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您的检索式：作者名="Christopher P.Johnson"
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| 1 | The complexity of sediment recycling as revealed by common Pb isotopes in K-feldspar显示文摘Detrital zircon U-Pb geochronology has become the gold standard in evaluating source to sink relationships in sedimentary basins. However, the physical and chemical robustness of zircon, which make it such a useful mineral for provenance studies, is also a hindrance as zircon can be recycled through numerous sedimentary basins, thus obscuring the first cycle source to sink relationship. An elegant approach to addressing this potential issue is to compare the Pb isotope composition of detrital K-feldspar, a mineral which is unlikely to survive more than one erosion-transport-deposition cycle, with that of magmatic K-feldspar from potential basement source terranes. Here we present new in situ Pb isotope data on detrital K-feldspar from two Proterozoic arkosic sandstones from Western Australia, and magmatic K-feldspar grains from potential igneous source rocks, as inferred by the age and Hf isotope composition of detrital zircon grains. The data indicate that the detrital zircon and K-feldspar grains could not have been liberated from the same source rocks, and that the zircon has most likely been recycled through older sedimentary basins. These results provide a more complete understanding of apparently simple source to sink relationships in this part of Proterozoic Western Australia. | Simon P.Johnson Christopher L.Kirkland Noreen J.Evans Brad J.McDonald Huntly N.Cutten | 2018 | Geoscience Frontiers2018，9，5： | 5 |
| 2 | 升温后泥炭孔隙水溶解有机碳浓度及其不稳定性:野外贫瘠沼泽地增温试验显示文摘北欧和北美的研究表明,近几十年来水生生态系统中溶解有机碳(DOC)浓度增加。尽管关于溶解有机碳提高的机制还没有定论,但是一般认为其根本原因在于升温、降水变率增加和大气沉降变化等气候变化因素。本实验历时长达3年,通过在泥炭地上方1.24 m处安装红外灯积极增温,测试了增温对泥炭孔隙水组成的影响。结果发现在泥炭地下5 c m处,生长季中各处理的平均温度(n=5)比对照处理高1.9±0.4℃(t=5.03,P=0.007)。同时,在泥炭地下25 c m处,生长季中各处理的孔隙水D O C浓度(73.4±3.2 m g/L)比对照处理(63.7±2.1 m g/L)高15%(t=4.69,P<0.001)。此外,升温后的处理中,D O C分解速率是实验室内对照处理的2倍,芳香性比对照组孔隙水更低(增温后泥炭在254 nm处的吸光度降低)。溶解有机氮(DON)浓度变化规律与DOC一致,每单位碳中溶解的氮随着温度升高而下降。以往的研究表明,在这个实验地,增温使净初级生产力增加;同时,几丁质酶和葡萄苷酶的活性增加。本实验观察到,增温条件下DOC浓度增加,可能是因为根际微生物和植物相互作用的结果。在能去质子化生物分子池中,也探测到增温后出现较多的、独特的含有较高双键(DBE)的含氮化合物(在通过超高分辨率离子电喷雾质谱鉴定达到的所有化合物中占16%),这些化合物可能是随着增温引起的植物、微生物和酶活性增加后的产物。随着泥炭地持续升温,相对不稳定的DOC含量升高,这可能导致地表径流中DOC浓度增加,还可能作为有效的电子供体(或者受体)源使陆地和水生环境中的CO2和CH4增加。 | Evan S.Kane Lynn R.Mazzoleni Carley J.Kratz John A.Hribljan Christopher P.Johnson Thomas G.Pypker Rodney Chimner 赵旋琪 王江静 赵红艳 刘莎莎 | 2016 | 腐植酸2016，，2： | 0 |
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