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Li Y.,South China Agricultural University | Li Y.,CAS South China Botanical Garden | Zeng S.-C.,South China Agricultural University | Zeng S.-C.,Key Laboratory of Ecological Agriculture | And 2 more authors.
Chinese Journal of Applied Ecology | Year: 2011

An in situ field experiment was conducted to study the effects of simulated nitrogen (N) deposition on soil acid phosphomonoesterase activity (APA) and soil available phosphorous (AP) content in Pinus massoniana forest (PF), coniferous and broad-leaved mixed forest (MF), and monsoon evergreen broad-leaved forest (MEBF) in Dinghushan Mountain. In PF and MF, three treatments were installed, i. e. , CK (0 kg N.hm -2 . a -1), low N (50 kg N.hm -2 . a -1), and medium N (100 kg N.hm -2 . a -1); in MEBF, four treatments were installed, i. e. , CK, low N, medium N, and high N (150 kg N . hm -2 . a -1). The soil APA and soil AP content decreased with soil depth. The soil APA was the highest in MEBF, while the AP content had no significant difference in the three forests. The effects of N addition on soil APA differed with forest types. In MEBF, the APA was the highest (19.52 μmol.g -1 .h -1) in low N treatment; while in PF and MF, the APA was the highest (12.74 and 11.02 μmol.g -1 .h -1, respectively) in medium N treatment. In the three forests, soil AP content was the highest in low N treatment, but had no significant differences among the N treatments. There was a significant positive correlation between soil APA and soil AP content.

Cai Q.-Y.,South China Agricultural University | Cai Q.-Y.,Key Laboratory of Ecological Agriculture | Cai Q.-Y.,Key Laboratory of Arable Land Conservation South China | Huang H.-J.,South China Agricultural University | And 9 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2012

Low molecular-mass nonylphenol ethoxylates (NPEOs) and 4-nonylphenol (NP) are biodegradation products of higher molecular mass NPEOs used as surface active agents, and they are endocrine-disrupting contaminants. In this study, surface soil (0-20 cm) samples and different vegetable samples were collected from 27 representative vegetable farms located in Shenzhen, Dongguan, and Huizhou within the Pearl River Delta region, South China, and NP and nonylphenol monoethoxylate (NP1EO) were analyzed using high-performance liquid chromatography with ultraviolet detection. The results show that NP and NP1EO were detected in soil and vegetable samples. The concentrations of NP and NP1EO in soil samples ranged from nondetectable (ND) to 7.22 μg kg -1 dry weight (dw) and from ND to 8.24 μg kg-1 dw, respectively. The average concentrations of both NP and NP 1EO in soil samples decreased in the following order: Dongguan>Huizhou> Shenzhen. The levels of NP and NP1EO in vegetable samples varied from 1.11 to 4.73 μg kg -1 dw and from 1.32 to 5.33 μg kg -1 dw, respectively. The greatest levels of both NP and NP 1EO were observed in water spinach, and the lowest levels of NP and NP 1EO were recorded in cowpea. The bioconcentration factors (the ratio of contaminant concentration in plant tissue to soil concentration) of NP and NP 1EOwere<1.0 (mean 0.535 and 0.550, respectively). The occurrences of NP and NP 1EO in this study are compared with other studies, and their potential sources are discussed. © Springer Science+Business Media, LLC 2011.

Zhao B.-L.,South China Agricultural University | Zhao B.-L.,Key Laboratory of Ecological Agriculture | Peng H.,South China Agricultural University | Zhang J.-E.,South China Agricultural University | And 3 more authors.
Chinese Journal of Ecology | Year: 2013

Golden apple snail is one of the 100 pernicious alien invasive species in the world. In this study, the shell powder of golden apple snail was used as the adsorbent to approach its characteristics and mechanisms of lead (Pb 2+ ) removal from aqueous solution under laboratory condition. It was found that the removal rate of Pb2+ by the shell powder was related to the shell powder amount, initial Pb2+ concentration, solution pH, and reaction time, while solution temperature had lesser effects. The fitting of Langumir model indicated that the Pb2+ adsorption capacity of the shell powder was 89.29 mg · g-1. The analysis of scanning electron microscopy showed that the Pb2+ removal process was mainly happened at the surface of the powder, and small particle was more active. The X-ray diffraction indicated that the adsorbed Pb2+ was in the form of PbCO3 existing on the powder. The mechanisms of the Pb2+ removal could be the ion exchange and precipitation on the aragonite and calcite in the powder. It was suggested that the shell of golden apple snail could be used as an effective bio-adsorbent for Pb2+ removal.

Wang Y.,University Putra Malaysia | Wang Y.,Guangdong Institute of Eco environmental and Soil Sciences | Wang Y.,Key Laboratory of Ecological Agriculture | Liang J.B.,University Putra Malaysia | And 5 more authors.
Industrial and Engineering Chemistry Research | Year: 2010

Sulfadiazine, a potent antibacterial agent belonging to the group of antibiotics called sulfonamides, has been reported to be present in surface and groundwater. This study investigated the degradation of sulfadiazine in a goethite (α-FeOOH)-oxalate Fenton-like system under UV irradiation. The results showed that sulfadiazine could be effectively photodegraded by the goethite-oxalate Fenton-like system as a result of the formation of the highly oxidizing hydroxyl radicals, ·OH. Among the iron oxides tested (α-FeOOH, γ-Fe2O3, γ-FeOOH, and α-Fe2O3), α-FeOOH was found to be the most effective. Degradation of sulfadiazine depended significantly on the pH and initial concentration of oxalic acid in the system, with optimal values of 3.5 and 4.0 mM, respectively, under UV irradiation. Five intermediate products of sulfadiazine degradation were identified using high-performance liquid chromatography-mass spectrometry (HPLC-MS), gas chromatography-mass spectrometry (GC-MS), and ion chromatography (IC), and a possible sulfadiazine degradation pathway in such a system was proposed. Organic sulfur and organic nitrogen mineralization were also observed, and the results indicated that cleavage of the sulfonylurea bridge was easier than the other potential cleavage bonds under the goethite-oxalate system. In addition, results from Biolog assays suggested that the ecological toxicity of the sulfadiazine solution was effectively reduced after degradation. © 2010 American Chemical Society.

Liu S.-Y.,South China Agricultural University | Liu S.-Y.,Key Laboratory of Ecological Agriculture | Liu Y.-X.,South China Agricultural University | Liu Y.-X.,Nanjing Forestry University | And 5 more authors.
Chinese Journal of Applied Ecology | Year: 2010

Soil samples were collected from the Eucalyptus plantations in the north, east, and west Guangdong and Pearl River Delta region to study their organic carbon content and density, and the main factors affecting the organic carbon density. In the plantations, the soil organic carbon content and density in A and B horizons were significantly different, with the values of (23.94±2.97) g · kg -1 and (9.68 ± 1.05) g · kg -1, and (27.64±7.72) t · hn -2 and (108.36±9.37) t · hn -2, respectively. In 0-50 cm soil layer, the organic carbon density was 66.72 ± 6.53 t · hm -2, being slightly higher than that in Masson pine and Chinese fir plantations in Guangdong. In both A and B horizons of Eucalyptus plantations, soil organic carbon density was significantly positively correlated with altitude, soil total porosity, capillary porosity, capillary moisture capacity, and total nitrogen content. Soil capillary porosity, capillary moisture capacity, and pH value were the main factors affecting the soil organic carbon density.

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