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1.
Kathryn M. Irvine Alix I. Gitelman Jennifer A. Hoeting 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(4):450-469
In a spatial regression context, scientists are often interested in a physical interpretation of components of the parametric
covariance function. For example, spatial covariance parameter estimates in ecological settings have been interpreted to describe
spatial heterogeneity or “patchiness” in a landscape that cannot be explained by measured covariates. In this article, we
investigate the influence of the strength of spatial dependence on maximum likelihood (ML) and restricted maximum likelihood
(REML) estimates of covariance parameters in an exponential-with-nugget model, and we also examine these influences under
different sampling designs—specifically, lattice designs and more realistic random and cluster designs—at differing intensities
of sampling (n=144 and 361). We find that neither ML nor REML estimates perform well when the range parameter and/or the nugget-to-sill
ratio is large—ML tends to underestimate the autocorrelation function and REML produces highly variable estimates of the autocorrelation
function. The best estimates of both the covariance parameters and the autocorrelation function come under the cluster sampling
design and large sample sizes. As a motivating example, we consider a spatial model for stream sulfate concentration. 相似文献
2.
The water-stability of soil and coprolite aggregates in soddy-podzolic soils and the participation of fungi in the formation
of water-stable aggregates from earthworm (Aporrectodea caliginosa) coprolites were assessed. The water stability of the soil and coprolite aggregates in the soils increased in the following
sequence: potato field—mown meadow—mixed forest. The fungal mycelium reserves increased in the same sequence. The water stability
of the coprolite aggregates of Aporrectodea caliginosa inhabiting these soils is 2–2.5 times higher than that of the soil aggregates of the same size (3–5 mm). The inhibition of
the growth of fungi by cycloheximide decreased the water stability of the coprolite aggregates, on the average, by 15–20%. 相似文献
3.
The impact of storm water runoff on a small urban stream 总被引:2,自引:0,他引:2
Vilmantė Karlavičienė Sigita Švedienė Danutė Elena Marčiulionienė Peter Randerson Mindaugas Rimeika William Hogland 《Journal of Soils and Sediments》2009,9(1):6-12
Background, aim, and scope In urban areas, storm water runoff often transports various pollutants, some of which settle and form sediments. In order
to have the comprehensive view of the ecological state of storm water runoff recipients, both water and sediments of the stream
must be assessed. In the Baltic Sea Area, the Water Framework Directive & HELCOM Recommendations aim to prevent or minimise
pollution caused by harmful substances arising from storm water runoff, in order to promote the ecological restoration of
the Baltic Sea—one of the most vulnerable seas. The aim of the study was to investigate the toxicity of bottom sediments of
a small storm water runoff recipient focusing on the potential impact of successive discharges of urban storm water. Some
storm water runoff quality parameters and the toxicity of bottom sediments of recipients was studied in this research.
Materials and methods During 9 years, at four discharge points, minimum four grab samples per year at each discharge point were taken for chemical
characterisation. General parameters (pH, SS, BOD7, CODCr and TPH) in liquid phase samples were analysed according to standard methods. Annual limit values were taken from the Lithuanian
EPA requirements for the management of storm water runoff with a focus on prevention and control of contamination. Eleven
composite samples of stream bottom sediments, each consisting of ten sub-samples, were collected in 2006. Toxicity screening
from sediments was performed using the plant Lepidium sativum according to modified I. Magone’s methodology (Magone I, Bioindication of phytotoxicity of transport emission. In: Kachalova
O-L, Zinatne (eds) Bioindication of toxicity of transport emissions in the impact of highway emissions on natural environment. Riga, pp 108–116, 1989). The level of toxic impact of Lepidium sativum (compared to control) was assessed according to the modified method of Wang (Rev Environ Contam Toxicol 126:88–127, 1992).
Results The mean pH of urban storm water runoff does not vary much from neutral, but range values are quite different, from 4.0 up
to 8.7. The highest concentration of SS reached 800 mg L−1, TPH—2.4 mg L−1, BOD7—300 mg O2 L−1 and CODCr—1,400 mg L−1. The SS was above the limit in 64% of total amount of grab samples, TPH—37%, BOD7—41% and CODCr—55%. The toxicity analysis of the bottom sediments showed varying toxicity of bottom sediments along the stream. From nine
analysed samples of bottom sediments, 30% had weak toxicity, 30% medium and 30% strong toxicity on the test organism plant
L. sativum. There was one single sample with no toxic effects, so that the results showed that urban storm water has an unacceptable
environmental impact on recipients. It was also indicated that storm water runoff discharge alone is not the potential source
of toxicity of bottom sediments. The litter demonstrated a weak toxicity of bottom sediments as well.
Discussion Most local authorities do not consider storm water runoff discharges to be a matter of great concern because they believe
that surface runoff arising from rainfall is still relatively clean. The study showed that the current method of monitoring
storm water runoff quality by chemical analyses is not the best tool for environmental impact assessment and must be combined
with toxicity tests of bottom sediments of recipients.
Recommendations and perspectives To avoid the environmental impact of storm water runoff more attention should be paid to the development and implementation
of storm water runoff pollution prevention measures. The study implies that future research concerning the relationships between
storm water runoff deposit characteristics and biological activities must be developed to evaluate the contamination potential
of stream sediment deposits for local aquatic ecosystems. Further studies should be developed to characterise the activities
of the microbial community of storm water runoff sediments, and to monitor bioremediation in situ. 相似文献
4.
Axel Dinter Mike Coulson Fred Heimbach Jürgen Keppler Wolfgang Krieg Uschi Kölzer 《Journal of Soils and Sediments》2008,8(5):333-339
Background, aim, and scope The aim of this review was to assess the degree to which recent litter bag studies performed between 2002 and 2004 have followed
the recommendations laid down in the ‘Effects of plant protection products on functional endpoints in soil (EPFES)’ guidance
document and the Organisation for Economic Co-Operation and Development (OECD) Guidance Document on the Breakdown of Organic
Matter in Litter bags (OECD, Guidance document on the breakdown of organic matter in litter bags, OECD series on testing and assessment, no 56, 36 pp, 2006), which can be required under European Union (EU) Directive 91/414/EEC (EU, Off J Eur Union, L230:1–32, 1991) for assessing the effect of plant protection products on non-target soil macro-organisms which contribute to the breakdown
of organic matter.
Materials and methods The current review covers the analysis of key parameters of the litter bag method of a total of 29 litter bag studies conducted
by six European Crop Protection Association companies.
Results The two validity criteria [i.e. 60% mass loss at the end of the study in the control and a maximum coefficient of variation
of 40% for mass loss in the control plots (n = 6) during the first 6 months of the test] were met in all of the studies reviewed. In over half of the studies, more than
60% mass loss was reached in the control litter bags after about 6 months. Statistically significant effects on organic matter
breakdown due to plant protection products were repeatedly observed during the first few months of the study conduct, including
effects >10% up to >25% compared to the control.
Discussion The survey of 29 study reports—performed from May 2002 to May 2004—showed that litter bag studies are generally being performed
following the ‘EPFES’ guidance document and the OECD guidance document no. 56. Transient, statistically significant effects
>10% up to >25% compared to the control were determined repeatedly during the first few months of the study conduct, thus
clearly indicating the sensitivity of the litter bag test system.
Conclusions and perspectives The litter bag study design is a valuable test system for the risk assessment of plant protection products on non-target soil
macro-organisms which contribute to the breakdown of organic matter under EU Directive 91/414/EEC (EU, Off J Eur Union, L230:1–32, 1991). In general, it can be concluded that the litter bag test, as proposed by EPFES and the OECD guidance document, provides
an integrative answer on the potential effects of plant protection products on organic matter breakdown in soil and can be
continued to be used if the studies follow the recommendations as presented in the guidance documents closely. 相似文献
5.
Nils Dittbrenner Hannah Schmitt Yvan Capowiez Rita Triebskorn 《Journal of Soils and Sediments》2011,11(6):1000-1010
Purpose
The use of only one or a few species—representing an entire taxon—in ecotoxicological standard tests poses risk of underestimating the impact of toxicants on the environment. In earthworm ecotoxicity tests, the species Eisenia fetida or Eisenia andrei are commonly used, and there is evidence that these species respond relatively insensitive towards environmental pollution. With the present study, we wanted to evaluate the risk of underestimating effects of the insecticide imidacloprid in soil organisms by comparing E. fetida with two other earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) regarding their sensitivities towards soil contaminated with this widely used insecticide. 相似文献6.
Fabio Gresta Giovanni Avola Emidio Albertini Lorenzo Raggi Valerio Abbate 《Genetic Resources and Crop Evolution》2010,57(4):523-531
In this paper molecular analysis, physical, technological, and chemical traits were used to estimate the level of variation
on five accessions of a locally adapted Sicilian faba bean (Vicia faba L.) landrace named ‘Larga di Leonforte’. DNA analysis was performed using the Amplified Fragment Length Polymorphism (AFLP)
molecular marker class and two other faba beans (cv. ‘Aguadulce Samba’—Spain—and landrace ‘Locale di Modica’—Sicily) were
used as controls. Although the accessions of ‘Larga di Leonforte’ varied significantly for most of the agronomical and physical
traits, this landrace generally had a heavy seed weight, short but large pods, and no more than two seeds per pod. This last
characteristic allowed for erect pod angle attitude at maturity. Idratation data showed difference among accessions in seed
weight at full hydration and in absorption rate at the very beginning of the hydration process, while any difference among
accessions emerged in terms of cooking properties. The six AFLP Eco+3/Mse+3 different primer combinations applied in this
research revealed different levels of polymorphism among the faba bean accessions and a total number of 346 amplicons were
generated. Around 60% of amplicons displayed a polymorphic pattern among different accessions. Cluster analysis on morphological,
technological, chemical and molecular data placed the all five ‘Larga di Leonforte’ accessions into a separated group, and
the Sicilian material shares a fairly large amount of similarity with respect to the cultivar ‘Aguadulce Samba’ selected in
Spain. 相似文献
7.
A. A. ShinkarevJr. I. P. Breus S. A. Neklyudov V. A. Breus 《Eurasian Soil Science》2010,43(9):993-1003
The effect of two methods for the preparation of soil samples for sorption experiments—hard (dehydration at 105°C) and mild
(drying over P2O5 at 20°C in vacuum) drying—on the values of the vaporphase sorption of p-xylene was studied depending on the content of organic matter in the soil. It was shown with dark gray forest and chernozemic
soils as examples that the hard drying of soil samples taken from the upper layer of the humus profile with a high content
(>4%) of organic carbon decreased their sorption capacity in the range of 0–5% by 7–81%. Therefore, the method is unsuitable
for these soils. It was also found that the mild method of soil preparation had obvious analytical advantages. 相似文献
8.
Goal, Scope and Background. Based on a bioassay battery covering only primary producers and consumers as well as degraders,
the potential ecological hazard of sediments to vertebrates cannot be estimated comprehensively. Therefore, there is an urgent
need to develop and standardize integrated vertebrate-based test systems for sediment investigation strategies. Whereas vertebratebased
in vitro systems have frequently been used for the investigation of aqueous samples, there is a significant lack of whole sediment
assays. Thus, the purpose of the present study was: (1) to develop a rapid and reliable, but comprehensive method to investigate
native sediments and particulate matters without preceding extraction procedures; (2) to compare the hazard potential of solid
phase sediments to the effects of corresponding pore waters and organic extracts in order to characterize the bioavailability
of the particle-bound pollutants; and (3) to relatively evaluate the embryotoxic effects of sediments from the catchment areas
of the rivers Rhine, Neckar and Danube.
Methods (or Main Features). To investigate the toxicity of sediment samples on vertebrates, the standard embryo toxicity test with the zebrafish (Danio rerio; Hamilton-Buchanan 1922) according to DIN 38415-6 was modified with respect to exposure scheme and toxicological endpoints.
Sediments from the catchment area of the Neckar River were assessed using pore waters, acetonic extracts and native sediments
in order to get inside into the potential bioavailability of particle-bound pollutants. A comprehensive test protocol for
the investigation of native sediments in the embryo toxicity test with the zebrafish is presented.
Results and Discussion. The fish embryo assay with Danio rerio can be carried out with both aqueous and organic sediment extracts as well as native (whole, solid phase) sediment samples.
Elongation of exposure time from 48 to up to 196 h significantly increased the mortality. Using the fish egg assay with native
sediments, a broad range of embryotoxic effects could be elucidated, including clear-cut dose-response curves for the embryotoxic
effects of contaminated sediments; in contrast, absence of embryotoxic effects could be demonstrated even for the highest
test concentrations of unpolluted sediments. With native sediments, embryotoxicity was clearly higher than with corresponding
pore waters, thus corroborating the view that — at least for fish eggs — the bioavailability of particle-bound lipophilic
substances in native sediments is higher than generally assumed. The relative ranking of sediment toxicity was identical using
both native sediments and sediment extracts, EC20 values of the latter, however, being eight time lower higher than with the native sediments. A comparison of the embryo toxic
effects of samples from the Neckar area with locations along the Rhine and Danube rivers elucidated a broad range of results,
thus indicating different levels of contamination.
Conclusions. A modified protocol of the zebrafish embryo test allows the assessment of sediment toxicity in both aqueous extracts and native
sediments. The isolated investigation of pore waters may result in a clear-cut underestimation of the bioavailability of lipophilic
particle-bound substances (as determined by native sediments).
Recommendations and Perspectives. The zebrafish embryo test with native (whole, solid phase) sediments appears very promising for the evaluation of the bioavailable
fraction of lipophilic particle-bound substances and can therefore be recommended for the evaluation of vertebrate toxicity
in tiered sediment test strategies and dredging directives such as the HABAB-WSV. Whereas acetone extracts may be tested as
a rough estimation of embryotoxicity, native sediment samples will provide a more comprehensive and realistic insight into
the bioavailable hazard potential 相似文献
9.
Crop movement often leads to genetic bottlenecks. The lentil was domesticated in the Eastern Mediterranean region. Dissemination
from highland Afghanistan into the Indo-Gangetic Plain, where it is of major importance today, caused a founder effect creating
a genetic bottleneck. To understand the process and assist breeders with broadening the consequent narrow genetic base, this
study re-constructs the founder effect by a re-examination of historical world germplasm evaluations at an intermediate elevation
site in Pakistan–Islamabad, and at a low elevation site—Faisalabad representative of the Indo-Gangetic Plain. At Islamabad
72% of landrace accessions of an Afghan origin did not flower and the remaining Afghan accessions were among the latest flowering
accessions in the world germplasm collection. At Faisalabad late flowering accessions produced low yields with each week’s
delay in flowering giving a yield loss of 9.2%. Prehistorically Afghan lentil germplasm probably harboured recessive alleles
for time to flower, possibly from introgression with wild lentil (Lens culinaris ssp. orientalis) in Afghanistan, which were then cyclically recombined and selected for as part of the dissemination process into the Indo-Gangetic
Plain. 相似文献
10.
S. Yu. Gryuntal’ 《Eurasian Soil Science》2009,42(11):1282-1290
In the burozems of the plains, the composition of the invertebrates and saprophages (the prevailing primary destroyers) differed
from that in the mountainous soils only by the absence of millipedes of the Geophilomorpha order. At the same time, the differences
in these characteristics between the burozems and soddypodzolic soils of the neighboring coniferous-broad-leaved forests were
more significant: in the latter, the composition of the ecological groups of earthworms was more diverse. Among the earthworms,
secondary destroyers (detritophages) consuming well-decomposed residues of plants and animals predominated: Aporrectodea caliginosa, A. rosea, and Octolasium lacteum. In the taiga burozems, among the secondary destroyers, very few O. lacteum among the earthworms, and Polyzonium germanicum among the millipede diplopods were found. Primary destroyers that only comminute plant tissues (Dendrobaena octaedra and Dendrodrilus rubidus f. tenuis) were the main representatives in the invertebrate population of these soils. The differences also concerned the group composition
and the proportion between the life forms of the earthworms. In the southern taiga burozems, only the litter (Dendrobaena octaedra and Dendrodrilus rubidus f. tenuis) earthworms and species of the upper soil layer (Octolasium lacteum) were present. In the mountainous burozems of the Transcarpathian region, litter inhabitants (Dendrobaena attemsi and Aporrectodea submontana), soil-litter inhabitants (Dendrobaena alpina—Transcarpathian region), and inhabitants of the upper (Helodrilus cernosvitovianus) and middle (Aporrectodea carpathica and A. sturanyi) soil layers (in the Primorskii region, only the soil-litter Eisenia nordenskioldi) were identified. In the soddy-podzolic soils, dwellers of the middle soil layers (Aporrectodea caliginosa, A. rosea, and Lumbricus terrestris) were constantly present along with the species dwelling in the litter and in the upper soil layers (in the litter—Dendrobaena octaedra, Dendrodrilus rubidus f. tenuis, and L. castaneus; in the litter-soil layer—L. rubellus; in the upper soil layer—Octolasium lacteum). The higher diversity of the earthworm life forms in the soddy-podzolic soils points to the stronger development of their
humus horizons as compared to those horizons in the burozems of the southern taiga and mountains. 相似文献
11.
Nikolai V. Alov Roman V. Bulgachev Kirill V. Oskolok 《Journal of Soils and Sediments》2001,1(3):164-167
X-ray fluorescence monitoring of technogenic metal pollution of Moscow soil near two highways with heavy traffic was fulfilled.
As a result of vehicles running, the macro and microelement composition of Moscow roadside soil was seen to substantially
differ from the composition of both soddy podzolic soil (typical for Moscow region) and any other soil of the temperate climatic
region of Russia. The average Fe, Mn and Ti contents in soil were found to exceed the usual background level by 2–5-fold,
maximum Pb content — by 10–15-fold. The lateral and depth distribution of enumerated metal contents in soil near the highways
was studied. It was shown that the behavior of lateral pollutant distribution in soil has no specific exponential shape. It
has local extremuma and depends on the metal nature and the roadside terrain topography. For Pb — one of the most dangerous
pollutants — the mechanism of chemical transformations and the interrelation of the pollutant chemical form, its molecular
weight, the dwelling time in atmosphere and the distance to the highway were discussed. 相似文献
12.
Background River and lake sediments constitute complex and difficult analytical samples. On the other hand, sediments play a fundamental
role in the distribution of toxic compounds in aquatic systems and in the evaluation of the current state and the course of
changes taking place in the environment.
Among elements present in the environment in trace concentrations, but having well-elaborated toxic properties, one of most
dangerous is arsenic. The element occurs in the environment in several chemical forms, predominant are inorganic forms of
As(V) and As(III), and methylated forms such as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA).
Objectives Reported herein are experiments, which were undertaken with the aim of examining the dynamics of arsenic sorption in sediments
and its dependence on speciation of the element and the pH in the environment. Simultaneously, influence of organic matter
content and chemical composition of the sediments on As sorption, were investigated.
Methods Sediment samples (upper 10 cm layer) were collected from three sites located in the vicinity of Cracow:
Using XRD and IR methods, mineral composition of sediments was analysed. Concentrations of iron, manganese, aluminium and
arsenic as well as organic matter content in solid samples were analysed.
Sorption experiment 100 g of dry sediment sample was placed in a 400 ml volume glass beaker. 300 ml of arsenic containing solution was poured
into the beaker. Every 30 min (total experiment time span equalled 7 to 7.5 hours), 0.5 ml of the suspension’ (the beaker
content was constantly mixed) was collected and centrifuged, and the concentration of arsenic was determined in the supernatant.
In the series of experiments, solution contained about 0.05 μg/ml of arsenic in organic (DMAA) and inorganic forms, at different
pH values — 3, 5, 7 and 9.
Results and Discussion Examined sediments of Vistula river and Dobczyce Lake were characterised by relatively high concentrations of arsenic, iron,
manganese and aluminium.Rudawa river. At pH 3, the concentration of inorganic As in solution decreased from an initial value of 0.049 μg/ml to 0.012 μg/ml in
7.5 hours time. The same decreasing tendency was found at pH 5 (initial value 0.046 μg/ml, after 7.5 hours - 0.015 μg/ml).
Less distinct sorption effects were noted at pH 7 and 9.
Vistula river. At all pH values, a very significant decrease of inorganic As concentration up to 80% of the initial value, as well as a
short time of achieving an equilibrium state (1 – 2.5 hours), was found.
Dobczyce lake. Inorganic As was distinctly accumulated in sediments at pH 3 (decrease of As concentration in solution from 0.052 to 0.007
μg/ml after 7.5 hours of the experiment) and at pH 5. At pH 7, about 40% of As was accumulated in sediments (solution As concentration
decrease from 0.050 to 0.030). Only 20% of As adsorbed on sediments at pH 9.Very weak accumulation of organic form of As (DMAA)
was found in all examined sediments at pH 3 and 5. At higher pH values no sorption was registered.
Conclusions The following facts were established:
Recommendations The presented method of analysis of As sorption in sediments and results visualization (based on a newly defined coefficient)
provides a useful tool for the characterization of sorptive properties of sediments and may be used for other compounds as
well. Crucial, functional information — how much of a given element may be accumulated in sediments at a certain pH — is obtained
without digestion of the sediment sample, in an experiment taking less than one day. 相似文献
• | Rudawa river — 37 km long river, flowing mainly through the suburban area; |
• | Vistula river — heavily contaminated, main Polish river; |
• | Dobczyce reservoir — artificial reservoir on Raba river, total capacity of 125,000,000 m3, supplying about 60% of drinking water to the city of Cracow. |
• | inorganic form of arsenic was effectively accumulated in all analysed sediments; |
• | inorganic As sorption in sediments strongly depended on pH — for sediments of Rudawa river and Dobczyce lake, the highest sorption was found at pH 3, and a decrease of accumulated As was noted with an increase of pH (at pH 9, the lowest amount of As was immobilised in sediments); in the case of Vistula river sediments, a reverse tendency was found; |
• | organic form of arsenic (DMAA) was accumulated only at pH 3 in all sediments and less significantly at pH 5 (Vistula river sediments); no sorption of that form of As was found in the other sediment samples; |
• | state of equilibrium (no change in inorganic As concentration in liquid medium) was achieved in 1 hour for Vistula river sediments, after about 2 hours for Rudawa river and after about 4 hours for Dobczyce lake sediments. |
13.
V. M. Kolesnikova I. O. Alyabina L. A. Vorob’eva E. N. Molchanov S. A. Shoba V. A. Rozhkov 《Eurasian Soil Science》2010,43(8):839-847
Russia has long needed a world-level soil attribute (profile) information database which should become the basis for creating
a system of monitoring of the state of soils and for developing measures for their conservation and efficient land use. A
unified system of gathering and storing information on soils, which at the same time would be open for general use, is needed.
The present work is devoted to problems of the concept and methodology of creating a soil geographic database (SGDB) of Russia.
The structure and content of the soil attribute database, underlying which is the concept of representative soils profiles,
are given. A list of classifiers for preparing data presentation formats in the SGDB on the basis of existing concepts of
soil morphology and classifiers characterizing the main physicochemical properties of soils is developed. The work underlies
the creation of an information resource—“Soil-Geographic Database of Russia. Project of the Dokuchaev Soil Science Society”—on
the Internet at the address . 相似文献
14.
The aim of this study was to compare the concentration of tannins and their capacity to precipitate proteins in the dominant
species of ground vegetation (Deschampsia flexuosa (L.) Trin., Pleurozium schreberi (Brid.) Mitt., Vaccinium myrtillus (L.), and Vaccinium vitis-idaea (L.)) and in different layers of the soil organic horizon (litter layer—L, fermentation layer—F, humified layer—H) under
silver birch (Betula pendula Roth.), Norway spruce (Picea abies (L.) Karst.), and Scots pine (Pinus sylvestris L.). Total tannin concentrations were also measured in leaves or needles of birch, spruce, and pine. The study site is located
in Kivalo, northern Finland, close to the Arctic Circle. Differences in total tannin concentrations in ground vegetation were
due mainly to species, with Vaccinium species having the highest values. The influence of the dominant tree species was less important. Protein precipitating capacity
was dependent on plant species; the highest values occurred in Vaccinium species and spruce. Because of their relatively high protein precipitating capacity but low total tannin concentration, D. flexuosa and P. schreberi seemed to have more astringent tannins. Concentrations of total tannin and hydrolyzable tannin in the soil organic horizon
differed depending on the layer and tree species. In general, the highest concentrations of total tannins were found under
birch and spruce in the L layer and the lowest concentrations under pine. Protein precipitating capacity was usually the lowest
in the H layer and highest under birch and spruce in the F and H layers. We showed that lignin from rotted pine wood can also
precipitate proteins but only small amounts; additionally, lignin can be an important source of error for soil total tannin
measurements. 相似文献
15.
Recent developments in the analysis of periodically correlated time series are used to analyze data in a new approach to modeling plant growth. The data—carbon dioxide (CO2) exchange rates in plants—were gathered using a novel and innovative system for near-continuous measurement of CO2 exchange. Least squares estimates are derived for a piecewise polynomial trend, which carries over in an obvious fashion to a general linear model. The residuals from fitting this trend have seasonal components that are well modeled using a periodic autoregressive moving average (PARMA) model. Standard errors for the trend estimates are then derived based on the fitted PARMA model. 相似文献
16.
Changes in the physical, physicochemical, and biological properties of cultivated gray forest soils after their abandoning
and overgrowing with meadow and forest vegetation for 8–10 years are clearly seen in the upper part of the former plow layer.
The organic matter content and the content of available forms of phosphorus and potassium increase; a significant increase
in the root biomass and in the soil biological activity is observed. Changes in the physical properties—an increase in the
degree of soil aggregation and a decrease in the bulk density values—are seen in the upper and middle parts of the former
plow layer. The biological factor is the major factor of transformation of formerly cultivated gray forest soils upon their
abandoning and overgrowing with meadow and forest vegetation. At the same time, a significant role in the improvement of the
structural state of the soils belongs to the physical shrink-swell and freezing-thawing processes. 相似文献
17.
The results of experimental studying of the organic matter status in soils using methods of granulodensimetric fractionation
and the geochemistry of the stable carbon and nitrogen isotopes are presented. The organic and organomineral matter in chestnut
soils representing a chronoseries—stages of natural changes in the vegetation with different carbon isotope compositions—were
investigated. The organomineral fractions and fractions of free organic matter were distinguished, the changes in their proportion
due to the changes in the vegetation were analyzed, and the residence time of the carbon in the organic matter of the fractions
was assessed. 相似文献
18.
Tiago Natal-da-Luz Serena Tidona Bruno Jesus Paula V. Morais José P. Sousa 《Journal of Soils and Sediments》2009,9(3):246-260
Background, aim, and scope Sewage sludge use in agriculture should be limited by the presence of metals and other persistent environmental pollutants.
The present study aims to contribute for the definition of a test battery of ecotoxicological assays that allows a proper
ecotoxicological characterization of sludges, providing information on their potential hazard and identified “safe” application
levels.
Materials and methods Three sludges from distinct sources (urban, olive-processing, and electroplating industries) were tested using avoidance and
reproduction tests with earthworms (Eisenia andrei) and springtails (Folsomia candida) and plant growth tests with turnips (Brassica rapa) and oats (Avena sativa). Different soil–sludge mixture concentrations mimicking recommended/realistic field dosages were tested.
Results Only the sludge from the electroplating industry induced an avoidance response from the earthworms (EC50 = 0.4 t/ha) and collembolans (no observed effect concentration (NOEC) = 15 t/ha). This sludge was the only sludge responsible
for any effect on the reproductive output of the earthworms (EC50 = 7.74 t/ha). Regarding collembolans, none of the sludges tested caused any significant decrease in reproduction. In higher
plant tests, the two industrial sludges were toxic, causing a decrease growth in both species. The EC20 values determined for B. rapa were 20.3 and 24.2 t/ha and for A. sativa 14.7 and 16.2 t/ha for sludges from olive-processing and electroplating industries, respectively.
Discussion The metal loadings of the different test sludges could partially explain the results obtained. The toxicity of the test sludge
from electroplating industry observed on the tested invertebrates and plants could be explained by the high amount of total
chromium from which 22.3% was in the most toxic oxidation state—Cr(VI). However, the toxicity caused by the sludge from the
olive-processing industry in the test plants could be attributed to the presence of other compounds (not measured in this
study) since the metal content was not high enough to induce such an effect. The absence of toxicity showed by the urban test
sludge was in agreement with its low levels of metals.
Conclusions The response of the different test organisms and end points varied according to the sludge type. The urban sludge was non-toxic
whereas the sludge from the electroplating industry caused a toxic effect on almost all parameters measured (avoidance behavior
of both test organisms, reproduction of earthworms, and growth of both plant species). Sludge from the olive-processing industry
only caused a toxic effect on growth of both plant species. By analyzing the sensitivity of the different parameters for the
most toxic sludge, it was found that avoidance and reproduction were more sensitive than plant growth, whereas plant seed
germination was not sensitive at all.
Recommendations and perspectives The ecotoxicological evaluation of wastes can be used as an environmental safety control of sludge use in agriculture. A tiered
approach could be adopted for this purpose, incorporating avoidance tests in the first tier (screening level) and reproduction
and plant growth tests in a second tier. But more evidence aiming to define the most suitable ecotoxicological test battery
for specific sludges with a different contamination profile is still needed. 相似文献
19.
General concepts of tectology—the universal organization science—are discussed. It is shown that some of them can be applied
for the formal analysis of visual images of soil systems obtained at different levels of their organization—from photos of
thin sections to soil maps—and the corresponding attribute data. The structure of visual and attribute data at the level of
thin sections and the methods of their analysis do not differ from those applied upon the analysis of soil cartographic materials.
In particular, this concerns the procedures for data classification—the universal tool to analyze empirical data and to generate
various hypotheses. These procedures include the methods of multivariate statistics and data convolution, the development
of systems of information indices, the development of hierarchical and/or ordinate structures of soil objects, etc. Modern
information technologies, including data bases and geographic information systems with solid mathematical support, make it
possible to advance the ideas of tectology with the aim to improve the efficiency of theoretical and applied studies in soil
science. 相似文献
20.
Michael K. Saiki Barbara A. Martin Thomas W. May William G. Brumbaugh 《Water, air, and soil pollution》2012,223(4):1671-1683
We assessed the suitability of two nonnative poeciliid fishes—western mosquitofish (Gambusia affinis) and sailfin mollies (Poecilia latipinna)—for monitoring selenium exposure in desert pupfish (Cyprinodon macularius). Our investigation was prompted by a need to avoid lethal take of an endangered species (pupfish) when sampling fish for
chemical analysis. Total selenium (SeTot) concentrations in both poeciliids were highly correlated with SeTot concentrations
in pupfish. However, mean SeTot concentrations varied among fish species, with higher concentrations measured in mosquitofish
than in mollies and pupfish from one of three sampled agricultural drains. Moreover, regression equations describing the relationship
of selenomethionine to SeTot differed between mosquitofish and pupfish, but not between mollies and pupfish. Because selenium
accumulates in animals primarily through dietary exposure, we examined fish trophic relationships by measuring stable isotopes
(δ
13C and δ
15N) and gut contents. According to δ
13C measurements, the trophic pathway leading to mosquitofish was more carbon-depleted than trophic pathways leading to mollies
and pupfish, suggesting that energy flow to mosquitofish originated from allochthonous sources (terrestrial vegetation, emergent
macrophytes, or both), whereas energy flow to mollies and pupfish originated from autochthonous sources (filamentous algae,
submerged macrophytes, or both). The δ
15N measurements indicated that mosquitofish and mollies occupied similar trophic levels, whereas pupfish occupied a slightly
higher trophic level. Analysis of gut contents showed that mosquitofish consumed mostly winged insects (an indication of terrestrial
taxa), whereas mollies and pupfish consumed mostly organic detritus. Judging from our results, only mollies (not mosquitofish)
are suitable for monitoring selenium exposure in pupfish. 相似文献