Nitrate (NO₃ ⁻) contamination of freshwater is considered one of the most prevalent global environmental problems. Dual stable isotopic compositions (δ¹⁵N and δ¹⁸O) of NO₃ ⁻ can provide helpful information and have been well documented as being a powerful tool to track the source of NO₃ ⁻ in freshwater ecosystems. The ion-exchange method is a reliable and precise technique for measuring the δ¹⁵N and δ¹⁸O of NO₃ ⁻ and has been widely employed to collect NO₃ ⁻ from freshwater ecosystems. This review summarizes and presents the principles, affecting factors and corresponding significant improvements of the ion-exchange method. Finally, potential improvements and perspectives for the applicability of this method are also discussed, as are suggestions for further research and development drawn from the overall conclusions.

In this study, a pot experiment was conducted to evaluate the effect of phosphate (PO₄ ³⁻) addition on iron (Fe) cycling in mangrove ecosystem. Kandelia obovata (S. L.), one of the dominant mangrove species in the southeast of China, was cultivated in rhizoboxes under three different levels of P concentrations. Results showed the solid-phase Fe distribution and Fe(II)/Fe(III) values in both the root zone (rhizosphere) and bulk soil (non-rhizosphere) were comparable among all P levels (p > 0.05); P addition significantly decreased the pore water Fe content both in the rhizosphere and non-rhizosphere zone (p < 0.05); higher amount of reactive Fe was found in rhizosphere sediments, while in the non-rhizosphere sediments, higher concentration of crystalline Fe was determined; P significantly increased iron plaque formation and iron accumulation in K. obovata (S. L.) tissues (p < 0.05); P addition increased K. obovata (S. L.) biomass and chlorophyll content. It was suggested that P is implicated in the Fe cycling in mangrove plants; more reactive iron, higher abundance of root Fe-reducing bacteria (FeRB) and Fe-oxidizing bacteria (FeOB), and together with higher amount of K. obovata (S. L.) root organic acids exudation result in a rapid Fe cycling in rhizosphere, which contribute to comparable solid-phase iron distribution among different P levels.

Fish is a major source for the intake of polybrominated diphenyl ethers (PBDEs). However, fish is scarcely consumed without being cooked, and previous studies showed that the heating of salmon fillet contaminated with BDE-209 for longer periods of time was accompanied with the partial transformation of this brominated flame retardant. In this study, we heated salmon fillet spiked with BDE-209 and verified that this process was linked with the formation of polybrominated dibenzofurans (PBDFs) in the fish. Each minute of heating 1 g salmon fillet spiked with 200 ng BDE-209 generated about 0.5 ‰ PBDFs relative to the initial amount of the pre-dioxin BDE-209. This result of the chemical analysis by gas chromatography with mass spectrometry (GC/MS) was verified by means of an effect-directed bio-assay (DR CALUX). While unheated salmon with BDE-209 and heated salmon without BDE-209 were tested nontoxic, the bioanalytical response of fish linearly increased upon heating. We also found that PBDF formation did neither occur with BDE-47 nor when BDE-209 was heated in edible oil instead of salmon fillet. Due to the formation of PBDFs in this process, the consumption of heated, BDE-209 contaminated fish may add to the uptake of dioxin-like compounds with our diet.

In Hungary, the dam of a red mud reservoir breached shortly after noon on October 4, 2010. Approximately 0.7–1 million m³ highly alkaline red mud with very low dry matter content flowed into the Torna Creek and the surrounding area, covering 1017 ha of agricultural land. Results of the risk assessment of the accident indicated that the red mud should be removed from the surface of fields where it formed a continuous layer of more than 5 cm. After the removal, samples were taken manually from depths of 0.0–0.2 m and 0.2–0.4 m in a sampling grid and background samples unaffected by red mud from the depth of 0.0–0.3 m. Total element contents (Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sn, Zn, and Na) and pH values were measured, and the results were analysed using correlation analysis and the Kruskal–Wallis probe. Dependence of the measured variables from elevation above sea level was studied using a 10 m by 10 m digital elevation model. Only ∼6.5 % of the flooded area was temporarily designated as unsuitable for the production of food and fodder crops. In summary, the clean-up operation can be said to have been a success.

Links between environmental chemicals and human health have emerged, but the effects on self-rated health were less studied. Therefore, it was aimed to study the relationships of different sets of urinary environmental chemicals and the self-rated health in a national and population-based study in recent years. Data was retrieved from the US National Health and Nutrition Examination Surveys, 2011–2012, including demographics, serum measurements, lifestyle factors, self-rated health (with two grouping approaches) and urinary environmental chemical concentrations. T test and survey-weighted logistic regression modeling were performed. Among American adults aged 12–80 (n = 6833), 5892 people had reported their general health condition. Two thousand three hundred sixty-nine (40.2 %) people reported their general health condition as excellent or very good while 3523 (59.8 %) reported good, fair, or poor. People who reported their general health condition as good, fair, or poor had higher levels of urinary arsenic, heavy metals (including cadmium, cobalt, manganese, molybdenum, lead, antimony, strontium, tungsten and uranium), phthalates, pesticides and polyaromatic hydrocarbons but lower levels of benzophenone-3 and triclosan. There were no associations with urinary parabens, perchlorate, nitrate, thiocyanate or polyfluorinated compounds. However, only urinary cadmium, benzophenone-3, triclosan, and 2-hydroxynaphthalene remained significant when comparing between “good to excellent” and “poor to fair.” This is the first time observing risk associations of urinary arsenic, heavy metal, phthalate, pesticide, and hydrocarbon concentrations and self-rated health in people aged 12–80, although the causality cannot be established. Further elimination of these environmental chemicals in humans might need to be considered in health and environmental policies.

The perchlorate reduction kinetic parameters of a microbial consortium using elemental sulfur (S⁰) as an electron donor were investigated in batch experiments. Standard Monod substrate utilization and biomass accumulation models were employed to fit the experimental data for microbial perchlorate reduction. The maximum observed yield coefficient for the microbial consortium was 0.19 mg dry weight (DW) mg⁻¹ ClO₄ ⁻, suggesting that the microbial consortium had a slow growth rate using S⁰ as the electron donor. The maximum specific substrate utilization rate (q ₘₐₓ) and half saturation constant (K ₛ) for microbial perchlorate reduction were 0.14 mg ClO₄ ⁻ mg⁻¹ DW day⁻¹ and 5.71 mg L⁻¹, respectively, which indicated that the microbial consortium could effectively utilize perchlorate as an electron acceptor. The variation of q ₘₐₓ with pH was described well by using a Gaussian peak equation, and the maximal value of q ₘₐₓ was obtained at pH 6.7. The presence of nitrate in perchlorate-contaminated water delayed the onset of sulfur autotrophic perchlorate reduction. The modified Gompertz equation could adequately describe the formation of Cl⁻ and SO₄ ²⁻ during the process of sulfur autotrophic perchlorate reduction. The SO₄ ²⁻ production exceeded the theoretical SO₄ ²⁻ production due to S⁰ disproportionation. The kinetic parameters for microbial perchlorate reduction are essential to design biological treatment systems, as well as to predict and evaluate their performance.

Sorption-desorption behavior of six pesticides and some degradation products was assessed on seven agricultural volcanic and nonvolcanic soils belonging to Andisol, Ultisol, Mollisol, and Alfisol orders. The global interpretation of sorption data was performed by principal component analysis. Results showed exceptionally high sorption of glyphosate and aminomethylphosphonic acid (AMPA) (the breakdown product) on volcanic soils (K f > 1500 μg¹ ⁻ ¹ / ⁿ mL¹ / ⁿ g⁻¹) related mainly to contents of amorphous aluminum oxides (Andisols) and crystalline minerals (Ultisols). The lower sorption on nonvolcanic soils was associated to low organic matter contents and lack of significant minerals. Metsulfuron-methyl and 3,5,6-trichloro-2-pyridinol (metabolite of chlorpyrifos) were weakly to substantially sorbed on Andisols and Ultisols, but the first one was not sorbed at pH > 6.4, including nonvolcanic soils. The metabolite of diazinon, 2-isopropyl-4-methyl-6-hydroxypyrimidine, was weakly sorbed on all soils (K f = 0.4 to 3.6 μg¹ ⁻ ¹ / ⁿ mL¹ / ⁿ g⁻¹). Acidic compounds would be lixiviated in Mollisols and Alfisols, but they could leach also in Andisols and Ultisols if they reach greater depths. Atrazine and deethylatrazine sorption was related to organic carbon content; therefore, they were weakly retained on nonvolcanic soils (K f = 0.7 to 2.2 μg¹ ⁻ ¹ / ⁿ mL¹ / ⁿ g⁻¹). Chlorpyrifos was highly sorbed on all soils reaching K OC values of >8000. Finally, the significant retention of chlorothalonil and diazinon on Mollisols and Alfisols in spite of their low OC contents showed the contribution of clay minerals in the sorption process.

Watershed sediment fluxes and reservoir sediment accumulation rates were analyzed in two contrasting reservoir systems in central and western Virginia. Lake Pelham, located in the Piedmont geologic province, is a human-impacted reservoir with a watershed dominated by agricultural, residential and industrial land uses. Conversely, Lake Moomaw has a largely undeveloped watershed characterized by very steep slopes and forested land use located in the Valley and Ridge province. The Revised Universal Soil Loss Equation (RUSLE) and sediment delivery ratios (SDRs) were used to estimate soil losses in the two watersheds. Bathymetric and sediment accumulation surveys of the two reservoirs were also conducted using a multi-frequency hydroacoustic surveying system. The RUSLE/SDR erosion model estimates 2150 kg ha⁻¹ year⁻¹ for Lake Pelham and 2720 kg ha⁻¹ year⁻¹ for Lake Moomaw, a 410 and 13 % increase from assumed pristine (100 % forested) land use for the respective basins. Mean sediment accumulation rates of 1.51 and 0.60 cm year⁻¹ were estimated from the hydroacoustic survey of Lake Pelham and Lake Moomaw, respectively. Overall, Lake Moomaw has relatively low sediment accumulation rates; however, the reservoir is vulnerable to increases in sediment fluxes with further human development due to the steep slopes and highly erodible colluvial soils that characterize the basin. Higher erosion and sediment accumulation rates in Lake Pelham are most likely reflecting the impact of human development on sedimentation processes, where the loss of vegetal buffers and increase in impervious surfaces exacerbates both the surficial soil losses as well as intrinsic stream sediment production leading to the current annual reservoir capacity loss of 0.4 %.

The distribution of Paraquat dichloride in different matrices of Warri River, Western Niger Delta, Nigeria was examined. The samplings and physicochemical parameters of the river were carried out during the dry and wet seasons, and stations were visited on monthly basis. The downstream stations had significant (p < 0.05) higher values than the control station. Seasonal variation revealed that, in water, the pesticide level was higher in the dry season than in wet season, and there was no significant difference between the seasons (p > 0.05). The reverse was the case for sediments and fish. The physicochemical parameters of the river’s water were within the recommended limits accepted by Federal Environmental Protection Agency, Nigeria. The observed Paraquat dichloride concentrations were above ecological bench, an observation that calls for regular monitoring and strict law enforcement to develop a strategy to manage environmental hazards and to improve environmental protection of this area.

The non-tanned proteinaceous tannery solid waste animal fleshing (ANFL), containing high nutritive value, was hydrolyzed using bacteria Selenomonas ruminantium HM000123 through submerged (SmF) and solid-state (SSF) fermentation processes. In addition, the effects of ANFL fermentative hydrolysate on growth, yield and biochemical properties of tomato plants were investigated. The treatments included T1 (SmF-ANFL), T2 (SSF-ANFL), T3 (recommended dose of NPK fertilizers) and a control without any amendment. Hydrolysates of both SmF-ANFL and SSF-ANFL treatments increased the biomass and yield as evidenced by plant height, stem girth, number of leaves and fruit yield when compared with both NPK and control plants. In this 90-day study, significant (p ≤ 0.05) changes were observed in SSF-ANFL treated plants compared to the other treatments. Protein profile analyzed through SDS-PAGE indicates the expression of a high molecular weight protein (205 kDa) and other proteins in the leaves of the SSF-ANFL treated plants. Overall results revealed that SSF-ANFL can be successfully utilized as a fertilizer particularly for cultivating tomato plants.