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In this study, we present seasonal changes (monthly samples from September 2001 to August 2003) in the abundance and composition of dissolved and particulate amino acids, at one station in the lower Mississippi and Pearl Rivers (LA, MS: USA). Spatial changes over a 4-day transmit from river km 390 to river mouth (Head of Passes, LA) in the Mississippi River, and a two-day downstream sampling from Jackson (MS) to Stennis Space Center (MS) were also determined. Temporal data in the lower Mississippi River showed significantly lower concentrations of dissolved combined amino acids (DCAA, 0.8 to 2.2 μM) and dissolved amino acids in high molecular weight fraction (HMW DAA, 0.2–0.4 μM) than in the Pearl River (DCAA, 1.4–4.3 μM; HMW DAA, 0.4–1.4 μM). Dissolved free amino acids (DFAA) were significantly lower than DCAA in both rivers, and displayed minimal seasonal variability. DCAA, HMW DAA, and particulate amino acids (PAA) were generally higher during high-flow periods, which may have suggested dominance in terrestrial sources. Carbon-normalized yield of PAA (%C-PAA) was generally higher during low-flow conditions and positively correlated with chlorophyll-a (chl-a), reflective of in situ sources. Downstream variability in the lower Mississippi River showed stable DCAA concentrations, a decline in PAA (from 1.06 to 0.43 μM), and a gradual increase in mole percent of non-protein amino acids (%NPAA). This likely reflected bacterial degradation of phytoplankton biomass during falling discharge. Nitrogen-normalized yield of PAA (%N-PAA) was inversely correlated with PAA (R = − 0.7, n = 48), indicative of short-term sedimentation and resuspension events. Conversely, downstream decreases in DCAA and middle-reach peaks of PAA and %N-PAA in the Pearl River, likely resulted from photochemical degradation of DOM as well as algal production during base-flow conditions. The comparisons in abundance and composition of DAA and PAA in these different river systems provides important information on in situ nitrogen and carbon cycling as related to riverine inputs of organic matter to coastal ocean. 相似文献
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不同阻垢剂对方解石和磷酸钙表面电位的影响 总被引：7，自引：0，他引：7
采用微电泳法考察了１５种阻垢剂对方解石和磷酸钙颗粒表面电位的影响。实验结果表明,在各种药剂中,丙烯酸／２丙烯酰胺基２甲基丙磺酸／次磷酸调聚物对难溶盐表面电位影响最大,乙二胺四乙酸二钠盐的影响最小。乙二胺四甲叉膦酸的溶垢能力和对表面电位的影响都较强。各种药剂对两种难溶盐表面电位影响的排序差异不显著。根据配位化学和表面化学原理解释了实验结果。 相似文献
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分析了PAA无固相冲洗液对坍塌层胶结护壁的作用机理，介绍了该冲洗液在吉林镍业公司富家矿千米钻使用过程中，酸性和含水合铁离子水质对PAA冲洗配制及使用的影响及应对措施，同时，介绍了PAA无固相冲洗液强防塌性能的发挥及使用。 相似文献
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介绍了PAA高分子聚合物冲洗液在狮子庙金矿区复杂地层钻探中的成功应用，分析和探讨了PAA高分子聚合物冲洗液对复杂地层中护壁的作用机理。 相似文献
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总结了西华山钨矿区综合治理复杂地层的经验;着重介绍了PAA聚合物在断层破碎带、易水化碎裂岩体中的使用方法和护壁堵漏效果;提出了治理复杂地层应采取“‘辨证论治’、灵活运用”的思路方法,最大限度地降低施工成本,提高钻进效率。 相似文献
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会泽矿区水平钻孔地层复杂,钻孔坍塌、缩径严重,试验采用PAA泥浆,取得较好效果。介绍了PAA泥浆的配方、配制方法和应用效果。 相似文献
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