD), catalase (CAT), glutathione (GSH) concentration and soluble protein content (SP) were determined at the mature stages (90 days after transplanting). The results showed that under the treatments of EDDS and NTA, no significant differences were observed for the root biomass, root length, root surface area, root volume and lateral roots of A. hybridus in 10 mg/ kg Cd contaminated soil. Moreover, chelant addition significantly increased the POD and CAT activities, glutathione (GSH) concentration and soluble protein content in roots of A. hybridus in 10 mg/ kg Cd contaminated soil. When EDDS and NTA were applied to the 100 mg/ kg Cd contaminated soil, root biomass, root length, root surface area, root volume and lateral roots of A. hybridus decreased by 12.30%—23.98%, 17.01%—24.90%, 41.87%—57.93%, 16.46%—32.94% and 23.48%—3.35%, and EDDS addition significantly improved the POD and CAT activities, GSH concentration and soluble protein content in roots. However, under the application of NTA, POD activities in roots were decreased by 4.12%—35.95%, and CAT activities and soluble protein content in roots significantly decreased by 14.66%— 15.79% and 26.81%—30.48% compared to the control, respectively after the addition of 2 mmol/ kg NTA. Moreover, under the addition of EDDS and NTA, GSH concentration increased by 14. 73%—65. 65% and 28. 05%—84. 10%, respectively. When the Cd concentrations were 10 and 100 mg/ kg, the application of chelants significantly enhanced the Cd concentrations in roots of A. hybridus by 40.76%—103.10% and 15.03%—49.49%, respectively. In conclusion, the application of biodegradable EDDS and NTA in Cd contaminated soils could influence the root morphology and physiological-biochemical characteristics to resist the increased Cd concentrations. © 2014, Science Press. All rights reserved.


Shen Y.,Key Laboratory of Soil Environment Protection of Sichuan Province | Shen Y.,Sichuan Agricultural University | Zhang S.,Sichuan Agricultural University | Li S.,Key Laboratory of Soil Environment Protection of Sichuan Province | And 4 more authors.
Chemosphere | Year: 2014

Guanglin 9 (Eucalyptus grandis×Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200mgkg-1, while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200mgkg-1, and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. © 2014 Elsevier Ltd.

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