Northwest Stream Research Articles

One stream or two - exploring Andromeda’s North West stream

Abstract We present results of our dynamical stream modelling for the North West Stream in the outer halo of the Andromeda galaxy (M31). Comprising two main segments, the North West Stream was thought to be a single structured arching around M31. However, recent evidence suggests that it is two separate, unrelated, streams. To test this hypothesis we use observational data from 6 fields associated with the upper segment of the North West Stream together with 8 fields and 5 globular clusters associated with the lower segment to constrain model orbits. We fit both segments of the stream using a fixed potential model for M31 and an orbit integrator to compare orbits with the observed streams. We measure the central tracks and predict proper motions for for the upper segment (lower segment) finding ${\mu ^*_{\alpha }}$ = 0.078$^{+0.015}_{-0.012}$ (0.085$^{+0.001}_{-0.002}$) mas/yr and μδ = $-0.05^{+0.008}_{-0.009}$ ($-0.095^{+0.003}_{-0.005}$) mas/yr. Our results support the hypothesis that the dwarf spheroidal galaxy Andromeda XXVII is the progenitor of the upper segment of the North West Stream and that the upper and lower segments do not comprise a single structure. We propose that the upper segment, which appears to be on an infall trajectory with M31, be renamed the “Andromeda XXVII Stream” and the lower segment, also apparently infalling towards M31, retain the name “North West Stream”.

Differential Response of Nutrients to Seasonal Hydrological Changes and a Rain Event in a Subtropical Watershed, Southeast China

A large amount of terrestrial nutrients are discharged into the ocean through rivers. However, the impact of seasonal hydrological variations on riverine nutrient concentrations and fluxes remains unclear, especially in the medium-sized subtropical rivers that are highly influenced by human activities. In this study, we investigated the monthly changes in nutrient concentrations (soluble reactive phosphorus, SRP; dissolved silicate, DSi; and dissolved inorganic nitrogen, DIN) in the North Stream (NS) and West Stream (WS) of the Jiulong River (JLR). The results show that the concentrations of SRP and DSi in the NS and the WS displayed a similar seasonal variability, which was different from the pattern of DIN. Hydrological conditions, chemical fertilizer loss and biogeochemical processes are responsible for the seasonal changes in the nutrients in the two streams, especially during extreme rain events. Nutrient concentrations in the NS exhibited a clockwise trajectory along with river discharge during rain events, while a reverse pattern in the WS was observed since it experienced a moderately long rain event. Different rainfall features between the two main tributaries resulted in the majority of nutrients being exported at the start of the rain event in the NS and the end of rain event in the WS. Indeed, the annual high flow (Q/Qm > 3) accounts for ~17.3% of the annual nutrient flux in the JLR even though this period spans only ~4.0% of a year, which suggests the importance of rain events on nutrient export in these subtropical rivers. Although the annual fluxes of DIN and SRP in the JLR were smaller than many rivers worldwide, higher areal yields of DIN and SRP were observed, indicating that the JLR is highly influenced by human activities. Our study systematically evaluated the response of nutrient concentrations to hydrological changes in two tributaries of the JLR, which is useful in better understanding the nutrient dynamics in medium-sized subtropical rivers.

Diurnal Wind Pattern and Climate Condition on the Coastal Region of Qatar

Climate pattern in the Persian Gulf is of great interest due to the strategic geographical location of the gulf as a waterway of major oil transportation and its increasing regional economic importance. However, long term and continues climate observations in this region are rare, especially for high resolution data. High resolution wind pattern and climate conditions were measured at 3 heights on a 9 m tower on the shoreline north of Qatar (26.08 N, 51.36 E) from August 2015 to September 2016. In this work, the annual wind and climate patterns (wind velocity, temperature, relative humidity, and air pressure) are first presented. Drag coefficient, turbulent kinetic energy and sensible heat flux are calculated using the high speed measured data to explain the observed climate pattern. The results show the wind in the southern part of the gulf is dominant by a northwest stream with a diurnal average speed of 4.7 m/s. During the test year, the diurnal average temperature and relative humidity were 27°C and 70%, respectively. The drag coefficient is much higher for the wind from 270o-330o, corresponding to the wind coming mainly from northwest. The Turbulent Kinetic Energy (TKE) is strong during the daytime, especially around noon when the diurnal value is at its peak, and weak during the night. The result of this analysis may be used for better understanding of the local climate, allowing for further assessment of wind energy and pollution diffusion in the region.

Assessment of the Coastal Marchica Watershed through Ecotoxicological Indices of Trace Elements in Superficial Sediments

This study analyses the seasonal distribution in the superficial sediments of the Marchica watershed of trace and major elements, grain size, and total organic carbon. Samples were taken during the wet and dry seasons of 2018 in the mainstream valleys carrying the discharges to the Marchica Lagoon. Ecotoxicological indices (Enrichment Factor, Contamination Factor, Pollution-Load Index) and sedimen-quality guidelines were used to evaluate the ecotoxicological risk. The results revealed during both wet and dry seasons contamination by lead in all stream valleys. The northwest stream valley, characterized by some industrial activities, and the stream valley crossing the abandoned mine were the most polluted by zinc and copper. Minimal pollution for Cr, Co, and Ba was found during both the wet and dry seasons. Despite the restoration actions achieved around the Ramsar site of Marchica lagoon during the last decades, the watershed continues to have a negative impact on this ecosystem. Therefore, an environmental management strategy isnecessary, taking into account the rehabilitation of the abandoned mining sites, the rational use of pesticides and fertilizers in agriculture, and the environmental responsibility of industrial companies, especially those installed before the implementation of the national law on environmental impact studies.

A dwarf disrupting – Andromeda XXVII and the North West Stream

ABSTRACT We present a kinematic and spectroscopic analysis of 38 red giant branch stars, in seven fields, spanning the dwarf spheroidal galaxy Andromeda XXVII and the upper segment of the North West Stream. Both features are located in the outer halo of the Andromeda galaxy at a projected radius of 50–80 kpc, with the stream extending for ∼3° on the sky. Our data are obtained as part of the PAndAS survey and enables us to confirm that Andromeda XXVII’s heliocentric distance is 827 ± 47 kpc and spectroscopic metallicity is $-2.1^{+0.4}_{-0.5}$. We also re-derive Andromeda XXVII’s kinematic properties, measuring a systemic velocity = $-526.1^{+10.0}_{-11.0}$ km s−1 and a velocity dispersion that we find to be non-Gaussian but for which we derive a formal value of 27.0$^{+2.2}_{-3.9}$ km s−1. In the upper segment of the North West Stream we measure mean values for the metallicity = −1.8 ± 0.4, systemic velocity = −519.4 ± 4.0 km s−1, and velocity dispersion = 10.0 ± 4.0 km s−1. We also detect a velocity gradient of 1.7 ± 0.3 km s−1 kpc−1 on an infall trajectory towards M31. With a similar gradient, acting in the same direction, in the lower segment we suggest that the North West Stream is not a single structure. As the properties of the upper segment of the North West Stream and Andromeda XXVII are consistent within 90 per cent confidence limits, it is likely that the two are related and plausible that Andromeda XXVII is the progenitor of this stream.

신라 초기 습비부(習比部) 고라촌[高耶村]의 위치

Kora-chon near Myeonghwal Hill converted to Suppbi-bu was one of the Six Villages(六村) in the early Silla. It had been believed that some of the Six Villages were in the field area surrounded by North Stream(北川), West Stream(西川), South Stream(南川) and Myeonghwal Hill(明活山) in Gyeongju. However some researchers thought there were few inhabitants in the field area till the 5th or 6th century, for it was low swampy place which was easy to be damaged by flood. It seems true that the area was developed late, but its cause was not frequent flood but external aggression and cold northwestern seasonal wind. So we should find Kora-chon at the east side of Myeonghwal Hill. Suppi meant forest and Kora meant basin. The place name at the east side of Myeonghwal Hill whose meaning is close to forest is Seopdeul[薪坪] meaning forest field and close to basin is ‘Gorae’ meaning subsided ground. Seopdel is correspond to Suppi(習比) and Gorae to Kora(高耶). At last we can believe Kora-chon was located in the subsided ground at the foot of Myeonghwal Hill. The suitable place to assigned to Kora-chon is Cheongun Village (千軍). It is most fertile, cozy and safe place around Myeonghwal Hill.

Large Wood and Instream Habitat for Juvenile Coho Salmon and Larval Lampreys in a Pacific Northwest Stream

AbstractThe influences of large wood on Pacific salmon are well‐studied, but such studies on nonsalmonid species such as lampreys are uncommon. To address this need, we evaluated the potential effects of large wood on larval lampreys (Pacific Lamprey Entosphenus tridentatus and potentially Western Brook Lamprey Lampetra richardsoni) as well as on juvenile Coho Salmon Oncorhynchus kisutch in a small, coastal, Oregon stream. Our objectives were to (1) identify instream habitat characteristics associated with the presence of larval lampreys and abundance of juvenile Coho Salmon and (2) evaluate how these characteristics were associated with instream wood. To address habitat use, we quantified presence of larval lampreys in 92 pools and abundance of juvenile Coho Salmon in 44 pools during summer low flows. We focused on a study reach where large wood was introduced into the stream between 2008 and 2009. Results indicated that presence of larval lampreys was significantly associated with the availability of fine sediment and deeper substrate. The abundance of juvenile Coho Salmon (fish per pool) was strongly associated with pool surface area and to a weaker extent with the proportion of cobble and boulder substrates in pools. Pools with wood, regardless of whether they were formed by wood, had significantly greater coverage of fine sediment, deeper substrate, and greater pool surface area. Taken together, these results suggest that instream wood can provide habitat associated with the presence of larval lampreys and greater abundance of juvenile Coho Salmon.Received September 11, 2016; accepted March 25, 2017 Published online May 31, 2017

Rapid ecosystem response to restoration in an urban stream

Stream restoration seeks to re-establish ecological structure and function of river systems, and understanding its ecological consequences is a current focus of stream ecology. To characterize the short-term ecosystem response to restoration in an urbanized Pacific Northwest stream, we measured whole-system ammonium and phosphorus uptake, benthic and drifting aquatic insects, and fish community composition before and after restoration. We predicted that (1) nutrient demand would temporarily decrease ammonium and phosphorus concentrations, (2) periphyton accrual would structure the insect consumer response, and (3) restoration would change the fish community. After restoration, nutrient demand for ammonium and phosphorus temporarily increased to levels that have rarely been reported, but demand for both recovered to background levels within 35 days. Aquatic insect density tracked rapid periphyton accrual after restoration, and benthic insect density stabilized in less than a month whereas composition continued changing for 10 weeks. Within 11 months, the fish community returned to its pre-restoration composition dominated by non-native eastern brook trout (Salvelinus fontinalis). Restoration did not alter the community and ecosystem metrics we studied, but this urban stream underwent rapid succession during restoration-induced disturbance, perhaps because urban streams have resilient communities well-suited to rapid recovery.

景德镇市异常高温的分析与预报

本文统计分析了景德镇市1953~2013年异常高温的气候特点及天气形势、本站要素等特点，提出了预报指标，归纳了天气学概念模型。主要结论如下：1) 38℃以上高温天气平均每年有3.3天，最多28天，有23年未出现38℃以上的高温天气，占总数的37.7%。大约9~10年内会有一个较为炎热的年份。异常高温绝大部分均出现在7~9月，40℃以上高温天气非常稀少，每8年才会出现1次。2) 异常高温常连续出现，连续2天出现的共有45个过程，年均0.74个；连续3天出现的共有26个过程，年均0.43个；大致每10年会有一次连续5天或以上持续38℃或以上的高温天气过程。3) 造成景德镇市异常高温的天气形势绝大部分是在强大的副热带高压控制下发生的，其余可分为台风西北侧型、台风西侧型、台风北侧型和西北气流型等4种形势。4) 建立的概念模型显示，河套以南的我国东部地区为强盛的副热带高压控制，850 hPa在长江下游至入海口和湖北北部地区有24℃或以上的暖中心，景德镇位于暖中心以南的22℃等温线附近。850 hPaTd > 16℃线位于江西东部与浙江、福建的交界处，在江西北部~浙江大部500 hPa有T-Td > 20℃的干舌，干舌位于低层暖中心东南部，景德镇位于高层干舌与低层露点高值区的交界处。 In this article, climate characteristic and weather pattern have been analyzed, and synoptic model is also induced. Main conclusions are as following: 1) An average level of 38˚C or above is 3.3 days per year and tops at 28. Totally, there are 23 years that abnormal high temperature days have never shown up, making up 37.7% of all the 61 years. A hot year occurs almost once every 9 to 10 years and most high temperature appears between July and September. 40˚C-above days are very rare, which happens once every 8 years. 2) Abnormal high temperature days are always consecu-tive. There are totally 45 processes of 2 consecutive hot days and 26 processes of 3 consecutive hot days, making up average days of 0.74 and 0.43 per year. Once every 10 years, there would be a 38˚C-above process lasting 5 days or more. 3) The weather pattern that induces abnormal high temperature usually shows as under the control of a strong subtropical anticyclone, while the rest could be divided as the north-west typhoon pattern, west typhoon pattern, north typhoon pattern and north-west stream pattern. 4) The synoptic model shows the areas of east China at the south of Hetao are controlled by strong subtropical anticyclone and there exists a warm center of 24˚C or above at the lower Yangtze River and north Hubei province on 850 hPa while Jingdezhen locates at 22˚C isotherm in the south of the center. Td > 16˚C area locates at the east Jiangxi and the border of Zhejiang and Fujian on 850 hPa while on 500hPa exists a dry tongue of T-Td > 20˚C at the north of Jiangxi and Zhejiang. This dry tongue locates at the southeast part of the low level warm center and Jingdezhen is right on the border of the dry tongue in the high level and the high Td area in the low level.

KINEMATICS OF OUTER HALO GLOBULAR CLUSTERS IN M31

We present the first kinematic analysis of the far outer halo globular cluster (GC) population in the Local Group galaxy M31. Our sample contains 53 objects with projected radii of ~20-130 kpc, of which 44 have no previous spectroscopic information. GCs with projected radii >30 kpc are found to exhibit net rotation around the minor axis of M31, in the same sense as the inner GCs, albeit with a smaller amplitude of 79 +/-19 km/s. The rotation-corrected velocity dispersion of the full halo GC sample is 106 +/-12 km/s, which we observe to decrease with increasing projected radius. We find compelling evidence for kinematic-coherence amongst GCs which project on top of halo substructure, including a clear signature of infall for GCs lying along the North-West stream. Using the tracer mass estimator, we estimate the dynamical mass of M31 within 200 kpc to be M_M31 = (1.2-1.5) +/- 0.2 x 10^12 M_sun. This value is highly dependent on the chosen model and assumptions within.

Low thermal tolerances of stream amphibians in the Pacific Northwest: Implications for riparian and forest management

Temperature has a profound effect on survival and ecology of amphibians. In the Pacific Northwest, timber harvest is known to increase peak stream temperatures to 24 ◦ C or higher, which has potential to negatively impact cold-water stream amphibians. I determined the Critical Thermal Maxima (CTmax) for two salamanders that are endemic to the Pacific Northwest. Rhyacotriton variegatus larvae acclimated at 10 ◦ C had mean CTmax of 26.7 ± 0. 7S D ◦ C and adults acclimated at 11 ◦ C had mean CTmax of 27.9 ± 1.1 ◦ C. These were among the lowest known values for any amphibian. Values were significantly higher for larval Dicamptodon tenebrosus acclimated at 14 ◦ C ( ¯ x = 29.1 ± 0.2 ◦ C). Although the smallest R. variegatus had some of the lowest values, size of larvae and adults did not influence CTmax in this species. Current forest practices retain riparian buffers along larger fish-bearing streams; however, such buffers along smaller headwaters and non-fish bearing streams may provide favorable habitat conditions for coldwater-associated species in the Pacific Northwest. The current study lends further evidence to the need for protection of Northwest stream amphibians from environmental perturbations. Forest guidelines that include riparian buffer zones and configurations of upland stands should be developed, while monitoring amphibian responses to determine their success.

Residual Gasoline in a Turbulent Pacific Northwest Stream Following Release and Subsequent Ignition

ABSTRACT Approximately 5,500 barrels of unleaded gasoline escaped from a ruptured pipeline in Bellingham, Washington on June 10, 1999. The majority of the product entered Whatcom Creek, with a flow of approximately 0.3 m3/s (10 cfs). The gasoline affected approximately 4.8 km (3 miles) of the creek. After a period of approximately 4 hours, the product contacted an ignition source. Twenty hours following the incident, a water-sampling program at 8 stations in Whatcom Creek and 12 stations in Bellingham Bay was implemented. Ultimately, nearly 400 water-column samples were analyzed for gasoline range hydrocarbons (GRHs), including BTEX compounds and MTBE. Samples were collected every 4 hours for the first 5 days, daily for the next 17 days, and 16 of the following 32 days. Initial maximum concentrations found in water samples were 20,800 ug/L GRH, 2,600 ug/L total xylenes, 1,300 ug/l toluene, 340 ug/L ethylbenzene, 110 ug/L benzene, and 6.9 ug/L MTBE. Product concentrations in the stream declined rapidly. Within 140 hours of the incident, GRHs subsided two orders of magnitude. Instream waters met State of Washington Groundwater Cleanup Standards (Washington Administrative Code, Chapter 173–340.) in an average of 131 hours from the time of the release for benzene, 127 hours for ethylbenzene, 66 hours for toluene, and 207 hours for xylene. Volatilization of BTEX during transport downstream was evidenced by a consistent gradient of reduced concentrations with distance from the source. Sediment pore water and bulk sediments were also sampled. Initial pore-water GRH ranged widely from nondetect to 110,000 ug/L. GRH in bulk sediment samples ranged from nondetect to 447,000 ug/L. A remediation program was conducted to release product trapped in the streambed that reduced contaminants to levels deemed acceptable by a risk-based approach for survival of salmonid fry populations. This approach and resultant guidelines are described.

Gasdynamics in the LINER Galaxy NGC 5005: Episodic Fueling of a Nuclear Disk

We report high-resolution CO(1¨0) observations in the central 6 kpc (1@) of the LINER galaxy NGC 5005 with the Owens Valley Radio Observatory millimeter array. Molecular gas is distributed in three componentsa ring at a radius of about 3 kpc, a strong central condensation, and a stream to the northwest of the nucleus but inside the 3 kpc ring. The ring shows systematic noncircular motions, with apparent inward velocities of D50 km s~1 on the minor axis. The central condensation is a disk of D1 kpc radius with a central depression of D50 pc radius. This disk has a molecular gas mass of D2 ) 109 it shows a steep velocity gradient and a velocity range (D750 km s~1) 30% larger than the velocity M _ ; width of the rest of the galaxy. The stream between the 3 kpc ring and the nuclear disk lies on a straight dust lane seen in the optical. If this material moves in the plane of the galaxy, it lies at a radius of D1 kpc but has a velocity oUset by up to D150 km s~1 from galactic rotation. We suggest that an optically inconspicuous stellar bar lying within the 3 kpc ring can explain the observed gasdynamics. This bar is expected to connect the nuclear disk and the ring along the position angle of the northwest stream. A position-velocity cut in this direction reveals features that match the characteristic motions of gas in a barred potential. Our model indicates that gas in the northwest stream is on an orbit at the bars x 1 leading edge; it is falling into the nucleus with a large noncircular velocity and will eventually contribute D2 ) 108 to the nuclear disk. If most of this material merges with the disk on its —rst passage of M _ pericenter, the gas accretion rate during the collision will be D50 yr~1. We associate the disk with M _ an inner 2:1 Lindblad resonance and attribute its large line width to favorably oriented elliptical orbits rather than (necessarily) to a large central mass. The 3 kpc ring is likely an inner 4:1 Lindblad resonance ringor a pair of tightly wound spiral armsarising at the bar ends. Both scenarios can explain the apparent noncircular motions in the ring. The high rate of bar-driven in—ow and the irregular appear- ance of the northwest stream suggest that a major fueling event is in progress in NGC 5005. Such epi- sodic (rather than continuous) gas supply can regulate the triggering of starburst and accretion activity in galactic nuclei. Subject headings: galaxies: activegalaxies: ISMgalaxies: kinematics and dynamics ¨ galaxies: spiralgalaxies: starburst

Nitrogen Dynamics in Stream Wood Samples Incubated with [ 14 C]Lignocellulose and Potassium [ 15 N]Nitrate

Surface wood samples obtained from a Douglas fir log (Pseudotsuga menziesii) in a Pacific Northwest stream were incubated in vitro with [C]lignocellulose in a defined mineral salts medium supplemented with 10 mg of N liter of N-labeled NO(3) (50 atom% N). Evolution of CO(2), distribution and isotopic dilution of N, filtrate N concentrations, and the rates of denitrification, N(2) fixation, and respiration were measured at 6, 12, and 18 days of incubation. The organic N content of the lignocellulose-wood sample mixture had increased from 132 mug of N to a maximum of 231 mug of N per treatment after 6 days of incubation. Rates of [C]lignocellulose decomposition were greatest during the first 6 days and then began to decline over the remaining 12 days. Total CO(2) evolution was also highest at day 6 and declined steadily over the remaining duration of the incubation. Filtrate NH(4)-N increased from background levels to a final value of 57 mug of N per treatment. Filtrate NO(3) N completely disappeared by day 6, and organic N showed a slight decline between days 12 and 18. The majority of the N that could be recovered appeared in the particulate organic fraction by day 6 (41 mug of N), and the filtrate NH(4) N fraction contained 11 mug of N by day 18. The N enrichment values of the filtrate NH(4) and the inorganic N associated with the particulate fraction had increased to approximately 20 atom% N by 18 days of incubation, whereas the particulate organic fraction reached its highest enrichment by day 6. Measurements of N(2) fixation and denitrification indicated an insignificant gain or loss of N from the experimental system by these processes. The data show that woody debris in stream ecosystems might function as a rapid and efficient sink for exogenous N, resulting in stimulation of wood decomposition and subsequent activation of other N cycling processes.

Impact of Nitrogen and Phosphorus on [ 14 C]Lignocellulose Decomposition by Stream Wood Microflora

Nutritional and physical factors affecting the decomposition of [C]lignocellulose prepared from Douglas fir (Pseudotsuga menziesii) were examined by incubating the labeled substrate with homogenized surface wood scrapings obtained from a Douglas fir log in a Pacific Northwest stream. Incubations were conducted in distilled water, in stream water collected from four different sources, or in a defined mineral salts solution with or without supplemental N (KNO(3)). Decomposition rates of [C]lignocellulose, as measured by CO(2) evolution, were greater in each of the four filter-sterilized sources of stream water than in distilled water alone. Decomposition experiments conducted in stream water media with the addition of defined mineral salts demonstrated that [C]cellulose decomposition was stimulated 50% by the addition of either KNO(3) or KH(2)PO(4)/K(2)HPO(4) and further enhanced (167%) by a combination of both. In contrast, [C]lignin decomposition was stimulated (65%) only by the addition of both N and P. Decomposition of [C]lignocellulose was greatest when supplemental KNO(3) was supplied in concentrations of at least 10.0 mg of N liter but not increased further by higher concentrations. The decomposition of [C]lignocellulose increased as the incubation temperature was raised and NO(3)-N supplementation further increased these rates between three-and sevenfold over the range of temperatures examined (5 to 22 degrees C). Accumulation of NH(4) (2 to 4 mg of N liter) was always observed in culture filtrates of incubations which had been supplemented with KNO(3), the quantity being independent of NO(3) concentrations >/= 10 mg of N liter. The role of supplemental NO(3) in the decomposition of [C]lignocellulose is discussed in relation to wood decomposition and the low concentrations of N found in stream ecosystems of the Pacific Northwest.

Microbial Decomposition of Wood in Streams: Distribution of Microflora and Factors Affecting [ 14 C]Lignocellulose Mineralization

The distribution and lignocellulolytic activity of the microbial community was determined on a large log of Douglas fir (Pseudotsuga menziesii) in a Pacific Northwest stream. Scanning electron microscopy, plate counts, and degradation of [C]lignocelluloses prepared from Douglas fir and incubated with samples of wood taken from the surface and within the log revealed that most of the microbial colonization and lignocellulose-degrading activity occurred on the surface. Labeled lignocellulose and surface wood samples were incubated in vitro with nutrient supplements to determine potential limiting factors of [C]lignocellulose degradation. Incubations carried out in a nitrogenless mineral salts and trace elements solution were no more favorable to degradation than those carried out in distilled water alone. Incubations supplemented with either (NH(4))(2)SO(4) or organic nitrogen sources showed large increases in the rates of mineralization over incubations with mineral salts and trace elements alone, with the greatest effect being observed from an addition of (NH(4))(2)SO(4). Subsequent incubations with (NH(4))(2)SO(4), KNO(3), and NH(4)NO(3) revealed that KNO(3) was the most favorable for lignin degradation, whereas all three supplements were equally favorable for cellulose degradation. Supplementation with glucose repressed both lignin and cellulose mineralization. The results reported in this study indicate that nitrogen limitation of wood decomposition may exist in streams of the Pacific Northwest. The radiotracer technique was shown to be a sensitive and useful tool for assessing relative patterns of lignocellulose decay and microbial activity in wood, along with the importance of thoroughly characterizing the experimental system before its general acceptance.