Potential of weed species applied to remediation of soils contaminated with heavy metals

To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially.

Bioremediation of Soil Contaminated with Petroleum Using Forced-Aeration Composting

Laboratory simulation studies and composting pilot study wereconducted to evaluate the capacity of three strains of fungi,indigenous fungus Fusarium sp. And Phanerochaete chrysosporium andCoriolus Versicolor, to remediate petroleum-contaminated soils. Inlaboratory, the fungi were inoculated into a liquid Culture mediumand the petroleum-contaminated soil samples for incubation of 40 and50 days, respectively. In the 200-day pilot study, nutrient contentsand moisture were adjusted and maintained under aerobic Condition incomposting units using concrete container (118.5 cm×65.5 cm×12.5cm) designed specially For this study.

Effects of soil moisture and soil depth on nitrogen mineralization process under Mongolian pine plantations in Zhanggutai sandy land, P. R. China

The rates of soil N mineralization at soil depths of 0-15, 15-30, 30-45 and45-60 cm and moisture regimes were measured at three sand-fixation plantations of Pinus sylvestrisvar. mongolica by laboratory aerobic incubation method. The results showed that average rates ofsoil net N-mineralization across soil depth varied from 1.06 to 7.52 mg · kg^(-1)·month^(-1) atsoil depths from 0 to 60 cm. Statistical analyses indicated that the effects of different soildepths, moistures and their interactions on net N-mineralization rates were significant (P < 0.05).The net N-mineralization rates significantly decreased with increasing soil depths and at depth 0-15cm accounted for 60.52% of that at depth of 0-60 cm. There was no difference in soil netN-mineralization rates between half and fully-saturated water treatments, however these rates weresubstantially higher than that without water treatment (P < 0.05). The factors influencing Nmineralization process have to be studied further in these semiarid pine ecosystems.

Ecological toxicity of reactive X-3B red dye and cadmium acting on wheat (Triticum aestivum)

Ecological toxicity of reactive X\|3B red dye and cadmium in both their single form and their combined form on wheat was studied using the experimental method of seed and root exposure. The single factor exposure indicated that the inhibitory rate of wheat root elongation was significantly increased with the increase in the concentration of the dye in the cultural solution, although seed germination of wheat was not sensitive to the dye. The toxicity of cadmium was greatly higher than that of the dye, but low concentration cadmium (<40 mg/L) could promote the germination of wheat seed. Interactive effects of the dye and cadmium on wheat were complicated. There was no significant correlation between the inhibitory rate of seed germination and the concentrations of the dye and cadmium. Low concentration cadmium could strengthen the toxicity of the dye acting on root elongation. On the contrary, high concentration cadmium could weaken the toxicity of the dye acting on root elongation.

Pedogenic and Anthropogenic Influence on Calcium and Magnesium Behaviors in Stagnic Anthrosols

The formation of Stagnic Anthrosols is closely related to rice planting and parent materials. Six representative pedons, two from each of three Stagnic Anthrosol subgroups, Vertic Haplic-, Vertic Gleyic-, and Sulfic Gleyic-Stagnic Anthrosols, from different parent materials and soil formation processes, from Liaoning Province, China, were selected and used along with additional supporting data to assess the potential impact in each soil subgroup combination of both pedogenic and anthropogenic factors on the migration and geochemical characteristics of calcium (Ca) and magnesium (Mg) and their relations to soil particle-size composition. Results revealed that exchangeable Mg was correlated positively with clay and silt content, but negatively with sand content, suggesting that clay and silt could retain more exchangeable Mg than sand. Also, in the six pedons exchangeable Ca/Mg ratios generally decreased with depth, which was most likely due to the preferential retention of Mg below the Apl horizon and the effects of bio-cycling in rice-soil systems. The pedons with high pH had smaller exchangeable Ca/Mg ratios than those with low pH. Thus, it was concluded that exchangeable Ca/Mg ratios could be helpful in classification of Stagnic Anthrosols.

Responses of Nematode Communities to Inorganic Fertilizer Disturbance in a Farmland Ecosystem

Nematode communities were monitored in a field study at depths of 0～10 cmand 10～20 cm throughout a corn (Zea mays L.) growing season in the black soil region of NortheastChina. Plots were cropped corn with (IF) and without (NF) nitrogen fertilization. Fifteen familiesand 16 genera were observed in the nematode suspensions. Cephalobidae, Rhabditidae, Aphelenchus,Filenchus, and Helicotylenchus were found to be dominant genera/families in both plots at bothdepths. Significant differences were found between treatments and corn growing stages in the totalnumbers of nematodes during the study period. The total numbers of nematodes at the 0～10 cm depthwere higher in the inorganic fertilizer plot than in the control plot (no fertilizer applications)across jointing, filling, and mature stages. Bacterivores were the most abundant trophic groupsunder two treatments and at both depths, and the relative abundance averaged 42.8%.Omuivores-predators at both depths were lower in the inorganic fertilizer plot than in the controlplot during the study period, excluding corn jointing stage. Maturity index (MI) and plant parasiteindex (PPI) were used to detect the differences between the two treatments, MI and PPI wereeffective in distinguishing differences in nematode communities during corn growing season. The roleof nematode communities as bioindicators of ecosystem disturbance due to fertilization is noted.

Comparative study on active soil organic matter in Chinese fir plantation and native broad-leaved forest in subtropical China

Active soil organic matter (ASOM) has a main effect on biochemical cycles of soil nutrient elements such as N, P and S, and the quality and quantity of ASOM reflect soil primary productivity. The changes of ASOM fractions and soil nutrients in the first rotation site and the second rotation site of Chinese fir plantation and the native broad-leaved forest were investigated and analyzed by soil sampling at the Huitong Experimental Station of Forestry Ecology (at latitude 26°48′N and longitude 109°30′E under a subtropical climate conditions), Chinese Academy of Sciences in March, 2004. The results showed that values of ASOM fractions for the Chinese fir plantations were lower than those for the broad-leaved forest. The contents of easily oxidisable carbon (EOC), microbial biomass carbon (MBC), water soluble carbohydrate (WSC) and water-soluble organic carbon (WSOC) for the first rotation of Chinese fir plantation were 35.9%, 13.7%, 87.8% and 50.9% higher than those for the second rotation of Chinese fir plantation, and were 15.8%, 47.3%, 38.1% and 30.2% separately lower than those for the broad-leaved forest. For the three investigated forest sites, the contents of MBC and WSOC had a larger decrease, followed by WSC, and the change of EOC was least. Moreover, soil physico-chemistry properties such as soil nutrients in Chinese fir plantation were lower than those in broad-leaved forest. It suggested that soil fertility declined after Chinese fir plantation replaced native broad-leaved forest through continuous artificial plantation.

Distribution of Soil Zinc，Iron，Copper and Manganese Fractions and Its Relationship with Plant Availability

The distribution of various fractions of Zn, Fe, Cu and Mn in 15 types of sods in China and its rela-tionship with plant availability were studied. Wactions of various elements were found to have some similarcharacteristic distribution regularities in wirious types of soils, but various soil types derered to varyingdegrees in the distribution of each fraction. Soil physico-chemical properties, such as pH, CEC and thecontents of OM, CaCO_3, free Fe, free Mn and P_2O_5, were signdicantly correlated with the distribution ofelemental fractions, and a significazit correlation also existed between the distribution and plant amilabilityof elemental fractions. Varfous fractions of each element were divided into two groups bed on their plantavailability. The correlation between the distribution of combination fractions aiid plaxit availability indi-cated a significantly or an extremely significantly positive correlation for Group I but a significantly or anextremely significantly negative correlation for Group II. Therefore, the fractions in Group I were primarypools of available nutrients, while those in Group II could hardly provide available nutrients for plants. Descreasing the transformation of corresponding elements into fractions of Group 11 and increasing the storagecapacity of various fractions of Group I were an important direction for regulation and controiling of soilnutrients. However, some Particular soils with too high contents of Zn, Fe, Cu and Mn should be regulatedand controlled adversely

Diversity and Dynamics of Soil Free-Living Nematode Populations in a Mediterranean Agroecosystem

To determine the effect of agricultural management on the dynamics and functional diversity of soil nematode communities in a carrot field at Kibbutz Ramat Hakovesh, Israel, soil samples from 0-10 cm and 10-20 cm depths were collected during the growing season of carrot. Indices were used to compare and assess the response of soil free-living nernatode communities to agricultural management. Eighteen nematode families and 20 genera were observed during the growing period, with Cephalobus, Rhabditidae, Aphelenchus, Tylenchus, and Dorylaimus being the dominant genera/families. During the planting, mid-season and post-harvest periods the total number of nematodes at both depths was significantly lower (P < 0.01) in the carrot treatment than in the control plots, while during the harvest period at both depths total nematodes and bacterivores were significantly higher in the treatment plots (P < 0.01). The values of the maturity index (MI) at both depths were found to be significantly lower in the treatment plots than in the control plots during the pre-planting period (P < 0.05). Overall, WI, MI and PPI were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to agricultural management in a Mediterranean agroecosystem

Dicyandiamide Sorption-Desorption Behavior on Soils and Peat Humus

The sorption-desorption behavior of dicyandiamide (DCD) is an importantchemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCDsorption-desorption on a phaeozem (Mollisol), a burozem (Alfisol), a soil with organicmatter-removed and peat humus using the batch-equilibration procedure, and identified soilproperties that influenced DCD sorption. The sorption on peat humus was higher than that on thephaeozem and the burozem, with much lower sorption observed on the soil with organic matter-removed,indicating that soil organic matter was the main carrier of DCD sorption. Due to its amphipathicproperty the DCD molecule sorption on the phaeozem and the burozem decreased as pH increased fromabout 2 to 5, but a further increase in pH led to a rise in DCD sorption. The DCD desorptionhysteretic effect for peat humus was greater than that for the phaeozem and the burozem using 0.01mol L^(-1) CaCl_2 as the background electrolyte, suggesting that the hydrophobic domains of organicmatter may play an important role in DCD sorption.

Tomato Root Response to Subsurface Drip Irrigation

Four depth treatments of subsurface drip irrigation pipes were designated as 1) at 20,2) 30 and 3) 40 cm depths all with a drip-proof flumes underneath,and 4) at 30 cm without a drip-proof flume to investigate the responses of a tomato root system to different technical parameters of subsurface drip irrigation in a glass greenhouse,to evaluate tomato growth as affected by subsurface drip irrigation,and to develop an integrated subsurface drip irrigation method for optimal tomato yield and water use in a glass greenhouse. Tomato seedlings were planted above the subsurface drip irrigation pipe. Most of the tomato roots in treatment 1 were found in the top 0-20 cm soil depth with weak root activity but with yield and water use efficiency (WUE) significantly less (P ---- 0.05) than treatment 2; root activity and tomato yield were significantly higher (P = 0.05) with treatment 3 compared to treatment 1; and with treatment 2 the tomato roots and shoots grew harmoniously with root activity,nutrient uptake,tomato yield and WUE significantly higher (P= 0.05) or as high as the other treatments. These findings suggested that subsurface drip irrigation with pipes at 30 cm depth with a drip-proof flume placed underneath was best for tomato production in greenhouses. In addition,the irrigation interval should be about 7-8 days and the irrigation rate should be set to 225 m3 ha-1 per event.

Community analysis of ammonia oxidizer in the oxygen-limited nitritation stage of OLAND system by DGGE of PCR amplified 16S rDNA fragments and FISH

OLAND(oxygen limited autotrophic nitrification and denitrification) nitrogen removal system was constructed by coupling with oxygen limited nitritation stage and anaerobic ammonium oxidation stage. Ammonia oxidizer, as a kind of key bacteria in N cycle, plays an important role at the oxygen limited nitritation stage of OLAND nitrogen removal system. In this study, specific amplification of 16S rDNA fragment of ammonia oxidizer by nested PCR, separation of mixed PCR samples by denaturing gradient gel electrophoresis(DGGE), and the quantification of ammonia oxidizer by fluorescence in situ hybridization(FISH) were combined to investigate the shifts of community composition and quantity of ammonia oxidizer of the oxygen limited nitritation stage in OLAND system. It showed that the community composition of ammonia oxidizer changed drastically when dissolved oxygen was decreased gradually, and the dominant ammonia oxidizer of the steady nitrite accumulation stage were completely different from that of the early stage of oxygen limited nitritation identified by DGGE . It was concluded that the Nitrosomonas may be the dominant genus of ammonia oxidizer at the oxygen limited nitritation stage of OLAND system characterized by nested PCR-DGGE and FISH, and the percentage of Nitrosomonas was 72.5% ±0.8% of ammonia oxidizer at the steady nitrite accumulation stage detected by FISH.

Heavy metal concentrations in redeveloping soil of mine spoil under plantations of certain native woody species in dry tropical environment, India

Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Tectona grandis and Dendrocalamus strictus. The data recorded in the present study were compared with other unplanted coal mine spoil colliery, which was around to the study site and adjoining area of dry tropical forest. Among all the heavy metals, the maximum concentration was found for Fe and minimum for Cd. However, among all four species, total concentrations of these heavy metals were recorded maximally in the plantation plots of T. grandis except for Fe, while minimally in A. lebbeck except for Zn, whereas, the maximum concentration of Fe and Zn was in the plantation plots of D. strictus and A. procera. Statistical analysis revealed significant differences due to species for all the heavy metals except Cu. Among four species, A. lebbeck, A. procera and D. strictus showed more efficient for reducing heavy metal concentrations whereas T. grandis was not more effective to reduce heavy metal concentrations in redeveloping soil of mine spoil.

Ecological Behavior of Linear Alkylbenzene Sulfonate (LAS) in Soil-Plant Systems

More and more linear alkylbenzene sulfonate (LAS) has contaminated the water and soil ma pollution discharge, making it important to identify the ecological behavior and toxicity of LAS so as to carry out measures that will reduce its negative effects on the ecosystem. The ecological behavior of LAS. including degradation, migration, and plant uptake, in both soil-paddy rice and soil-soybean systems was studied. Reduction of LAS in pot and field plots followed the first order reaction kinetics with degradation half-lives of 35-50 days with LAS decreasing to very low concentrations after a season of crop growth. Strong migration ability for LAS was found and the breakthrough time in a 1.5 in soil monolith was significantly shortened to 23 days by preferential flow. Leachate volumes of soil-paddy and soil-soybean systems at preferential breakthrough were much different, while the leachate volumes at equilibrium governed by soil adsorption/desorption processes were very similar. Significant uptake of LAS in both paddy rice and sovbeans was observed in pot and field experiments (P < 0.05). In aquatic culture, 20 μg mL-1 and above of LAS significantly inhibited the growth of paddy seedlings (P < 0.05). The critical concentration for LAS in soil inhibiting the growth and yield of paddy was 160 μg g-1; when higher, there was a strong negative influence, with decreases in height, spike length, and production, when lower than 80 μg g-1, paddy growth was stimulated. There was little effect of LAS on soybeans.

Stomatal response of Pinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

Four-year-old Pinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol-1) and high CO2 concentrations (500 and 700 μmol·mol-1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42oN, 128oE). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol-1 CO2 grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol-1CO2). High-[CO2]-grown plants exhibited lower ci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However, ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

Forest cutting and regeneration methodology on Changbai Mountain

This paper discussed the characteristics of degenerated forest ecosystems in Changbai Mountain area,which include over-harvest natural forest,typical secondary forest,derived forest,and artificial forest.Forest cutting and regeneration methods that were historically used in the region were summarized.They lnclude diameter-class selective cutting,clearcutting,upbringing selective cutting,and selective sutting.We proposed cutting methods for the broad-leaved Korean pine mixed forest,spruce-fir forest,and larch forest.The measures for restoring the original mixed forest ecosystems were recommended.

Profile Distribution and Storage of Soil Organic Carbon in an Aquic BrownSoil as Affected by Land Use

Many attempts have been made to estimate the soil organic carbon (SOC) storage under different land uses, especiallyfrom the conversion of forest land or grassland into cultivated field, but limited reports were found on the estimation ofthis storage after cultivated field converted into woodland or grassland, especially in small scales. This study is aimed toinvestigate the dynamics of SOC concentration, its storage and carbon /nitrogen (C/N) ratio in an aquic brown soil at theShenyang Experimental Station of Ecology, Chinese Academy of Sciences under four land use patterns over 14 years. Thefour land use patterns were paddy field (PF), maize field (MF), fallow field (FF) and woodland (WL). In each pedon at 0-150cm depth, soil samples were collected from ten layers. The results showed that the profile distribution of SOC was differentunder different land uses, indicating the effect of land use on SOC. Soil organic carbon was significantly related with soiltotal N, and the correlation was slightly closer in nature ecosystems (with R2=0.990 and P<0.001 in both WL and FF, n=30)than in agroecosystems (with R2=0.976 and P<0.001 in PF, and R2=0.980 and P<0.001 in MF, n=30). The C/N ratio in theprofiles decreased generally with depth under the four land use patterns, and was comparatively higher in WL and lowerin PF. The C/N ratio of the FF was closer to that in the same soil depths of MF than to that of PF. Within 100 cm depth, theannual sequestration of SOC was 4.25, 2.87, and 4.48 t ha-1 more in WL than in PF, MF and FF, the annual SOC increasingrate being 6.15, 3.26, and 5.09 % higher, respectively. As a result, the SOC storage was significantly greater in WL than inany of the other three land use patterns, P=0.001, 0.008, and 0.008 as compared with PF, MF, and FF, respectively, whilethere was no significant difference among the other three land uses. It is suggested that woodland has the potential tomake a significant contribution to C storage and environmental quality.

Phytotoxicity assessment of phenanthrene, pyrene and their mixtures by a soil-based seedling emergence test

Seedling emergence tests were conducted in a meadow brown soil using five plant species(i.e., Chinese cabbage, green onion, tomato, turnip and wheat) to determine the phytotoxicity of phenanthrene, pyrene and their mixtures. The soil was amended with up to 1000 mg/kg soil of phenanthrene or 600 mg/kg soil of pyrene. Seedling emergence and root growth were measured. The results indicated that root elongation was more sensitive than seedling emergence. Root length decreased with increasing phenanthrene or pyrene concentrations(p≤0 05). Phenanthrene was more phytotoxic than pyrene. The lowest observable adverse effect concentration(LOAEC) was 10 mg/kg for phenanthrene when tested with green onion, and 50 mg/kg for pyrene when tested with wheat. Among the five species, wheat was found to be the most sensitive. When amended jointly at or below their respective LOAEC, phenanthrene and pyrene produced a synergistic toxic effect.

Landscape pattern change in the upper valley of Min River

The upper valley of Min River (102° 59′ –104° 14′ E, 31° 26′ – 33° 16′ N), which is consisted of the counties Wenchuan, Maoxian, Lixian, Heishui, and Songpan, refers to the part up to Dujiangyan City, and locates on the transition zone from the Tibetan Plateau to the Si- chuan Basin. It is one of the most important forest areas in China, especially in Sichuan Province. Over past two decades, the landscape changed remarkably in the region. The 3S techniques (Remote Sensing (RS), Geographic Information System (GIS) and Global Position System (GPS)) were used to classify the images and analyze the landscape change. The remotely sensed data of Landsat TM 1986 and Landsat ETM+ 2000 were used to analyze the landscape change of the region. The landscape were classified into 10 types of cropland, for- est, shrub land, economic forest, grassland, build up land, river, lake, swamp, and unused land. The results showed that: 1) the woodland and grassland were dominating landscape types in the upper valley of Min River, which is more than 91% of the study area; 2) the alteration of the landscape was mainly happened among forest, shrub land, grassland, economic forest, cropland, and build up land, where forest de- creased from 51.17% to 47.56%; 3) the landscape fragmentation in the upper valley of Min River was aggravated from 1986 to 2000.

Identification of Taxus cuspidata Sieb. et Zucc. endophytic fungi-new species, species known and their metabolite

A total of 94 isolates of endophytic fungi were isolated from the bark of 200-yr.-old Taxus cuspidata Sieb. et Zucc.in the primeval forest of the Changbai Mountain Natural Reserve, and 19 species of endophytic fungi were identified, including 10 new recorded-genus-species, 2 new species (Phomopsis Iongiscoleosporu Y. Xiang et Lu An Guo Wu Wen Fang, Coniothyrium macrospoum Y. Xiang J.X. et Lu An Guo Wu Wen Fang), 1 new varied species (Alternaria alternata (Fr.) Keissler var. taxi Y.Xiang et Lu An Guo) and 6 known species of China (Eurotium amstelodomi Mgngin, Eurotium repens de Bary, Botrytis sp.,Penicillium citrinum Thom, Epicoccum nigrium LinK, Fusarium sp.). Through thin layer chromatography (TLC), liquid fermentation metabolite of the strains was determined, and four strains (Alternaria alternata (Fr.) Keissler var. taxi Y. Xiang et Lu An Guo Wu Wen Fang, Botrytis sp., Eurotium amsteloodomi Mgngin, Eurotium repens de Bary) were screened out, whose metabolites reacted positively with the vanillic aldehyde that was one special taxoid developer. Among the four strains, Alternaria alternata (Fr.) Keissler var. taxi Y. Xiang et Lu An Guo, produced one compound largely, which positively reacted with one alkaloids developer-Bismuth potassium iodide. The compound is identified as taxoids type through spectrum analysis. This demonstrates that Alternaria alternata (Fr.) Keissler var. taxiY. Xiang et Lu An Guo can highly produce taxoids largely.