Diphenylamine and derivatives in the environment: a review

Diphenylamine (DPA) is a compound from the third European Union (EU) list of priority pollutants. It was assigned by the EU to Germany to assess and control its environmental risks. DPA and derivatives are most commonly used as stabilizers in nitrocellulose-containing explosives and propellants, in the perfumery, and as antioxidants in the rubber and elastomer industry. DPA is also widely used to prevent post-harvest deterioration of apple and pear crops. DPA is a parent compound of many derivatives, which are used for the production of dyes, pharmaceuticals, photography chemicals and further small-scale applications. Diphenylamines are still produced worldwide by the chemical industries. First reports showed that DPA was found in soil and groundwater. Some ecotoxicological studies demonstrated the potential hazard of various diphenylamines to the aquatic environment and to bacteria and animals. Studies on the biodegradability of DPA and its derivatives are very sparse. Therefore, further investigation is required to determine the complete dimension of the potential environmental hazard and to introduce possible (bio)remediation techniques for sites that are contaminated with this class of compounds. This is the first detailed review on DPA and some derivatives summarizing their environmental relevance as it is published in the literature so far and this review will recommend conducting further research in the future.     

Variations in exposure to in-vehicle particle mass and number concentrations in different road environments

Road environments significantly affect in cabin concentration of particulate matter (PM). This study conducted measurements of in-vehicle and on-road concentrations of PM10, PM2.5, PM1, and particle number (PN) in size of 0.02–1 µm, under six ventilation settings in different urban road environments (tunnels, surface roads and elevated roads). Linear regression was then used to analyze the contributions of multiple predictor variables (including on-road concentrations, temperature, relative humidity, time of day, and ventilation settings) to measured variations. On-road measurements of PM2.5, PM1, and PN concentrations from the open surface roads were 5.5%, 3.7%, and 16% lower, respectively, than those measured in tunnels, but 7.6%, 7.1% and 24% higher, respectively, than those on elevated roads. The highest on-road PM10 concentration was observed on surface roads. The time series pattern of in-vehicle particle concentrations closely tracked the on-road concentrations outside of the car and exhibited a smoother profile. Irrespective of road environment, the average I/O ratio of particles was found to be the lowest when air conditioning was on with internal recirculation, the highest purification efficiency via ventilation was obtained by switching on external air recirculation and air conditioning. Statistical models showed that on-road concentration, temperature, and ventilation setting are common factors of significance that explained 58%-80%, 64%-97%, and 87%-98% of the variations in in-vehicle PM concentrations on surface roads, on elevated roads, and in tunnels, respectively.

Implications: Inside vehicles, both driver and passengers will be exposed to elevated particle concentrations. However, for in-vehicle particles, there has been no comprehensive comparative study of the three-dimensional traffic environment including tunnels surface roads and elevated roads. This study focuses on the analysis of the trends and main influencing factors of particle concentrations in different road environments. The results can provide suggestions for the driver's behavior, and provide data support for the environmental protection department to develop pollutant concentration limits within the vehicle.     

Kinetics of phenol and chlorophenol utilization by Acinetobacter species

Although microbial transformations via cometabolism have been widely observed, the few available kinetic models of cometabolism have not adequately addressed the case of inhibition from both the growth and nongrowth substrates. The present study investigated the degradation kinetics of self-inhibitory growth (phenol) and nongrowth (4-chlorophenol, 4-CP) substrates, present individually and in combination. Specifically, batch experiments were performed using an Acinetobacter isolate growing on phenol alone and with 4-CP present. In addition, batch experiments were also performed to evaluate the transformation of 4-CP by resting, phenol-induced Acinetobacter cultures. The Haldane kinetic model adequately predicted the biodegradation of phenol alone, although a slight discrepancy was noted in cases of higher initial phenol concentrations. Similarly, a Haldane model for substrate utilization was also able to describe the trends in 4-CP transformation by the resting cell cultures. The 4-CP transformation by the Acinetobacter species growing on phenol was modeled using a competitive kinetic model of cometabolism, which included growth and nongrowth substrate inhibition and cross-inhibition terms. Excellent agreement was obtained between the model predictions using experimentally estimated parameter values and the experimental data for the synchronous disappearance of phenol and 4-CP.     

Umweltrelevanz von Diphenylamin — Ein Stoff der 3. EU-Altstoffprioritätenliste

Diphenylamine (DPA), the simplest secondary aromatic amine, is a compound from the third European Union (EU) list of priority pollutants. It was assigned to Germany to assess and control its environmental risks. DPA is most commonly used as a stabilizer agent in nitrocellulose-containing explosives and propellants, in the perfumery, and as an antioxidant in the rubber and elastomer industry. DPA is also widely used to prevent the post-harvest deterioration of apple and pear crops. It is a parent compound of many derivatives which are used for the production of dyes, pharmaceuticals, photography chemicals and further small-scale applications. At the beginning of the eighties, the estimated world production of DPA was ?40,000 tons per year (in Germany ?4,000 tons per year). The compound is still produced world-wide by the chemical industries. Recently published reports showed that DPA was found in soil and groundwater (within the ppb to ppm range). Some ecotoxicological reports demonstrated the potential hazard of various diphenylamines to the aquatic environment and to bacteria and animals as well. Studies on the biodegradability of DPA and its derivatives are very sparse. Therefore, further investigations are required to determine the complete dimensions of the potential environmental hazard and to introduce possible (bio)remediation techniques for sites that are contaminated with this compound or its derivatives. This review summarizes the environmental relevance of DPA as has been published in the literature thus far. It may possibly support the German authorities in their assessment of the risks of this priority pollutant.     

Ökonomische Ansätze zur Ökosystembewertung am Beispiel des Bodens

As it is practically impossible in an industrial society to reduce impacts into ecosystems to a level that would preclude any damages, the need for damage valuation arises. One of the available valuation tools is the economic approach. Subsequent publications present this approach using the example of soils. In the first part, soils as part of ecosystems are considered from an ecological and a conventional economic point of view. In the following so-called ecological-economic perspective, more recent developments in economic valuation research are introduced. It is shown how ecological and economic valuation can complement one another. It is emphasized that economic valuations should be restricted to a critical soil structure which, in economic terms, is determined by the non-substitutable services of the ecological asset.     

Near-term forecasts of stream temperature using deep learning and data assimilation in support of management decisions

Deep learning (DL) models are increasingly used to make accurate hindcasts of management-relevant variables, but they are less commonly used in forecasting applications. Data assimilation (DA) can be used for forecasts to leverage real-time observations, where the difference between model predictions and observations today is used to adjust the model to make better predictions tomorrow. In this use case, we developed a process-guided DL and DA approach to make 7-day probabilistic forecasts of daily maximum water temperature in the Delaware River Basin in support of water management decisions. Our modeling system produced forecasts of daily maximum water temperature with an average root mean squared error (RMSE) from 1.1 to 1.4°C for 1-day-ahead and 1.4 to 1.9°C for 7-day-ahead forecasts across all sites. The DA algorithm marginally improved forecast performance when compared with forecasts produced using the process-guided DL model alone (0%–14% lower RMSE with the DA algorithm). Across all sites and lead times, 65%–82% of observations were within 90% forecast confidence intervals, which allowed managers to anticipate probability of exceedances of ecologically relevant thresholds and aid in decisions about releasing reservoir water downstream. The flexibility of DL models shows promise for forecasting other important environmental variables and aid in decision-making.     

Predictors of food-related aggression in wild Assamese macaques and the role of conflict avoidance

The quality, availability and distribution of food resources and their influence on types and levels of feeding competition play a central role in ecological models of female social structure in mammals. Here, we investigate the impact of social and ecological factors on rates of food-related aggression and the use of potential conflict avoidance mechanisms in wild Assamese macaques (Macaca assamensis) in northeastern Thailand. These questions were addressed by examining feeding competition at the level of individual food patches which provides detailed information on resource characteristics, aggression and feeding party composition. Results suggest that the frequency of aggression in food patches increases with increasing feeding group size and decreasing patch size but is not affected by ecological variables representing resource value (abundance and nutritional value of food items in a patch). Interestingly, females appear to employ several mechanisms to avoid direct conflicts, including the use of alternative feeding sites within food patches, delayed arrival at feeding sites, storing food in cheek pouches and co-feeding with individuals they share strong social bonds with. Conflict avoidance may be partially responsible for the absence of a rank-related skew in female energy intake in this population and may explain other cases where empirical data do not fit the predictions of socio-ecological theory. Our findings also inform the debate about the mechanisms generating fitness benefits from strong social bonds by suggesting that by increasing feeding tolerance, social bonds may enhance resource acquisition, reduce the risk of injuries and lower levels of agonism-related stress.     

Dominance rank,female reproductive synchrony,and male reproductive skew in wild Assamese macaques

In groups with multiple males, direct mate competition may select for the evolution of dominance hierarchies that sort males into a queue for access to fertile females. The priority-of-access (PoA) model proposed by Altmann in 1962 makes explicit predictions about the resulting paternity distribution based on an interaction between male dominance rank and the overlap of female receptive phases. Here, we investigated whether the logic of the PoA model predicted the distribution of paternity across ranks in a seasonal breeder with high reproductive synchrony over six consecutive mating seasons. We studied 18 males that resided in a group of wild Assamese macaques (Macaca assamensis) in their natural habitat at Phu Khieo Wildlife Sanctuary, Thailand, between 2006 and 2011 with 5 to 13 conceptions per season. We assessed whether mate guarding increased paternity success, described “short-term” deviations from predicted paternity distribution, and examined how these are related to the number of competitors and fertile females. We determined genetic paternity of 43 (93 %) offspring born into the study group and found reproductive skew to be relatively low with 29 % alpha male paternity in accordance with the high degree of female reproductive synchrony observed. Short-term deviations from expected paternity distribution over ranks were not explained by the number of resident males or the number of conceiving females or their interaction. Within the limits of this study, these results suggest that even if males cannot discern female fertile phases, if reproduction is seasonal, and if reproductive synchrony is high, males may also compete directly over access to females.