Abstract: We present an analysis of extensive nutrient data sets from two river-dominated coastal ecosystems, the northern Adriatic Sea and the northern Gulf of Mexico, demonstrating significant changes in surface nutrient ratios over a period of 30 years. The silicon:nitrogen ratios have decreased, indicating increased potential for silicon limitation. The nitrogen:phosphorus and the silicon:phosphorus ratios have also changed substantially, and the coastal nutrient structures have become more balanced and potentially less limiting for phytoplankton growth. It is likely that net phytoplankton productivity increased under these conditions and was accompanied by increasing bottom water hypoxia and major changes in community species composition. These findings support the hypothesis that increasing coastal eutrophication to date may be associated with stoichiometric nutrient balance, due to increasing potential for silicon limitation and decreasing potential for nitrogen and phosphorus limitation. On a worldwide basis, coastal ecosystems adjacent to rivers influenced by anthropogenic nutrient loads may experience similar alterations.

Abstract: Publisher Summary The chapter discusses the more common classification as well as functions of macro- and micronutrients, with typical examples of the various functions of macronutrients. The importance of the reduction and assimilation of nitrate for plant life is similar to that of the reduction and assimilation of carbon dioxide (CO2) in photosynthesis. Nitrate reductase is an enzyme that is regulated by several different modes exerted at different levels—namely, enzyme synthesis, degradation, and reversible inactivation, as well as regulation of effectors and the concentration of substrate. In addition to its function in inducing synthesis of nitrate reductase, nitrate, together with light, might act as a “signal” altering the partitioning of photosynthetic carbon flow in leaves. With an increasing supply of nitrate, the capacity for nitrate reduction in the roots becomes a limiting factor, and an increasing proportion of the total nitrogen is translocated to the shoots in the form of nitrate. The carbon skeletons for these different amino acids are derived mainly from intermediates of photosynthesis, glycolysis, and the tricarboxylic acid cycle. The highest growth rates and plant yields are obtained by a combined supply of both ammonium and nitrate. Depending on the plant species, their development stage, and organ, the nitrogen content required for optimal growth varies between 2% and 5% of the plant dry weight. When the potassium supply is abundant “luxury consumption” of potassium often occurs, which deserves attention for its possible interference with the uptake and physiological availability of magnesium and calcium.

Abstract: Linder, S. 1995. Foliar analysis for detecting and correcting nutrient imbalances inNorway spruce. - Ecol. Bull. (Copenhagen) 44: 118-19O.Results are presented from the first seven years of a nutrient optimisation experiment rnyoung stands of Norway spruce in northem Sweden. The principal aim of the experi-ment was to eliminate water and mineral nutrients as growth-limiting factors, at thesame time as leaching to the groundwater was avoided. The approach applied was thedefininition oftarset values for the foliase concentration ofeach nutrient element. Onthe basis ofrepeatid fbliar analysis and predicted growth response the proportions andamounts ofnutrients applied were adjusted annually. Imbalances in the nutrient statusof the trees, induced by fertilisation as determined by foliage analysis, were success-fully corrected by adjustment of the amount and composition of the fertiliser mix.Accumulation, followed by depletion, of starch in needles during summer had apronounced ef'fect on nutrient concentrations, thus making evaluation of nutritionalstatus difficult. A variation in needle dry weight of up to 30% occurred during thegrowing season. The depletion of starch coincided with the onset of growth and wasboth earlier and faster in fertilised trees than in control trees. This indicates that thegrowth rate in non-treated stands was not limited by carbon, but rather by nutrientavailability. It is recommended that for diagnostic purposes, several age-classcs offoliage are sampled on a number of occasions during the season(s). If sampling isrestricted to one age-class of foliage, it is recommended that one-year-old foliage isused, to reduce between-year variation and to enable sampling throughout the season.If nutrient concentrations are assessed on samples taken during the period late spring toearly autumn, the carbohydrate content must be determined to allow values to benormalised. Nutrient imbalances can, however, be detected without correcting forcarbohydrate reserves, by calculating the ratio between elements. Experience obtainedduring the first seven seasons has indicated that the nutrient quotients relative tonitrogen, based on detailed studies of plant nutrition, have been more generally validthan the concentrations regarded as optimal for Norway spruce.S. Liruler. Dept of Ecology and Environmental Res., Sw'edish Unir. of AgriculturalSciences. P. O. Box 7072, 5-750 07 Uppsala, Sv'eden.

Abstract: Preface Introduction Algae Wetlands Algae Definition and Classification Morphology Biological Forms Structure of Algal Cells Reproduction Life Histories Ecology Evolution and Phylogeny of Algae Nutrients Nutritional Types Toxicity Photosynthesis and Respiration Primary Productivity Utilization of Algae Algae as Nuisance factors Eutrophication Algal Viruses, Pathogen Bacteria and Fungi Algal Classes-Brief Review Wetlands Definitions and Classifications of Wetlands Wetland Terminology Vegetation Wetland Soils Chemical Mass Balance of Wetlands Wetland Hydrology Macronutrients Carbon Nitrogen Phosphorus Sulfur Potassium Magnesium Micronutrients Calcium Iron Manganese Zinc Copper Molybdenum Sodium Cobalt Boron Silicon Vanadium Halogens Selenium Other Elements Arsenic Cadmium Chromium Lead Mercury Nickel Appendix A. Standing crop, productivity, element uptake rates and element standing stocks of aquatic and wetland plants B. List of algal genera mentioned in the book References Subject Index

Abstract: summary In most natural ecosystems a significant portion of carbon fixed through photosynthesis is allocated to the production and maintenance of fine roots, the ephemeral portion of the root system that absorbs growth-limiting moisture and nutrients. In turn, senescence of fine roots can be the greatest source of C input to forest soils. Consequently, important questions in ecology entail the extent to which increasing atmospheric CO2 may alter the allocation of carbon to, and demography of, fine roots. Using microvideo and image analysis technology, we demonstrate that elevated atmospheric CO2 increases the rates of both fine root production and mortality. Rates of root mortality also increased substantially as soil nitrogen availability increased, regardless of CO2 concentration. Nitrogen greatly influenced the proportional allocation of carbon to leaves vs. fine roots. The amount of available nitrogen in the soil appears to be the most important factor regulating fine root demography in Populus trees.

Abstract: This study examines the impacts of woody, N2-fixing invasive Acacia spp. on the patterns of nutrient cycling in two invaded ecosystems of differing nutrient status in the Cape floristic region. Patterns of soil nutrient mineralization were measured by a field incubation method while the significance of the fixation process in altering nutrient cycling was assessed by the δ15N natural abundance technique. The results confirm earlier reports that invasion by woody shrubs results in organic matter and nutrient enrichment of surface soils of both ecosystems. However, patterns of nutrient availability (phosphorus and nitrogen) were not necessarily enhanced. In the more fertile strandveld both phosphorus and nitrogen (significant at P<0.10) showed trends towards enhanced annual mineralization rates upon invasion, while in the low nutrient fynbos system only phosphorus followed this trend. It is unclear whether this differential response is a consequence of plant- or soil-derived feedbacks on the decomposition processes in each system. The δ15N values of the soils from the invaded sites of both ecosystems indicated a strong influence of the alien species on the soil nitrogen component. However, as with other studies of natural ecosystems, the contribution of nitrogen from fixation could not be readily quantified with the δ15N natural abundance method because of problems in selecting suitable non-N2-fixing reference plants. A technique of disrupting nodule structure and function, by fumigation with O2, to obtain the δ15N value of a non-N2-fixing speciment of the study species was tried and found to overcome some of the problems associated with the lack of suitable reference plants. With this technique it was possible to detect the almost total dependence of A. saligna on N2-fixation in the fynbos soils with their low nitrogen mineralization rates. In the strandveld ecosystem with much higher soil nitrogen release rates A. cyclops was only partly dependent on fixation (about half) for its nitrogen. The nutrient enrichment of both ecosystems and trends towards enhanced rates of nutrient mineralization could have profound implications on the long-term success of alien invader clearing operations and the restoration of the indigenous flora at these sites.

Abstract: ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhytoremediation of Organic and Nutrient ContaminantsJERALD L. SCHNOOR, LOUIS A. LICHT, STEVEN C. McCUTCHEON, N. LEE WOLFE, and LAURA H. CARREIRACite this: Environ. Sci. Technol. 1995, 29, 7, 318A–323APublication Date (Print):July 1, 1995Publication History Published online30 May 2012Published inissue 1 July 1995https://pubs.acs.org/doi/10.1021/es00007a747https://doi.org/10.1021/es00007a747research-articleACS PublicationsRequest reuse permissionsArticle Views1575Altmetric-Citations604LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Abstract: Publisher Summary The chapter summarizes the role of micronutrients followed by their deficiencies and toxicities. The section on iron covers chloroplast development and photosynthesis, localization and binding state of iron, and root responses to iron deficiency and iron toxicity. The section on manganese covers manganese-containing enzymes, manganese-dependent or activated enzymes, photosynthesis and oxygen (O2) evolution, proteins, carbohydrates, lipids, and cell division. Copper covers copper proteins, carbohydrates, lipid and nitrogen metabolism, lignification, pollen formation, and fertilization. The section on zinc covers zinc-containing enzymes, zinc-activated enzymes, protein synthesis, carbohydrate metabolism, tryptophan and indoleacetic acid synthesis, membrane integrity, zinc-binding forms, and bioavailability. Nickel covers nickel-containing enzymes, role of nickel in nitrogen metabolism, and nickel content in plants. The enzymes covered under molybdenum are nitrate reductase, nitrogenase, xanthine oxidase/dehydrogenase, and sulfite reductase. The section also documents gross metabolic changes of molybdenum. Boron covers boron complexes with organic structures, root elongation and nucleic acid metabolism, cell wall synthesis, phenol metabolism, auxin (IAA) and tissue differentiation, membrane function, pollen germination and pollen tube growth, carbohydrate, and protein metabolism. The section on chlorine discusses photosynthetic O2 evolution, tonoplast proton-pumping ATPase, stomatal regulation, chlorine supply and plant growth, and chlorine supply and osmoregulation. The chapter also includes a summary on the mechanism of (heavy) metal tolerance in higher plants and the various mechanisms into which they can be grouped.

Abstract: 1. Increased nutrient loading to wetlands often results in an increase in emergent plant biomass and a decrease in species diversity. While these patterns are broadly predictable, the underlying mechanisms are unknown. We tested two related hypotheses by growing plants under standardized conditions: (1) emergent plants typical of infertile wetlands have higher tissue nutrient contents than plants from fertile wetlands and (2) plants belonging to different functional groups (ruderal, interstitial and matrix) have different tissue nutrient contents. 2. Concentrations of N and P in above-ground phytomass were measured for 41 plant species, from contrasting kinds of wetlands, after one season of growth in excess fertilizer (NPK in ratios 7:11:27 and 15:0:0). Tissue nutrient concentrations ranged from 0.25 to 2.14% dry weight for N and from 0.13 to 1.07% dry weight for P. 3. There was no significant difference in nutrient content between plants from infertile sites and plants from fertile sites. However, plants with «ruderal» life history traits (e.g. annual or functional annual/fast-growing) had significantly lower N and P tissue concentrations than plants having «interstitial» or «matrix» life-history traits. Interstitial perennials had significantly higher N concentrations than matrix perennials. Therefore, plant functional groups are likely to respond differently to eutrophication. 4. Plant size, estimated by maximum species biomass, explained 67% (r 2 =0.67, P<0.001, n=31) of the variation in N tissue concentrations but only 5% of the variation in P tissue concentrations

Abstract: Although cadmium is known to be very toxic, it exhibits nutrientlike vertical concentration profiles in the open ocean. Recent work has shown that under conditions of zinc limitation, cadmium enhances the growth of the marine diatom Thalassiosira weissflogii. Here, we conclusively demonstrate that Cd is a nutrient for T. weissflogii at inorganic Zn and Cd concentrations typical of surface seawater, although Cd cannot completely replace Zn. Over a wide range of external Cd and Zn concentrations, Cd uptake kinetics are regulated and the intracellular Cd quotas are maintained at relatively constant levels. The same low level of inorganic Cd that enhances the growth rate of Zn-limited cells restores the activity of carbonic anhydrase (CA), thought to be the key enzyme limiting growth of T. weissflogii at low Zn. Cd also coelutes with some of the isoforms of CA, indicating that Cd substitution in CA is likely partly responsible for the nutritional role of Cd. The substitution of Cd for Zn in CA links the geochemical cycle of Cd to those of Zn and C.

Abstract: About 60 MT y−1 of P from agricultural runoff have flowed into an area of the northern Everglades marshes of Florida since the late 1960s, creating a nutrient enrichment gradient. The objectives of this study were to determine (i) in what forms the added and native P have been stored over the past 3

Abstract: Field levels of soil microbial biomass C and N, determined by the chloroform fumigation-extraction method, showed no marked seasonal pattern in limed and unlimed gaps and the surrounding beech stand; average contents were 530, 532 and 674 kg microbial C ha −1 ; and 65, 68 and 87 kg microbial N ha −1 respectively. Liming increased microbial biomass in the stand but had no influence on the size of the microbial pool in the gap. The decrease in microbial biomass in gaps was attributed to a decline of ectomycorrhizal hyphae. Due to the absence of available carbon soil microbial biomass was not a significant nutrient sink following forest disturbance. In situ N mineralization at these sites could not be explained by fluctuations in microbial N. Laboratory measurements of CO 2 evolution from soil samples, which were in good agreement with field CO 2 measurements, indicated a decline in easily decomposable soil organic matter during the growing season. High metabolic quotients (μg CO 2 -C mg C mic −1 d −1 ) of the microflora in gaps indicated inefficient energy use

Abstract: Nutrient-use efficiency is conceived as the product of uptake efficiency, i.e., the ratio of actual uptake to potential supply, and utilization efficiency, i.e., the ratio of yield to actual uptake. Both depend on the availability of the nutrient in relation to other growth factors, and require N, P and K perfectly in balance to reach their maximum values. Hence, the cause of a low recovery of fertilizer nutrients may be wastage due to unbalanced supplies of nutrients, apart from fixation in the soil or loss from the soil. The ratios of the supplies of N, P and K for nutritional balance were established and used for the calculation of ‘nutrient supply equivalent’, defined as the supply of a nutrient that has the same effect on yield as a supply of 1 kg N. A triangular diagram is proposed with supply equivalents of N, P and K along the sides. At each point in the diagram, the sum of supply equivalents is 100%, and maximum nutrient efficiency is found in the centre. In the field, the influence of other growth factors on nutrient-use efficiency usually consisted of a direct effect on nutrient utilization efficiency, and an indirect effect on nutrient uptake efficiency. The latter was partly driven by utilization efficiency. Sunny weather and soil biological activity acted positively in this way, and soil acidification and moisture stress negatively.

Abstract: Which nutrients limit primary production in coastal marine environments? Using large (13 000 1) mesocosms with sediments we explored nutrient limitation in Narragansett Bay, Rhode Island, USA, over a 9 wk period. Separate and combined additions of phosphorus and nitrogen were made to the enclosures. Phytoplankton biomass, daytime whole system oxygen production and nighttime whole system respiration showed an approximately 5-fold increase in nitrogen and nitrogen + phosphorus treatments, whereas phosphorus treatments had somewhat lower phytoplankton biomass and metabolism than controls. In these whole system experiments nitrogen was the nutrient most limiting to primary production.

Abstract: Physical, chemical, biochemical and microbial properties of riparian soils beneath native scmb (Leptospermum scoparium), grazed pasture, and set-aside pasture along the edge of a third order stream near Taupo, New Zealand were compared. In the 12 years since retirement from grazing, dominant vegetation in the set-aside areas changed from pasture grasses to native tussock (Poa cita). Riparian set-aside soils had an extremely high hydraulic conductivity in the surface horizon (6340 mm h -L) compared with that in the riparian grazed pasture ( 15 mm h-1) indicating that surface runoff water transported into the zone would infiltrate, fill soil pores and emerge as subsurface flow at the stream edge. Phosphorus available for transport was highest in riparian set-aside soils, indicating P saturation of the zone. Nitrate pool size was strongly correlated to nitrifying potential ( Spearman' s p = 0.897), with both being extremely low in riparian set-aside. Microbial biomass was greater in riparian set-aside ( 1900 mg C g- 1 ) than riparian native ( 1460 mg C g- t ) or riparian pasture ( 1080 mg C g- ~ ). The results imply that riparian set-aside has led to the development of a zone likely to supply runoff to the adjacent stream that is depleted in sediment-bound nutrients and dissolved N but enriched in dissolved P.

Abstract: In streams, aquatic hyphomycetes degrade leaf litter and transform it into a more suitable resource for invertebrate detritivores. Previous studies have demonstrated that fungi comprise a major portion of the microbial biomass associated with decomposing leaves and that inputs of leaves in the autumn reduce the concentration of soluble phosphorus in the water. These observations indicate that fungi obtain inorganic nutrients from the water passing over leaf surfaces. However, very little is known concerning the effects of nutrients on the activity of the fungi growing within leaves. To examine this question, I determined fungal biomass (from ergosterol concentrations) and sporulation rates during the breakdown of yellow poplar (Liriodendron tulipifera) leaves in three streams that differed in water chemistry. I also estimated instantaneous growth rates by measuring rates of [14C]acetate incorporation into ergosterol and calculated fungal productivity from growth rates and biomass. Growth rates and product...

Abstract: As an even-aged stand develops growth is concentrated first on leaves and fine roots, as a result nutrient accumulation is very rapid. During this early stage there is a distinct species effect whereas later nutrient uptake becomes a function of growth rate irrespective of species. Once canopy is closed up to two thirds of the nutrients required for growth can be obtained by retranslocation from older or dying tissues, an efficient conservation mechanism that leads to a reduction in the demands that are further reduced by the cycle through the litter layer. In consequence nutritional problems are most likely in the early years while the green crown is being constructed. Later in the rotation problems are unlikely unless nutrient cycles are disturbed, for example by thinning or as a result of excessive accumulation of humus. The eventual clear felling is a major disruption to nutrient cycles. Accelerated litter decomposition can lead to leaching losses, although this can be short lived, and burning if practised can have a major impact on poor sites. Nutrient loss in material removed from the felling site, whether or not harvested, is not high but is much increased if crowns are removed, particularly for the heavily crowned species. The importance of such loss clearly varies with site but may be significant for more than just loss of nitrogen, with loss of calcium, phosphorus or even organic matter per se all being possibly causes of worry.

Abstract: In a sustainable forestry recirculation of nutrients through the application of ashes from forest residues can be an essential way to guarantee healthy and vital forests. Wood ashes can also be regarded as a measure against soil acidification. Wood ashes were applied at various rates to the soil in a 35 years old pine (Pinus sylvestris, L) stand at Ringamala in Blekinge, South Sweden. The experiments started in 1984. The different treatments gave a clear effect on soil chemistry with decreased acidity and aluminum ion concentrations. The base saturation increased in both mor and upper mineral soil layers. Generally no significant increases were found in soil concentrations of heavy metals, except for Cu which increased significantly in the mor layer. Also the extractable Mn concentration increased, in spite of the increased pH in the soil after application of ashes. In order to achieve a biological circulation of nutrients through ash application without polluting the environment, it is of ultimate importance that the wood chips used in power plants and other furnaces have a low concentration of heavy metals and other pollutants.

Abstract: We examined the 10-day response of soil microbial biomass-N to additions of carbon (dextrose) and nitrogen (NH4NO3) to water-amended soils in a factorial experiment in four plant communities of the Chihuahuan desert of New Mexico (U.S.A.). In each site, microbial biomass-N and soil carbohydrates increased and extractable soil N decreased in response to watering alone. Fertilization with N increased microbial biomass-N in grassland soils; whereas, fertilization with C increased microbial biomass-N and decreased extractable N and P in all communities dominated by shrubs, which have invaded large areas of grassland in the Chihuahuan desert during the last 100 years. Our results support the hypothesis that the control of soil microbial biomass shifts from N to C when the ratio of C to N decreases during desertification.

Abstract: We compared the flux of energy and nutrients in a mineral forest soil in which paper birch ( Betula papyrifera ) seedlings had grown with soils that had been exposed to one of five other tree species over a 22 week growing period. Soil basal respiration rate, metabolic quotient, soil available C ( AC ), and the affinity of soil microoganisms for substrate-C left in the soil after harvest all increased significantly, in soils treated with birch root systems. Concentrations of AC in birch-treated soils related to the energy-only limited microbial biomass (MB E ), but not the nutritionally limited microbial biomass (MB N ). Amounts of rhizosphere activity, described as root-supported MB E per unit root and per unit fine root, were one order of magnitude higher in the birch rhizosphere. Plant uptake of soil-N during the growing period was high while the soil mineral-N pool was low in birch experimental units relative to those of other species, suggesting that birch competed well against soil microorganisms for available mineral-N. Anaerobic N mineralization rates were significantly higher while the MB N -to-MB E ratio, which describes the degree of nutritional limitation of the microbial biomass, was significantly lower in birch-treated soils. Significant negative correlations were found between the MB N -to-MB E ratio and both AC and MB E . These results suggest that high amounts of root labile C compounds in conjunction with rapid mineral-N uptake by birch roots can stimulate microbial communities to acquire nutrients from the native soil.

Abstract: In previous experiments systematic differences have been found in the morphology, carbon economy and chemical composition of seedlings of inherently fast- and slow-growing plant species, grown at a non-limiting nutrient supply. In the present experiment it was investigated whether these differences persist when plants are grown at suboptimal nutrient supply rates. To this end, plants of the inherently fast-growing Holcus lanatus L. and the inherently slow-growing Deschampsia flexuosa (L.) Trin. were grown in sand at two levels of nitrate supply. Growth, photosynthesis, respiration and carbon and nitrogen content were studied over a period of 4 to 7 weeks.

Abstract: Since the studies by Liebig (1856), it is well known that plants, as long as they are adequately supplied with light and mineral nutrients, can live in the absence of the organic and inorganic structural components of the soil. Nowadays the use of hydroponics is popular not only among plant physiologists but also in certain commercial activities.

Abstract: The chapter describes the mineral nutrition and yield response and tries to analyze the processes that primarily affect the source site. In crop species where storage organs such as fruits, seeds, and tubers represent yield, the effects of mineral nutrient supply on yield response curves often reflect sink limitations imposed either by a deficiency or an excessive supply of mineral nutrients during certain critical periods of plant development, including flower induction, pollination, and tuber initiation. These effects can be either direct (as in the case of nutrient deficiency) or indirect (for example, effects on the levels of photosynthates or phytohormones). In root and tuber crops, unlike grain crops, the sink–source relationship is quite labile even after the onset of the storage process. This has to be considered, for example, in the application of nitrogen fertilizer to potato. In principle, each of the mineral nutrients can become the dominant factor inducing source limitation on the final yield of seeds, fruits, and tubers, provided that it can be readily retranslocated from the source. The examples given in the chapter illustrate the role of mineral nutrients as yield-limiting factors when fruits, seeds, or other organs are the dominant sink sites and the mineral nutrient uptake by the roots is declining.