[Effects of Agricultural Organic Waste Incorporation on the Metabolic Capacity of Microbial Carbon Sources of Dissolved Organic Matter in Paddy Soil].

A long-term fertilization experiment with a system of rice-wheat rotation was conducted in Chengdu Plain. Three fertilization treatments including conventional fertilization (T1), pig manure substituting for 50% nitrogen fertilizer (T2), and T2 plus straw (T3) were set up to study the characteristics of microbial carbon source utilization of soil and dissolved organic matter (DOM). The results showed that T3 improved the soil microbial carbon source metabolism in comparison with those of the T1 and T2 treatments; the average color change rate (AWCD) increased by 16% and 48%, respectively. Meanwhile, T3 improved the soil DOM microbial carbon source metabolism, and the AWCD value was 0.43. The highest Shannon, Simpson, and McIntosh indexes of soil and DOM were all found in the T3 treatment, and the Shannon, Simpson, and McIntosh indexes of DOM were 2.73, 0.91, and 3.75, respectively. The results of principal component analysis and enrichment analysis showed that the main carbon sources used by microorganisms of soil and DOM were different under different fertilization treatments. For DOM, the main carbon source used by microorganisms in the T1 and T2 treatments was sugar, whereas T3 increased the utilization of amino acids, carboxylic acids, polymers, and amines. The changes in soil pH and texture were the main factors that caused the difference in soil DOM microbial carbon source metabolism. In conclusion, the application of organic fertilizer (pig manure plus straw) significantly increased the microbial community diversity and carbon source metabolic capacity of soil and DOM and promoted the diversification of microbial carbon source preference.

[Optimal operating condition of ICP-aES for determination of soil nutrients extracted by Mehlich 3 through solution simulation].

As a key process of fertilization with soil test, the determination of soil effective nutrients has received great attention in recent years. Based on a series of standard solution mixtures, which simulate the soil nutrients extracted by Mehlich 3 (M3) reagent, the optimal operating condition of ICP-AES was explored in a systematic way. The results show that the 20 key nutrient elements (P, K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Cd, Cr, Pb, Ni, Al, B, Mo, S, Si, Se, and As) in the solutions can be determined correctly and proficiently when ICP-AES is set at 0.80 L x min(-1) of carrier gas flux, with observation height 15 mm and power 1200 W. This study supplies a primary experimental foundation for establishing the determination technique of essential nutrient elements, extracted from soils in China with the general soil-nutrient extractant M3 reagent.

[Stoichiometry of multi-elements in the zinc-cadmium hyperaccumulator Thlaspi caerulescens grown hydroponically under different zinc concentrations determined by ICP-AES].

Thlaspi caerulescens is commonly known as a zinc (Zn) and cadmium (Cd) hyperaccumulator, which can be used to clean up the Zn- and/or Cd-contaminated soil. However, it is unclear whether high soil Zn concentrations will stimulate undue accumulations of other elements to such an extent as to cause the nutrient unbalance in the soil. To address this question, the inductively coupled plasma-atomic emission spectrometry (ICP-AES) was employed to investigate the effect of Zn on the stoichiometry of Zn, Cd, K, P, Mg, Ca, Fe, Mn and Cu in T. caerulescens (Ganges ecotype) exposed to low, middle and high Zn concentrations (5, 50 and 500 micromol x L(-1), respectively) in a hydroponic experiment. The results showed that there were no significant variations in contents of Cd, K, P, Mg, Ca, Fe, Mn and Cu in the shoot of T. caerulescens, however, the Zn content in the shoot and root with 500 mciromol x L(-1) Zn treatment increased as much as 13 times higher than that with low Zn exposure, indicating that the plant is capable of Zn hyperaccumulating. The authors' study suggests that it is improbable to induce soil nutrient unbalance when T. caerulescensis (Ganges) is used for phytoremediation of Zn-contaminated soil, in that over-uptake of nutrient elements from the soil other than Zn was not observed, at least for the elements K, P, Mg, Ca, Fe, Mn and Cu.

[Study on the response of middle and trace elements in Humulus scandens leaves to atmospheric reactive nitrogen with ICP-AES].

Based on field measurements, the effects of atmospheric reactive nitrogen (ARN) on the middle/trace element concentrations in the leaves of wild plant humulus scandens were analyzed. Leaves of H. scandens were collected from six sites around Beijing in the North China Plain, and the concentrations of Ca, Mg, S, Fe, Mn, Cu, Zn, B, and Na in the leaves were determined with inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that element concentrations in leaves ranked as Ca (41 106) > S (8 370) > Mg (6 628) > Fe(476) > Na (92) > B (78) > Mn (49) > Zn (38) > Cu (15) mg x kg(-1) dry matter; There were no significant difference in any of the individual element in the H. scandens leaves along the gradient of ARN, suggesting that the increasing demand of H. scandens for middle/trace elements, induced by the enhanced nitrogen availability from ARN, was not yet beyond the nutrient-supply limits of the local soils. This study offers reference to scientific assessments of the middle/trace element status in terrestrial herbaceous plants under the global background of increasing nitrogen deposition.

[Inorganic nitrogen wet deposition in eastern China: Comparison of different land use-based monitoring sites in north and south regions]. / ä¸­å›½ä¸œéƒ¨åœ°åŒºæ— æœºæ°®æ¹¿æ²‰é™: 南-北不同类型监测点的比较.

China is one of the global hotspots of atmospheric nitrogen (N) deposition. This is especially true for eastern China, an economically developed and densely populated area, which emits large quantities of anthropogenic reactive N species to the air and experiences high levels of atmospheric N deposition. Few studies, however, have examined spatial variations of N deposition across different ecosystems in northern and southern regions of eastern China. Using the traditional rain gauge (SDM6A) method, we conducted a three-year (2011-2013) study to quantify wet N deposition fluxes at twelve sites (six northern and six southern monitoring sites, covering urban, rural and background land use types) in China. The annual volume-weighted mean (VWM) concentrations of NH4+-N, NO3--N and total inorganic N (TIN) atmonitoring sites were in the ranges of 0.62-2.76, 0.54-2.50 and 1.25-4.92 mg N·L-1, and averaged 1.4, 1.5 and 2.9 mg N·L-1, respectively. Northern sites showed higher concentrations of N species in precipitation than southern sites. Annual deposition fluxes of NH4+-N, NO3--N and TIN were in the ranges of 7.0-18.3, 6.9-18.9 and 14.9-32.6 kg N·hm-2·a-1, averaging 11.5, 12.2 and 23.7 kg N·hm-2·a-1, respectively. There were significant differences in total N deposition fluxes among different land use types in the north, showing the decreasing order of urban sites (26.3±6.4 kg N·hm-2·a-1)> rural sites (21.8±3.5 kg N·hm-2·a-1)> background (15.5±1.3 kg N·hm-2·a-1). Total N deposition fluxes at urban, rural and background sites in the south were (26.8±2.7), (25.5±2.9) and (20.5±2.4) kg N·hm-2·a-1, respectively, showing no significant spatial variation. While urban sites did not show obvious regional differences, total N wet deposition fluxes at rural and background sites in the south were significantly higher than those at corresponding sites in the north. Our results revealed that both south and north regions of eastern China (including background areas) are receiving high levels of wet N deposition and associated ecological and environmental risks should be considered.