Excess Organic Matter Research Articles

The influences of various anthropogenic sources of deterioration on meiobenthos (Ostracoda) over the last 100 years in Suo-Nada in the Seto Inland Sea, southwest Japan

This study focuses on the relationships of water and sediment quality with meiobenthos (Ostracoda) over the past 100years, using a sediment core obtained from Suo-Nada in the Seto Inland Sea, Japan. We compared high-resolution ostracode results with geochemical and sedimentological data obtained from the study core as well as with rich environmental monitoring data that are available. R-mode cluster analysis revealed two bioassociations (BC, KA). Until the1960s, assemblages continued to show high diversity. They changed in approximately 1970, when excessive nutrients and organic matter began to be supplied, and most species decreased in number. All species of bioassociation BC were dominant again by the mid-1990s; however, those of bioassociation KA containing infaunal species did not increase and have been absent or rare since the 1970s because organic pollution of sediments has continued to date. This study provided robust baseline for ostracode-based long-term environmental monitoring in East Asia.

Soil Organic Matter Accumulation in Creeping Bentgrass Greens: A Chronosequence with Implications for Management and Carbon Sequestration

Excessive organic matter (OM) accumulation in creeping bentgrass (Agrostis palustris Huds.) putting greens, and its restriction of permeability, is one of the most difficult problems in turfgrass management. In this transition zone study, we characterized temporal and spatial aspects of OM accumulation, in an attempt to assess the effectiveness of management and to begin to uncover the processes controlling C sequestration. Root zone samples were collected from sand‐based putting greens at 49 golf courses of various ages, generating 212 individual observations. Organic matter accumulated hyperbolically over time in the top 2.5 cm; apparent critical levels of 40 g kg−1 were exceeded within 5 yr. At a depth of 2.5 to 7.6 cm, accumulation was much slower and linear over time, and critical levels were not reached even after 20 yr. Oxygen levels were never depressed more than 15%, indicating that intensive management of the upper soil profile was successfully allowing gas exchange into the root zone. Carbon accumulated in the soil profile hyperbolically, reflecting changes in the large OM pool near the soil surface. The sequestration rate of 59 g m−2 yr−1 over 25 yr was less than that observed by others examining soil under bentgrass greens in different environments. The evidence indicates that OM and C accumulation are strongly influenced by increasing microbial degradation rates as turfgrass systems age.

Carbon cycling in a zero-discharge mariculture system

Interest in mariculture systems will rise in the near future due to the decreased ability of the ocean to supply the increasing demand for seafood. We present a trace study using stable carbon and nitrogen isotopes and chemical profiles of a zero-discharge mariculture system stocked with the gilthead seabream ( Sparus aurata). Water quality maintenance in the system is based on two biofiltration steps. Firstly, an aerobic treatment step comprising a trickling filter in which ammonia is oxidized to nitrate. Secondly, an anaerobic step comprised of a digestion basin and a fluidized bed reactor where excess organic matter and nitrate are removed. Dissolved inorganic carbon and alkalinity values were higher in the anaerobic loop than in the aerobic loop, in agreement with the main biological processes taking place in the two treatment steps. The δ 13C of the dissolved inorganic carbon (δ 13C DIC) was depleted in 13C in the anaerobic loop as compared to the aerobic loop by 2.5–3‰. This is in agreement with the higher dissolved inorganic carbon concentrations in the anaerobic loop and the low water retention time and the chemolithotrophic activity of the aerobic loop. The δ 13C and δ 15N of organic matter in the mariculture system indicated that fish fed solely on feed pellets. Compared to feed pellets and particulate organic matter, the sludge in the digestion basin was enriched in 15N while δ 13C was not significantly different. This latter finding points to an intensive microbial degradation of the organic matter taking place in the anaerobic treatment step of the system.

Core sampling test in large-scale compost cells for microorganism isolation

Composting is a process by which organic wastes are transformed into fertilizer, preventing excess organic matter accumulation. Microbes that carry out this transformation have application in biotechnology. Composting cell assembling is a complex process, it can reach several m3 of diverse materials. It is desirable a sampling methodology that allows the microbial analysis, however, this matter has not yet been approached by other researchers. In this work we tested soil auger to probe large-scale compost piles at the Sao Paulo Zoo, in Sao Paulo, Brazil. The criterion for auger selection was percentage loss of material and microbe isolation from samples. Key words: Core sampling, compost, microorganism isolation, auger.

<strong>Polychaete fauna in the vicinity of bluefin tuna sea-cages in Ensenada, Baja California, Mexico</strong>

This paper describes the polychaete fauna in Salsipuedes Bay, Baja California. Sea-cage farming results in a rain of organic matter onto the underlying benthos. There is growing concern over the effects of tuna sea-cages on the local sediment chemistry and benthic communities. Eighteen stations were sampled with a Van Veen grab (0.1 m2) from the oceanographic vessel Francisco de Ulloa in March 2003 and October 2004. Redox potential in 2003 ranged between ‑113 and ‑200 mV, while in 2004 it ranged between ‑110 and ‑302 mV. Organic carbon concentrations varied between 0.20% and 2.53 %, lowest values were located in the southern part of the bay; highest concentrations were found at stations 18–22 situated in the northern section, west of the tuna pens. Organic N varied between 0.02% and0.12%, highest concentrations (0.07–0.12%) were located at stations 16–21 in the northern section of the bay; stations situated at the south and near the coast presented the lowest N concentrations (0.02–0.04%). A total of 9,291 organisms belonging to seven phyla were collected: Polychaeta, Mollusca, Crustacea, Echinodermata, Cnidaria, Sipuncula, and Bryozoa. Polychaetes accounted for 62% of all invertebrate macrofauna, with 5,765 specimens representing 34 families and 146 species. The best represented families in 2003 and 2004 were Paraonidae, Cirratulidae, Spionidae, Capitellidae, Syllidae, Nephtyidae, Lumbrineridae, and Glyceridae. Polychaetes were dominant at almost all sampling stations. Families with the highest species richness were Paraonidae (14 spp.), Spionidae (11 spp.), Onuphidae (11 spp.), Maldanidae (10 spp.), Syllidae (9 spp.), Cirratulidae and Ampharetidae with 7 species each. Among the most abundant species were Aphelochaeta multifilis, Mediomastus ambiseta, Prionospio steenstrupi Spiophanes bombyx, Apoprionospio pygmaea, Paraonella sp., Monticellina sp., Aricidea (Allia) ramosa, Spiophanes bombyx, Spiophanes duplex, and Levinsenia gracilis. The dominant trophic group was deposit-feeders, followed by carnivores. In 2003 Shannon index varied between 2.26 and 3.40 bits/ind.; the highest diversity values were found in the southern section of Salsipuedes Bay. In 2004 diversity fluctuated between 2.31and 3.35; the highest values were found at three stations in the northern section south of the tuna pens. Stress-predictability modeling characterized 85% of stations in 2003 and 78% in 2004 as presenting favorable and stable conditions, the rest were considered moderately disturbed. Non-metric multidimensional scaling (MDS) separated stations depending on the distance to the tuna pens. Our results indicate that Salsipuedes Bay is still a favorable environment for polychaetes. Apparently local circulation has at least partially dispersed the excess organic matter.

Arsenic, iron and organic matter in sediments and groundwater in the Pannonian Basin, Hungary

In the central part of the Pannonian Basin, factors controlling the distribution of As in sediments and groundwater of the upper 500 m were studied. In core samples, the amounts of As, Fe and Mn extractable with hydroxylamine hydrochloride (NH 2OH · HCl) in 25% acetic acid, the proportion of the <0.063 mm size fraction, and the sediment organic C (C org) contents were measured. In the groundwaters concentrations of As, humic substances, and selected major chemical components were determined. In most core samples extractable Fe, as FeOOH, and C org are correlated, but some samples have excess Fe, or organic matter. In cases where either excess Fe or excess organic matter is found, the amount of As is also elevated. The spatial distribution of As in the groundwater and the lack of a consistent correlation of As with a single component indicate that there is no single factor controlling the concentration of dissolved As over the entire study area. The only consistent feature is enrichment of As relative to Fe in the groundwater, compared to the sediments. This suggests that the dissolution of Fe minerals, which primarily adsorb As, is not congruent. In reducing conditions Fe(III) oxyhydroxides together with adsorbed As dissolve, and siderite with little or no As precipitates. When sub-regions are separated and studied individually, it can be shown that hydrogeological features of the sediments, the proportions of Fe minerals and sedimentary organic matter, and the concentration of dissolved humic materials, all influence the accumulation and mobilization of As. The significance of the different mobilizing processes, however, and the mean concentration of As, is different in the recharge, through-flow and discharge areas.

Cultural eutrophication in the Choptank and Patuxent estuaries of Chesapeake Bay

The Choptank and Patuxent tributaries of Chesapeake Bay have become eutrophic over the last 50–100 years. Systematic monitoring of nutrient inputs began in ~1970, and there have been 2–5‐fold increases in nitrogen (N) and phosphorus (P) inputs during 1970–2004 due to sewage discharges, fertilizer applications, atmospheric deposition, and changes in land use. Hydrochemical modeling and land‐use yield coefficients suggest that current input rates are 4–20 times higher for N and P than under forested conditions existing 350 yr ago. Sewage is a major cause of increased nutrients in the Patuxent; agricultural inputs dominate in the Choptank. These loading increases have caused three major water‐quality problems: (1) increased nutrients, phytoplankton, and turbidity; (2) decreased submerged grasses due to higher turbidity and epiphyton shading; and (3) bottom‐water hypoxia due to respiration of excess organic matter. Oxygen in the Patuxent is consistently &lt;3 mg L−1 in bottom waters in summer, whereas oxygen in Choptank bottom waters has been decreasing for the last 20 yr and is now approaching 3 mg L−1 in wet years. The low N: P of sewage inputs to the Patuxent results in an N‐limited, P‐saturated system, whereas the Choptank is primarily limited by N, but with P limitation of phytoplankton during spring river flows. Insufficient action has been taken to improve the water and habitat quality of these estuaries, although reduced eutrophication in dry years suggests that both estuaries will respond to significant decreases in nutrients.

Small-scale burial of macroalgal detritus in marine sediments: Effects of Ulva spp. on the spatial distribution of macrofauna assemblages

Patches of dead seaweeds can deposit, bury, and age into the sediment. Decomposition and release of algal-derived nutrients can influence patterns of distribution of benthic organisms. Here, I investigated how small-scale burial of Ulva spp. affected spatial variation of macrofauna in intertidal sediment. I deliberately buried Ulva detritus under the surface of 50 × 50 cm 2 patches of sediment in three intertidal flats of the Oosterschelde estuary (The Netherlands). Results showed that there was no accumulation of particulate organic carbon and nitrogen in the sediment at the scales examined. The biomass of microphytobenthos did not show any change and there was evidence that grazing was important all over the study area. Burial did not alter composition and diversity of macrofauna, but some animals ( Corophium volutator, Eteone spp. and Scoloplos armiger) had less numbers in the plots where detritus was buried than in the controls. These findings showed that burial of macroalgal detritus does not represent a major source of variation at the scales examined. It is suggested that in these sediments, recycling of detritus is fast and it buffers the effects of excess organic matter in the system.

Relationships Between Chemical Characteristics of Sediments and Macrofaunal Communities in the Cabras Lagoon (Western Mediterranean, Italy)

The Cabras lagoon is a large and shallow transitional system which periodically suffers from dystrophic events leading to massive losses of its biological resources. Excessive organic matter (OM) and sulphur compounds in sediments are often claimed to be major environmental co-factors triggering these events. However, still limited information is available on their relationships with benthic macrofaunal communities in coastal lagoons. In order to assess these relationships, we conducted monthly field investigations between 2001 and 2002, at three regularly-spaced stations set between the inlet and the mouth of the Cabras lagoon. Results showed reduced conditions of sediments, worsening during the warm season. This was consistent with very high OM contents, up to >‰20%, with annual means of 14–16%. Organic pollution-tolerant taxa, such as Tubificidae nc, Neanthes succinea and Polydora ciliata, dominated poor macrofaunal communities. Results of multivariate analysis indicated significant differences in both environmental variables and macrofaunal community structure and species composition between stations and through different periods. This study documented for the first time in a coastal lagoon that inorganic reduced sulphur pools (acid volatile sulphide and chromium reduced sulphur) of sediments are leading (‚best-matching’) environmental factors influencing the spatial and temporal distribution of macrofaunal abundance and biomass. We conclude that impoverished macrofaunal communities in the Cabras lagoon may show a slight recovery during winter–spring, but tend to regress to an early stage of faunal succession in late summer. We suggest that the combination of excessive amounts of sedimentary organic matter and high temperatures tends to lead to anoxic conditions especially in relatively deeper and more saline waters. These events may concur to periodic increase of production rates of toxic hydrogen sulphide in sediments, which rapidly diffuses to the water column with deleterious effects both on the benthic and pelagic components of the lagoon ecosystem.

Seasonal shift in net ecosystem production in a tropical estuary

Net ecosystem production was examined in the Mandovi and Zuari estuaries (southwestern India) and the adjoining coastal waters for a period of 1 yr (January to December 1998). The study period encompassed premonsoon, monsoon, and postmonsoon seasons. At the estuarine stations, net ecosystem production showed monthly variation and a transition from net autotrophy of 49 mmol C m−2 d−1 during the nonmonsoon seasons (premonsoon and postmonsoon) to net heterotrophy of —46 mmol C m−2 d−1 in the monsoon season. Seasonal monsoon‐driven changes such as increased allochthonous inputs resulted in enhanced heterotrophic respiration and reduced primary production in the estuaries. In the coastal station, the monthly variation in net ecosystem production was not significant, and net heterotrophy was prevalent whenever measurements were made, thereby potentially serving as the net source of carbon dioxide to the atmosphere. Results suggest that the excess organic matter from these tropical estuaries supports heterotrophy in the adjacent coastal ecosystem.

Bottom Soil and Water Quality Management in Shrimp Ponds

ABSTRACT Marine shrimp farming has become an important component of aquaculture. Water and soil conditions have a great influence on the efficiency of shrimp production, and a review of water quality and bottom soil management will be provided. After a shrimp pond has been drained for harvest, organic carbon analyses can indicate if organic matter concentrations are too low (< 0.5%) or too high (> 3 or 4%). Bottoms should be dried for 2 to 3 weeks to enhance oxidation of organic matter and other reduced substances. Soil pH should be measured and agricultural limestone applied to acidic pond bottoms. In soil with excessive organic matter, nitrogen fertilizers may be applied at 200 to 400 kg/ha to enhance microbial activity. Nitrate nitrogen is especially effective as a nitrogen source for treating pond bottoms because it also is a soil oxidant. Empty pond bottoms also may be tilled to 5 to 10 cm depth with a disk harrow to encourage oxidation. Once ponds have been filled with water, chemical fertilizer containing both nitrogen and phosphorus should be used to encourage natural productivity. Applications of 2 to 4 kg/ha of N and P2O5 at 2- to 3-day intervals are usually adequate. Within 1 or 2 weeks, natural food should be abundant and postlarvae can be stocked. Fertilization with 1-2 kg N and 0.5-1 kg P2O5/ha at intervals of about 1 week should be continued for a few weeks. However, once feeding rates exceed 20 to 30 kg/ha per day, fertilization should be used cautiously because of the danger of causing excessive phytoplankton blooms. Mechanical aeration can be used to increase feeding rates and allow higher levels of shrimp production. Water exchange is widely used in shrimp farming, but water exchange often can be reduced to muchlower levels than commonly applied. Suggestions on the use of better practices to minimize possible adverse environmental effects of shrimp farming are provided.

Integrated Quantitative Stratigraphy of the Cenomanian-Turonian Bridge Creek Limestone Member Using Evolutive Harmonic Analysis and Stratigraphic Modeling

ABSTRACT Secular changes in bulk sedimentation have a significant impact on the preservation of climatic signals in rhythmically bedded strata. In this study a quantitative cyclostratigraphic methodology is developed to use these signal distortions as a means to reconstruct sedimentation. The method exploits a moving-window Fourier technique that we designate evolutive harmonic analysis (EHA). We calibrate this methodology to a specific set of geologic conditions (i.e., changes in bulk sedimentation) using a series of stratigraphic models and then apply the technique to the Cenomanian-Turonian Greenhorn Formation of the Western Interior basin. Application of EHA to strata that preserve a record of orbital forcing allows the reconstruction of a high-resolution sedimentation history in which bulk sedimentation rates and hiatuses are quantified. Using the data on bulk sedimentation rate, rates of accumulation for geochemical proxies representing detrital, biogenic, and authigenic contributions to the sediment can be calculated. By integrating these quantitative assessments of siliciclastic dilution, primary production, and depositional redox conditions within a high-resolution chronostratigraphic framework, we are able to deconvolve secular trends in hemipelagic sedimentation during the Late Cenomanian-Early Turonian in the Western Interior basin. This integrated quantitative stratigraphic approach allows a reevaluation of hypotheses for the accumulation of excess organic matter in the Western Interior basin during the interval representing Oceanic Anoxic Event II.

Overview of hypoxia around the world.

No other environmental variable of such ecological importance to estuarine and coastal marine ecosystems around the world has changed so drastically, in such a short period of time, as dissolved oxygen. While hypoxic and anoxic environments have existed through geological time, their occurrence in shallow coastal and estuarine areas appears to be increasing, most likely accelerated by human activities. Several large systems, with historical data, that never reported hypoxia at the turn of the 19th century (e.g., Kattegat, the sea between Sweden and Denmark) now experience severe seasonal hypoxia. Synthesis of literature pertaining to benthic hypoxia and anoxia revealed that the oxygen budgets of many major coastal ecosystems have been adversely affected mainly through the process of eutrophication (the production of excess organic matter). It appears that many ecosystems that are now severely stressed by hypoxia may be near or at a threshold of change or collapse (loss of fisheries, loss of biodiversity, alteration of food webs).

A Small Misconception

Regarding “Carbon sink: A clue from Biosphere 2?” (R. L. Walford, Science 's Compass, 15 Jan. p. [330][1]), I want to clear up a small misconception that has been widely repeated in the press (and also in the Perspective by J. E. Cohen and D. Tilman, 15 Nov. 1996, p. [1150][2]), namely that “carbon dioxide [CO2] was combining with the cement of the structure, carrying oxygen along with it to form calcium carbonate… hence the fall in oxygen concentration.” The cement in Biosphere 2 did not cause the oxygen loss. It is true that the CO2 reacted with the cement and that CO2 contains oxygen atoms. But it is molecular oxygen (O2) rather than oxygen atoms that was being lost from the air in Biosphere 2. The amount of oxygen atoms present in the water in Biosphere 2 is about 200 times more than the amount of oxygen atoms present as O2, so the loss of oxygen atoms to the cement was insignificant. Rather, what caused the O2 loss was the excess of organic matter in the soil, which supported an imbalance of O2-consuming respiration over O2-producing photosynthesis. The reaction of CO2 with the cement only made it a little harder for us to find the true cause of O2 loss, by scrubbing from the air the telltale product of respiration, CO2. Walford correctly points out that concrete absorbs CO2, but he does not point out that the Ca(OH)2 responsible for this uptake was obtained by driving CO2 off of limestone. Because some of the CaO2 becomes silicate-bound and some remains unreacted, concrete manufacture is a net source rather than a net sink for CO2. Further, the contribution of concrete manufacture to global CO2 production is only about 0.2 gigaton of carbon (GiC), compared with 6.5 or so GiC produced by fossil fuel burning and to a continental sink of about 1.7 GiC (S. Fan et al. , Reports, 16 Oct. p. [442][3]). Hence, even if limestone were slaked at one region and the concrete were used in another, the impact on the distribution of CO2 in the global atmosphere would be negligible. [1]: /lookup/doi/10.1126/science.283.5400.327g [2]: /lookup/doi/10.1126/science.283.5405.1150 [3]: /lookup/doi/10.1126/science.282.5388.442

Effects of fish farming on seagrass ( Posidonia oceanica) in a Mediterranean bay: seagrass decline after organic loading cessation

The effects of fish farming on a seagrass ( Posidonia oceanica) meadow at Fornells Bay, Minorca (Balearic Islands) were studied. Changes in plant and meadow features (e.g. shoot morphology, shoot density, biomass, rhizome growth, nutrient and soluble sugars concentrations…) in three stations along a transect from a disturbed (organic pollution due to fish cultures) to an undisturbed site were assessed. The fish culture had ceased in 1991; however, seagrass decline, already reported in a previous study for the period 1988–1990, was still taking place at the time of sampling (July 1994). Differences between stations were very clear; the station closest to the fish cages showed reduced shoot density, shoot size, underground biomass, sucrose concentration and photosynthetic capacities. In contrast, shoots from the most polluted station showed higher P-concentration in tissues and higher epiphyte biomass than the other two. Since water conditions had recovered completely by the time of the sampling mission, it is proposed that the persistence of the seagrass decline was due to the excess organic matter remaining in the sediment.

Ten Years of Artificial Mixing and Oxygenation: No Effect on the Internal Phosphorus Loading of Two Eutrophic Lakes

Hypolimnetic aeration was used in conjunction with reductions in phosphorus (P) inputs in order to lower the P concentrations in two eutrophic lakes. Based on more than 10 years of experience with artificial mixing and hypolimnetic oxygenation we conclude that the lakes' internal P cycling was not affected by increased hypolimnetic dissolved oxygen (D.O.) concentrations. We show that irrespective of oxic conditions in the hypolimnion the sediment/water interface remained anoxic due to unchanged high sedimentation rates of organic matter. This may explain why oxygenation did not increase the P retention capacity of the sediment. However, the presented information indicates that, contrary to general assumption, anoxic sediment surface and high P release rates from lake sediments may not be cause-effect related but simply two parallel symptoms of one common cause: excessive organic matter and P sedimentation exhausting the stock of hypolimnetic D.O. and exceeding the P retention capacity of the sediment after diagenesis. Therefore, it is not surprising that fighting one symptom (an anoxic hypolimnion and sediment surface) does not solve the other one (a high P release rate). These findings and considerations based on more than 10 years of experimental experience warrant a reevaluation of the well accepted theoretical management strategy of limiting lake internal P cycling by maintaining an aerobic hypolimnion and sediment surface.

Development of a New Laboratory Freshwater/sediment Microcosm Test

A new laboratory freshwater/sediment microcosm test is proposed. This 2-L microcosm includes synthetic water, sediment composed of quartz sand, cellulose and fish food flakes (TetraMin®), pelagic organisms (microalgae, duckweeds, cladocerans) and benthic organisms (amphipods, chironomids). We conducted four experiments to determine conditions suitable for the development of organisms for a 4-week duration. The sensitivity of the system was then studied with a copper-spiked sediment. A TetraMin® dose of 0.4 g for 260 g sediment was found optimal to allow growth and emergence of chironomid larvae without bacterial contamination due to excess organic matter. The test with copper sulfate led to a range of effects. For concentrations higher than 10 ppm, systems were severely impaired (growth inhibition of algae and duckweeds >50%, 100% mortality within a few days for cladocerans, mortality >45% within 15 days for amphipods, 80% mortality within 15 days and no emergence for chironomids). At 10 ppm, a shift of the algal peak was observed, duckweed growth was reduced by 39%, partial mortality but no reduced reproduction was found for Daphnia magna whereas Simocephalus vetulus survived only after reinoculation on day 10. Amphipods also survived but were smaller. For chironomids, partial mortality was observed as soon as day 22 and emergence was inhibited by 50% but growth was not affected.

Culture technology of marine rotifers and the implications for intensive culture of marine fish in Japan

In order to expand the practice of rearing marine finfish larvae, it is necessary to increase and stabilize the production of live feed. Latest researches on rotifer culture technology in Japan have aimed at these objectives. This paper summarizes the progress on the technology of high-density rotifer mass cultures. The high-density culture of the marine rotifer Brachionus rotundiformis (so-called S-type) enables production that is at least 100 times more efficient than that by the conventional method, with less cost for production. The technology is based on the use of highly concentrated algal biomass as food for rotifers. Rotifers are mass-cultured at 10000-30000 individuals mL-1 by feeding them exclusively on condensed freshwater Chlorella. Cultures are generally supplied with constant O2; pH is adjusted to 7 by addition of HCI to avoid an increase of free ammonia in the culture system. The excess suspended organic matter can be efficiently removed by a nylon filtration mat.

A concept of Gleyization and its role in the pedogenesis

Three simple factors ‐ excessive moistening, anaerobic microflora and organic matter, are indispensable and sufficient conditions for gley formation. This process is always characterised by a non‐silicate iron loss from the soil fine earth or soil plasma. Gley formation takes place under conditions of stagnant or stagnant‐percolative water regimes. In the second case gley formation induces a drastic acidification of the mineral soil part, lessivage, removal of iron, aluminium, calcium, magnesium, bleaching of the soil fine earth, and it appears the features of soil with eluvial, acid, bleached horizons. Therefore soils with such horizons should be regarded as manifestations of gley formation in conditions stagnant ‐percolative water regime on acid, neutral or leached parent material. Under influence of stagnant water regimes Fe of mineral substrat is removed and unconsiderable eluviation of Ca and Mg takes place. pH of parent material does not change or has the trend to increase. In this case does not arise a soil with bleached horizons.

Regression statistics as a tool to evaluate excess (anthropogenic) phosphorus, nitrogen, and organic matter in classification of Swedish fresh water quality

Concentrations of phophorus, nitrogen, CODMn, and humic matter in streams from small protected Swedish watersheds have been used to build statistical models useful in the evaluation of the state of the water quality. The precision of the models has been tested on data sets from other SEPA (Swedish Environmental Protection Agency) reference programs as well as international data sets. The models refer to watersheds, where most of the samples have a pH above 5.0. For the nutrients two delimitations have been defined. The lowest delimitation,the most likely upper limit for pristine concentration, corresponds to the models estimate minus 1 standard error. The highest delimitation,the most likely upper limit for none or insignificant influence, corresponds to twice the lowest delimitation, which also can be considered as a management concentration [c m]. The calulated export coefficients for phosphorus agree with coefficients reported in the literature. The export coefficients for nitrogen seems to be dependent on the atmospheric deposition of nitrogen. A nutrient pollution index (NPI) has been calibrated against existing trophic state classification systems. The NPI for phosphorus show a considerable decrease in southern Sweden since the inroduction of chemical treatment plants. The nirogen conditions have not been improved to the same extent.