Monitoring the amount and composition of airborne particulate matter (PM) in the urban environment is a crucial aspect to guarantee citizen health. To focus the action of stakeholders in limiting air pollution, fast and highly spatially resolved methods for monitoring PM are required. Recently, the trees’ capability in capturing PM inspired the development of several methods intended to use trees as biomonitors; this results in the potential of having an ultra-spatially resolved network of low-cost PM monitoring stations throughout cities, without the needing of on-site stations. Within this context, we propose a fast and reliable method to qualitatively and quantitatively characterize the PM present in urban air based on the analysis of tree leaves by scanning electron microscopy combined with X-ray spectroscopy (SEM/EDX). We have tested our method in the Real Bosco di Capodimonte urban park (Naples, Italy), by collecting leaves from Quercus ilex trees along transects parallel to the main wind directions. The coarse (PM₁₀–₂.₅) and fine (PM₂.₅) amounts obtained per unit leaf area have been validated by weighting the PM washed from leaves belonging to the same sample sets. PM size distribution and elemental composition match appropriately with the known pollution sources in the sample sites (i.e., traffic and marine aerosol). The proposed methodology will then allow the use of the urban forest as an ultra-spatially resolved PM monitoring network, also supporting the work of urban green planners and stakeholders.

The simulation of snowmelt runoff in alpine mountainous areas is of great significance not only for the risk assessment of snowmelt flood in spring and summer, but also for the development and management of water resources in the basin. An improved snowmelt runoff model (SRM) is constructed based on the analysis of change characteristics of climate, runoff, and snow and ice cover in the middle and upper reaches of the Taxkorgan River in Xinjiang Province, China. Because of the large evaporation in the study basin, the evaporation loss is added to the model. The SRM and the improved SRM are calibrated and verified by using data such as temperature, precipitation, water vapor pressure, and snow-covered area (SCA) ratio in the study basin from 2002 to 2012. The results show that, compared with the SRM, the average Nash–Sutcliffe coefficient (NSE) of annual runoff simulation increases from 0.80 to 0.86 in the calibration and increases from 0.74 to 0.83 in the validation through the improved model, and the average runoff error reduces from − 12.8 to 1.32% in the calibration and reduces from − 20.0 to − 11.51% in the validation. After adding the measured flow rate for real-time correction, the average NSE of annual runoff simulation increases from 0.91 to 0.93 and the average annual runoff error reduces from − 7.76 to − 3.91% in the calibration. The average NSE increases from 0.85 to 0.89 and the average runoff error reduces from − 12.35 to − 2.76% in the validation. It indicates that the SRM structure with increased evaporation loss is more in line with the actual situation. The short-term simulation effect of the model is greatly improved by adding the measured flow rate for real-time correction. At the same time, the improved SRM and the hypothetical climate change scenario are used to analyze the impact analysis of the snowmelt runoff simulation in the partial wet year. The results show that in the case of rising temperature, the ice and snow ablation period is prolonged, and the annual runoff also changes significantly in time distribution. It is of guiding significance for the influence of climate change on the runoff of recharged rivers with ice–snow meltwater in the other alpine regions.

This study critically evaluates two COP proposals on Malaysia that have been under consideration to reduce climate damage. A top-down disaggregation framework deploying an “Empirical Regional Downscaling Dynamic Integrated Model of Climate and the Economy” is used to evaluate the local government climate roadmap and Malaysia’s emissions reduction agendas under COP21 and subsequently COP22 proposals. The findings show that the costs from climate damage over the period 2010–2110 under the Malaysian Optimal Climate Action scenario will amount to MYR5,483 (US$1589) billion. The commensurate climate damage costs under the COP21 and COP22 scenario would be MYR5, 264 (US$1526) billion. Thus, the effective proposal for reducing climate damage in Malaysia over the period 2010–2110 is the COP22 time-adjusted COP21 proposal but there are a number of macroeconomic cost implications for savings and consumption that policy makers must address before acting.

An incubation experiment was conducted to investigate whether the type of crop straw added to soil influenced the temperature sensitivity of soil microbial respiration. The soil for incubation was collected from a winter wheat-soybean rotation cropland. Five temperature levels (5, 10, 15, 20, and 25 °C), five crop straw types (soybean, peanut, rice, winter wheat, and maize), and a control (CK, no crop straw addition) were established. Soil microbial respiration rates were measured on days 1, 2, 3, 5, 7, 10, 14, 20, and 27 after crop straw addition using an infrared CO₂ analyser. Soil enzyme activities of invertase, urea, and catalase and the dissolved organic carbon (DOC) content were measured after incubation. Estimated Q₁₀ (temperature sensitivity of soil microbial respiration) ranged from 1.472 ± 0.045 to 1.970 ± 0.020 and showed no significant (P > 0.05) difference between straw addition treatments, but there was significantly (P < 0.001) higher temperature sensitivity (1.970 ± 0.020) for CK. A significant (P = 0.002) relationship was found between the Q₁₀ of cumulative soil microbial respiration and basal soil microbial respiration (soil microbial respiration at 0 °C). Moreover, a marginally significant (P < 0.1) relationship was found between the Q₁₀ at different incubation stages and basal soil microbial respiration. A quadratic function was used to explain the relationship between estimated basal microbial respiration and the lignin content. Soil microbial respiration was positively correlated with the activities of invertase, urease, and catalase and the dissolved organic carbon (DOC) content in all treatments. This study indicated that crop straw addition significantly (P < 0.001) reduced the Q₁₀ of soil microbial respiration and that the types of crop straw added to soil did not significantly (P > 0.05) change the Q₁₀ value.

In this work, trace determination of nitrite in river water samples was studied using solvent stir bar microextraction system with three-hollow fiber configuration (3HF-SSBME) as a preconcentration step prior to UV–Vis spectrophotometry. The obtained results showed that the increase in the number of solvent bars can improve the extraction performance by increasing the contact area between acceptor and sample solutions. The extraction process relies on the well-known oxidation–reduction reaction of nitrite with iodide excess in acidic donor phase to form triiodide, and then its extraction into organic acceptor phase using a cationic surfactant. Various extraction parameters affecting the method were optimized and examined in detail. Detection limit of 1.6 μg L⁻¹ and preconcentration factor of 282 can be attained after an extraction time of 8 min under the optimum conditions of this technique. The proposed method showed a linear response up to 1000 μg L⁻¹ (r² = 0.996) with relative standard deviation values less than 4.0%. The accuracy of the developed method was assessed using the Griess technique. Finally, the proposed method was successfully employed for quantification of nitrite in river water samples (Ghezelozan, Zanjan, Iran).

Phosphate solubilizing bacteria (PSB) can convert insoluble forms of phosphorus (P) to accessible forms. 11 strains of PSB, including five inorganic phosphate solubilizing bacteria (IPSBs) and six organic phosphate solubilizing bacteria (OPSBs), were isolated from rhizosphere soils of three plants Scirpus planiculmis, Zizania latifolia, and Phrnagmites australis in the Yeyahu Wetland of Beijing, China to investigate P-solubilizing activities. In addition, the distributions of P fractions in soil samples were also observed. All strains evaluated above 1.0 by the ratio of transparent circle diameter to colony diameter (D/d) on Ca₃(PO₄)₂ or lecithin plates were identified by 16S rRNA sequencing. Results showed that Ca-bound P (Ca-P) was the main species of inorganic P (IP), and highly resistant organic P (HR-OP) accounted for the most part of organic P (OP). These strains were identified as bacterial species of Enterobacter asburiae, Acinetobacter sp., Bacillus cereus strain, and so on. The most efficient IPSB strain could convert over 430 mg L⁻¹ orthophosphate, while the equivalent OPSB strain only liberated less than 4 mg L⁻¹ in liquid culture, which indicated that IPSBs have a better P-solubilizing ability than OPSBs in rhizosphere soils of the Yeyahu Wetland and IPSBs are likely to regulate the P transformation process in this wetland. Graphical abstract ᅟ

Design and synthesis of arsenic adsorbents with high performance and excellent stability has been still a significant challenge. In this study, we anchored nano-zero-valent iron (NZVI) on the surface of graphene-silica composites (GS) with high specific surface area, forming the NZVI/GS nano-composite. The prepared nano-materials were used to remove As(III) and As(V) through adsorption from aqueous solutions. The results indicated that NZVI particles were dispersed well on the surface of GS, and the NZVI/GS showed great potential to remove As(III) and As(V). Adsorption performance of NZVI/GS for As(III) and As(V) highly depended on the pH of solutions. The experimental data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm model. The calculated maximum adsorption capacities of NZVI/GS for As(III) and As(V) were up to 45.57 mg/g and 45.12 mg/g at 298 K, respectively, and the adsorption equilibrium could be reached within 60 min. The residual concentrations of As(III) and As(V) after treatment with 0.4 g/L NZVI/GS can meet with the drinking water standard of WHO when the initial concentrations were below 4 mg/L and 3 mg/L, respectively. Moreover, the as-prepared NZVI/GS had excellent anti-interference ability during the process of As removal in the presence of foreign ions. During the As removal process, As(III) was oxidized to As(V), which could be removed through adsorption by electrostatic attraction and complexation. These results indicated that the as-synthesized NZVI/GS composite is a promising adsorbent for the removal of arsenic from aqueous solutions.

South Asia is susceptible to drought due to high variation in monthly precipitation. The drought indices deriving from remote sensing data have been used to monitor drought events. To secure agricultural land in South Asia, timely and effective drought monitoring is very important. In this study, TRMM data was utilized along with remote sensing techniques for reliable drought monitoring. The Drought Severity Index (DSI), Temperature Vegetation Drought Index (TVDI), NDVI, and Normalized Vegetation Supply Water Index (NVSWI) are more helpful in describing the drought events in South Asia due to the dryness and low vegetation. To categorize drought-affected areas, the spatial maps of TRMM were used to confirm MODIS-derived TVDI, DSI, and NVSWI. The DSI, TVDI, NVSWI, and Normalized Monthly Precipitation Anomaly Percentage (NAP) indices with an integrated use of MODIS-derived ET/PET and NDVI were selected as a tool for monitoring drought in South Asia. The seasonal DSI, TVDI, NVSWI, NAP, and NDVI values confirmed that South Asia suffered an extreme drought in 2001, which continued up to 2003. The correlation was generated among DSI, NAP, NVWSI, NDVI, TVDI, and TCI on a seasonal basis. The significantly positive correlation values of DSI, TVDI, and NVSWI were in DJF, MAM, and SON seasons, which were described as good drought monitoring indices during these seasons. During summer, the distribution values of drought indicated that more droughts occurred in the southwest regions as compared to the northeast region of South Asia. From 2001 to 2017, the change trend of drought was characterized; the difference of drought trend was obviously indicated among different regions. In South Asia, generally, the frequency of drought showed declining trends from 2001 to 2017. It was verified that these drought indices are a comprehensive drought monitoring indicator and would reduce drought risk in South Asia.

Advanced oxidation processes (AOPs) have been highly efficient in degrading contaminants of emerging concern (CEC). This study investigated the efficiency of photolysis, peroxidation, photoperoxidation, and ozonation at different pH values to degrade doxycycline (DC) in three aqueous matrices: fountain, tap, and ultrapure water. More than 99.6% of DC degradation resulted from the UV/H₂O₂ and ozonation processes. Also, to evaluate the toxicity of the original solution and throughout the degradation time, antimicrobial activity tests were conducted using Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, and acute toxicity test using the bioluminescent marine bacterium (Vibrio fischeri). Antimicrobial activity reduced as the drug degradation increased in UV/H₂O₂ and ozonation processes, wherein the first process only 6 min was required to reduce 100% of both bacteria activity. In ozonation, 27.7 mg L⁻¹ of ozone was responsible for reducing 100% of the antimicrobial activity. When applied the photoperoxidation process, an increase in the toxicity occurred as the high levels of degradation were achieved; it means that toxic intermediates were formed. The ozonated solutions did not present toxicity.

Plantago lanceolata L. is a common grassland and roadside plant, widely used in many countries in food and herbal preparations. In this study, samples of this wild plant were collected from rural, suburban/urban, and industrial environments; the concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, P, Pb, V, and Zn were measured in the edible parts of the plant (leaves), in the roots, and in the soils in order to calculate the bioaccumulation and translocation factors. The data obtained were compared with literature data available. Except for samples collected near mines and smelting plants, where Cd, Pb, and Zn concentrations were up to 15 times higher, in all other cases, no differences were observed with respect to samples from rural areas, except for Pb concentration, which was 3 times higher in urban areas. In the samples collected in our study area, the metal content does not pose particular health risks; however, even within a quite restricted region like the investigated area, high metal concentrations, possibly due to the presence of particular substrates, were observed in some samples collected from areas considered “clean” and suitable for wild food plant gathering.