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Riparian zones are essential to preserve water quality of rivers adjacent to large areas of irrigated agriculture. We used HYDRUS (2D/3D) to quantify the long-term (8 years) influence of crops (almonds, wine grapes and potato-carrot) irrigated with recycled water on water and solute exchange at the Gawler River interface in relation to vegetation buffer widths from 10 to 110 m. We found that under almond and annual horticulture the likely average annual water flow from the irrigated area to the river was nearly twice as much (2.1 and 1.8, respectively) that under wine grapes. The hydraulic exchange at river interface for different irrigated crops was found to be sensitive to the buffer widths. For wine grapes, almonds and annual horticulture, the average annual hydraulic balance reached an equilibrium at 20, 65 and 55 m buffer widths, respectively. Furthermore, for wine grapes, with a 20 m buffer width, the average annual load of salts became negligible. This study shows that buffer widths of 20, 60, and 40 m for irrigated wine grapes, almond, and annual horticulture, respectively, are needed to restrict the migration of salts to the river. Further refinements are possible by incorporating the influence of preferential flow paths, improved water stress response functions, and addressing the data limitations for calibration of the model for solute dynamics.

A survey was conducted in eight secondary schools located in two watersheds in Gujarat and Rajasthan (semi-arid region of India) to assess students' perceptions about groundwater scarcity issues and the impact of the scarcity on their educational opportunities. Survey responses to a detailed questionnaire by a cohort of students in both watersheds; school attendance records of year 8 class students (13-14 years old) and responses gathered via a socio-economic survey involving 500 families in the study area were used in the study. In both watersheds, >90% students identified groundwater scarcity as a major issue. Required to work at home or farm, about 65% students in Gujarat and 60% in Rajasthan missed school for up to 2 days/month; and a smaller proportion (~ 30%) missed schools for 4 or more days/month. School absenteeism was found to be linked with gender; female students missed schools more frequently than their male counterpart. The school attendance records in Rajasthan showed that the frequency of female students missing schools for 5 or more days/month was on an average 2-10 times greater than that for males. The gender difference in absenteeism in all schools was statistically significant (P < 0.018**). The study highlighted that groundwater scarcity in the study area, and consequent demand on their time for household work including fetching drinking water are contributing factors towards limiting their educational and economic opportunities. Groundwater scarcity can be one of the key factors that can limit inclusiveness and empowerment of women and need to be considered in policy-making.

The abiotic protection of low molecular weight organic compounds (LMWOC) in soils may be an important regulator of C cycling. The study of the protection of LMWOC through sorption typically employs soils shaken in solution, which may be compromised by biological activity. We used [sup.14]C-labelled glucose as a LMWOC in batch assays of four different soils with contrasting physico-chemical properties (Arenosol, Luvisol, Ferralsol and Andisol). The commonly used biocides Na[N.sub.3] and Hg[Cl.sub.2] were employed alone or in concert across a range of concentrations to assess their efficacy in inhibiting microbial degradation. For short ( Additional keywords: abiotic process, LMWOCs, mercuric chloride, radiolabelled compounds, sodium azide, soil organic matter., Introduction The presence of low molecular weight organic compounds (LMWOCs), such as amino acids and carbohydrates, in soil is attributed to root exudation and turnover (Farrar et al. 2003; Boddy [...]

The application of biochar technology for soil amendment is largely based on evidence about soil fertility and crop productivity gains made in the Amazonian Black Earth (term preta). However, the uncertainty of production gains at realistic application rates of biochars and lack of knowledge about other benefits and other concerns may have resulted in poor uptake of biochar technology in Australia so far. In this review, we identify important opportunities as well as challenges in the adoption of biochar technology for broadacre farming and other sectors in Australia. The paper highlights that for biochar technology to be cost-effective and successful, we need to look beyond carbon sequestration and explore other opportunities to value-add to biochar. Therefore, some emerging and novel applications of biochar are identified. We also suggest some priority research areas that need immediate attention in order to realise the full potential of biochar technology in agriculture and other sectors in Australia. Additional keywords: biochar characterisation, contaminants, herbicide efficacy, heavy metals, nitrous oxide, plant growth media, regulations., Introduction Biochar is a carbon (C)-rich, solid material produced by thermal decomposition of organic material or biomass in the absence, or under limited supply, of oxygen (Lehmann and Joseph 2009). [...]

The role of biochar in sequestration of carbon, reducing the emission of greenhouse gases, and improving the soil fertility is increasingly being recognised and is leading to the recommendations of biochar amendment of soils. However, the implications of such amendments to the environmental fate and efficacy of pesticides are not well understood. The published work on the role of black carbon (which includes charcoal, soot, and other pyrolytic carbon materials) in the environmental fate and effect of organic contaminants is reviewed here, together with the studies on bioavailability and efficacy of some herbicides in soils amended with freshly produced biochars. Biochars, due to their unique properties especially their highly carbonaceous and aromatic nature and high specific surface area, have been reported to be up to >2000 times more effective than soil in sorbing pesticides. The incorporation of relatively small amounts of fresh biochars in soil (0.05% by wt) has also been shown to inhibit the microbial degradation of organic compounds including pesticides as well as reduce their plant availability and efficacy. Based on limited published research on biochars and related research on black carbon reviewed here, biochar amendments to soils are likely to reduce the bioavailability and efficacy of pesticides. Furthermore, these amendments can influence the potential accumulation and ecotoxicological impact of pesticides and other organic contaminants in the soil environment. The implications of heterogeneity and ageing of biochars applied to soils for sorption and desorption processes and in turn for other environmental fate processes need to be understood to seek the appropriate balance between carbon sequestration and pesticide efficacy. While biochar amendment of soil holds appeal from a carbon accounting and soil conditioning perspective, further research is urgently required to determine how biochar influences the efficacy and environmental fate of agrochemicals such as pesticides. Additional keywords: biochar, black carbon, pesticides, efficacy, carbon sequestration, ecosystem health., Introduction The potential role of biochar in carbon sequestration, reduction in the emission of greenhouse gases, and improving the soil fertility has led to the establishment of the International Biochar [...]

Off-site movement of pesticides from furrow-irrigated agriculture has been a concern in the Ord River Irrigation Area, Western Australia. After consultation with growers a range of management strategies were tested to assess the effectiveness of various practices to minimise off-site movement of pesticides during irrigation. This paper reports on the effectiveness of the additions of high molecular weight, anionic, polyacrylamide (PAM) to irrigation water to minimise off-site movement of endosulfan, chlorothalonil, bupirimate, and atrazine. Water leaving from 4 separate irrigation bays, which consisted of 25 furrows per irrigation bay (Expt 1) or 39 furrows per irrigation bay (Expt 2), was monitored over time. The average concentration of endosulfan α and β and bupirimate leaving the irrigation bays for the duration of the single irrigation event was generally always less for the PAM-treated irrigation bays than the control (control treatment). The addition of PAM to the irrigation water significantly decreased the cumulative runofflosses (g) of total endosulfan by 54% from 11.41 to 5.19 g/ha (P < 0.05), and of chlorothalonil by 49% from 53.65 to 27.32 g/ha (P < 0.001). There was no statistical difference in the load of atrazine or bupirimate leaving either treatment. Although the addition of PAM to irrigation water effectively decreased the off-site movement of 2 fairly strongly sorbed pesticides, endosulfan and chlorothalonil, it did not decrease the total load moving offsite of the more weakly sorbed pesticides, bupirimate and atrazine. The addition of PAM as a liquid to irrigation water was not found to increase the infiltration of a soluble pesticide, atrazine, into the soil profile. The mode of application of PAM, however, may affect water infiltration and hence vertical movement of soluble pesticides and requires further investigation. Additional keywords: bupirimate, endosulfan, chlorothalonil, atrazine., Introduction The Ord River Irrigation Area (ORIA), located around the township of Kununurra in the tropical north of Western Australia near the Northern Territory border, is one of the main [...]

Researchers measured the soil organic matter (SOM) structural composition of 27 diverse soils in Pakistan and Australia. Researchers believe that the aromatic quality of the soil organic matter will tell whether or not the soil can bind to nonionic pesticides. Tables illustrate soil quality and research findings.

Environmental context: There are great concerns around current wide usage of copper-based agrochemicals. We compare the fate of nano- and conventional forms of copper, in particular their resistance to wash-off by rain (rainfastness), following their application to citrus leaves. Results showing large differences between the formulations in the amount and forms of copper washed from the leaves provide essential information to optimise agrochemical efficacy while minimising the environmental impact. This study compares the rainfastness of nine forms of Cu, including nano and conventional Cu-based fungicide formulations, as well as their salt or bulk equivalents. Rainfastness is the ability to resist wash-off; it is a key property for improving pesticide formulations and for assessing the potential transfer of pesticides to the soil. A new protocol was developed to characterise losses of Cu from treated leaves. It consisted of dipping the leaves in rainwater and then in an acid/ethanol mixture followed by size fractionation. The proportion of Cu lost by wash-off from citrus leaves ranged from <2 % (Tribasic, nCuO or Cu(OH)2) up to 93 % (CuSO4) of the initial amount of Cu applied. Intermediate Cu losses were observed for formulations with silica (nano)particles (9–14 % of applied Cu), Kocide (22 %), ChampDP (31 %), and a formulation with graphene oxide (47 %). Smaller particles generally resulted in less wash-off, possibly due to stronger attachment to the leaf surface, but other factors such as the particle shape and solubility also played an essential role. The retention of nCuO to the leaves was particularly high, and the exact mechanisms involved (e.g. foliar uptake) deserve further work. Most of the Cu was washed off in its ionic form (>74 %). Two Cu formulations (one commercial formulation and the formulation with graphene oxide) also showed wash off in significant proportions of Cu (~17 %) in the nano-sized fraction. This study provides essential information on the amounts and forms of Cu that may reach the soil after the application of Cu-based agrochemicals. The great diversity in behaviour across the range of formulations considered highlights the need for more systematic research to fully exploit the potential improvements of current agrochemicals through (nano)formulation technologies. Environmental context. There are great concerns around current wide usage of copper-based agrochemicals. We compare the fate of nano- and conventional forms of copper, in particular their resistance to wash-off by rain (rainfastness), following their application to citrus leaves. Results showing large differences between the formulations in the amount and forms of copper washed from the leaves provide essential information to optimise agrochemical efficacy while minimising the environmental impact. [ABSTRACT FROM AUTHOR]

The effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia are examined. The results have suggested the cause and effect between nutrients loading into the creek, shift in bacterial communities through habitat change and alteration of capacity for biogeochemical cycling of N.

A chromatographic model (VARLEACH) and a process-based model (LEACHM) were evaluated under low and high water input regimes (`rainfall' and `rainfall + irrigation', respectively) using experimental data for a non-reactive tracer (KBr), and 3 sulfonylurea herbicides: triasulfuron, metsulfuron-methyl, and chlorsulfuron. Both qualitative and quantitative comparisons of predicted and measured water contents revealed that both models performed well under `rainfall', but prediction was less satisfactory under the treatment of `rainfall + irrigation'. Both models failed to simulate the bimodal distribution of [Br.sup.-] and the herbicides observed under `rainfall + irrigation' treatment. Distribution of [Br.sup.-] and the 3 herbicides in the profile was over- or under-estimated at certain depths and times, probably due to the limitations inherent to the models (e.g. inability to deal with the macropore flow), and to simplifications associated with some input data. Simulations for a dry (1 decile), median (5 decile), and wet year (9 decile) with LEACHM and VARLEACH models using long-term weather data for the site showed that leaching and persistence of the herbicides are highly dependent on the amount of rainfall the site receives. The results indicate that the risk of injury to herbicide-sensitive crops in the following year of application of herbicides is likely to be greater when the herbicides are applied in a drier rather than a wetter year. Additional keywords: simulation, herbicide persistence, transport, modelling efficiency., Introduction Computer simulation models are useful in understanding the behaviour of agricultural chemicals in the soil and their movement into the groundwater (Khakural et al. 1995) under a range of [...]

Fullerenes (e.g. C 60 , C 70 , etc.) present in soil may undergo changes in its retention with aging. In this study, the partitioning behavior of ( 14 C)-C 60 aged up to 12 weeks was investigated in biosolids-amended soil. Spiked samples were subjected to sequential partitioning using water, methanol, and toluene followed by total combustion of solids; the distribution of 14 C across solvents and matrices were used to provide insights on C 60 behavior. In most samples, 14 C only partitioned in toluene with the remaining (non-extractable) activity detected in the solid phase. In all biosolids-amended soil samples, an increase in non-extractable 14 C were observed for those exposed to light (vs dark) with the greatest difference observed in biosolids + sand samples. Possible processes that contribute to the observed 14 C distribution, i.e. retention and potential transformation of C 60, were discussed. Over-all, results suggest that environmental exposure to C 60 and potentially transformed C 60 species, as a result of their release from soils, is likely to be low. [ABSTRACT FROM AUTHOR]

Char as a carbon-rich material, can be produced under pyrolytic conditions, wildfires or prescribed burn offs for fire management. The objective of this study was to elucidate mechanistic interactions of copper (Cu 2+ ) and nickel (Ni 2+ ) with different chars produced by pyrolysis (green waste, GW; blue-Mallee, BM) and forest fires (fresh-burnt by prescribed fire, FC; aged char produced by wild fire, AC). The pyrolytic chars were more effective sorbents of Cu 2+ (∼11 times) and Ni 2+ (∼5 times) compared with the forest fire chars. Both cross-polarization (CPMAS-NMR) and Bloch decay (BDMAS-NMR) 13 C NMR spectroscopies showed that forest fire chars have higher woody components (aromatic functional groups) and lower polar groups (e.g. O -alkyl C) compared with the pyrolytic chars. The polarity index was greater in the pyrolytic chars (0.99–1.34) than in the fire-generated chars (0.98–1.15), while aromaticity was lower in the former than in the latter. Fourier transform infrared (FTIR) and Raman spectroscopies indicated the binding of carbonate and phosphate with both Cu 2+ and Ni 2+ in all chars, but with a greater extent in pyrolytic than forest fire-generated chars. These findings have demonstrated the key role of char's oxygen-containing functional groups in determining their sorption capacity for the Cu 2+ and Ni 2+ in contaminated lands. [ABSTRACT FROM AUTHOR]

Two pesticide risk indicators, Pesticide Impact Rating Index (PIRI) and Environmental Potential Risk Indicator for Pesticides (EPRIP), were used to determine the likelihood of off-site transport to surface water of pesticides used in a cherry ( Prunus avium cultivars) and an apple ( Malus domestica cultivars) orchard. The predictions of off-site transport of some of the pesticides were verified against actual pesticide concentrations in surface water continuously monitored over two years. To our knowledge, only one other study in the published literature has attempted this. Of the chemicals monitored there was good agreement between the predictions and the field measurements from the apple orchard, but less so for the cherry orchard. In both risk indicators the attenuation factor based on the width of the buffer strip over-estimated the effectiveness of the buffer strip. There was good agreement between the EPRIP and PIRI risk assessment except for ethephon which EPRIP rated a higher risk than PIRI and dithianon which EPRIP rated a lower risk than PIRI. A strong correlation was found between the field observations and the EPRIP predicted environmental concentrations for the majority of cases. This study showed that even simple risk indicators (e.g. PIRI and EPRIP) can be good predictors for a first tier risk assessment of pesticide transport to neighbouring water bodies. [ABSTRACT FROM AUTHOR]

A survey was conducted in eight secondary schools located in two watersheds in Gujarat and Rajasthan (semi-arid region of India) to assess students’ perceptions about groundwater scarcity issues and the impact of the scarcity on their educational opportunities. Survey responses to a detailed questionnaire by a cohort of students in both watersheds; school attendance records of year 8 class students (13–14 years old) and responses gathered via a socio-economic survey involving 500 families in the study area were used in the study. In both watersheds, >90% students identified groundwater scarcity as a major issue. Required to work at home or farm, about 65% students in Gujarat and 60% in Rajasthan missed school for up to 2 days/month; and a smaller proportion (∼ 30%) missed schools for 4 or more days/month. School absenteeism was found to be linked with gender; female students missed schools more frequently than their male counterpart. The school attendance records in Rajasthan showed that the frequency of female students missing schools for 5 or more days/month was on an average 2–10 times greater than that for males. The gender difference in absenteeism in all schools was statistically significant (P < .018**). The study highlighted that groundwater scarcity in the study area, and consequent demand on their time for household work including fetching drinking water are contributing factors towards limiting their educational and economic opportunities. Groundwater scarcity can be one of the key factors that can limit inclusiveness and empowerment of women and need to be considered in policy-making. [ABSTRACT FROM PUBLISHER]

Spills of hydraulic fracturing (HF) fluids and of produced water during unconventional gas extraction operations may cause soil contamination. We studied the degradation and microbial toxicity of selected HF chemical components including two biocides (methylisothiozolinone- MIT, chloromethylisothiozolinone- CMIT), a gel-breaker aid (triethanolamine -TEA), and three geogenic chemicals (phenol, m- cresol and p- cresol) in ultrapure water, HF fluid and produced water in five different soil types (surface and subsurface soils). The degradation of the two biocides (in soils treated with HF fluid or ultrapure water) and of the three geogenic chemicals (in soils treated with produced water) was rapid (in all cases DT 50 values < 2 days in surface soils). In contrast, the loss of TEA was much slower in soils, especially in those treated with HF fluid (DT 50 > 30 days). Sorption coefficients (K oc in L/Kg) in these soils ranged from 71 to 733 for TEA, 64–408 for MIT and 11–72 for CMIT. In terms of soil microbial toxicity, exposure to HF fluid and produced water reduced microbial respiration, albeit temporarily. The overall microbial activities in surface soils contaminated with produced water had fully recovered in most soils. In contrast, the HF fluid addition to soils completely inhibited the nitrification in all soils, with little recovery over the 60 day experimental period. In the case of produced water exposure, three out of five surface soils showed complete recovery in nitrification during the study period. The functional genes for nitrogen fixation (nifH) and carbon cycling (GA1) and microbial community composition (16 S rRNA) were significantly affected by HF fluid in some soils. Overall, the study shows that the HF fluid can have significant detrimental impact on soil microbial functions, especially on nitrogen cycling. More work is needed to identify the exact cause of microbial toxicity in soils contaminated with HF fluid. [Display omitted] • Hydraulic fracturing (HF) fluid inhibited soil nitrification and altered the microbial community. • Substrate induced nitrification did not recover 60 days after HF fluid addition. • Triethanolamine degradation was markedly reduced in HF fluid treated soils. • Biocides and target geogenic organic chemicals disappeared from soils within two days. • Biocides showed little sorption to soils and were considered to be mobile. [ABSTRACT FROM AUTHOR]

Canola ( Brassica napus L.) is the third largest field crop in Australia by area sown. Genetically modified (GM) and non-GM canola varieties released or being developed in Australia include Clearfield® (imidazolinone tolerant), TT (triazine tolerant), InVigor® (glufosinate-ammonium tolerant), Roundup Ready® - RR® (glyphosate tolerant) and Hyola® RT® (tolerant to both glyphosate and triazine). We used two risk assessment approaches – the Environmental Impact Quotient (EIQ) and the Pesticide Impact Rating Index (PIRI) – to compare the environmental risks associated with herbicides used in the canola varieties (GM and non-GM) that are currently grown or may be grown in the future. Risk assessments found that from an environmental impact viewpoint a number of herbicides used in the production of TT canola showed high relative risk in terms of mobility and ecotoxicity of herbicides. The EIQ field use rating values for atrazine and simazine in particular were high compared with those for glyphosate and trifluralin. Imazapic and imazapyr, which are only used in Clearfield® canola, had extremely low EIQ field use rating values, likely reflecting the very low application rates used for these chemicals (0.02 to 0.04 kg/ha) compared with those used for atrazine and simazine (1.2 to 1.5 kg/ha). The PIRI assessment showed that irrespective of the canola variety grown, trifluralin posed a high toxicity risk to fish (Rainbow trout, Oncorhynchus mykiss ), algae and Daphnia sp. While the replacement of trifluralin with propyzamide had little effect on the mobility score, it greatly decreased the ecotoxicity score to fish, algae and Daphnia sp. due to the lower LC50 values for propyzamide compared with trifluralin. This study has shown that based on likelihood of off-site transport of herbicides in surface water and potential toxicity to non-target organisms, the GM canola varieties have no advantage over non-herbicide tolerant (non HT) or Clearfield® canola. [ABSTRACT FROM AUTHOR]