Performing a Nutrient Diffusion Substrata Test (original) (raw)
Related papers
Journal of the American Water Resources Association, 1998
The decline of water quality in United States' lotic ecosystems (streams and rivers) has been linked to nonpoint source nutrient loading (U.S. EPA, 1990). Determining limiting nutrients in streams is difficult due to the variable nature of lotic ecosystems. We developed a quantitative passive diffusion periphyton nutrient enrichment system, called the Matlock Periphytometer, to measure the response of attached algae (periphyton) to nutrient enrichment. The system is simple to build and provides quantitative nutrient enrichment of a surface for periphytic growth. The periphyton grow on a glass fiber filter, which allows complete recovery of periphyton for chlorophyll a analysis. A 14-kilodalton dialysis membrane was used as a biofilter to prevent bacterial and algal contamination of the nutrient solution. We determined the rates of diffusion of nitrogen and phosphorus ions across the Matlock Periphytometer's dialysis membrane and glass fiber filter over a 21-day period (42 and 22 tg/cm2/hr, respectively). We used the Matlock Periphytometer to determine the limiting nutrient in a woodland stream. Six replicates each of a control, nitrogen, and phosphorus treatment were placed in the stream for 14 days. The results indicated that phosphorus was the limiting nutrient in the stream for the period and location sampled. (KEY TERMS: aquatic ecosystems; nutrient limitation; periphyton; nitrogen, phosphorus.)
Journal of the North American Benthological Society, 2009
Many streams and rivers in the Pacific Northwest of the US are inherently oligotrophic, and primary production in these ecosystems is assumed to be nutrient-limited. In many of these streams, reductions in the amount of marine-derived nutrients delivered by spawning salmonids could be exacerbating the degree of oligotrophication. To test whether primary producers are nutrient-limited, nutrient diffusing substrate (NDS) experiments were used to measure algal responses to amendments of N, P, and a combination of N and P (N+P) in 13 Salmon River basin streams in central Idaho, USA. Thirtyeight experiments were conducted between 2003 and 2006 to determine whether nutrient limitation varied among streams and over time within individual streams. Primary producers in most streams showed some form of nutrient limitation. Thirty-nine percent of our experiments suggested N and P colimitation, 18% suggested N limitation, 11% suggested primary N and secondary P limitation, and 32% did not indicate limitation by either N or P. The type of nutrient limitation within individual streams varied with time, and the relative importance of N or P changed seasonally or annually in 7 of the 13 streams. Algal accrual rates on control and treatment substrates were most strongly predicted by water temperature, light, and ambient concentrations of N and P. Among all of the experiments, algal accrual rates were greater on N substrates in streams with lower ambient N concentrations and greater ambient P concentrations. Our results suggest that a combination of N and P typically limits primary producers in these streams. Our efforts to characterize current nutrient limitation in these streams will be of value to managers considering nutrient additions as a tool to improve stream productivity to benefit threatened and endangered salmonids.
Development and application of a nutrient-diffusing bioassay for large rivers
Freshwater Biology, 1997
1. Laboratory and field experiments were performed to develop and then apply a nutrient-diffusing substratum (NDS) design suitable for use in large, fast-flowing rivers. 2. Initial laboratory experiments quantified diffusion of PO 4 and NO 3 from new and previously used clay pots, which were soaked in deionized distilled water. Mean release rates initially exceeded 2.4 and 725 µmol l -1 day -1 P and 0.22 and 18 µmol l -1 day -1 N from new and used pots, respectively, but declined rapidly with increasing time spent in deionized distilled water and were below detectable levels after about 18 and 29 days, respectively. 3. A phosphorus (P) dose-response experiment in a P-limited reach of the Athabasca River, Alberta, Canada showed that epilithic biomass and macroinvertebrate density on NDS increased with increasing concentrations of KH 2 PO 4 up to about 0.5 M. Beyond this threshold, biomasses and densities were unaffected by initial KH 2 PO 4 concentration. Coefficients of variation of epilithic biomass estimates declined with increasing KH 2 PO 4 whereas invertebrate density appeared to be unaffected by KH 2 PO 4 levels. 4. Release rates of both P and N from NDS filled with 0.5 M KH 2 PO 4 or 0.5 M NaNO 3 declined at a log-negative rate from about 5000 µmol N-NO 3 l -1 day -1 and 3500 µmol P-PO 4 l -1 day -1 on day 2, to 200 µmol l -1 day -1 for both N and P on day 32. 5. After development, we used the diffusing substrata to identify spatial patterns in nutrient limitation at seven sites along a 120 km reach in the Athabasca River, that receives two known point-source nutrient inputs. NDS consisting of N, P, N ϩ P and unenriched controls were attached to the river bottom for 22-23 days and then retrieved and sampled for epilithic chlorophyll a. Physicochemical parameters and epilithic biomasses on upper stone surfaces were also quantified when NDS were deployed and retrieved from each site. 6. Sites located immediately downstream of the two point source inputs had higher water column concentrations of PO 4 and epilithic biomasses than the site immediately upstream; epilithic biomass was positively related to PO 4 in the late autumn (r 2 ϭ 0.58) but not in early autumn. Sites located immediately below nutrient inputs were not nutrient-limited, whereas upstream reference sites were P-limited.
In situ nitrogen enrichment experiments in two Idaho (U.S.A.) streams
Environmental Monitoring and Assessment, 1984
We conducted a series of in situ experimental nutrient additions in two Idaho streams: Deep Creek, a desert stream located in Southeastern Idaho, and Big Wood River, situated in a mountainous region of Central Idaho. In both streams, a homogeneous reach was partitioned into almost identical channels. This allowed us to vary nutrient levels and measure algal response in experiments uncomplicated by differences in other factors.
Method of evaluating nutrient loads through the atmosphere onto lakes
Desalination, 2008
The amounts of atmospheric depositions were measured by two types of bulk deposit-samplers (BDS). One of them was a commonly used dry-type BDS mounted with a conical polyethylene (PE) funnel on a PE-reservoir (d-BDS). The second BDS was a wet-type BDS which was devised to evaluate the nutrient loads deposited directly from the atmosphere onto lakes, and mounted with a cylindrical funnel filled with 0.005-M H 2 SO 4 at 5 cm in depth (w-BDS). The water sample in the reservoirs was collected after an appropriate time interval. As the funnel sizes of d-BDSs decreased from 20 to 9 cm in diameter, the trapping efficiencies of TN and TP increased, as measurement accuracies decreased. The efficiencies measured by w-BDSs were not affected by the funnel size in the tested range from 20 to 43 cm. Based on the data continuously measured by d-BDS 20 and w-BDS 20 mounted each with a 20 cm funnel for one year, the atmospheric deposition of TN and TP measured by d-BDS 20 were 18.1 and 0.745 kg ha −1 y −1 , which were apparently smaller than 20.7 and 0.921 kg ha −1 y −1 measured by w-BDS 20 . It is recommended from the results that the direct nutrient-loads from atmosphere into lakes should be evaluated on the base of the more reliable unit loads measured by a w-BDS mounted with a funnel larger than around 30 cm in diameter.
Inland Waters, 2013
The purpose of this study was to experimentally evaluate the effects of nutrient ratios and nutrient concentration (NC) on periphyton biomass using water from 4 Irish streams. Stream water nitrogen to phosphorus (N:P) ratios were manipulated (high >50, medium 15–30, low <10) and crossed with 3 different NCs over a 2-week period. Algal biomass as chlorophyll a (Chl-a) showed variable response to the treatments compared to the control in 3 streams and no response to the treatments in the forth stream. The 3 streams showed significant interaction between N:P ratio and NC. Periphyton response to the NC treatments and N:P ratio was varied; 2 streams had a significant response to both NC treatments and N:P ratios. In these 2 streams Chl-a was positively correlated to dissolved inorganic N but not to soluble reactive P, indicating N limitations despite the high N:P ratio from the ambient stream water. The third stream showed a significant response to NC and was again co-limited by N ...
Influence of transient storage on stream nutrient uptake based on substrata manipulation
Aquatic Sciences, 2011
Quantification of the transient storage zone (A s ) has become critical in stream biogeochemical studies addressed to examine factors controlling nutrient uptake. It is expected that higher A s may enhance the interaction between nutrients and biota and thus, increase nutrient uptake. However, results from the literature are controversial. We hypothesized that besides of the size of A s , the intrinsic physical and biological characteristics of stream structures that generate A s are also relevant for nutrient uptake. We performed 24 additions of phosphate, ammonium, and chloride in 4 reaches of a manmade channel where we introduced 3 types of naturally-colonized substrata packs (mud, sand and cobbles) to modify A s . We estimated ammonium and phosphate uptake coefficients in both the main channel and A s using a solute transport model (OTIS-P) and compared the results among reaches with different substrata types. The introduction of substrata packs decreased water velocity and increased A s similarly among treatments. Nutrient uptake coefficients in the main channel were similar among reaches with different type substrata packs; however, nutrient uptake coefficients measured in A s differed among them as well as the ratio between ammonium and phosphorus uptake coefficients in A s , which were 1.6 in reaches with mud packs and 0.02 in reaches with sand or cobble packs. Results obtained in this study suggest that the contribution of A s in nutrient uptake not only depends on the size of A s but on the type of materials used to increase A s , and thus, have biogeochemical implications on restoration projects aimed to modify channel morphology.