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Accordingly, the result of water quality index (WQI) revealed that the groundwater in the Guilan aquifer could categorize from excellent to poor quality classes. However, the majority of water samples in Astaneh region mostly fall into the poor water class. The calculation of corrosiveness and scaling indices as Ryznar stability index (RSI) illustrated that a large number of the samples could be classified into aggressive and very aggressive categories. The results additionally showed that tendency to form scale based on Puckorius scaling index (PSI) was observed in some groundwater samples. Overall, the status of groundwater quality in Talesh region was noteworthy better than the other studied regions, while Astaneh region is more vulnerable with elevated contents of ions and physicochemical parameters.To evaluate the hazard assessment of anthropogenic activities on coastal ecosystems, fractionation and bioaccumulation of trace metals were carried out for sediment and coral samples of three distinct habitats including petroleum exploration area of Kharg, the rural harbor of Chirouyeh, and unpopulated area of Hendorabi. Fractionation results suggested that Ni (~ 51%), Pb (~ 49%), and V (~ 45%) in Kharg; Ni (~ 46%), Pb (~ 84%), and Zn (~ 47%) in Chirouyeh; and Cd (~ 51%) in Hendorabi were the predominant metals in the non-resistant fractions of the sediment samples. Risk Assessment Code (RAC), individual contamination factor (ICF), and global contamination factor (GCF) were derived. The highest relative risk for Cd, Cu, and Ti was observed in Kharg, whereas the highest relative risk for Ni, Pb, V, and Zn was recorded in Chirouyeh. The lowest risk for almost all of the trace metals was observed in Hendorabi. Biota-sediment accumulation factor (BSAF) values of coral samples revealed that species examined in the present study are reliable biomonitors for Cd, Ni, Pb, and Zn contamination. Principal component analysis (PCA) and Pearson’s correlation coefficient (PCC) suggested that Pb, Ni, and Zn can be considered the main pollutants of the Persian Gulf which originated mainly from petroleum industries. Furthermore, the metal uptake rates of coral samples seemed to be dependent on bioabsorption pathways and coral species. Overall, the present work constitutes a good basis for further studies on trace metal fractionation, risk assessment, and source apportionment in the Persian Gulf, which could contribute to more effective decisions for reducing the anthropogenic trace metal pollution.Biochar has been found to be a potentially suitable amendment for landfill cover material and agricultural soil. The addition of biochar can improve the physical (e.g., adsorption capacity) and hydrological properties (e.g., water/gas permeability) of soil. selleck inhibitor However, no experimental study is available about the effect of biochar content (BC) on the gas diffusion coefficient (DP) of soil. The present study investigated the effect of BC on DP under different degree of compaction (DOC; 85%, 90%, and 95%) and soil air contents (SAC; 5%, 10%, and 15%). It was found that DOC and BC had negligible effects on DP when SAC was low (~ 5%). In contrast, when the SAC was relatively high (~ 15%), soil with DOC of 85% had the largest DP for BC ranging from 0 to 15% (w/w). Only when the SAC was large (~ 15%), the addition of biochar generally increased DP.Arsenic is among the major drinking water contaminants affecting populations in many countries because it causes serious health problems on long-term exposure. Two low-cost micro-sized iron oxyhydroxide-based adsorbents (which are by-products of the industrial production process of granular adsorbents), namely, micro granular ferric hydroxide (μGFH) and micro tetravalent manganese feroxyhyte (μTMF), were applied in batch adsorption kinetic tests and submerged microfiltration membrane adsorption hybrid system (SMAHS) to remove pentavalent arsenic (As(V)) from modeled drinking water. The adsorbents media were characterized in terms of iron content, BET surface area, pore volume, and particle size. The results of adsorption kinetics show that initial adsorption rate of As(V) by μTMF is faster than μGFH. The SMAHS results revealed that hydraulic residence time of As(V) in the slurry reactor plays a critical role. At longer residence time, the achieved adsorption capacities at As(V) permeate concentration of 10 μg/L (WHO guideline value) are 0.95 and 1.04 μg/mg for μGFH and μTMF, respectively. At shorter residence time of ~ 3 h, μTMF was able to treat 1.4 times more volumes of arsenic-polluted water than μGFH under the optimized experimental conditions due to its fast kinetic behavior. The outcomes of this study confirm that micro-sized iron oyxhydroxides, by-products of conventional adsorbent production processes, can successfully be employed in the proposed hybrid water treatment system to achieve drinking water guideline value for arsenic, without considerable fouling of the porous membrane. Graphical abstract.The interactions between Cd and Zn in their effects on plants are inconsistent and difficult to predict. A hydroponic experiment was conducted to investigate the effects of Cd and Zn and their interactions on root morphology and metal translocation in two populations of Hylotelephium spectabile (Boreau) H. Ohba (Crassulaceae, HB1 and HB2). Both populations showed relative tolerance to high levels of Cd and Zn, except that the leaf biomass of HB1 significantly decreased by 44.6% with 5-mg/L Cd plus 10-mg/L Zn. Root growth was inhibited in both populations by addition of 20-mg/L Zn under Cd stress, while 10-mg/L Zn showed little impact on the root growth inhibition of HB2. Roots with diameter 0.1-0.4 mm contributed most of the total root length (RL) and root surface area (RSA) of H. spectabile. In both populations, these root parameters showed greater suppression with the combined stress of Cd plus Zn than under Cd or Zn single stress, except by adding 10-mg/L Zn under Cd stress. Moreover, HB2 maintained relatively higher RL and RSA than HB1 under the different treatments, which implied that HB2 might possess a more effective mechanism than HB1 for coping in response to Cd and Zn stress. The addition of Zn not only affected the absorption of Cd but also significantly affected the distribution of Cd in different tissues of H. spectabile. A low level of Zn led to increased Cd in the stem of HB2, but an increase in Cd in the leaf and root of HB1. Addition of 10-mg/L Zn led to a significant increase by 188% and 170% in Cd accumulation in aboveground part of HB2 under 2- and 5-mg/L Cd stress, whereas the addition of Zn had little effect on Cd accumulation in HB1. Thus, strong positive interactions of Cd and Zn occurred in HB2, which showed great potential for application in phytoremediation of soil contaminated with both Cd and Zn, warranting further investigation under field condition.