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11. |
Microbial enzymatic response to catchment‐scale variations in supply of dissolved organic carbon |
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New Zealand Journal of Marine and Freshwater Research,
Volume 31,
Issue 5,
1997,
Page 701-706
Stuart Findlay,
ChristopherW. Hickey,
JohnM. Quinn,
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摘要:
A suite of exoenzyme activities was assayed in three New Zealand streams draining pasture, native forest, and a pine catchment. There were differences among catchments in activity of three of the five enzymes assayed (cello‐biohydrolase, N‐acetylglucosaminidase, and dihydroxylphenylalanine oxidation). A principal components analysis (PCA) demonstrates that patterns of enzyme activity can be used to separate the three stream types. An experimental addition of algal‐leachate, leaf‐litter leachate, and high dissolved organic carbon (DOC) water from a small seep also resulted in marked shifts in epilithic enzyme activities 1 day after DOC additions. Oxidative enzymes showed a particularly strong response to additions of humic DOC. As for the field samples, a PCA showed large differences among treatments indicating that exoenzyme patterns can be used to examine which DOC sources predominate in different streams. Application of this approach to describing differences among streams will require detailed seasonal sampling together with longer‐term experiments.
ISSN:0028-8330
DOI:10.1080/00288330.1997.9516800
出版商:Taylor & Francis Group
年代:1997
数据来源: Taylor
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12. |
Predicting the effects of shade on water temperature in small streams |
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New Zealand Journal of Marine and Freshwater Research,
Volume 31,
Issue 5,
1997,
Page 707-721
J. Christopher Rutherford,
Shane Blackett,
Colin Blackett,
Laurel Saito,
RobertJ. Davies‐Colley,
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PDF (1206KB)
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摘要:
A computer model for stream water temperature was developed, and tested in a small pasture stream near Hamilton, New Zealand. The model quantifies shading by riparian vegetation, hillsides, and stream banks using three coefficients: canopy angle, topography angle, and canopy shade factor. Shade was measured directly and found to vary significantly along the channel. Using the maximum measured shade, a close match was achieved between observed and predicted daily maximum and minimum water and bed sediment temperature. Model predictions of incoming and outgoing long‐wave radiation flux closely matched measurements, but there were unexplained discrepancies in short‐wave radiation flux. Model predictions indicate that moderate shade levels (c. 70%) may be sufficient in temperate climates to restore headwater pasture stream temperatures to 20°C, an estimate of the thermal tolerance for sensitive invertebrates.
ISSN:0028-8330
DOI:10.1080/00288330.1997.9516801
出版商:Taylor & Francis Group
年代:1997
数据来源: Taylor
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