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1.
Vertical measurements of , and N2O concentrations, and uptake, and oxidation rates were measured at 5 sites in western Cook Strait, New Zealand, between 31 March and 3 April 1983. Nitrate increased with depth at all stations reaching a maximum of 10.5 μg-atom at the most strongly stratified station whereas was relatively constant with depth at all stations (~0.1 μg-atom ). The highest rates of oxidation generally occurred in the near surface waters and decreased with depth. N2O levels were near saturation with respect to the air above the sea surface and showed no obvious changes during 24 h incubation. oxidation by nitrifying bacteria may account for about 30% of the total utilization (i.e. bacterial+agal) and, assuming oxidation through to , may supply about 40% of the algal requirements of in the study area. These results suggest that bacterial nitrification is of potential importance to the nitrogen dynamics of the western Cook Strait, particularly with respect to the nitrogen demands of the phytoplankton. 相似文献
2.
海水中低含量铵氮的高灵敏度荧光法测定 总被引:3,自引:0,他引:3
提出了一种改进的、可测定海水中低含量铵氮的高灵敏度荧光分析方法。其原理是在硼酸缓冲溶液的作用下,海水中的铵氮与邻苯二甲醛(OPA)发生衍生化反应,通过测定生成的荧光产物来确定水体中铵氮的浓度。方法的检测限极低(0.002 5μmol/L),重现性好,且水样用量少(10 mL),适用于海水中溶解有机物的光铵化研究及其他低铵含量水样的测定。 相似文献
3.
不同氮源对微小亚历山大藻生长和毒素产生的影响 总被引:12,自引:0,他引:12
通过尿素、氯化铵、酵母浸出粉和硝酸钠等氮源对微小亚历山大藻(Alexandrium minutum)生长及毒素产生的影响研究,分析了微小亚历山大藻对不同氮源利用状况的差异.结果表明,在氮饥饿条件下,加入硝酸钠和酵母浸出粉能显著促进微小亚历山大藻的生长;高浓度的氯化铵在加入后对微小亚历山大藻有一定的毒性效应,表现为生长停滞,但毒性效应在5 d后消失,并得到与添加硝酸钠及酵母浸出粉相似的增长速率0.21 d-1;添加尿素对微小亚历山大藻的生长没有显著促进作用.在四种氮源中,尿素对微小亚历山大藻毒素产生的刺激作用也最弱,在稳定期每个细胞藻细胞毒素含量维持在6.00~8.00 fmol;添加硝酸钠、氯化铵和酵母浸出粉的藻细胞在稳定期毒素含量分别达到11.85,12.86和14.64 fmol.硝酸钠和氯化铵刺激藻毒素产生的效果比酵母浸出粉更为直接.四种含氮营养盐对微小亚历山大藻毒素组成的影响都很小. 相似文献
4.
利用有机-无机(矿物)控释材料对碳酸氢铵进行改性,制成改性碳酸氢铵。盆栽试验结果显示,在等重条件下,改性碳酸氢铵较普通碳酸氢铵有较大幅度的增产。运用X射线衍射分析及红外光谱对改性碳酸氢铵的结构进行研究,发现其晶体结构发生较大的变化,差热分析结果也表明,改性碳酸氢铵的热分解温度比普通碳酸氢铵提高30℃。这种晶体结构的变化增加了改性碳酸氢氨的稳定性,从而延长了其肥效并提高了N的利用率。 相似文献
5.
Stanley N. Davis Stephen Moysey DeWayne L. Cecil Marek Zreda 《Hydrogeology Journal》2003,11(2):217-227
Natural production of the radionuclide chlorine-36 (36Cl) has provided a valuable tracer for groundwater studies. The nuclear industry, especially the testing of thermonuclear
weapons, has also produced large amounts of 36Cl that can be detected in many samples of groundwater. In order to be most useful in hydrologic studies, the natural production
prior to 1952 should be distinguished from more recent artificial sources. The object of this study was to reconstruct the
probable preanthropogenic levels of 36Cl in groundwater in the United States. Although significant local variations exist, they are superimposed on a broad regional
pattern of 36Cl/Cl ratios in the United States. Owing to the influence of atmospherically transported ocean salt, natural ratios of 36Cl/total Cl are lowest near the coast and increase to a maximum in the central Rocky Mountains of the United States.
Electronic Publication 相似文献
6.
R. G. Derwent W. J. Collins M. E. Jenkin C. E. Johnson D. S. Stevenson 《Journal of Atmospheric Chemistry》2003,44(1):57-95
A global 3-D Lagrangian chemistry-transport model STOCHEM is used to describe the tropospheric distributions of four components of the secondary atmospheric aerosol: nitrate, sulphate, ammonium and organic compounds. The model describes the detailed chemistry of the formation of the acid precursors from the oxidation of SO2, DMS, NOx, NH3 and terpenes and their uptake into the aerosol. Model results are compared in some detail with the available surface observations. Comparisons are made between the global budgets and burdens found in other modelling studies. The global distributions of the total mass of secondary aerosols have been estimated for the pre-industrial, present day and 2030 emissions and large changes have been estimated in the mass fractions of the different secondary aerosol components. 相似文献
7.
铅—试铁灵络合物吸附波及溴化十六烷基三甲基铵增敏效应的研究 总被引:1,自引:0,他引:1
在030mol/LHAc介质中,Pb(Ⅱ)与7_碘_8_羟基喹啉_5_磺酸(试铁灵,Feron)的络合物于-054V(vs.SCE)产生一尖锐的极谱波,加入溴化十六烷基三甲基铵(CTMAB)显著增敏,可使极谱波增高约4倍。峰电流与Pb(Ⅱ)浓度在96×10-9~48×10-6mol/L呈良好的线性关系,检出限为48×10-9mol/L。用多种电化学方法研究了该极谱波的性质及电极反应机理表明,络合物组成比为nPb(Ⅱ)∶nFeron=1∶1,极谱波为吸附波,峰电流由中心离子Pb(Ⅱ)还原产生,电子转移数为2。试验了多种离子对峰电流的影响,拟定的方法用于矿样分析,结果与原结果相符。 相似文献
8.
碘化氨除锡后封闭酸溶-电感耦合等离子体质谱测定锡矿石中的共生和伴生元素 总被引:1,自引:1,他引:0
锡矿石是难分解的矿物,主要存在形式是锡石(SnO_2),且共生和伴生元素多,常用的酸溶方法几乎不能溶解SnO_2,从而给锡矿石中的共生与伴生元素的准确测定带来困难。本文基于碘化氨在较低温度下熔融可产生无水状态的碘化氢,利用碘化氢的酸性和氨的还原性分解SnO_2,使Sn呈SnI_4升华分离的原理处理锡矿石。实验中以高纯铂丝作催化剂,加入碘化铵在450℃的马弗炉中分解锡矿石30 min,使得Sn以SnI_4形式挥发,除锡率达到98%以上,再用2 mL氢氟酸和1 mL硝酸封闭溶解残渣,电感耦合等离子体质谱测定钴镍铜铌钽钍铀等24个共生和伴生元素。元素检出限在0. 001~2. 9μg/g之间,90%以上元素的相对标准偏差(RSD)小于5%,相对误差小于10%。本方法解决了锡矿石难分解的问题,可测定共存金属元素,也适合测定Sn含量在1. 27%~62. 49%之间的锡矿石中的微量和痕量元素及锡精矿中的微量元素。 相似文献
9.
Nitrogen and sulfur species in Antarctic aerosols at Mawson,Palmer Station,and Marsh (King George Island) 总被引:4,自引:0,他引:4
D. L. Savoie J. M. Prospero R. J. Larsen F. Huang M. A. Izaguirre T. Huang T. H. Snowdon L. Custals C. G. Sanderson 《Journal of Atmospheric Chemistry》1993,17(2):95-122
High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60° S, 62.50° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77° S, 64.06° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18° S, 58.30° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na+, SO
4
2–
, NO
3
–
, methanesulfonate (MSA), NH
4
+
,210Pb, and7Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na+, 68–151 ng m–3; NO
3
–
, 25–30 ng m–3; nss SO
4
2–
, 81–97 ng m–3; MSA, 19–28 ng m–3; NH
4
+
, 16–21 ng m–3;210Pb, 0.75–0.86 fCi m–3. Results from multiple variable regression of non-sea-salt (nss) SO
4
2–
with MSA and NO
3
–
as the independent variables indicates that, at Mawson, the nss SO
4
2–
/MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80±0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71±0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO
4
2–
during transport over Antarctica from the oceanic source region. The mean210Pb concentrations at Palmer and Marsh and the mean NO
3
–
concentration at Palmer are about a factor of two lower than those at Mawson. The210Pb distributions are consistent with a210Pb minimum in the marine boundary layer in the region of 40°–60° S. These features and the similar seasonalities of NO
3
–
and210Pb at Mawson support the conclusion that the primary source regions for NO
3
–
are continental. In contrast, the mean concentrations of MSA, nss SO
4
2–
, and NH
4
+
at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO
4
2–
by 10%; and NH
4
+
by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differences generally occur during the austral summer when the concentrations of most of the species are highest. NH
4
+
/(nss SO
4
2–
+MSA) equivalent ratios indicate that NH3 neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March. 相似文献
10.
Jean Servant Robert Delmas Jacques Rancher Marcel Rodriguez 《Journal of Atmospheric Chemistry》1984,1(4):391-401
A partial balance of mineral N is given for the basins of two coastal rivers in a forest zone in the Ivory Coast. The dry and wet depositions on the basin surfaces is given for particulate matter (NO3
–, NH4
+). The quantity of mineral N washed away in the rivers is evaluated. The losses from leaching of the soils by rainwater are about 0.33 to 1.0% of the atmospheric depositions for NH4
+–N and 2.2 to 5.8% for NO3
––N. The yearly atmospheric input of N compounds to the ecosystem, about 1.4 g N m–2 y–1, is at least 14% of mineral N formed in the soils and is therefore quite significant. 相似文献