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In Northern Iran mean annual precipitation and vegetation vary significantly over short distance from a semi-desert to a forest biome. These ecosystems likely responded differently on past climate changes. We here aim at i) testing the applicability of biomarkers (leave-derived n-alkanes, their stable carbon isotope composition, and C and N stable isotopes of soil organic matter) in loess-derived soils to identify and differentiate past ecosystems, and ii) elucidating the variability of these biomarkers in palaeosols. We sampled modern topsoils and palaeosol horizons within an ecological gradient covering a range in mean annual precipitation from 200 to 750 mm from the Kopet Dag semi-desert to the Hyrcanian forest on the footslopes of the Alborz Mountains. C org , N, δ 13 C org , δ 15 N, and n-alkanes (and their compound-specific δ 13 C) were analyzed to characterize organic matter composition and sources. In modern soils a systematic increase in C org and N was observed with precipitation. The δ 15 N decreased from about 6 to 4‰ pointing to systematically more degraded organic matter in semi-desert soils. The leave-wax specific ratio of (nC 31 + nC 33 )/(nC 27 + nC 29 )-n-alkanes was >1 for semi-desert soils and 13 C org showed no systematic trend in this gradient. In loess and palaeosol profiles, contents of C org , N and n-alkanes dropped about a factor 10 compared to modern soils. The n-alkane ratio and δ 15 N ratios remained on comparable levels as did the compound-specific δ 13 C in n-alkanes. However, bulk δ 13 C org was altered from about −27 in modern soil to −23‰ in loess-palaeosols. Systematically higher C org and N values were observed in palaeo-topsoils compared to loess and subsoil. Stable C isotopes varied rather unsystematically within loess-palaeosol sequences, while δ 15 N revealed trends within palaeosols, however, in contrasting directions with palaesol depth. The (temporal) average n-alkane ratio for all palaeosol horizons of one site systematically followed the modern precipitation gradient indicating that in all periods of soil formation a climatic gradient developed.

Despite increasing need for cargo shipping, little knowledge exists on emissions from inland navigation. Here we characterized and compared patterns of metals, and parent-, thio- and alkylated PAHs in gaseous and particulate emissions from inland navigation vessels (INVs) with those of road traffic, domestic heating (solid fuels) and ocean going vessels (OGVs) using data from this study and the literature. Diagnostic tools for tracing the environmental impact of inland navigation are proposed. INV and diesel fueled road traffic emissions were differentiated from OGVs and coal combustion via V/Ni values. The PAH inventory of particulate INV emissions also differed significantly from other emitters via a higher proportion of three ring PAHs. The ratio of phenanthrene to dibenzothiophene distinguished diesel fueled road traffic, lignite combustion, OGVs and INVs from gasoline fueled road traffic and wood combustion. The 1,7/(1,7 + 2,6) and 1,7/(1,7 + x4) dimethylphenanthrene ratios (x4 = sum of 1,3-, 2,10-, 3,9- and 3,10-dimethylphenanthrene) separated INV, road traffic (diesel), domestic heating and OGV emissions and are recommended for future application in environmental quality studies.

For the assessment of black carbon (BC), its oxidation to benzene polycarboxylic acids (BPCAs) is an established method. However, doubts about biological precursors remain and not all published data were obtained at low carbon concentration. We hypothesised that a considerable proportion of BC may be produced during sample treatment in the presence of a high amount of organic carbon (OC). We therefore tested whether and to which degree (i) BC-free material from stems of Zea mays L. (maize straw) and leaves of Capsicum annuum L. (bell pepper), as well as (ii) cyclic and non-cyclic carbon forms (chlorophyllin, ellagic acid and β-carotene) afford BPCAs when method protocols are overloaded with a sample above the recommended amount of 5 mg OC. The results showed that small amounts (

Inland navigation is of increasing economic and ecological interest, however its contribution to environmental quality is hardly known. We hypothesized that i) inland navigation emits considerable amounts of soot-Black Carbon (BC) as a product of incomplete combustion of diesel fuel, which is then deposited on soils along river valleys, that ii) improvement of fuel quality by sulfur reduction in 2011 decreased BC inputs to soil, and that iii) this provides a tracer for the spatial impact of inland navigation emissions. The spatial and temporal patterns of soil BC deposits from inland navigation were investigated yearly (2010–2013) working within transects perpendicular to the rivers Rhine, Moselle and Ahr, Germany (the Ahr Valley is free of shipping and served as a reference). In rural areas at inland waterways navigation likely represented the dominant BC emitter. Topsoils (0–10 cm depth) were sampled in vineyards. Their BC content and composition was determined via oxidation of bulk soil organic matter to benzene polycarboxylic acids (BPCAs). The highly trafficked Rhine Valley yielded only little more BC (64.7 ± 12 g BC kg −1 soil organic carbon (SOC) compared to 51.7 ± 9 at the Moselle, and 53.6 ± 6 at the reference Ahr Valley). At both inland waterways soil BC increased towards the river, following the simulated dispersal of ship-derived BC using a Lagrangian model. In the course of ship fuel regulation, soil BC deposits at the Rhine and Moselle waterways decreased significantly from 70.2 ± 3.2 to 47.9 ± 1.1 and 57.6 ± 1.3 to 41.7 ± 0.9 g BC kg −1 SOC within 3 years. Even more pronounced was the change in BC composition, i.e., the ratio of pentacarboxylated to mellitic acid increased from 0.75 to 1.3 (Rhine) and 1 to 1.4 (Moselle) during this time span. From this we calculated that ∼30% less BC was deposited by inland navigation likely due to reduced BC emissions after sulfur regulation in ship diesel.

At least 300 Mio t of plastic are produced annually, from which large parts end up in the environment, where it persists over decades, harms biota and enters the food chain. Yet, almost nothing is known about plastic pollution of soil; hence, the aims of this work are to review current knowledge on i) available methods for the quantification and identification of plastic in soil, ii) the quantity and possible input pathways of plastic into soil, (including first preliminary screening of plastic in compost), and iii) its fate in soil. Methods for plastic analyses in sediments can potentially be adjusted for application to soil; yet, the applicability of these methods for soil needs to be tested. Consequently, the current data base on soil pollution with plastic is still poor. Soils may receive plastic inputs via plastic mulching or the application of plastic containing soil amendments. In compost up to 2.38–1200 mg plastic kg − 1 have been found so far; the plastic concentration of sewage sludge varies between 1000 and 24,000 plastic items kg − 1 . Also irrigation with untreated and treated wastewater (1000–627,000 and 0–125,000 plastic items m − 3 , respectively) as well as flooding with lake water (0.82–4.42 plastic items m − 3 ) or river water (0–13,751 items km − 2 ) can provide major input pathways for plastic into soil. Additional sources comprise littering along roads and trails, illegal waste dumping, road runoff as well as atmospheric input. With these input pathways, plastic concentrations in soil might reach the per mill range of soil organic carbon. Most of plastic (especially > 1 μm) will presumably be retained in soil, where it persists for decades or longer. Accordingly, further research on the prevalence and fate of such synthetic polymers in soils is urgently warranted.