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The reclamation time was examined by combining field investigation and remote sensing image analysis in the Linze desert oasis area in the middle of the Hexi Corridor. Characteristics of soil organic carbon storage (SOCD) in cropland (0-20 cm) with different reclamation backgrounds were compared to understand the evolution trend of SOCD during reclamation. The SOCD of crop¬land (0-20 cm) varied from 2.41 to 32.97 t • hm-2, with an average of 17.22 t • hm 2. The ave¬rage SOCD of cropland in saline-alkali land, Gobi and sandy land background was 19.36, 16.10, and 15.93 t • hm-2, respectively. The SOCD under three different reclamation conditions showed an increasing trend after cultivation. The cropland in sandy land and the Gobi background slowly increased after 20 years reclamation. The cropland in saline-alkali background showed a slowdown after 25 years reclamation. The SOC sequestration rates of the cropland under sandy land, Gobi and saline-alkali land background were 0.424, 0.485 and 0.811 t • hm-2 •a-1, respectively. The SOCD were positively correlated with total nitrogen, total phosphorus, available nitrogen, and available phosphorus content, but had no significant correlation with available potassium and soil pLL In conclusion, the SOC sequestration rate in the saline-alkali land background was significantly higher than that in Gobi and sandy land background. Lowever, SOCD were at a relatively low level after 30 years reclamation. Therefore, cropland management needs to be carried out for different reclamation backgrounds to improve land use efficiency and productivity in desert oasis. [ABSTRACT FROM AUTHOR]

With the sandy farmland in the marginal oasis in middle reaches of Heihe River Basin, Northwest China as test object, this paper studied soil NO3--N accumulation and leaching under effects of different farmland use type and winter irrigation. The results showed that the mean NO3--N concentration in 0-300 cm soil profile in different farmlands ranged from 1.27 mg∙kg-1 to 83.60 mg∙kg-1. Soil NO3--N concentration was higher in 0-40 cm and 135-300 cm layers, but lower in 40-135 cm layer. Greenhouse vegetable field had a significantly higher soil NO3--N concentration than the other farmland use types. The accumulated amount of soil NO3--N decreased in the order of greenhouse vegetable field > tomato field > cotton field>seed maize field>maize-wheat rotation field>maize-wheat stripe intercropping field > alfalfa field > jujube plantation. The NO3--N accumulation in 0-300 cm soil profile in greenhouse vegetable filed reached 2171.45 kg∙hm-2, which would be a serious menace to groundwater quality, followed by tomato field and cotton field. Lesser accumulation of soil NO3--N was found in seed maize field, maize-wheat intercropping field, maize-wheat rotation field, alfalfa field, and jujube plantation, but its pollution potential would not be neglected. After winter irrigation, soil NO3--N concentration decreased in 0-80 cm layer but increased in 80-300 cm layer, indicating that winter irrigation caused NO3--N leaching into deeper soil depth. The leached amount of soil NO3--N to deeper layers increased with increasing amount of winter irrigation. To mitigate soil NO3--N leaching and groundwater contamination, a comprehensive consideration should be made on the rational arrangement of farmland use type, proper decrease of planting N-accumulated crops, and reasonable winter irrigation. [ABSTRACT FROM AUTHOR]

Both Agriophyllum squarrosum and Artemisia halodendron play essential roles in the vegetation rehabilitation process in Horqin desert. Responses of germination to temperature, water potential, and burial depth in the two species were studied experimentally. The results showed that: (1) seeds of the two species could germinate with high final percentages (> 67%) at prevailing surface soil (0-5 cm) temperatures from April to July. However, Agriophyllum squarrosum had more efficient mechanisms to ensure that seeds germinate quickly at prevailing May temperatures but slowly at the temperatures of April and July, in comparison to Artemisia halodendron; (2) Artemisia halodendron had higher final germination percentages than Agriophyllum squarrosum when water potential was low (p < .0.01); and (3) seedlings of Artemisia halodendron emerged well only at a depth less than 1 cm and did not emerge at all when the burial depth reached 4 cm, while those of Agriophyllum squarrosum emerged with a final percentage of 21.6% even at the depth of 4 cm. These different characteristics of seed germination and seedling emergence could partially explain the phenomenon that Agriophyllum squarrosum always precedes Artemisia halodendron in establishing on moving sand dunes in Horqin desert. [ABSTRACT FROM AUTHOR]

Abstract: Soil C and N contents play a crucial role in sustaining soil quality and environmental quality. The conversion of annually cultivated land to forage grasses has potential to increase C and N sequestration. The objective of this study was to investigate the short-term changes in soil organic C (SOC) and N pools after annual crops were converted to alfalfa (Medicago sativa L. Algonguin) forage for 4 years. Soil from 24 sets of paired sites, alfalfa field versus adjacent cropland, were sampled at depths of 0–5, 5–10 and 10–20cm. Total soil organic C and N, particulate organic matter (POM) C and N were determined. Organic C, total N, POM-C, and POM-N contents in the 0–5cm layer were significantly greater in alfalfa field than in adjacent cropland. However, when the entire 0–20cm layer was considered, there were significant differences in SOC, POM-C and POM-N but not in total N between alfalfa and crop soils. Also, greater differences in POM-C and POM-N were between the two land-use treatments than in SOC and total N were found. Across all sites, SOC and total N in the 0–20cm profile averaged 22.1MgCha−1 and 2.3MgNha−1 for alfalfa soils, and 19.8MgCha−1and 2.2MgNha−1 for adjacent crop soils. Estimated C sequestration rate (0–20cm) following crops to alfalfa conversions averaged 0.57MgCha−1 year−1. Sandy soils have more significant C accumulation than silt loam soils after conversion. The result of this suggests that the soils studied have great C sequestration potential, and the conversion of crops to alfalfa should be widely used to sequester C and improve soil quality in this region. [Copyright &y& Elsevier]

Objective: To investigate the overview of thrombosis in myeloproliferative neoplasms(MPN) patients, and to explore the risk factors of thrombosis at diagnosis and during follow-up., Methods: The clinical data of 388 MPN patients treated in our hospital were collected. The patients were followed up by outpatient and phone. The risk factors of thrombosis were analyzed by statistical methods., Results: Among 388 MPN patients, 161 patients (41.49%) showed thromboses at diagnosis or during follow-up. Among them, 92.55% were arterial thromboses, 146 cases (96.27%) were complicated with thromboses at diagnosis, and 36 cases (11.46%) showed newly thromboses or progression of previous thromboses among the 314 received full follow-up patients. Age (P＜0.001, HR:1.033, 95%CI:1.016-1.051), JAK2V617F mutation (P=0.037, HR:1.72, 95%CI: 1.033-2.862), hypertension (P＜0.001, HR:2.639, 95%CI:1.659-4.197) and hyperlipidemia (P＜0.001, HR:2.659, 95%CI:1.626-4.347) were the independent risk factors affecting thrombosis at diagnosis of the patients. During the follow-up, age (P=0.016, HR:1.032, 95%CI: 1.006-1.059) and previous thrombosis history (P=0.019, HR:2.194, 95%CI: 1.135-4.242) were the independent risk factors affecting the progression of thrombosis at different sites or on the basis of the previous thrombosis in the patients., Conclusion: Patients with advanced age, JAK2V617F mutation or complicated with hypertension and hyperlipidemia shows a higher risk of thrombosis at diagnosis, while the patients with advanced age or previous thrombosis history shows a higher risk of progression of thrombosis during the follow-up.

Objective: To investigate the difference of clinical characteristics between young patients(age≤40 years old) and middle-older patients(age>40 years old) with the myeloproliferative neoplasms（MPN）., Methods: The clinical data (gene mutations， peripheral blood routine examinations， imaging examination and past history) of 269 MPN patients was collected and analyzed., Results: In essential thrombocythemia (ET) group, the proportion of triple-negative type in young patients was higher than that in middle-older group, while the peripheral white blood cell（WBC） and platelets（PLT） counts in the first visit were lower. In polycythemia vera (PV) group, the total detection rate of JAK2V617F (80.65%) was lower than that of other research reports. Young patients with PV showed the lower JAK2V617F rate and lower WBC count, compared with the middle-older aged patients. Both CALR and MPL mutations were not found in PV patients. There was only 1 primary myelofibrosis (PMF) patient aged <40 years old. 91.67% of the patients merged splenomegaly and this rate was higher than that of ET or PV patients. It was found that there were a diagnosed familial MPN family and an undiagnosed family， and the youngest patient was only 8 years old. The second-generation gene sequencing detection for them was not carried out., Conclusion: Age is an important reference index in the assessment of risks. The MPN patients with different age and types show much difference in gene mutations, peripheral blood cell counts, thrombotic events and sizes of spleen. The onset ages of patients with familial MPN trends to be generational younger.

The reclamation time was examined by combining field investigation and remote sensing image analysis in the Linze desert oasis area in the middle of the Hexi Corridor. Characteristics of soil organic carbon storage (SOCD) in cropland (0-20 cm) with different reclamation backgrounds were compared to understand the evolution trend of SOCD during reclamation. The SOCD of cropland (0-20 cm) varied from 2.41 to 32.97 t·hm -2 , with an average of 17.22 t·hm -2 . The ave-rage SOCD of cropland in saline-alkali land, Gobi and sandy land background was 19.36, 16.10, and 15.93 t·hm -2 , respectively. The SOCD under three different reclamation conditions showed an increasing trend after cultivation. The cropland in sandy land and the Gobi background slowly increased after 20 years reclamation. The cropland in saline-alkali background showed a slowdown after 25 years reclamation. The SOC sequestration rates of the cropland under sandy land, Gobi and saline-alkali land background were 0.424, 0.485 and 0.811 t·hm -2 ·a -1 , respectively. The SOCD were positively correlated with total nitrogen, total phosphorus, available nitrogen, and available phosphorus content, but had no significant correlation with available potassium and soil pH. In conclusion, the SOC sequestration rate in the saline-alkali land background was significantly higher than that in Gobi and sandy land background. However, SOCD were at a relatively low level after 30 years reclamation. Therefore, cropland management needs to be carried out for different reclamation backgrounds to improve land use efficiency and productivity in desert oasis.

In irrigated agricultural ecosystems, the accumulation, distribution and transfer of nitrate nitrogen (NO(3-)-N) in soil profile and groundwater nitrate pollution were influenced by irrigation and fertilization, and were closely related to soil textural characteristics. In this study, a monitoring section with 10 groundwater observation wells along Heihe River flood land-old oasis croplands-newly cultivated sandy croplands-fixed sandy land outside oasis was established in Pingchuan desert-oasis in Linze county in the middle of Heihe river basin, and groundwater NO(3-)-N concentration was continuously monitored. Soil texture and NO(3-)-N concentration in the unsaturated zone at different landscape locations were determined. The NO(3-)-N transfer change in soil profile, nitrate leaching of soils with different texture and fertility levels in the 0-100 cm layer were analyzed. The results indicated that the vertical distribution of soil texture was sandy loam in the 0-130 cm depth, loam in the 130-190 cm and clay loam in the 190-300 cm for the old oasis croplands. For newly cultivated sandy croplands, sand content was more than 80% in each soil layer of the 0-300 cm profile, although a thin clay layer occurred in the 140-160 cm depth. The clay layer occurred 160 cm below the sand-fixing zone outside oasis. There were significant correlations between soil NO(3-)-N concentration and silt + clay content, and the order of significant degree was the natural soils of sandy lands > the newly cultivated sandy croplands > the old oasis croplands. The loss of N leaching was closely correlated to the silt + caly content in the 0-100 cm soil depth. The groundwater NO(3-)-N concentration varied from 1.01 to 5.17 mg · L(-1), with a mean value of 2.65 mg · L(-1) and from 6.6 to 29.5 mg · L(-1), with an average of 20.8 mg · L(-1) in the area of old oasis croplands and the newly cultivated croplands, respectively. The averaged groundwater NO(3-)-N concentration in the area of newly cultivated sandy croplands during the period of May and October, 2013 was 26.5 mg · L(-1), which was increased by 9.5 mg · L(-1) in comparison with the same period of 2012. There was a clear increasing trend in groundwater NO(3-)-N concentration in the sand-fixing zone outside oasis. The textural characteristics of soil unsaturated zone in the shallow groundwater distribution area was the key determining factor for controlling soil NO(3-)-N leaching and groundwater nitrate pollution. The newly cultivated sandy croplands were the nitrate vulnerable zones and high-risk areas of groundwater nitrate pollution. The implementation of cultivation pattern and irrigation and fertilization management that could effectively reduce groundwater NO(3-)-N pollution should be considered in the development of ecological agriculture.

This paper studied the characteristics of soil nematode community following the conversion of native sandy desert soil to irrigated farmland in a marginal oasis of the middle reaches of Heihe River basin, aimed to approach the bioindicating function of soil nematodes in soil evolution process. A total of 27921 soil nematode individuals were captured, belonging to 25 families and 34 genera. The total number of nematodes increased gradually with increasing age of cultivation. At all sampling sites, bacterivores and plant parasites were the dominant trophic groups, and made up the main parts of nematode community in oasis farmland. Through the analysis of the evenness index (J) and dominance index (lambda) of nematode community, the ecosystems were found to be fragile for the farmlands having cultivated for 0, 10, and > 50 years. The maturity index MI2-5 and MMI decreased with increasing cultivation age, suggesting that the practice of agricultural use enhanced the disturbance on farmland. The soil properties changed significantly after 10 years of cultivation, which was at a significant change stage for the structure stability of soil ecosystems. The characteristics of soil nematode community could be used as the bioindicator of soil evolution following the conversion of native desert soil to irrigated farmland.

In order to curb the deterioration of ecological environment and promote the economic and social sustainable development of Shiyang River Basin, the Minqin government implemented water-saving measures of the shut-in and pressure fields and water discharge engineering in Shiyang River downstream in 2001 and in 2006, respectively. Sixty-five groundwater samples were collected in Minqin County in 2008 and the concentrations of major ions were analyzed in laboratory. The hydrochemistry characteristic of the groundwater was studied by traditional statistical analysis method. Results indicated the concentrations of the major ions, such as SO4(2-), Cl-, HCO3, CO3(2-), Na+, Mg2+, Ca2+ and K+ in the groundwater samples, were (921 +/- 1042), (241 +/- 211), (282 +/- 123), (4.7 +/- 11.7), (468 +/- 599), (156 +/- 166), (142 +/- 89) and (17.6 +/- 34.5) mg/L, respectively. There was increasing tendency for major ion concentrations along the groundwater flow direction. The groundwater mineralization was (2.2 +/- 1.9) g/L in 2008. The type of water samples in Minqin oasis mainly belonged to SO4(2-) - Cl- -Na+ -Mg2+. The average concentration of the NO3- was (8.1 +/- 9.9) mg/L in the groundwater of Minqin, and the nitrate-N content was over 10 mg/L in 1.54% of all of water samples, which was unsuitable for drinking. Based on the data of groundwater mineralization in 2002, 2005 and 2008, the spatial-temporal variations of groundwater mineralization were studied by geo-statistical analysis method. Kringing interpolation results showed that groundwater mineralization at the spatial distribution scale were took on a gradual increase pattern from south to north. As for the change trend of groundwater mineralization in south area of Minqin County, there was increasing trend from 2002 to 2005, but decreasing trend was occurred from 2005 to 2008. Change trend of groundwater mineralization in north area of Minqin oasis was opposite to that of in south area. There was decreasing trend for the groundwater mineralization in south area from 2005 to 2008, which was due to the impact on water discharge in Shiyang River Basin. There was no significant improvement for groundwater by single water-saving measure, but the quality of groundwater was improved after water discharge in Shiyang River Basin.

With the sandy farmland in the marginal oasis in middle reaches of Heihe River Basin, Northwest China as test object, this paper studied soil NO3- -N accumulation and leaching under effects of different farmland use type and winter irrigation. The results showed that the mean NO3- -N concentration in 0-300 cm soil profile in different farmlands ranged from 1.27 mg x kg(-1) to 83.60 mg x kg(-1) Soil NO3- -N concentration was higher in 0-40 cm and 135-300 cm layers, but lower in 40-135 cm layer. Greenhouse vegetable field had a significantly higher soil NO3- -N concentration than the other farmland use types. The accumulated amount of soil NO3- -N decreased in the order of greenhouse vegetable field > tomato field > cotton field > seed maize field > maize-wheat rotation field > maize-wheat stripe intercropping field > alfalfa field > jujube plantation. The NO3- -N accumulation in 0-300 cm soil profile in greenhouse vegetable filed reached 2171.45 kg x hm(-2), which would be a serious menace to groundwater quality, followed by tomato field and cotton field. Lesser accumulation of soil NO3- -N was found in seed maize field, maize-wheat intercropping field, maize-wheat rotation field, alfalfa field, and jujube plantation, but its pollution potential would not be neglected. After winter irrigation, soil NO3- -N concentration decreased in 0-80 cm layer but increased in 80-300 cm layer, indicating that winter irrigation caused NO3- -N leaching into deeper soil depth. The leached amount of soil NO3- -N to deeper layers increased with increasing amount of winter irrigation. To mitigate soil NO3- -N leaching and groundwater contamination, a comprehensive consideration should be made on the rational arrangement of farmland use type, proper decrease of planting N-accumulated crops, and reasonable winter irrigation.

Changes in soil organic carbon (SOC) and total nitrogen (TN) stocks were studied following croplands were converted to forage grasslands (alfalfa) for five years on the marginal land at the edge of oasis in the middle reaches of Heihe river basin. Soil from 12 paired forage land/adjacent cropland on the two soil types (Typic Torripsamments and Typic Calciorthids) was sampled at the three depths of 0-5, 5-10 and 10-20 cm and analyzed for SOC and TN, particulate organic carbon (POC) and nitrogen (PON). The studied soils had very low SOC and N concentrations. SOC stock at the 0-20 cm depth increased by 22.1%-27.8% after conversion of annually crop to perennial alfalfa for four years, and carbon sequestration rate was estimated to be on average 0.47 Mg/(hm2 x a). The greatest change in SOC stock occurred at the 0-5 cm surface layer with an increase of 32%-66%. No significant TN stock was found at the 0-20 cm depth, however, it increased at the 0-5 cm surface layer by 12.8% and 48.1% for Typic Torripsamments and Typic Calciorthids, respectively. Changes in POC and PON stocks were more significant than those in SOC and total N following conversion of crop to forage, and the percentage of distributions of POC and PON increased. POC and PON stocks at the 0-20 cm depth increased by 22.8%-42.7% and 18.6%-57.6% with the greatest increases at the 0-5 cm layer. The increase in soil C pool was mainly attributed to the increase of POC formation after the marginal lands converted to perennial forage cover. Typic Calciorthids with lower SOC concentration had relatively lower C sequestration rate but more significant effects of C and N sequestration compared with Typic Torripsamments.