Sorption of ammonium and phosphate from aqueous solution by biochar derived from phytoremediation plants

The study on biochar derived from plant biomass for environmental applications is attracting more and more attention. Twelve sets of biochar were obtained by treating four phytoremediation plants, Salix rosthornii Seemen, Thalia dealbata, Vetiveria zizanioides, and Phragmites sp., sequentially through pyrolysis at 500 °C in a N2 environment, and under different temperatures(500, 600, and 700 °C) in a CO2 environment. The cation exchange capacity and specific surface area of biochar varied with both plant species and pyrolysis temperature. The magnesium(Mg) content of biochar derived from T. dealbata(TC) was obviously higher than that of the other plant biochars. This biochar also had the highest sorption capacity for phosphate and ammonium. In terms of biomass yields, adsorption capacity, and energy cost, T. dealbata biochar produced at 600 °C(TC600) is the most promising sorbent for removing contaminants(N and P) from aqueous solution. Therefore, T. dealbata appears to be the best candidate for phytoremediation application as its biomass can make a good biochar for environmental cleaning.     

Accumulation and distribution of arsenic and cadmium by tea plants

It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field inves- tigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order: feeding roots>stems≈main roots>old leaves>young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the above- ground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosyn- thetic rate, transpiration rate and biomass production of tea plants.     

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time

Effects of cadmium (Cd) on microbial biomass, activity and community diversity were assessed in a representative variable charge soil (Typic Aquult) using an incubation study. Cadmium was added as Cd(NO3)2> to reach a concentration range of 0～16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil mi-crobial biomass was enhanced at low Cd levels (0.5～1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (<0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (<1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1～16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.     

Response of ATP sulfurylase and serine acetyltransferase towards cadmium in hyperaccumulator Sedum alfredii Hance

We studied the responses of the activities of adenosine-triphosphate (ATP) sulfurylase (ATPS) and serine acetyl-transferase (SAT) to cadmium (Cd) levels and treatment time in hyperaccumulating ecotype (HE) Sedum alfredii Hance, as compared with its non-hyperaccumulating ecotype (NHE). The results show that plant growth was inhibited in NHE but promoted in HE when exposed to high Cd level. Cd concentrations in leaves and shoots rapidly increased in HE rather than in NHE, and they became much higher in HE than in NHE along with increasing treatment time and Cd supply levels. ATPS activity was higher in HE than in NHE in all Cd treatments, and increased with increasing Cd supply levels in both HE and NHE when exposed to Cd treatment within 8 h. However, a marked difference of ATPS activity between HE and NHE was found with Cd treatment for 168 h, where ATPS activity increased in HE but decreased in NHE. Similarly, SAT activity was higher in HE than in NHE at all Cd treatments, but was more sensitive in NHE than in HE. Both ATPS and SAT activities in NHE leaves tended to decrease with increasing treatment time after 8 h at all Cd levels. The results reveal the different responses in sulfur assimilation enzymes and Cd accumulation between HE and NHE. With increasing Cd stress, the activities of sulfur assimilation enzymes (ATPS and SAT) were induced in HE, which may contribute to Cd accumulation in the hyperaccumulator Sedum alfredii Hance.     

Mechanisms of phosphate removal from aqueous solution by blast furnace slag and steel furnace slag

We report the adsorption of phosphate and discuss the mechanisms of phosphate removal from aqueous solution by burst furnace slag （BFS） and steel furnace slag （SFS）. The results show that the adsorption of phosphate on the slag was rapid and the majority of adsorption was completed in 5-10 min. The adsorption capacity of phosphate by the slag was reduced dramatically by acid treatment. The relative contribution of adsorption to the total removal of phosphate was 26%-28%. Phosphate adsorption on BFS and SFS follows the Freundlich isotherm, with the related constants of k 6.372 and 1/n 1.739 for BFS, and of k 1.705 and 1/n 1.718 for SFS. The pH and Ca^2＋ concentration were decreased with the addition of phosphate, suggesting the formation of calcium phosphate precipitation. At pH 2.93 and 6.93, phosphate was desorbed by about 36%-43% and 9%-11%, respectively. These results indicate that the P adsorption on the slag is not completely reversible and that the bond between the slag particles and adsorbed phosphate is strong. The X-ray diffraction （XRD） patterns of BFS and SFS before and after phosphate adsorption verify the formation of phosphate salts （CaHPO4·2H2O） after adsorption process. We conclude that the removal of phosphate by BFS and SFS is related to the formation of phosphate calcium precipitation and the adsorption on hydroxylated oxides. The results show that BFS and SFS removed phosphate nearly 100%, indicating they are promising adsorbents for the phosphate removal in wastewater treatment and pollution control.     

Response of ATP sulfurylase and serine acetyltransferase towards cadmium in hyperaccumulator Sedum alfredii Hance

We studied the responses of the activities of adenosine-triphosphate (ATP) sulfurylase (ATPS) and serine acetyltransferase (SAT) to cadmium (Cd) levels and treatment time in hyperaccumulating ecotype (HE) Sedum alfredii Hance, as compared with its non-hyperaccumulating ecotype (NHE). The results show that plant growth was inhibited in NHE but promoted in HE when exposed to high Cd level. Cd concentrations in leaves and shoots rapidly increased in HE rather than in NHE, and they became much higher in HE than in NHE along with increasing treatment time and Cd supply levels. ATPS activity was higher in HE than in NHE in all Cd treatments, and increased with increasing Cd supply levels in both HE and NHE when exposed to Cd treatment within 8 h. However, a marked difference of ATPS activity between HE and NHE was found with Cd treatment for 168 h, where ATPS activity increased in HE but decreased in NHE. Similarly, SAT activity was higher in HE than in NHE at all Cd treatments, but was more sensitive in NHE than in HE. Both ATPS and SAT activities in NHE leaves tended to decrease with increasing treatment time after 8 h at all Cd levels. The results reveal the different responses in sulfur assimilation enzymes and Cd accumulation between HE and NHE. With increasing Cd stress, the activities of sulfur assimilation enzymes (ATPS and SAT) were induced in HE, which may contribute to Cd accumulation in the hyperaccumulator Sedum alfredii Hance. Project supported by the National Natural Science Foundation of China (No. 30630046) and the Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z386), and the Program for Changjiang Scholars and Innovative Research Team in University, China (No. IRT0536)     

Simultaneous removal of ethyl acetate,benzene and toluene with gliding arc gas discharge

The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge （GA） reactor. Good decomposition efficiencies are obtained which proves that the GA is effective for the treatment of volatile organic compounds （VOCs） with either low or high concentration. A theoretical decomposition mechanism is proposed based on detection of the species in the plasma region and analysis of the decomposition by-products. This preliminary investigation reveals that the GA has potential to be applied to the treatment of exhaust air during color printing and coating works, by either direct removal or combination with activated carbon adsorption/desorption process.     

Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie （Sedum alfredii Hance）

Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined, The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn2 and/or 200 μmol/L Cd2 increased linearly within 15 d. Contents of total S, glutathione (GSH) and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd2 treatment than under Zn2 treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn2 -treated shoots than in Cd2 -treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2 -treated leaf than in the Cd2 -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2 and Cd2 for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Oar results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.     

热压法制备PVA/短切上段稻草复合材料研究

基于农作物秸秆的复合材料有利于减轻资源短缺与环境污染等问题.采用热压方法制备了PVA(聚乙烯醇)/短切上段稻草复合材料,研究了PVA用量、热压温度、热压时间对复合材料拉伸性能及硬度的影响.结果表明,在选定的条件范围内,随着PVA用量增加,材料拉伸强度增加,随着热压温度和热压时间增加,材料拉伸强度降低;材料硬度受加工条件影响较小.     

影响方解石去除水体中高浓度磷酸盐的因素

通过探讨方解石去除水体中高浓度磷酸盐的影响因素,为能够有效地对工业废水中磷酸盐污染物进行深度处理提供理论基础。研究了典型pH值条件下以及水体中可能存在的其他离子对方解石去除磷效率的影响。结果表明,pH值显著影响方解石对高浓度磷的去除,当pH=6.0时,方解石溶解游离出的Ca2＋与水体中的H2PO4-形成磷酸钙的沉淀,同时溶液中的其他离子（例如Mg2＋,SO42-,NH4＋和草酸）对方解石去除磷起到抑制作用。当pH=10.0时,方解石对磷的去除主要以吸附过程为主,溶液中的Mg2＋对方解石去除磷有促进作用,NH4＋与草酸都对其有抑制作用,而SO42-的影响作用不明显。当Mg2＋和NH4＋共存时,通过生成磷酸铵镁沉淀物与方解石共同去除水体中的磷。     

Foam separation of chromium （VI） from aqueous solution

Removal of chromium (VI) dissolved in water by intermittent foam separation was implemented with cetyl trimethy-ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration is 10 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal efficiency of chromium (VI) reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the equivalent rate equation is obtained.     

Spatial distribution of Cd and Cu in soils in Shenyang Zhangshi Irrigation Area （SZIA）, China

Heavy metal contamination of soils, derived from sewage irrigation, mining and inappropriate utilization of various agrochemicals and pesticides, and so on, has been of wide concern in the last several decades. The Shenyang Zhangshi Irrigation Area (SZIA) in China is a representative area of heavy metal contamination of soils resulting from sewage irrigation for about 30 years. This study investigated the spatial distribution and temporal variation of soil cadmium (Cd) and copper (Cu) contamination in the SZIA. The soil samples were collected from the SZIA in 1990 and 2004; Cd and Cu in soils was analyzed and then the spatial distribution and temporal variation of Cd and Cu in soils were modeled using Kriging methods. The results show that long-term sewage irrigation had caused serious Cd and Cu contamination in soils. The mean and the maximum of soil Cd are markedly higher than the levels in second grade standard soil (LSGSS) in China, and the maximum of soil Cu is close to the LSGSS in China in 2004 and is more than the LSGSS in China in 1990. The contamination magnitude of soil Cd and the soil extent of Cd con- tamination had evidently increased since sewage irrigation ceased in 1992. The contamination magnitude of soil Cu and the soil extent of Cu contamination had evidently increased in topsoil, but obviously decresed in subsoil. The soil contamination of Cd and Cu was mainly related to Cd and Cu reactivation of contaminated sediments in Shenyang Xi River and the import of Cd and Cu during irrigation. The eluviation of Cd and Cu in contaminated topsoil with rainfall and irrigation water was another factor of temporal-spatial variability of Cd and Cu contamination in soils.     

Manganese removal from the Qiantang River source water by pre-oxidation: A case study

We evaluated several different pre-oxidation treatments, namely the introduction of either potassium permanganate （KMnO4）, chlorine （Cl2）, or both to remove manganese （Mn） from the Qiantang River source water. Our results showed that Mn removal percentages were 12.7%, 71.0%, 17.4% and 58.7% when none of the oxidants, KMnO4 only, Cl2 only, or both oxidants were added, respectively. Furthermore, a field study showed that when the available Mn concentration in the source water was 0.14 mg/L, it could be reduced to less than 0.05 mg/L when a solution of KMnO4 （0.47 mg/L） was added as the oxidant.     

Discrimination of rice panicles by hyperspectral reflectance data based on principal component analysis and support vector classification

Detection of crop health conditions plays an important role in making control strategies of crop disease and insect damage and gaining high-quality production at late growth stages. In this study, hyperspectral reflectance of rice panicles was measured at the visible and near-infrared regions. The panicles were divided into three groups according to health conditions: healthy panicles, empty panicles caused by Nilaparvata lugens Stul, and panicles infected with Ustilaginoidea virens. Low order derivative sp...     

cDNA cloning and sequence analysis of genome segments S8 from rice black-streaked dwarf virus

Genome segments S8 of two Chinese isolates of rice black-streaked dwarf virus (RBSDV), one from Zhejiang Province and another from Hebei Province, were amplified by RT-PCR and sequenced. Both segments consisted of 1936 nts in full length (EMBL accession numbers were AJ297431 and AJ297432, respectively) and contained only one big open reading frame which encoded a polypeptide with molecular weight of 68kD. The two Chinese isolates shared 94.0% and 96.5% identity at nucleotide and amino acid level, respectively. They shared 94.5-94.9% and 92.5-92.9% homology with S8 of RBSDV Japanese isolate at nucleotide and amino acid level, respectively; shared 85.1-87.6% and 91.7-91.9% homology with S7 of Italian MRDV (maize rough dwarf virus).     

Identification of candidate genes for drought stress tolerance in rice by the integration of a genetic （QTL） map with the rice genome physical map

INTRODUCTION Drought stress is a major constraint to rice(Oryza sativa) production and yield stability in rainedecosystems (Dey and Upadhyaya, 1996). Rice mustbe made more drought tolerant, but this is a somewhatcontradictory objective considering that rice is mostcommonly grown under flooded conditions. Achiev-ing drought tolerance in rice will require a deeperunderstanding of the possible physiological mecha-nisms available for water stress tolerance and theidentification of favo…     

Assessment of rice fields by GIS/GPS-supported classification of MODIS data

The new Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite image offers a large choice of opportunities for operational applications. The 1-km Advanced Very High Resolution Radiometer (AVHRR) image is not suitable for retrieval of field level parameter and Landsat data are not frequent enough for monitoring changes in crop parameters during the critical crop growth periods. A methodology to map areas of paddy fields using MODIS, geographic information system (GIS) and global position system (GPS) is introduced in this paper. Training samples are selected and located with the help of GPS to provide maximal accuracy. A concept of assessing areas of potential cultivation of rice is suggested by means of GIS integration. By integration of MODIS with GIS and GPS technologies the actual areas of rice fields in 2002 have been mapped. The classification accuracy was 95.7% percent compared with the statistical data of the Agricultural Bureau of Zhejiang Province.     

Assessment of rice fields by GIS/GPS-supported classification of MODIS data

INTRODUCTIONInthelastdecade,remotesensinghasbeenincreasinglyidentifiedasanobjective,standardized,possiblycheaperandfastermethodologyforcropproductionsurveysthanconventionalfieldinves-tigations(Bauman,1992).Muchprogresshasbeenmadethroughintensivestudiesoninventoryandproductionforecastingformajorcrops,suchaswheat,rice,cottonandmaize(Tennakoonetal.,1992;Rayetal.,1994;Fangetal.,1998).China,adevelopingcountrywith1.2billionpeople,hasbeenpayingcloseattentiontoitsex-istingandfuturefoodproduction…     

Comparative mapping of QTLs for Al tolerance in rice and identification of positional Al-induced genes

INTRODUCTION Aluminum (Al) toxicity is one of the mostimportant yield-limiting factors for crop grown onacid upland and lowland acid sulphate soils (IRRI,1978). Al toxicity results in a reduced and damagedroot system, which in turn causes the affectedplants to be susceptible to drought stress and min-eral nutrient deficiencies (Foy, 1988). The physio-logical and biochemical mechanisms of the toxiceffect of Al on root elongation had been extensivelyinvestigated (Matsumoto, 2000). T…     

Comparative mapping of QTLs for Al tolerance in rice and identification of positional Al-induced genes

Aluminum (Al) toxicity is the major factor limiting crop productivity in acid soils. In this study, a recombinant inbreed line (RIL) population derived from a cross between an A1 sensitive lowland indica rice variety IR1552 and an Al tolerant upland japonica rice variety Azucena, was used for mapping quantitative trait loci (QTLs) for A1 tolerance. Three QTLs for relative root length (RRL) were detected on chromosome 1, 9, 12, respectively, and I QTL for root length under Al stress is identical on chromosome I after one week and two weeks stress. Comparison of QTLs on chromosome 1 from different studies indicated an identical interval between C86 and RZ801 with gene(s) for Al tolerance. This interval provides an important start point for isolating genes responsible for A1 tolerance and understanding the genetic nature of Al tolerance in rice. Four Al induced ESTs located in this interval were screened by reverse Northern analysis and confirmed by Northern analysis. They would be candidate genes for the QTL.