Effects of Water and Substratum Nutrient Supplies on Lotic Periphyton Growth: An Integrated Bioassay

1987 ◽  
Vol 44 (3) ◽  
pp. 619-629 ◽  
Author(s):  
Catherine M. Pringle
Keyword(s):  
Algal Growth ◽  
Nutrient Release ◽  
Spatial And Temporal Variability ◽  
Enrichment Technique ◽  
P Release ◽  
Constant Rate ◽  
Limiting Nutrients ◽  
Flow Through ◽  
Nutrient Diffusing Substrata ◽  
The Vertical Distribution

Effects of substratum and water nutrient perturbations on periphyton growth were assessed in a nutrient-poor stream by combining a substratum enrichment technique with a flow-through bioassay system. Periphyton growth (chlorophyll a, total biovolume) responded to combined influences of water and substratum enrichment in an additive manner when both compartments were amended with N and P to yield an optimal ratio [Formula: see text]. When NO3-N was added to the substratum and PO4-P to the water, algal growth response was synergistic. Analysis of the vertical distribution of P fractions in cores taken from nutrient-diffusing substrata indicates that attached microorganisms mediate P release from underlying substrata, acting as a filter or temporary sink. Nutrient-diffusing substrata are useful detectors of limiting nutrients in aquatic systems; however, their function and application differ from water enrichment assays where nutrients are added at a constant rate. Differences are partially attributed to spatial and temporal variability of nutrient release and the strictly localized influence of substratum flora on ambient water chemistry.

scholarly journals Study of C, N, P and K Release from Residues of Newly Proposed Cover Crops in a Spanish Olive Grove

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1041 ◽  
Author(s):  
Antonio Rodríguez-Lizana ◽  
Miguel Ángel Repullo-Ruibérriz de Torres ◽  
Rosa Carbonell-Bojollo ◽  
Manuel Moreno-García ◽  
Rafaela Ordóñez-Fernández
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Crop Residues ◽  
Soil Cover ◽  
Brachypodium Distachyon ◽  
Nutrient Release ◽  
Grab Sampling ◽  
P Release ◽  
Olive Groves ◽  
C And N

Cover crops (CC)s are increasingly employed by farmers in olive groves. Spontaneous soil cover is the most commonly used CC. Its continuous utilization changes ruderal flora. It is necessary to study new CCs. Living CCs provide C and nutrients to soil during decomposition. Information on this issue in olive groves is scarce. A 4-year field study involving grab sampling of Brachypodium distachyon, Sinapis alba and spontaneous CC residues was conducted to study C and nutrient release from cover crop residues. Throughout the decomposition cycles, C, N and P release accounted for 40 to 58% of the C, N and P amounts in the residues after mowing. Most K was released (80–90%). Expressed in kg per hectare, the release of C and N in Brachypodium (C: 4602, N: 181, P: 29, K: 231) and Sinapis (C: 4806, N: 152, P: 18, K: 195) was greater than that in spontaneous CC (C: 3115, N: 138, P: 21, K: 256). The opposite results were observed for K. The Rickman model, employed to estimate the amount of C, N and P in residues, yielded a good match between the simulated and measured values. In comparison to spontaneous CC, the newly proposed CCs have a higher potential to provide soil with C and N.

scholarly journals Do Silvi-Medicinal Plantations Affect Tree Litter Decomposition and Nutrient Mineralization?

2019 ◽  
Vol 11 (18) ◽  
pp. 5138 ◽  
Author(s):  
Xiaoxi Zhang ◽  
Hangyu Lei ◽  
Yujie Chong ◽  
Jiawei Hu ◽  
Wenrong Che ◽  
...  
Keyword(s):  
Litter Decomposition ◽  
Plant Secondary Metabolites ◽  
Cellulase Activity ◽  
Nutrient Release ◽  
Medicinal Herbs ◽  
Inhibitory Effects ◽  
Nutrient Mineralization ◽  
Specific Effects ◽  
P Release ◽  
Tree Litter

In a silvi-medicinal system, the plant secondary metabolites (PSMs) released from medicinal herbs could affect tree litter decomposition and nutrient release. However, the specific effects of PSMs on arboreous litter decomposition are still not well understood. In this study, the extracts of nine types of medicinal herbs were used to treat Pinus armandii Franch. and Larix gmelinii (Rupr.) Kuzen. litter during a simulated half-year decomposition. The effects of the extracts on the decomposition and the N and P release of the conifer litter were investigated. The results indicated that most of the medicinal herb extracts significantly inhibited the late decomposition of P. armandii litter, whereas only two of them accelerated the entire decomposition process. Only a few significantly affected the decomposition of the L. gmelinii litter. Four of the nine types of extract significantly inhibited the N and P release of the P. armandii litter, while 3/9 and 6/9 inhibited the N and P release of the L. gmelinii litter, respectively. The accelerating effects of the extracts on the cellulase activity and the inhibitory effects on the polyphenol oxidase activity might be responsible for the early acceleration and late inhibition of litter decomposition, while the effects of the extracts on the activities of protease and phosphatase might not be the main reason for the inhibitory or accelerating effects on the N and P release. In general, the inhibitory effects of medicinal herbs on the nutrient cycling of ecosystems should be taken into consideration when building silvi-medicinal systems, especially in P. armandii forests.

Measurement of intracardiac pressure through a valve-tipped catheter

1975 ◽  
Vol 42 (2) ◽  
pp. 236-239 ◽  
Author(s):  
Jan Ekstedt ◽  
Bo Nyström ◽  
Rune Hugosson ◽  
Seth Högström
Keyword(s):  
Liquid Flow ◽  
Optimal Placement ◽  
Pressure Waves ◽  
Content Type ◽  
Cardiac Catheter ◽  
Pressure Recording ◽  
Constant Rate ◽  
Flow Through ◽  
Intracardiac Pressure ◽  
Fine Print

✓ Intracardiac pressure recording is a simple and effective way of obtaining optimal placement of the cardiac catheter during shunting procedures. We have also found this method applicable when using a catheter with a slit in its tip. Pressure waves can be accurately recorded by means of a constant rate liquid flow through the catheter.

scholarly journals The algal growth-limiting nutrient of lakes located at Mexico’s Mesa Central

2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
Fernando W. Bernal-Brooks ◽  
José J. Sánchez Chávez ◽  
Luis Bravo Inclán ◽  
Rubén Hernández Morales ◽  
Ana K. Martínez Cano ◽  
...  
Keyword(s):  
Case Studies ◽  
Algal Growth ◽  
Dry Season ◽  
Growth Potential ◽  
Sampling Station ◽  
Wet Season ◽  
N Limitation ◽  
P Limitation ◽  
Limiting Nutrients ◽  
Limiting Nutrient

<p>This paper reports on the algal growth-limiting nutrients of five lakes located on Mexico’s Mesa Central - a topic poorly known in the regional limnology of Mexico. The five case studies involved three contiguous watersheds of Michoacán State and provided a trophic state variation from mesotrophic to hypereutrophic; the case studies included Lakes Zirahuén, Pátzcuaro, Teremendo, Cuitzeo and the Cointzio Reservoir. The fieldwork involved the collection of physical and chemical data (including nutrients) from each case study during the dry and rainy seasons of 2010. Additionally, water samples (1 L) were obtained and filtered (0.45 µm) in the laboratory to keep the nutrient content available for bioassays. The chemical analyses suggested a phosphorus (P) limitation in the Cointzio Reservoir, Lake Teremendo and Lake Zirahuén relative to an N:P&gt;16:1. There was a nitrogen (N) limitation at three sampling stations of Lake Pátzcuaro, with an N:P&lt;16:1. As result of the bioassays conducted in July 2012, the Cointzio Reservoir and Lake Teremendo appeared to be P-limited and Lake Pátzcuaro appeared to be N-limited at three sampling stations. Lake Zirahuén showed seasonal variation, with an N limitation during the dry season and a P limitation during the wet season. Those cases with similar results from both methods confirmed the limiting nutrient identification. Lake Cuitzeo, Lake Zirahuén (dry season), and the shallowest sampling station in Lake Pátzcuaro produced unclear results because of divergent outcomes. In terms of the algal growth potential, the Cointzio Reservoir remained unaltered from one season to the next. However, for most of the lakes (with the exception of Lake Pátzcuaro sites 2 and 4), the rainy season provided a dilution effect. Effective lake management depends on a clear recognition of such elements that are in control of the aquatic productivity. In the area of Michoacán, both N and P may act as limiting nutrients.</p>

scholarly journals Litter production, decomposition and nutrient release in cleared and uncleared pasture systems of central Queensland, Australia

2006 ◽  
Vol 22 (2) ◽  
pp. 177-189 ◽  
Author(s):  
Kamaljit K. Sangha ◽  
Rajesh K. Jalota ◽  
David J. Midmore
Keyword(s):  
Litter Decomposition ◽  
Arid Zone ◽  
Nutrient Release ◽  
Nutrient Cycle ◽  
Litter Production ◽  
Continuous Release ◽  
P Release ◽  
Tree Communities ◽  
C And N ◽  
Eucalyptus Populnea

The temporal impact of clearing trees on litter production, litter decomposition and on C, N and P release through decomposition of litter was examined in the pasture systems of a semi-arid zone of central Queensland. Paired sites for cleared pastures (developed from clearing woodlands) and uncleared (intact woodland) pastures were selected to represent three dominant tree communities of the region i.e. Eucalyptus populnea, E. melanophloia and Acacia harpophylla, with three different time-since-clearing (5, 11–13 and 33 y) treatments. Yearly litter production was greater at uncleared sites (1732–1948 kg ha−1 y−1 for eucalypt and 2596 kg ha−1 y−1 for acacia communities) compared with cleared sites (1038–1282 kg ha−1 y−1 for eucalypt and 1100 kg ha−1 y−1 for acacia communities averaged over three time-since-clearing treatments). Rates of litter decomposition and of release of C, N and P from decomposing litter were higher at cleared than uncleared sites for all three tree communities. The cleared and uncleared sites did not differ significantly in total amount of C and N released per year since the concentrations of C and N were greater in litter from uncleared sites but the rate of release was less than that at cleared sites. Slow but continuous release of nutrients in eucalypt and acacia woodlands may be an adaptation of these communities to maintain the nutrient cycle and to avoid leaching of nutrients in the nutrient-poor soils of the region.

Research and application of in-situ control technology for sediment rehabilitation in eutrophic water bodies

2012 ◽  
Vol 65 (7) ◽  
pp. 1190-1199 ◽  
Author(s):  
Bo Liu ◽  
Xuegong Liu ◽  
Jie Yang ◽  
David E. J. Garman ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Algal Growth ◽  
Bentonite Clay ◽  
Field Trials ◽  
Application Rate ◽  
Control Technology ◽  
Overlying Water ◽  
P Release ◽  
In Situ Control ◽  
Limiting Nutrient

Phosphorus (P) is often the limiting nutrient for algal growth, and P in sediments can be released under suitable conditions. To control P release, in-situ control technology with lanthanum (La) modified bentonite clay (Phoslock®) was proposed and its effectiveness was tested and evaluated both in laboratory and field trials. The results of static and dynamic simulation experiments under different environmental conditions showed that with the application rate of Phoslock® at 0.5 kg/m2, the orthophosphate (PO4-P) concentration of the overlying water decreased to a low level (≤0.02 mg/L) within 10 days. Even under anaerobic and high pH (pH = 9.0) conditions, the phosphate release suppression efficiency reached 98.3%, and the P-release rate was −8.20 mg/m2 d (negative value indicates P adsorption by Phoslock®). The monitoring data of the field sediments rehabilitation project were consistent with the results achieved in laboratory experiments, thus showing that the application of Phoslock® could inhibit the internal P release effectively.

scholarly journals POPULATION DYNAMICS OF THE MICROBIOTA IN THE LITTER OF TWO TREE SPECIES OF THE ATLANTIC FOREST

FLORESTA ◽  
2020 ◽  
Vol 50 (3) ◽  
pp. 1449
Author(s):  
Fabiana Rodrigues Baldez ◽  
Marcos Gervasio Pereira ◽  
Tatiana Saldanha ◽  
Wilbert Valkinir Cabreira ◽  
Cristiane Figueira Da Silva ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Litter Decomposition ◽  
Atlantic Forest ◽  
Release Rate ◽  
Tree Species ◽  
Abiotic Factors ◽  
Nutrient Release ◽  
Release Rates ◽  
Litter Bags ◽  
P Release

This study analyzes microbiota population dynamics as a function of nutrient release rate during litter decomposition. For that, we observed two tree species native to the Atlantic Forest: brazilwood (Paubrasilia echinata) and inga (Inga laurina). To assess nitrogen (N), phosphorus (P), and potassium (K) release rates from the litter, we performed six collections over 365 days. In these collections, we placed polyvinyl bags called ‘litter bags’ below the treetops of the chosen species to collect dry leaves. To identify the groups of litter microorganisms (fungi, bacteria, and actinomycetes), we used the plate culture method to count the number of colony-forming units (CFU), and the fatty acid profile method, through biomarkers, associating nutrient release rate and abiotic factors (temperature and rainfall). Nutrient release rate correlates with litter decomposition at 140 days, and most microorganisms correlate with litter decomposition at 30 days. Nitrogen and phosphorus release rates correlate with rainfall. Fungi correlate with P release rate in inga litter decomposition. The bacteria biomarker 17:1 was the only one that correlated with N and P release rates. In conclusion, rainfall affects nutrient solubilization in the studied species, and microbiota differs between the species. When comparing the two methods to identify these microorganisms, information from one method complements information from the other, since both provide different but interdependent data.

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