The important effects of minerogenic particles delivered from watersheds on optical and phosphorus metrics of lacustrine water quality have recently been quantified through measurements of the projected area of these particles per unit volume of water (PAVₘ), using an individual particle analysis technique. A mass balance type model for PAVₘ, partitioned according to the contributions of four size classes, is developed and tested for Cayuga Lake, New York, supported by long-term monitoring of PAVₘ in the lake and its primary tributaries. The model represents the source of PAVₘ of tributary inputs and three in-lake loss processes: (1) size-dependent settling, (2) enhancement of settling through aggregation, and (3) filter feeding by dreissenid mussels. The central roles of major runoff events and localized external loads of minerogenic sediment at one end of the lake in driving patterns of PAVₘ in time and space are successfully simulated, including (1) the higher PAVₘ levels in a shallow area (“shelf”) adjoining these inputs, relative to pelagic waters, following runoff events; and (2) the positive dependence of the shelf increases on the magnitude of the event. Analyses conducted with the model establish that settling, with aggregation enhancement, dominates the loss of PAVₘ from the water column of the shelf, while mussel filtration increases in relative importance in pelagic waters. The utility of PAVₘ predictions to quantify the effects of these particles on optical and phosphorus concentration metrics of water quality is established.

This paper has its origin via an inadvertent error wherein a length of rubber hose was added to the sampling line of a sulphur gas analyser at the Australian Baseline Station at Cape Grim. This carbon disulphide (CS₂) contamination source was removed after a period of 10 weeks. In the interim, substantial data was collected and is here compared with the record of ambient station temperatures. CS₂ was found to vary with ambient temperature over both short and monthly time scales. Comparisons of linear, natural log (ln) and log₁₀ correlations yield the conclusion that log₁₀ and ln CS₂ emission vs. temperature (°C) associations provide the best correlations. No significant depletion of CS₂ emission from the rubber over a 10-week period was detected. Implications for regional and global emission inventories of CS₂ and carbonylsulphide (COS) are discussed.

Elevated plant-available cadmium (Cd) in soils results in contamination to cacao (Theobroma cacao L) beans. Effectiveness of vermicompost and zeolite in reducing available Cd in three cacao-growing soils was studied under laboratory conditions. Sorption–desorption experiments were conducted in soils and amendments. Cadmium was added at 0 or 5 mg kg⁻¹ (spiked), then, amendments were incorporated at 0, 0.5, or 2 %. Amended soils were incubated at room temperature for 28 days. Plant-available Cd was determined using 0.01 M CaCl₂ (WSE) and Mehlich 3 (M3) extraction procedures in subsamples taken from individual bags at six time intervals. Soils and amendments displayed different sorption characteristics and a better fit was attained with Freundlich model (R ² > 0.82). Amendments were ineffective in reducing extractable Cd in non-spiked soils. In Cd-spiked soils, vermicompost at 2 % significantly reduced WSE-Cd (P < 0.01) from 3.36, 0.54, and 0.38 mg kg⁻¹ to values lower that instrument’s detection in all the three soils and significantly diminished M3-extractable Cd (P < 0.05) from 4.62 to 4.11 mg kg⁻¹ in only one soil. Vermicompost at 0.5 % significantly decreased WSE-Cd (P < 0.01) from 3.04 and 0.31 to 1.69 and 0.20 mg kg⁻¹, respectively, in two soils with low sorption capacity for Cd. In contrast, zeolite failed to reduce WSE- or M3-extractable Cd in all studied soils. A negative correlation occurred between soil pH and WSE-Cd (r > −0.89, P < 0.01). The decrease in WSE-Cd appears to be associated with the increase in pH of the vermicompost-amended soils.

Particulate matter is an air pollutant that has resulted in tremendous health effects to the exposed populace. Air quality forecasting is an established process where air pollutants particularly, particulate matter (PM₁₀) concentration is predicted in advance, so that adequate measures are implemented to reduce the health effect of PM₁₀ to the barest level. The present study used daily average PM₁₀ concentration and meteorological parameters (temperature, humidity, wind speed and wind direction) for 5 years (2006–2010) from three industrial air quality monitoring stations in Malaysia (Balok Baru, Tasek and Paka). Time series plot was used to assess PM₁₀ pollution trend in the industrial areas. Additionally, step wise regression (SWR) analysis was used to predict next day PM₁₀ concentrations for the three industrial areas. The SWR method was compared with a persistence model to assess its predictive capabilities. The results for the trend analysis showed that, Balok Baru (BB) had higher PM₁₀ concentration levels, having high values in 2006, 2007 and 2009. These values were higher than the Malaysian Ambient Air Quality Guideline (MAAQG) of 150 μg/m³. Subsequently, the other two industrial areas Tasek (TK) and Paka (PK) had no record of violating the MAAQG. The results for the SWR analysis had significant R ² values of 0.64, 0.66 and 0.60, respectively. The model performance results for variance inflation factor (VIF) were less than 5 and Durbin-Watson test (DW) had value of 2 for each of the study areas, which were significant. The comparative analysis between SWR and persistence model showed that the SWR had better capabilities, having lower errors for the BB, TK and PK areas. Using root mean square error (RMSE), the results showed error differences of 7, 12 and 16 %, and higher predictability using index of agreement (IA), having a difference of 17, 19 and 16 % for BB, TK, and PK areas, respectively. The results showed that SWR can be used in predicting PM₁₀ next day average concentration, while the extreme event detection results showed that 100 μg/m³ were better detected than the 150 μg/m³ bench marked levels.

Acid rain caused a severe loss on agricultural productivity, aggravating the challenge for achieving sustainable food production to feed the increasing globe population. To clarify the mechanism on adaptation of rice root to acid rain, we studied the root morphology and growth regulated by nutrient absorption under hydroponic conditions. Our results show that acid rain (pH 5.0 or 3.5) increased the density of root hair and root volume by increasing concentrations of K⁺, Na⁺, and Ca²⁺ in rice roots, and the root dry weight was increased. However, strong acid rain (pH 2.5) decreased the root length, surface area, volume, and number of root tips by decreasing the concentrations of K⁺, Na⁺, and Mg²⁺ in rice root, and fresh and dry weight were both decreased. After a 5-day recovery, the root morphology of rice seedlings treated with acid rain (pH 5.0 or 3.5) was recovered to the control levels, and the concentrations of K⁺, Na⁺, Ca²⁺, and Mg²⁺ also had no difference from the control (p < 0.05). However, the root growth treated with strong acid rain (pH 2.5) was still lower than the control because the inhibition on root activity and hydrolytic activity of plasma membrane H⁺-ATPase might have exceeded the self-regulating capacity of rice seedlings, and the absorption of mineral nutrient could not sustain the growth. Hence, we concluded that the adaption of root morphology of rice seedlings to acid rain was related to regulation of mineral nutrient absorption in rice root.

Predicting the soil-to-plant transfer of metals in the context of global warming has become a major issue for food safety. It requires a better understanding of how the temperature alters the bioavailability of metals in cultivated soils. This study focuses on one agricultural soil contaminated by Cd, Zn and Pb. DGT measurements were performed at 10, 20 and 30 °C to assess how the bioavailability of metals was affected by a rise in soil temperature. A lettuce crop was cultivated in the same conditions to determine if the soil-to-plant transfer of metals increased with a rise in soil temperature. A gradual decline in Cd and Zn bioavailability was observed from 10 to 30 °C, which was attributed to more intense complexation of metals in the pore water at higher temperatures. Together with its aromaticity, the affinity of dissolved organic matter (DOM) for metals was indeed suspected to increase with soil temperature. One main output of the present work is a model which satisfactorily explains the thermal-induced changes in the characteristics of DOM reported in Cornu et al. (Geoderma 162:65–70, 2011) by assuming that the mineralization of initial aliphatic compounds followed a first-order reaction, increased with soil temperature according to the Arrhenius law, and due to a priming effect, led to the appearance of aromatic molecules. The soil-to-plant transfer of Cd and Zn was promoted at higher soil temperatures despite a parallel decrease in Cd and Zn bioavailability. This suggests that plant processes affect the soil-to-plant transfer of Cd and Zn the most when the soil temperature rises.

The concentrations and fractions of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in soils collected from Hailuogou Glacier foreland in eastern Tibetan Plateau were analyzed to decipher their mobility, and their eco-risk was assessed combined with multiple environmental indices. The concentrations of Cd were more than ten times higher than its local background in the O horizon and nearly three times higher in the A horizon. The concentrations of Pb and Zn were relatively high in the O horizon, whereas that of Cu increased with soil depth. The main fractions of metals in the surface horizons were reducible and acid-soluble for Cd, oxidizable and residual for Cu, reducible and oxidizable for Pb, and reducible and residual for Zn. The metal mobility generally followed the order of Cd > Pb > Zn > Cu in the O horizon and Cd > Pb > Cu > Zn in the A horizon. Sorption and complexation by soil organic matters imparted an important effect on the mobilization and transformation of Cd, Pb, and Zn in the soils. The oxidizable Cu fraction in the soils showed significant correlation with organic matters, and soil pH mainly modulated the acid-soluble and reducible Cu fractions. The concentrations and other environmental indices including contamination factor, enrichment factor, geoaccumulation index, and risk assessment index revealed that Cd reached high contamination and very high eco-risk, Pb had medium contamination but low eco-risk, Zn showed low contamination and low eco-risk, and Cu was not contaminated in the soils. The data indicated that Cd was the priority to concern in the soils of Hailuogou Glacier catchment.

Biochars from two different feedstocks (peanut shell-PB; wheat straw-WB) were used in this study to understand the sorption mechanisms of atrazine (ATR), 17α-ethinyl estradiol (EE2), and phenanthrene (PHEN) to help minimize the bioavailability of the organic pollutants in the environment. Sorption isotherms of ATR, EE2, and PHEN by WB and PB biochars followed the Freundlich model where the sorption parameter (n) shows the trend: ATR > EE2 and PHEN, while the sorption capacity (log K ₒc) increases from ATR < EE2 < PHEN and indicate that the most hydrophobic and planar organic pollutant (PHEN) is the most easily adsorbed organic compound on PB and WB. The higher H/C and (O + N)/C ratios of WB (0.099 and 0.525, respectively) suggest its stronger aliphaticity and polarity than PB (0.078 and 0.352, respectively) that induced stronger sorption affinity for ATR and PHEN. Higher specific surface area (m² g⁻¹) of PB (19.7) may be responsible for the higher sorption capacity for EE2 than WB (8.8) because it can accommodate the large molecule of EE2. Results from this study may be helpful to predict the bioavailability of organic pollutants when soils contaminated with pollutants are remediated with biochars produced from wheat straw and peanut shells.

Hexavalent chromium (VI) in wastewater is a great risk to human health and to the quality of water sources. However, adapted microorganisms can rapidly reduce this chemical species to the trivalent form (III) and make it less active. Our objective was to evaluate the capacity of bacterial isolates for Cr (VI) reduction in nutrient medium and in effluent and to compare indigenous microorganisms with those isolated from wastewater contaminated with Cr (VI). Cr (VI) reduction was also tested with different sources of carbon, nitrogen, and phosphorus at two temperatures (10 and 30 °C). Initially, the resistant microorganisms were isolated from the solution with 100 mg L⁻¹ of Cr (VI). Subsequently, we evaluated the effectiveness of the isolates in reducing Cr (VI) I in culture medium under temperature-controlled conditions, with concentrations of 10 and 100 mg L⁻¹ of Cr (VI). In the subsequent step, we studied the isolates and autochthonous microorganism efficiency to reduce Cr (VI) present in contaminated effluent, with the addition of nutrients and at different temperatures (10 and 30 °C). In the culture medium containing 10 mg L⁻¹ of Cr (VI), isolates were reduced by 100 % in 48 h. When tested against 100 mg L⁻¹ of Cr (VI), the decrease was 70 and 40 % at 120 h of incubation of the isolates 6 and 11, respectively. In the effluent, there was no significant reduction without nutritional biostimulation. When carbon and phosphorus were applied, isolates 6, 11, and indigenous microorganisms reduced 100 % of the Cr (VI) in 72 h. Nitrogen was not limited in terms of effluent characteristics. At 10 °C incubation temperature, Cr (VI) was completely reduced but slower compared to incubation at 30 °C. The results demonstrate that nutritional biostimulation aided by bioremediation is an excellent tool for reducing hexavalent chromium in wastewater.