Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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An innovative wood-chip-framework substrate used as slow-release carbon source to treat high-strength nitrogen wastewater
No full textRemoval of nitrogen in wastewater before discharge into receiving water courses is an important consideration in treatment systems. However, nitrogen removal efficiency is usually limited due to the low carbon/nitrogen (C/N) ratio. A common solution is to add external carbon sources, but amount of liquid is difficult to determine. Therefore, a combined wood-chip-framework substrate (with wood, slag and gravel) as a slow-release carbon source was constructed in baffled subsurface-flow constructed wetlands to overcome the problem. Results show that the removal rate of ammonia nitrogen (NH4+-N), total nitrogen (TN) and chemical oxygen demand (COD) could reach 37.5%-85%, 57.4%-86%, 32.4%-78%, respectively, indicating the combined substrate could diffuse sufficient oxygen for the nitrification process (slag and gravel zone) and provide carbon source for denitrification process (wood-chip zone). The nitrification and denitrification were determined according to the location of slag/gravel and wood-chip, respectively. Nitrogen removal was efficient at the steady phase before a shock loading using slag-wood-gravel combined substrate because of nitrification-denitrification process, while nitrogen removal was efficient under a shock loading with wood-slag-gravel combined substrate because of ANAMMOX process. This study provides a newidea for wetland treatment of high-strength nitrogen wastewater. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V
Effects of Sub-Soiling and Fertilization on Growth Restoration of Phragmites Australis Population in Saline Marsh of Northeast China
No full textInland salt marshes are widely spread in western Songnen Plain of Northeast China. Lacking of water resource was the main factor driving degradation of this inland saline marsh in the past decades, with the degeneration of the dominated plants, Phragmites auatralis production. Sub-soiling and fertilization are two kinds of agricultural technology, which are developed and used in agriculture to gain high production. Field mesocosm experiments were conducted in western Songnen Plain by using two distance sub-soiling and four different kinds of fertilizer, to restore the P. australis production and avoid the further degradation of saline marsh. After these technologies were used, the growth and production of P. australis were improved effectively. The height, stem diameter, heading number, ear length and biomass were increased significantly, although the plant density was not influenced by fertilizer. The increment was more for sub-soiling than for fertilizer. From the comparative results, we concluded that hardening in saline-alkaline soil was the key factor affecting plants growth rather than nutrition, and chemical fertilizer urea was more effective than others. Although these agricultural technology could be effective to restore the population growth of P. australis, water resource was still the key structure and environmental factor in marsh restoration
Two new species of the genus Euphthiracarus (Acari: Oribatida: Euphthiracaridae) from Hainan Island, China
No full textEuphthiracarus is the most speciose genus of the oribatid family Euphthiracaridae. In this study, two new species of Euphthiracarus (Oribatida: Euphthiracaridae) from Hainan Island, China, Euphthiracarus paraoblongussp. nov. and Euphthiracarus singularissp. nov., are described and illustrated. An updated key to all known species of Euphthiracarus in China is provided.http://zoobank.org/urn:lsid:zoobank.org:pub:C1A23769-58A1-4FA8-8CB3-EF58D297D09
Spatiotemporal changes in the length and heating degree days of the heating period in Northeast China
No full textAs the coolest region in China, Northeast China has long and severe winters and is a main region for the use of central heating. Accurately predicting the heating energy consumption in Northeast China is very important for energy management and planning. Based on daily mean temperature data from 70 weather stations, this study investigated the spatiotemporal changes in the starting date for heating (HS), the end date for heating (HE), and the length (HL) and the heating degree days (HDD) of the heating period in Northeast China. Over Northeast China, regional averaged HS has become later by 0.77 days decade(-1) and HE has become earlier by 1.19 days decade(-1) during 1960-2011. Accordingly, regional averaged HL and HDD decreased significantly by 1.97 days decade(-1) and 66.28 degrees C decade(-1) respectively; this implies a decreasing demand for heating throughout the region. Spatially, the temporal trends of each heating variable varied in different locations. The spatial patterning of the HL trend was unlike that of the HDD trend due to different responses of HL and HDD to climate change. Temperature increase seems to have larger impacts on HL in warm south localities but more obvious effects on HDD in cold north localities of Northeast China. These different sensitivities of HL and HDD to temperature change should be considered when attempts are made to predict heating energy consumption in Northeast China in a changing climate
Variation of Soil Enzyme Activities in Wetlands from Permafrost to Seasonally Frozen Soil Region in Northeast China
No full textSoil enzyme activities are sensitive indicators of soil organic matter (SOM) dynamics brought about by climate change. The distribution of soil enzyme activities in wetlands from different types of frozen region in Northeast China was evaluated in this paper. The results showed that the specific enzyme activities of P-glucosidase, invertase, dehydrogenase, urease, and acid phosphatase showed the highest values in seasonally frozen ground indicating faster turnover rate of SUM. Specific activities of invertase and acid phosphatase were higher in discontinuous permafrost than in continuous permafrost. The temperature, SUM and vegetation species regulated soil enzyme activities. Soil dehydrogenase and urease activities increased with soil MBC (microbial biomass carbon) concentrations. beta-Glucosidase and acid phosphatase activities were significantly related to DOC (dissolved organic carbon) concentrations suggesting that these two enzymes drive the release of labile components from the SUM. This study helps better understanding relations between soil enzyme and soil labile carbon fractions, and further facilitates the understanding of the stability of soil carbon pool in permafrost wetland of Northeast China
Grain Yield, Dry Weight and Phosphorus Accumulation and Translocation in Two Rice (Oryza sativa L.) Varieties as Affected by Salt-Alkali and Phosphorus
No full textSalt-alkali is the main threat to global crop production. The functioning of phosphorus (P) in alleviating damage to crops from saline-alkaline stress may be dependent on the variety of crop but there is little published research on the topic. This pot experiment was conducted to study if P has any effect on rice (Oryza sativa L.) yield, dry matter and P accumulation and translocation in salt-alkaline soils. Plant dry weight and P content at heading and harvest stages of two contrasting saline-alkaline tolerant (Dongdao-4) and sensitive (Tongyu-315) rice varieties were examined under two saline-alkaline (light versus severe) soils and five P supplements (P0, P50, P100, P150 and P200 kg ha(-1)). The results were: in light saline-alkaline soil, the optimal P levels were found for P150 for Dongdao-4 and for P100 for Tongyu-315 with the greatest grain dry weight and P content. Two rice varieties obtained relatively higher dry weight and P accumulation and translocation in P0. In severe saline-alkaline soil, however, dry weight and P accumulation and translocation, 1000-grain weight, seed-setting rate and grain yield significantly decreased, but effectively increased with P application for Dongdao-4. Tongyu-315 showed lower sensitivity to P nutrition. Thus, a more tolerant variety could have a stronger capacity to absorb and translocate P for grain filling, especially in severe salt-alkaline soils. This should be helpful for consideration in rice breeding and deciding a reasonable P application in saline-alkaline soil
Effects of vegetation type on surface elevation change in Liaohe River Delta wetlands facing accelerated sea level rise
No full textRising sea levels threaten the sustainability of coastal wetlands around the globe. The ability of coastal marshes to maintain their position in the intertidal zone depends on the accumulation of both organic and inorganic materials, and vegetation is important in these processes. To study the effects of vegetation type on surface elevation change, we measured surface accretion and elevation change from 2011 to 2016 using rod surface elevation table and feldspar marker horizon method (RSET-MH) in two Phragmites and two Suaeda marshes in the Liaohe River Delta. The Phragmites marshes exhibited higher rates of surface accretion and elevation change than the Suaeda marshes. The two Phragmites marsh sites had average surface elevation change rates at 8.78 mm/yr and 9.26 mm/yr and surface accretion rates at 17.56 mm/yr and 17.88 mm/yr, respectively. At the same time, the two Suaeda marsh sites had average surface elevation change rates at 5.77 mm/yr and 5.91 mm/yr and surface accretion rates at 13.42 mm/yr and 14.38 mm/yr, respectively. The elevation change rates in both the Phragmites marshes and the Suaeda marshes in the Liaohe River Delta could keep pace and even continue to gain elevation relative to averaged sea level rise in the Bohai Sea reported by the 2016 State Oceanic Administration, People's Republic of China projection (2.4-5.5 mm/yr) in current situations. Our data suggest that vegetation is important in the accretionary processes and vegetation type could regulate the wetland surface elevation. However, the vulnerability of coastal wetlands in the Liaohe River Delta need further assessment considering the accelerated sea level rise, the high rate of subsidence, and the declining sediment delivery, especially for the Suaeda marshes
Rhizobium hidalgonense sp nov., a nodule endophytic bacterium of Phaseolus vulgaris in acid soil
No full textOne Gram-negative, aerobic, motile, rod-shaped bacterium, designated as FH14(T), was isolated from nodules of Phaseolus vulgaris grown in Hidalgo State of Mexico. Results based upon 16S rRNA gene (>= 99.8 % similarities to known species), concatenated sequence (recA, atpD and glnII) analysis of three housekeeping genes (>= 93.4 % similarities to known species) and average nucleotide identity (ANI) values of genome sequence (ranged from 87.6 to 90.0 % to related species) indicated the distinct position of strain FH14(T) within the genus Rhizobium. In analyses of symbiotic genes, only nitrogen fixation gene nifH was amplified that had nucleotide sequence identical to those of the bean-nodulating strains in R. phaseoli and R. vallis, while nodulation gene nodC gene was not amplified. The failure of nodulation to its original host P. vulgaris and other legumes evidenced the loss of its nodulation capability. Strain FH14(T) contained summed feature 8 (C-18:1 omega 6c/C-18:1 omega 7c, 59.96 %), C-16:0 (10.6 %) and summed feature 2 (C-12:0 aldehyde/unknown 10.928, 10.24 %) as the major components of cellular fatty acids. Failure to utilize alaninamide, and utilizing l-alanine, l-asparagine and gamma-amino butyric acid as carbon source, distinguished the strain FH14(T) from the type strains for the related species. The genome size and DNA G+C content of FH14(T) were 6.94 Mbp and 60.8 mol %, respectively. Based on those results, a novel specie in Rhizobium, named Rhizobium hidalgonense sp. nov., was proposed, with FH14(T) (=HAMBI 3636(T) = LMG 29288(T)) as the type strain
Gully erosion regionalization of black soil area in northeastern China
No full textGully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention
Health risk assessment of heavy metals in soils and maize (Zea mays L.) from Yushu, Northeast China
No full textTo investigate heavy metal accumulation in soils and evaluate health risk through maize consumption, a total of 196 soils and 55 maize samples were collected from Yushu, China, one of the most important maize production bases. The mean contents of Cd, Cr, Cu, Zn and Pb were 0.119, 56.51, 19.21, 70.58, and 34.42 mg kg(-1) for soils and were 0.014, 0.68, 1.33, 17.15 and 0.02 mg kg(-1) for maize, respectively. The contents of Cr, Cu, Zn and Pb in all soil and maize samples did not exceed safety thresholds, but the percentages of Cd content above guideline values of Chinese Environmental Quality Standards for Soil and maximum permissible limits for maize were 6.6% and 1.8%, respectively. The spatial distribution and correlation analysis suggested that Cr and Cu in soil were of lithogenic origin, while Zn and Pb were associated with coal combustion exhausts and chemical fertilizer application. The main source of Cd may be phosphate fertilizer application. The average target hazard quotients were all less than 1 and the average hazard index for adults was 0.065, indicating that there was not a potential health risk through maize