Color analysis of storage roots from the USDA,ARS sweetpotato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>) germplasm collection

The United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Plant Genetic Resources Conservation Unit in Griffin, GA maintains the United States germplasm collection for Ipomoea spp. (Convolvulaceae). During 2012–2014, 737 sweetpotato, Ipomoea batatas (L.) Lam., plant introductions (PI) were acquired as tissue-culture plantlets and then acclimated to greenhouse conditions at the USDA, ARS, U. S. Vegetable Laboratory (USVL), Charleston, SC. Single plants were transferred to plastic-covered plant beds to produce cuttings for replicated field trials. Storage roots were harvested from 690 PIs grown in the field and 695 PIs grown in pots. Color coordinates were obtained for each PI using a tristimulus colorimeter. Hue angle values (h*) ranged from 8.2° to 88.3° (\( \bar{x} \) = 54.9°) for the periderm (peel or skin) of field-grown storage roots (n = 690 PIs) and ? 9.4° (= 350.6°) to 96.2° (\( \bar{x} \) = 51.3°) for pot-grown roots (n = 695 PIs). The red–green coordinate (a*) ranged from 0.8 to 30.7 (\( \bar{x} \) = 12.8) for the periderm of field-grown roots and ? 2.0 to 44.9 (\( \bar{x} \) = 16.1) for pot-grown roots. The yellow–blue coordinate (b*) ranged from 2.8 to 33.1 (\( \bar{x} \) = 19.4) for the periderm of field-grown roots and ? 7.4 to 38.1 (\( \bar{x} \) = 19.3) for pot-grown roots. Color saturation (chroma, C*) ranged from 13.7 to 35.8 (\( \bar{x} \) = 24.9) for the periderm of field-grown roots and 14.9–45.5 (\( \bar{x} \) = 29.3) for pot-grown roots. Lightness (white–black, L*) ranged from 32.6 to 81.7 (\( \bar{x} \) = 54.6) for the periderm of field-grown roots and 32.1–88.2 (\( \bar{x} \) = 64.0) for pot-grown roots. Hue angles ranged from ? 13.1° (= 346.9°) to 100.9° (\( \bar{x} \) = 80.9°) for the stele (flesh) of field-grown storage roots (n = 672 PIs) and ? 29.9° to 103.5° (\( \bar{x} \) = 81.6°) for pot-grown roots (n = 676 PIs); a* ranged from ? 5.6 to 35.0 (\( \bar{x} \) = 8.0) for the stele of field-grown roots and ? 6.0 to 41.0 (\( \bar{x} \) = 7.6) for pot-grown roots; and b* ranged from ? 7.7 to 56.1 (\( \bar{x} \) = 34.6) for the stele of field-grown roots and ? 12.6 to 56.1 (\( \bar{x} \) = 31.8) for pot-grown roots. C* ranged from 12.7 to 65.8 (\( \bar{x} \) = 37.2) for the stele of field-grown roots and 8.9–65.7 (\( \bar{x} \) = 34.5) for pot-grown roots; and L* ranged from 27.8 to 91.1 (\( \bar{x} \) = 77.7) for the stele of field-grown roots and 28.2–91.9 (\( \bar{x} \) = 80.4) for pot-grown roots. There were significant relationships between stele color (h*) and percent dry matter, with orange stele having a significantly lower % dry matter (\( \bar{x} \) = 25.6%, n = 183) compared with roots with cream/white stele (\( \bar{x} \) = 30.8%, n = 373). There appears to be wide genetic diversity for root color characteristics for the United States sweetpotato germplasm collection.     

Genetic diversity of a <Emphasis Type="Italic">Coffea</Emphasis> Germplasm Collection assessed by RAPD markers

Genetic diversity and relationships within and among nine species of Coffea, one species of Psilanthus and the Piatã hybrid from the Coffee Germplasm Collection of Instituto Agronômico de Campinas (IAC), Brazil were assessed using RAPD markers. Genetic diversity and relationships were evaluated by proportion of polymorphic loci (P), Shannon’s genetic index (H′ and G′_ST) and clustering analysis. The overall RAPD variation among all accessions was mostly partitioned between rather than within species. However, C. canephora and C. liberica showed a high genetic diversity within the species (\({\underline{\hbox{H}'}} \) _sp = 0.414 and \({\underline{\hbox{H}'}} \) _sp = 0.380, respectively) and this was highly structured (high \({\underline{\hbox{G}'}} \) _ST). Genetic diversity from C. congensis and C. arabica was also structured, but with lower levels of genetic diversity (\({\underline{\hbox{H}'}} \) _sp = 0.218 and \({\underline{\hbox{H}'}} \) _sp = 0.126, respectively). The results were consistent with agronomic and molecular studies and demonstrated that the IAC Coffea Collection is representative of the phylogenetic structure observed in the genera. This study devises sampling strategies for coffee germplasm collections and provides genetic diversity parameters for future comparisons among them.     

Vis/NIR Chemical Imaging Technique for Predicting Sodium Humate Contents in Aquaculture Environment

This study aimed to develop a visible and near-infrared (Vis/NIR) chemical imaging (400–1000 nm) technique to provide rapid prediction of the contents of sodium humate dissolved in aquaculture environment. Gray reference image with 5% reflectance value was first used to correct the obtained raw images in order to promote the reflectance values as compared to that with 99% reflectance for further spectral analysis. Successive projection algorithm (SPA) was introduced to extract four optimal wavelengths, which were then used for the establishment of back-propagation artificial neural network (BP-ANN) models. The results revealed that the BP-ANN model based on the selected four optimal wavelengths better performed (\( {R}_C^2 \) = 0.986, \( {R}_{CV}^2 \) = 0.985, \( {R}_P^2 \) = 0.993, RMSEC = 0.329 mg/L, RMSECV = 0.433, RMSEP = 0.734 mg/L) than that based on the whole 381 wavelengths (\( {R}_C^2 \) = 0.978, \( {R}_{CV}^2 \) = 0.996, \( {R}_P^2 \) = 0.977, RMSEC = 0.388 mg/L, RMSECV = 0.625, RMSEP = 0.734 mg/L). Finally, a series of chemical images were developed to clearly display the concentration distribution of the sodium humate dissolved in water, demonstrating that Vis/NIR chemical imaging technique was feasible to quantify the contents of sodium humate in the aquatic environment and could be further used for real-time monitoring the quality of aquaculture water.     

Bayesian Analysis of $$^{}$$Pb Dating

In studies of environmental change of the past few centuries, \(^{210}\)Pb dating is often used to obtain chronologies for sedimentary sequences. One of the most commonly used approaches to estimate the age of material at different depths in a sequence is to assume a constant rate of supply (CRS) or influx of ‘unsupported’ \(^{210}\)Pb from the atmosphere, together with a constant or varying amount of ‘supported’ \(^{210}\)Pb. Current \(^{210}\)Pb dating models do not use a proper statistical framework and provide poor estimates of the uncertainties. Here, we develop a new model for \(^{210}\)Pb dating, where ages and values of supported and unsupported \(^{210}\)Pb form part of the parameters. We apply our model to a case study from Canada as well as to some simulated examples. Our model can extend beyond the current CRS approach, deal with asymmetric errors and mix \(^{210}\)Pb with other types of dating, thus obtaining more robust, realistic and statistically better defined age estimates.     

Acid-base properties of dark gray forest soil under different wood plants and agrocenosis

A comparative study of chemical properties of soils under wood plants (pine, oak, and birch) and agrocenosis was performed. The profile distribution and spatial heterogeneity of \(pH_{H_2 O} \), pH_KCl, total acidity, and exchangeable Ca²⁺ and Mg²⁺ in soils were described. Soil acidity conditions were characterized using discriminant analysis and principal components analysis.     

Hazard Function Models to Estimate Mortality Rates Affecting Fish Populations with Application to the Sea Mullet (<Emphasis Type="BoldItalic">Mugil cephalus</Emphasis>) Fishery on the Queensland Coast (Australia)

Fisheries management agencies around the world collect age data for the purpose of assessing the status of natural resources in their jurisdiction. Estimates of mortality rates represent a key information to assess the sustainability of fish stocks exploitation. Contrary to medical research or manufacturing where survival analysis is routinely applied to estimate failure rates, survival analysis has seldom been applied in fisheries stock assessment despite similar purposes between these fields of applied statistics. In this paper, we developed hazard functions to model the dynamic of an exploited fish population. These functions were used to estimate all parameters necessary for stock assessment (including natural and fishing mortality rates as well as gear selectivity) by maximum likelihood using age data from a sample of catch. This novel application of survival analysis to fisheries stock assessment was tested by Monte Carlo simulations to assert that it provided unbiased estimations of relevant quantities. The method was applied to the data from the Queensland (Australia) sea mullet (Mugil cephalus) commercial fishery collected between 2007 and 2014. It provided, for the first time, an estimate of natural mortality affecting this stock: \(0.22 \pm 0.08\)  year\(^{-1}\).     

Comparison of Chemical Extraction Methods for Determination of Soil Potassium in Different Soil Types

Determining potassium supply of soil plays an important role in intensive crop production, since it is the basis for balancing nutrients and issuing fertilizer recommendations for achieving high and stable yields within economic feasibility. The aim of this study was to compare the different extraction methods of soil potassium from arable horizon of different types of soils with ammonium lactate method (K_AL), which is frequently used as analytical method for determining the accessibility of nutrients and it is a common method used for issuing fertilizer recommendations in many Europe countries. In addition to the ammonium lactate method (K_AL, pH 3.75), potassium was extracted with ammonium acetate (K_AA, pH 7), ammonium acetate ethylenediaminetetraacetic acid (K_AAEDTA, pH 4.6), Bray (K_BRAY, pH 2.6) and with barium chloride (\(K_{BaCl_2 }\), pH 8.1). The analyzed soils were extremely heterogeneous with a wide range of determined values. Soil pH reaction \(\left( {pH_{H_2 O} } \right)\) ranged from 4.77 to 8.75, organic matter content ranged from 1.87 to 4.94% and clay content from 8.03 to 37.07%. In relation to K_AL method as the standard method, \(K_{BaCl_2 }\) method extracts 12.9% more on average of soil potassium, while in relation to standard method, on average K_AA extracts 5.3%, K_AAEDTA 10.3%, and K_BRAY 27.5% less of potassium. Comparison of analyzed extraction methods of potassium from the soil is of high precision, and most reliable comparison was K_AL method with K_AAEDTA, followed by a: K_AA, \(K_{BaCl_2 }\) and K_BRAY method. Extremely significant statistical correlation between different extractive methods for determining potassium in the soil indicates that any of the methods can be used to accurately predict the concentration of potassium in the soil, and that carried out research can be used to create prediction model for concentration of potassium based on different methods of extraction.     

The Allometric Quarter-Power Scaling Model and Its Applicability to Grand Fir and <Emphasis Type="Italic">Eucalyptus</Emphasis> Trees

The use of the allometric model \(y = \beta x ^{\alpha }\) to describe the relative growth of morphological traits of trees is a source of contention in ecology. This is particularly so in a specific form, the West, Brown and Enquist model, which predicts values of \(\alpha \) that are multiples of 1/4 for various allometric relationships—the quarter-power scaling law. We use statistical techniques to test the appropriateness of the quarter-power scaling allometric model in a number of different relative growth relationships of trees. Two separate datasets are used, one of repeated measures of Abies grandis (Grand fir) trees, another of independent measures of Eucalyptus trees. Nonlinear mixed-effects modelling is used to fit allometric models to the datasets. Generalised additive models, equivalence testing and traditional significance testing are used to assess the adequacy of the allometric models fitted and the values of the estimated exponents relative to those predicted by the WBE model. In only one of the five models fitted was there empirical evidence for the WBE-predicted quarter-power exponent. However, the adequacy of the allometric models was generally supported, though a need for further analysis over a larger range of tree ages/sizes is indicated.Supplementary materials accompanying this paper appear online.     

Optimal Estimation Versus MCMC for $$\mathrm{{CO}}_{2}$$ Retrievals

The Orbiting Carbon Observatory-2 (OCO-2) collects infrared spectra from which atmospheric properties are retrieved. OCO-2 operational data processing uses optimal estimation (OE), a state-of-the-art approach to inference of atmospheric properties from satellite measurements. One of the main advantages of the OE approach is computational efficiency, but it only characterizes the first two moments of the posterior distribution of interest. Here we obtain samples from the posterior using a Markov Chain Monte Carlo (MCMC) algorithm and compare this empirical estimate of the true posterior to the OE results. We focus on 600 simulated soundings that represent the variability of physical conditions encountered by OCO-2 between November 2014 and January 2016. We treat the two retrieval methods as ensemble and density probabilistic forecasts, where the MCMC yields an ensemble from the posterior and the OE retrieval result provide the first two moments of a normal distribution. To compare these methods, we apply both univariate and multivariate diagnostic tools and proper scoring rules. The general impression from our study is that when compared to MCMC, the OE retrieval performs reasonably well for the main quantity of interest, the column-averaged \(\mathrm{{CO}}_{2}\) concentration \(X_{\mathrm{{CO}}_{2}}\), but not for the full state vector \(\mathbf {X}\) which includes a profile of \(\mathrm{{CO}}_{2}\) concentrations over 20 pressure levels, as well as several other atmospheric properties.Supplementary materials accompanying this paper appear on-line.     

Diversity in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) local populations from Greece

Cowpea cultivation in many countries around the Mediterranean Basin depends on a number of locally adapted populations conserved on-farm at a small scale, rather than on the use of modern varieties. Documentation, characterization and exploitation of traditional local populations could contribute to their conservation and utilization as sources of desirable characteristics. Therefore, a study was conducted to (a) characterize, (b) assess diversity and (c) classify 23 on-farm conserved local cowpea populations based on 32 agro-morphological traits. Investigations on diversity of characteristics related to seed yield, mineral and seed crude protein content as well as on correlations among them were carried out. A relatively high phenotypic diversity was observed. In particular, a high level of within population diversity was found (\( \bar{H}s \) = 0.34) exceeding that among populations’ diversity (Gst = 0.27). Principal component analysis classified the majority of local populations into two groups (mainly according to populations’ seed coat color and eye color), further divided into six subgroups regardless of the populations’ geographical origin. Significant differences were also observed among the populations studied for potassium and calcium, as well as for their seed crude protein content which ranged from 22.14 to 28.37 %. The results show appreciable levels of intra- and inter-phenotypic diversity in on-farm conserved cowpea populations, which indicates the existence of a valuable gene pool for future exploitation in breeding programs.     

Wet and dry deposition of sulphates and nitrates in Eastern Canada: 1979–1982

Daily air and precipitation chemistry observations at six rural locations in eastern Canada were analyzed to obtain wet and dry deposition. Dry deposition was calculated from air concentrations using deposition velocities originating from a recent literature review and synthesis exercise involving land use types. Total annual deposition ranges for \({\text{SO}}_{\text{4}}^{\text{ = }} \) from 10 to 86 mmol m^?2 and for \({\text{NO}}_{\text{3}}^{\text{ - }} \) excluding N0₂ contributions to dry deposition from 13 to 62 mmol m^?2. Dry deposition accounts for an estimated 22 and 21% of the total \({\text{SO}}_{\text{4}}^{\text{ = }} \) and \({\text{NO}}_{\text{3}}^{\text{ - }} \) deposition, respectively. For \({\text{NO}}_{\text{3}}^{\text{ - }} \) , this fraction increases to 30% if N0₂ concentration to dry deposition is included. There is a marked seasonal variation in total \({\text{SO}}_{\text{4}}^{\text{ = }} \) deposition but not in that of \({\text{NO}}_{\text{3}}^{\text{ - }} \) . Both wet and dry deposition are episodic. 20% of daily events deliver between 47 and 70% of the deposition.     

An Evaluation of Error Variance Bias in Spatial Designs

Spatial design and analysis are widely used, particularly in field experimentation. However, it is often the case that spatial analysis does not significantly enhance more traditional approaches such as row–column analysis. It is then of interest to gauge the degree of error variance bias that accrues when a spatially designed experiment is analysed as a row–column design. This paper uses uniformity data to study error variance bias in \(7\times 12\) spatial designs for 21 treatments.     

Agricultural Impacts on Lake and Stream Water Quality in Grand Lake St. Marys, Western Ohio

Agricultural activities release variable products into air, soil and water ecosystems. The study was conducted to evaluate the impact of agriculture and concentrated livestock operations on stream and lake water quality in Grand Lake St. Marys watershed of north-western Ohio. Temporal water samples from the lake and the 6 feeding streams were collected bimonthly from January 2005 to May 2007, processed and measured for temperature, turbidity, pH, electrical conductivity (E _C), ammonium $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , nitrate $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ , dissolved phosphorus (P), ultra-violet (UV) light absorption, and dissolved oxygen (DO), employing standard methods of analysis. The measured data were normalized and integrated into a simple index (WQ_Index) to evaluate overall water quality. Results showed that over 90% of the area in the watershed was under cropland with associated livestock operations. With a land area equal to 195 km² represented by the six major tributaries, the average animal density was over 240 units km^?2. As a result, land disposal of manure from confined feedings operations and direct deposit by grazing animals contributed to non-point sources of water pollution. While $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ and P concentration, turbidity, and UV absorption peaked during the summer, the $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ and DO concentration in both stream and lake water was lowest in the summer. Water sampled from the Coldwater, Beaver and Prairie creeks had higher turbidity, $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , and P than other creeks. However, DO concentration and UV absorption of water did not change significantly by the influence of streams. The WQ_Index peaked in both streams and lake water with greater water quality degradation in Beaver and Coldwater creek than other creeks. A significant relationship of WQ_Index with UV absorption and P accounted 84 to 90% of the variations in stream and lake water quality degradation. However, a strong linear relationship (r ²?=?0.81; p<0.01) between UV absorption and P concentration suggested a major contribution of P to the degradation of stream and lake water quality through algal blooming and associated eutrophication.     

Comparison of Activated Sludge Technologies by Particle Size Analysis

This paper analyses the influence of activated sludge technologies on the Particle Size Distribution (PSD) of urban wastewater treatment plants operating under real conditions. The activated sludge treatment systems selected for the analysis are the most widely used in wastewater treatment installations: (a) double step activated sludge, (b) medium load activated sludge, (c) prolonged aeration, and (d) membrane bioreactors The main quality parameters (suspended solids, turbidity, and COD) and PSD in the influent and effluent of each different activated sludge treatment were analyzed during 1?year. The PSD was fitted using the power law ( $ n\left( {{d_{\text{P}}}} \right) = \frac{{\partial {\text{N}}\left( {{d_{\text{p}}}} \right)}}{{\partial {d_{\text{p}}}}} = A \cdot d_{\text{p}}^{{ - b \cdot {\text{Log}}\left( {{d_{\text{p}}}} \right)}} $ ) obtaining coefficients A and b to define the particle distribution. Mathematical correlations between this coefficients and the rest of parameters studied were found $ \left( {\matrix{ {{\text{SS}} = {0}{.0126} \cdot {A^{{{0}{.781}}}},} &{{\text{Turbidity}} = 15.5814 + 1.164 \cdot {{10}^3} \cdot A{,}} &{{\text{COD}} = \frac{{1}}{{{0}{.0133} + \cdot \frac{{{49}{.85}}}{\text{A}}}}} \\ }<!end array> } \right) $ . The relation with the average particle size by mass was also found, ( $ {d_{\text{pma}}} = - 11.6502 + \frac{{50.4265}}{b} $ ). Moreover, a relation between PSD and the particle elimination efficiency of the secondary treatment was study, ( $ \eta = 0.1434 - \frac{{0.5602}}{{{A_{\text{rel}}}}} + \frac{{0.7490}}{{{b_{\text{rel}}}}} $ ). Finally, the particulate matter nature was assessed by SEM-EDX. It can be concluded that membrane bioreactor is the technology that produces the best water quality effluent due to physic process of particle separation by ultrafiltration membrane technology.     

The influence of selected chemical compounds used in winter road maintenance on the active capillarity of soils

Purpose

Winter road maintenance involves the use of various chemical compounds which affect the active capillarity of soils. The main goal of the study was to determine a model to predict changes in the active capillarity of soils using distilled water and water solutions of chemical compounds which are used in winter road maintenance. The purpose of the first part of the experiment was to determine a model to predict changes in the height of capillarity rise and the rate of capillary rise with time. The second part of the experiment investigated how water solutions of selected chemical compounds altered the soils’ active capillarity as determined using distilled water.

Materials and methods

The research was carried out on three soils from deposits in west-central Poland, and their separated fractions. Active capillarity was investigated with the use of distilled water and 5 and 10 % solutions of ten chemical compounds used in winter road maintenance. The rate and height of capillary rise were measured in transparent vertical tubes, placed vertically in a glass tank into which the distilled water or solutions of chemical compounds were poured.

Results and discussion

The rate of capillary rise was decreasing as a function of time. After the first part of the experiment had been completed, an analysis was made of the statistical fit between the experimental data for capillary rise of distilled water in the studied soils and soil fractions, and the model described by the formula $ h(t) = {h_1} + {v_1} \times ln(t) $ , where h ₁ denoted the height of capillary rise in the first second, v ₁ denoted the rate of capillary rise, and t denoted time. High determination coefficients indicated a good fit of the model to the experimental data. In the second part of the study, it was found that solutions of chemical compounds caused a reduction in the active capillarity of the studied soils relative to the capillarity determined using distilled water. It was possible to determine a capillarity coefficient w _k so as to compare the capillary rises in soil of distilled water and of the various chemical compounds in 5 and 10 % solution. Analysis of the results showed that the capillarity coefficient w _k is a characteristic feature which depends on the type and concentration of the chemical subject to capillary action and on the type and fraction of soil.

Conclusions

The active capillarity of soil depends on the type and concentration of the capillary fluid such as distilled water or water solutions of chemical compounds used in winter road maintenance and other factors. The relation between the height of capillary rise h and time t can be described using the formula $ h(t) = {h_1} + {v_1} \times \ln (t) $ . The water solutions of chemical compounds used in winter road maintenance caused a reduction in the active capillarity of the studied soils relative to the capillarity determined using distilled water. It was found that the susceptibility of soil to capillary rise can be determined based on the capillarity coefficient w _k . This coefficient depends on the type and concentration of the chemical compound in the soil and on the soil type and fraction. The effect of these factors can be accounted for using the formula $ h(t) = {w_k} \times {h_1} + {w_k} \times {v_1} \times ln(t) $ .     

Diversity of the composition and content of soluble carbohydrates in seeds of the genus <Emphasis Type="Italic">Vicia</Emphasis> (Leguminosae)

Low molecular weight carbohydrates of seeds of 10 species of Vicia, namely: V. angustifolia, V. articulata, V. cordata, V. ervilia, V. johannis, V. macrocarpa, V. monantha, V. narbonensis, V. pannonica and V. sativa were analyzed by the high resolution gas chromatography method. Seeds of the investigated species contain common (glucose, fructose, myo-inositol, sucrose, galactinol, di-galactosyl myo-inositol and raffinose family oligosaccharides—RFOs) and species-specific carbohydrates (d-pinitol and its α-d-galactosides—in V. articulata, V. monantha and V. pannonica or d-ononitol and its galactoside—in V. ervilia). Among the species containing in seeds RFOs as the main α-d-galactosides (V. angustifolia, V. cordata, V. johanensis, V. macrocarpa, V. narbonensis and V. sativa), an additional subgroup can be separated, which contains a set of unknown compounds (found in V. angustifolia, V. cordata and V. macrocarpa). Moreover, several other unidentified carbohydrate-containing compounds were detected exclusively in seeds of V. ervilia. The concentrations of total soluble carbohydrates (TSCs), including sugars, RFOs, cyclitols and galactosyl cyclitols and unknown compounds, in seeds differ significantly (P < 0.05) among the species. RFOs and sucrose are the main fractions in TSCs, with the exception of V. pannonica seeds, containing more galactosyl pinitols, and V. ervilia, in which unknown compounds account for 50% of TSCs. In V. ervilia RFOs occur at the lowest concentration (9.32 mg g^?1 seeds), and the concentration of DGMI (di-galactosyl myo-inositol) is comparable with that of RFOs, which is unusual among all the investigated Vicia species.     

The spatial and temporal variation of the sulphate to nitrate ratio in precipitation in eastern North America

Four years of precipitation chemistry data for eastern North America were used to investigate seasonal and geographical variations in \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) ratio. Several distinct regimes occur. One, in the region of heaviest acidic deposition extending from the states south of the Great Lakes across New England and southeastern Canada, has a very strong seasonal variation in the \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) molar ratio in deposition. The ratio ranges from about 1.5 in summer to about 0.5 in winter. Another, in the smaller area of Texas and surrounding states, shows the reverse seasonal pattern. Yet another, in the high plains states, has a double maximum in the ratio in Spring and Fall. The remainder of the region has an irregular seasonal pattern. Insight into the cause of \({\text{SO}}_{\text{4}}^{\text{ = }} {\text{/NO}}_{\text{3}}^{\text{ - }} \) variations was obtained using a simple chemical transport box model. It showed that the chemical transformation of S0₂ and NO_x in the atmosphere is a major factor. A comparison of model predictions and observations indicate that in the vicinity of mid-western American sources the molar ratio of amount of S0₂ oxidized in-cloud to that of N0₂ is O.5 in winter and 1.5 in summer.     

Adaptation of ecotypes and cultivars of subterranean clover (<Emphasis Type="Italic">Trifolium subterraneum</Emphasis> L.) to German environmental conditions and its suitability as living mulch

Abstract A total of 320 accessions of subterranean clover (Trifolium subterranenum L.) were screened for adaptation to the environmental conditions in southern Germany, as well as their suitability as cover crops or living mulches. The accessions, derived from collections of the Department of Agriculture and Food Western Australia and the International Research Center for Agriculture in Dry Areas, were propagated in the greenhouse and grown in rows. Selected accessions were then tested in plots and as an intercrop in wheat, in order to test their suitability as living mulch. Moreover, a frost resistance screening was carried out in a climate chamber. Adaptation to southern German conditions and frost tolerance was generally better than expected, as most accessions survived winters with snow cover and transitory temperatures as low as \(-\,10\,^\circ \)C. Accessions with particularly high frost tolerance were identified and several accessions persisted over four generations of self-reseeding. Although there was a large range of morphological characteristics, no differences concerning their suitability as living mulch could be observed. The results suggest that subterranean clover is sufficiently winter hardy to be grown as an overwintering cover crop or living mulch in southern Germany. Commercially available cultivars appear suitable in the first instance, even though these have not been selected for cold winters. However, adaptation might be further improved by targeted selection among accessions.     

Precipitation Chemistry as an Indicator of Urban Air Quality in Mersin, North-Eastern Mediterranean Region

The chemical composition of precipitation in the city of Mersin on the Mediterranean coast of Turkey has been studied. Spatial and temporal variability of rainwater constituents have been determined from samples collected at two central and two suburban stations for the December 2003–May 2005 period. A total of 246 samples covering all precipitation events were analyzed to determine pH, conductivity, as well as major anion (Cl^?, ${\text{NO}}_3^ - $ , ${\text{SO}}_4^{2 - } $ ); major cation (H⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, ${\text{NH}}_4^ + $ ) and formaldehyde (HCHO) concentrations. The pH varied within a range of 4.8–8.5, with only 8 out of 246 samples being acidic (pH?<?5.6), and the remaining highly alkaline samples being neutralized by either ${\text{NH}}_4^ + $ in rainwater, or by CaCO₃ resulting from wet deposition of atmospheric dust. The volume weighted mean ΣAnion/ΣCation ratio was 0.49. The equivalent concentration of major ionic species followed the order: ${\text{Ca}}^{2 + } > {\text{HCO}}_3^ - > {\text{SO}}_4^{2 - } > {\text{Cl}}^ - > {\text{NH}}_4^ + > {\text{Na}}^ + > {\text{Mg}}^{2 + } > {\text{NO}}_3^ - > {\text{K}}^ + > {\text{H}}^ + $ . Formaldehyde concentrations varied in the range of 0.01–17.9 μM, and was found to be dependent on precipitation volume. Relatively higher ${\text{NH}}_4^ + $ , ${\text{SO}}_4^{2 - } $ , ${\text{NO}}_3^ - $ and HCHO concentrations, mainly of anthropogenic origin, measured near the city center suggest increased pollution from local anthropogenic sources, e.g., residential heating, industrial and/or traffic emissions. In general, the results of this study suggest local precipitation chemistry is more strongly influenced by natural (mineral dust and marine) sources compared to anthropogenic ones.     

Immobilization of Cu and Cd in a contaminated soil: one- and four-year field effects

Purpose

Many amendments have been applied to immobilize heavy metals in soil. However, little information is available on the changes of immobilization efficiencies of heavy metals in contaminated soils over time. This work investigated the immobilization efficiencies of copper (Cu) and cadmium (Cd) in contaminated soils in situ remediated with one-time application of three amendments for 1 year and 4 years.

Materials and methods

Apatite, lime, and charcoal were mixed with the topsoil of each plot with the amounts of 22.3, 4.45, and 66.8 t/ha, respectively. Soil chemical properties and fractions of Cu and Cd were examined after in situ remediation for 1 year and 4 years. Soil sorption and retention capacities and desorption proportions for Cu and Cd were investigated by batch experiments.

Results and discussion

The addition of amendments significantly increased soil pH, but decreased exchange acid and aluminum (Al). The amendments significantly decreased the CaCl₂ extractable Cu and Cd and transformed them from active to inactive fractions. After the application of amendments for 1 year, the maximum sorption capacities ranged from 35.6 to 38.8 mmol/kg for Cu and from 14.4 to 17.0 mmol/kg for Cd, which were markedly higher than those of the application of amendments for 4 years (Cu, 29.6–34.7 mmol/kg; Cd, 10.9–16.4 mmol/kg). Desorption proportions (D) of Cu and Cd using three extractants followed the order of \( {D}_{{\mathrm{NaNO}}_3}<{D}_{{\mathrm{CaCI}}_2}<{D}_{{\mathrm{MgCI}}_2} \) . Moreover, the retention capacities (R) of Cu and Cd both increased and followed the order of R _apatite?>?R _lime?>?R _charcoal, resulting in higher Cu and Cd in the amended soils than the untreated soil.

Conclusions

Apatite, lime, and charcoal increased the soil sorption and retention capacities of Cu and Cd and resulted in higher immobilization efficiencies in the amended soils than the untreated soil. However, the immobilization efficiencies of Cu and Cd decreased with the decrease of sorption capacities after 4 years. It was concluded that apatite had the best effect on the long-term stability of immobilized Cu and Cd and can be applied to immobilize heavy metals in contaminated soils.