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In this study, the effectiveness of softwood-derived biochar (BC) in the retention of potentially toxic elements (PTE, i.e., Cu(II), Pb(II), As(V), and Sb(V)) was evaluated at different pH values (4.5, 6.0, and 7.0), along with its capacity to alleviate PTE phytotoxicity. At all pH values, sorption and kinetic isotherms followed the trend: Pb(II) (e.g., ~ 0.56 mmol g−1at pH 6.0) > Cu(II) (e.g., ~ 0.33 mmol g−1at pH 6.0) > As(V) (e.g., ~ 0.29 mmol g−1at pH 6.0) > Sb(V) (e.g. ~ 0.24 mmol g−1at pH 6.0). Kinetic data strongly correlated with the pseudo-second-order kinetic equation; Langmuir and Freundlich isotherm models suggested monolayer sorption of Cu(II), Pb(II), and As(V) onto the BC surface and the interaction of Sb(V) with BC sites characterized by distinct sorption energy (i.e., multilayer sorption). Scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis of PTE-saturated BC showed that Pb(II) was mainly associated with O, Sb(V) with Ca and Fe, while Cu(II) and As(V) with Fe and O. This suggested that hydroxyl and carboxyl functional groups, amorphous Fe oxy-hydroxides, as well as PTE precipitation with BC components were likely responsible for BC sorption capacity. Treatment of PTE-saturated BC with Ca(NO3)2and a range of environmentally relevant organic acids indicated that 6–11% of PTE were loosely bound and easily exchangeable, while up to 60% could be mobilized by the organic acids. Hydroponic plant-growth experiments using triticale plants showed that BC stimulated plant growth in the presence of PTE and reduced their phytotoxicity.

This study evaluated the influence of a municipal solid waste compost (MSWC) and monocalcium phosphate (MCP), alone or combined, on the mobility, toxicity, bioavailability and health risk of fluoride (1000 mg F

Softwood-derived biochar (5% w/w) was added to two mining soils (S1 and S2) contaminated with Cd (4.8–74 mg kg−1), Pb (318–1899 mg kg−1) and Zn (622–3803 mg kg−1), to evaluate its immobilization capabilities towards such potentially toxic elements (PTEs). Biochar addition (S + B) increased soil pH, organic carbon content, extractable phosphorous and calcium. Sequential extractions showed that biochar reduced the labile pools of PTEs (e.g. −29, 55 and 79% of water-soluble and exchangeable Cd, Zn and Pb respectively in S1 + B compared to S1) and at the same time increased their most stable and less mobile fractions. Leaching experiments revealed a significant decrease of DOC, N-NO3−, P and PTEs in biochar-treated soils, and an increase of leached K. Kinetic equations derived from leaching data showed that PTEs in control soils were quickly mobilized, while those in biochar-treated soils needed longer time to leachate. In vitro tests showed that biochar was effective at reducing the bioaccessibility of Cd and Pb in the gastric phase of S2 and that of Zn and Pb in the intestinal phase of S1. The results obtained showed that biochar could be used as alternative amendment for the recovery of PTEs-contaminated soils.

The use of organic-based amendments for gentle remediation options (GRO), i.e. the stabilization of trace elements (TE) in polluted soils and the reduction of their impact on soil microbial and biochemical features, has been constantly growing in last 10 years. To verify the effectiveness of biochar and compost in such context, biochar (1 and 3% w/w), compost (3% w/w) and their combination (compost 2% + biochar 2% w/w) were added to two sub-alkaline soils (FS and MS) contaminated with Sb (41–99 mg kg−1 respectively), As (~18 mg kg−1), and trace metals such as Ni (103–172 mg kg−1 respectively) and Cr (165–132 mg kg−1 respectively). Most of the treatments (especially 3% biochar) reduced labile TE pools (water-soluble and exchangeable) and increased their residual (non-extractable) fractions (e.g. +48, 56, 66, and 68% of residual Sb, As, Cr and Ni in MS-treated soil compared to the untreated control). The amendments addition had both stimulating and inhibiting effects on the activity of soil microbial communities, as shown by the Biolog community level physiological profiles. However, in both soils, 3% biochar produced the highest increase of metabolic potential as well as the use of carboxylic acids and polymers by the soil microbial communities. Likewise, soil dehydrogenase (DHG), β-glucosidase (β-GLU) and urease (URE) activities were significantly enhanced in FS and MS soils treated with 3% biochar (e.g. +77, 48, and 17% for DHG, URE and β-GLU in FS-3% biochar with respect to untreated FS). Overall, the results from this study showed that the amendments investigated (particularly 3% biochar) can be effectively used for GRO of sub-alkaline soils, being able to reduce labile TE and to increase the metabolic potential and actual biochemical activities of the respective soil microbial communities. The manifold environmental implications of such effects are discussed.

Assisted phytoremediation, i.e. the combination of amendment and plant cultivation to remove potentially toxic elements (PTE) from soil, or to reduce their mobility and toxicity, can represent an effective gentle remediation option for the recovery of PTE-contaminated soils. The aim of this study was to evaluate the suitability of different grass and legume species, such as Arundo donax L., Hordeum vulgare L. and Lupinus albus L., in assisted phytoremediation programs of PTE-contaminated soils in combination with a municipal solid waste compost (MSWC) used at 2 and 4% rates. The soil was heavily contaminated by different PTE, i.e. Pb (15,383 mg kg − 1 ), Zn (4,076 mg kg − 1 ), Sb (109 mg kg − 1 ), Cd (67 mg kg − 1 ) and As (49 mg kg − 1 ). The selected plant species were able to grow in the contaminated soil, and their biomass production was significantly influenced by the compost either positively (e.g. A. donax) or negatively (e.g. H. vulgare roots). Compost addition significantly decreased or did not influence the PTE uptake and bioaccumulation factors of A. donax and H. vulgare roots and shoots, while it increased those of L. albus (particularly in roots) with respect to As, Sb, Pb and Cu. Finally, MSWC increased the PTE removal efficiency of A. donax (and partially of L. albus but not by H. vulgare), i.e. its ability to bioaccumulate PTE in the below ground organs, especially when grown in soils amended with 4% MSWC. The results indicated that A. donax, and in selected cases L. albus, can be used in combination with MSWC for the phytostabilization of PTE-contaminated soils.

The photodegradation of the herbicide foramsulfuron (FRS) in simulated sunlight was studied in water and in the presence of photocatalysts and chars. The photodegradation in distilled water was rather slow and the metabolite 2-amino-4,6-dimethoxypyrimidine was the only by-product detected. In the presence of TiO 2 and ZnO, a very fast photodegradation occurred affording a complete mineralization of the herbicide. The presence of a biochar (BC), derived from the pyrolysis of woodlands, in irradiated FRS solution caused a slight slowdown of the FRS photodegradation rate. Instead, the addition of a liquid hydrochar (HC), obtained by the hydrothermal carbonization of maize, halved the half-life time of the herbicide. The addition of BC to FRS solutions containing TiO 2 or ZnO did not affect the herbicide degradation rate. On the other hand, the addition of HC, while not influencing significantly the FRS degradation catalysed by ZnO, slowed very much the TiO 2 -promoted degradation. The different trends of FRS photodegradation in the presence of BC or HC have been interpreted on the basis of the physico-chemical characteristics of the two chars. The addition of 2-propanol or EDTA, which are selective scavengers of radicals and holes respectively, to catalysed systems increased FRS half-life time. The addition of 2-propanol reduced the FRS photodegradation rate to a higher extent than EDTA, thus emphasizing the role of radicals in the photodecomposition mediated by the two semiconductors.

High amounts of antibiotics are introduced in the soil environment by manure amendment, which is the most important spreading route in soil, with a potential ecotoxicological impact on the environment. The objectives of this study were (a) to assess the tetracycline (Tc) bioavailability in a clay and in a sandy soil, and (b) to evaluate the effects of the Tc and cow manure on the structure and function of soil microbial communities. Clay and sandy soils were spiked with Tc at the concentrations of 100 and 500 mg Tc kg(-1) soil, and were amended or not with cow manure. The clay soil showed greater Tc sorption capacity and bioavailable Tc was between 0.157 and 4.602 mg kg(-1) soil. Tc dose and time-dependent effects on soil microbial communities were investigated by fluorescein diacetate activity, phospholipid fatty acids analysis, as well as by Biolog community level physiological profile and microbial counts at 2, 7 and 60 days after Tc and/or manure addition. The added Tc caused detrimental effect on the microbial activity and structure, particularly in the short term at the highest concentrations. However, the Tc effect was transient' it decreased after 7 days and totally disappeared within 60 days. Cow manure shifted the bacterial structure in both soils, increased the microbial activity in clay soil and contributed to recover the microbial structure in Tc-spiked manure treatments.

Mononuclear amidogold(III) complexes [Au(C,N,N)(NRR′)][PF 6 ] [C,N,N = N 2 C 10 H 7 (Cme 2 C 6 H 4 )-6, where N 2 C 10 H 8 = 2,2′-bipy; R = H, R′ = p -tolyl ( 5 ), o -xylyl ( 6 ), isobutyl ( 7 ), sec -butyl ( 8 ), R = R′ = Et ( 9 )], [Au(C,N)(AcO)(NHC 6 H 4 NO 2 -4)] ( 10 ) [C,N = NC 5 H 4 (CH 2 C 6 H 4 )-2, where NC 5 H 5 = py] and [Au(N,N)(NHC 6 H 4 NO 2 -4) 2 ][PF 6 ] ( 11 ) (N,N = 2,2′-bipy), have been synthesized in fairly good yields by reaction of the hydroxo, methoxo, or acetato complexes 1−4 {[Au(C,N,N)(OR)][PF 6 ] [R = H ( 1 ), Me ( 2 )], [Au(C,N)(AcO) 2 ] ( 3 ), [Au(N,N)(OH) 2 ][PF 6 ] ( 4 )} with amines. The structure of [Au(C,N,N)(NHC 6 H 3 Me 2 -2,6)][PF 6 ] ( 6 ) has been determined by X-ray diffraction. Reaction of the hydroxo complex 4 with NH 2 C 6 H 4 Me-4 gives metallic gold, the protonated ligand [N,NH][PF 6 ] and organic products, the main one being azotoluene.

6-Alkyl-2,2‘-bipyridines, HL, (N2C10H7R; R = CH2Me, HLet; CHMe2, HLip; CMe3, HLtb, CH2CMe3, HLnp, CMe2Ph, HLdm) react with Na2[PdCl4] to give either 1:1 adducts [Pd(HL)Cl2] (HLet, HLip, HLnp) or cyclometalated complexes [Pd(L)Cl] (HLtb, HLdm). Reaction of palladium(II) acetate, followed by exchange with LiCl, affords a series of cyclopalladated species [Pd(L)Cl] where L is a terdentate anionic N−N−C ligand which originates from HL through direct activation of a C(sp3)−H or a C(sp2)−H bond. The structures of [Pd(Ltb)Cl] and [Pd(Lnp)Cl], which contain a [5,5] or a [5,6] fused ring system, respectively, have been determined by X-ray diffraction and are compared. In the case of the ligand HLip, three different cyclometalated species have been isolated, [Pd(L)Cl], [Pd(L)Cl]2, and [Pd{N2C10H7[CH(CH2OC(O)CH3)(CH2)]}Cl], the latter one arising from activation of both methyl groups of the substituent. The isolation of two [Pd(Ldm)Cl] species (compounds 8 and 9), having an aromatic or an aliphatic carbon−metal bond...

Replacement of the chloride ligand in the cyclometallated complexes [Au(C,N,N)Cl][PF6] (C,N,N = N2C10H7(CH2C6H4)-6 1, N2C10H7(CHMeC6H4)-6 2, or N2C10H7(CMe2C6H4)-6 3, where N2C10H8 = 2,2′-bipy) by C, N, O and S donor anionic ligands Y was accomplished through different routes depending both on the nature of HY or the C,N,N ligand. Stable alkoxo [Au(C,N,N)(OR)][PF6] (R = Me or Et) and amido [Au(C,N,N)(NHAr)][PF6] (Ar = C6H4NO2-4) complexes were obtained in fairly good yields. The molecular structure of the thiolato complex [Au{N2C10H7(CMe2C6H4)-6}(SPh)][PF6] has been determined by X-ray crystallography. The diorganogold(III) complex [Au(C,N,N)(C2Ph)][PF6] on addition of PPh3 (1∶2) undergoes reductive elimination to give [Au(PPh3)2][PF6] and an unsymmetric diarylacetylene.

The reaction of 1-phenylpyrazole (HL), with gold(III) chloride has been studied. Besides a 1:1 adduct [Au(HL)Cl 3 ] 1 , where the ligand is bonded through the nitrogen atom, several C(4) aurated species have been isolated. Thus treatment of [AuCl 3 ] 2 with HL in dichloromethane solution affords a complex, [Au(L)Cl 2 . HCl] n , 2 , where the gold atom is bonded to the 4-carbon atom of the pyrazole ligand. Deprotonation of complex 2 by means of the not coordinating base 1,8-bis(dimethylamino)naphthalene (proton sponge), B, affords the salt [BH][Au(L)Cl 3 ], 3 , whereas reaction of 2 with 3,5-Me 2 py and PPh 3 (molar ratio 1:2) gives the neutral species trans -[Au(L)(3,5-Me 2 py)Cl 2 ], 4 , and cis -[Au(L)(PPh 3 )Cl 2 ], 5 , respectively. The structure of compound 4 solved by X-ray diffraction, unambiguously shows the anionic ligand L bonded to the gold ion through the C4 atom. Alternatively, compounds 4 and 5 can be obtained in two steps, i.e. deprotonation of 2 with NaOH to give [Au(L)Cl 2 ] n , 6 , and reaction of 6 with 3,5-Me 2 py and PPh 3 , respectively. The new species were characterized by elemental analyses, conductivity measurements, IR, NMR and FAB-MS spectroscopy.

The reactivity of a series of gold(III) adducts [Au(HL)Cl3] 1a–4a with 6-alkyl-2,2′-bipyridines HL (N2C10H7R, R = CH2Me 1, CHMe2 2, CMe3 3 and CH2CMe3 4) has been studied. The reactions of 1a–4a with silver(I) ions or MeCO2Na afford cationic complexes [Au2(HL)2(µ-O)2]2+ 1b–4b (as BF4 or PF6 salts) having the gold atom bonded to the nitrogen atoms of the bipyridine and to two oxygen atoms. The crystal structure of 4b[PF6]2, solved by X-ray diffraction, shows that the cation is a centrosymmetric dimer with two oxo (O2–) groups bridging two [Au{N2C10H7(CH2CMe3)-6}] moieties. In the case of 2a, besides the oxo species, mononuclear ionic derivatives [Au(L*)Cl]+ 2*c [HL* = N2C10H7(CMe2OH)-6; BF4, PF6 or AuCl4 salts] have been isolated. The latter complexes contain an unexpected Au–O bond. The spectroscopic data and the crystal structure of 2*c[AuCl4] indicate a tridentate N,N,O behaviour of the ligand which forms a [5,5]-fused ring system.

The study describes the soil sorption of the herbicide Lumax®, composed of S-metolachlor (MTC), terbuthylazine (TBZ), and mesotrione (MST), as influenced by mineral and organic fertilizers. The investigation was performed on a sandy soil of an agricultural area designated as a Nitrate Vulnerable Zone, where mineral and organic fertilizers were applied for many years. Two organic fertilizers, cattle manure and slurry, respectively, and a mineral fertilizer with a nitrification inhibitor, Entec®, were compared. According to the experiments, performed with a batch method, the sorption conformed to Freundlich model. The extent of sorption of Lumax® ingredients was closely related to their octanol-water partition coefficient Kow. The respective desorption was hysteretic. Leaching trials were carried out by using water or solutions of DOM or Entec® as the eluants. Only the elution with the mineral fertilizer promoted the leaching of Lumax® active ingredients.

The sorption of meta and para isomers of the herbicide imazamethabenz-methyl, methyl 6-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-m- or p-toluate, by three soils and soil organic matter, was studied. Sorption isotherms conformed to the Freundlich equation. It was found that pH was the main factor influencing the adsorption in all of the systems. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, at low pH value, the soil rich in smectite clays, favoured the sorption of meta rather than para isomer. The higher affinity of clay surfaces for the meta isomer of the herbicide is due to the stabilization of the meta protonated form by resonance. At all pH values, the sorption on soil organic matter did not differ between two isomers.

In this study we investigated the sorption of sulfamethazine (SMZ) in two soils with different physico-chemical properties and the sulfonamide short-term influence on the microbial community structure and function. The presence of manure increased the SMZ sorption, the uppermost level being measured on soil with the lower pH and the higher manure content allowed by the Italian regulation. The sulfonamide desorption was hysteretic on both soils. SMZ addition to soil at the concentration of 53.6 μg/g had a significant short-term negative impact on readily culturable bacteria, potential metabolic activity (Biolog CLPP) and soil enzyme activity. Moreover, a shift of the culturable microbial populations towards a lower bacteria/fungi ratio was observed after SMZ addition. Despite the observed SMZ effects disappeared almost completely after 7 day, structural changes of microbial communities were still present in SMZ-treated soils. The results presented are remarkable since previous studies addressing the SMZ impact on soil microbial parameters failed to highlight any significant effect of the sulfonamide on microbial abundance and diversity.

The photodegradation of two quinolinecarboxylic herbicides, 7-chloro-3-methylquinoline-8-carboxylic acid (QMe) and 3,7-dichloroquinoline-8-carboxylic acid (QCl), was studied in aqueous solution at different irradiation wavelengths. The effect of sunlight irradiation was investigated also in the presence of titanium dioxide (TiO 2 ). UV irradiation degraded rapidly QMe affording 7-chloro-3-methylquinoline (MeQ) through a decarboxylation reaction. The reaction rate was lower in the presence of dissolved organic carbon (DOC) because of the adsorption of the herbicide on the organic components. Instead, QCl was stable under both UV light and sunlight irradiation. The irradiation of QMe or QCl solutions with simulated sunlight in the presence of TiO 2 produced the complete mineralization of the two herbicides.

The photodegradation of the aryloxyphenoxy propionic herbicide cyhalofop-butyl (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]butylpropanoate (CyB), and of its primary metabolite (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid (CyA) was studied in water at different irradiation wavelengths. The sunlight irradiation was investigated also in the presence of humic acid (HA), Fe oxide, titanium dioxide (TiO2) and zinc oxide (ZnO) as photocatalysts. CyB and CyA were rapidly degraded by UV irradiation. CyB afforded the butyl ester of 2-[3-(4-cyano-2-fluorophenyl)-4-hydroxy-phenoxy]propanoic acid (CyI), a metabolite arising from a photo-Fries rearrangement. Instead, CyA yielded (R)-2-4-(4-carboxyl-2-fluorophenoxy)phenoxypropanoic acid (CyD), a dicarboxylic acid arising from the photo-hydrolysis of cyano group via amide. CyB was stable in simulated sunlight also in the presence of the catalysts tested. The irradiation of a CyA solution, in the presence of HA or Fe oxide, with simulated sunlight did not produce any significant degradation. In the same experimental conditions, CyA was totally mineralized in the presence of TiO2 and ZnO.

The influence of municipal sewage sludge (SL) as a soil amendment on the sorption and activity of the herbicide triasulfuron (TRS, [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide]) was studied. Weed control was checked in a greenhouse on a wheat (Triticum turgidum L. subsp. durum) crop. At the highest SL amount allowed by Italian regulation, TRS sorption onto soil increased by 7 times and weed control was unaffected. A vegetative bloom and an early heading phase were noted. To compare inorganic fertilization (N, P, and K) and SL amendment, a greenhouse fertilization experiment was carried out. The SL-amended crop developed larger leaf surfaces, higher biomass, and a forward heading compared to that fertilized with N, P, and K. The SL hormone-like activity was evaluated by measuring auxin- and gibberellin-like activity of sewage sludge.

The adsorption of fenhexamid (FEN) [N-(2,3-dichloro-4-hydroxyphenyl)-1-methylcyclohexanecarboxamide] on vineyard soil amended with wine lees (WL) produced by vinery was studied. The adsorption extent depends on WL fraction. The addition of the centrifuged solid lees (SWL) increases the FEN adsorption on soil. Most likely, the organic insoluble fraction formed mainly by dead fermentation yeasts is responsible for the observed increase. The adsorption measured on some deactivated yeasts of wine fermentation shows that Saccharomyces cerevisiae are the most active in FEN retention. On the other hand, the soil amendment with whole WL decreases considerably the fungicide adsorption. This opposite effect may be the result of FEN hydrophobic bonds with the dissolved organic matter of lees that keeps fungicide in solution. This hypothesis is substantiated by the increased FEN solubility in the supernatant of centrifuged wine lees (LWL). The results of soil column mobility confirm that the elution with LWL increases the mobility of FEN in soil.

A study was undertaken to investigate the stability of cyhalofop-butyl (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]butylpropanoate (CyB), an aryloxyphenoxy-propionic herbicide, at different pH values. The hydrolysis of CyB was faster in nonsterile than in sterile water. In sterile medium, CyB degraded only to (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid (CyA), whereas in nonsterile water, also the metabolites (2R)-2-[4-(4-carbamoyl-2-fluorophenoxy)phenoxy]propanoic acid (CyAA) and (2R)-2-[4-(4-carboxyl-2-fluorophenoxy)phenoxy]propanoic acid (CyD) were detected. The adsorption of CyB onto clays, iron oxide, and dissolved organic matter (DOM), using a batch equilibrium method, was also studied. A lipophilic bond is responsible for CyB adsorption on DOM. CyB was adsorbed on FeIII- and Ca-clays through hydrogen bonding between the carbonyl oxygen and water surrounding the exchangeable cations. In the interlayer of K-clay, CyB was hydrolyzed to CyA, which remained adsorbed therein as a monomer. The acid CyA was adsorbed only by the Fe-oxide through complexation. The CyA−Fe-oxide complex was stable and did not undergo degradation.

The effect of undesalted dissolved organic matter (DOM) extracted from composts on the degradation, adsorption, and mobility of cyhalofop herbicide in soils was studied. A paddy-field sediment poor in organic matter (OM), an OM-rich forest soil, and DOM from agroindustrial or municipal waste compost were used. DOM increased the cyhalofop-acid but not the cyhalofop-butyl solubility in water. The degradation of cyhalofop-butyl in the sediment was slow, giving cyhalofop-acid as the only metabolite, whereas in forest soil, the process was faster, and three byproducts were detected. Soil pretreatment with DOM did not modify the degradation pattern but only reduced the adsorption of cyhalofop-butyl by soil, whereas it increased the adsorption of cyhalofop-acid. Among the cationic components of DOM solutions, the potassium ion seems to be related to the increased adsorption of the cyhalofop-acid in both OM-poor and OM-rich soils, yielding reversible complexes with the former and favoring hydrophobic interactions with the latter.

The photodegradation of the sulfonylurea herbicide azimsulfuron, N-[[(4,6-dimethoxypyrimidin-2-yl)amino]carbonyl]-1-methyl-4-(2-methyl-2H-tetrazole-5-yl)-1H-pyrazole-5-sulfonamide (AZS), was studied in water at different wavelengths and in the presence of photocatalysts. AZS was rapidly degraded by UV light, affording three photoproducts. The main product, accounting for about 70% of photodegraded herbicide, was identified as 6-amino-5-[(4,6-dimethoxypyrimidin-2-yl)methylamino]-1,5,6,8-tetrahydro-7-oxa-8lambda(6)-tia-1,2,5,6-tetraza-azulen-4-one (ADTA) by single-crystal X-ray diffraction. With simulated sunlight irradiation, the reaction was slower and 2-amino-4,6-dimethoxypyrimidine (DPA) and 1-methyl-4-(2-methyl-2H-tetrazole-5-yl)-1H-pyrazole-5-sulfonamide (MPS), arising from a photohydrolytic cleavage of the sulfonylurea bridge, were the only byproducts observed. The reactions followed first-order kinetics. The addition of dissolved organic matter (DOM) did not modify significantly the AZS photodegradation rate. The presence of Fe2O3 accelerated more than twice the reaction rate affording two major products, DPA and MPS, together with minor amounts of N-[[(5-hydroxy-4,6-dimethoxypyrimidin-2-yl)amino]carbonyl]-1-methyl-4-(2-methyl-2H-tetrazole-5-yl)-1H-pyrazole-5-sulfonamide (AZS-OH). The greatest degradation rate was detected in the presence of TiO2. Only the photohydroxylation product AZS-OH was observed, which was transformed rapidly into oxalic acid.

The sorption and desorption of the herbicide azimsulfuron, N-[[(4-dimethoxypyrimidin-2-yl)amino]carbonyl]1-methyl-4-(2-methyl-2H-tetrazole-5-yl)1H-pyrazole-5-sulfonamide, were studied using five soils. Sorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the sorption and that the sorption on soils was negatively correlated with pH. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, inorganic soil colloids, for example, smectite clay minerals and iron oxides, contributed to the sorption of azimsulfuron. Desorption was hysteretic on soils with high organic and inorganic colloid contents. Keywords: Azimsulfuron; herbicide; sorption; desorption; organic matter; humic acid

The reaction of the gold(III) cyclometallated complexes [Au(L)Cl][BF4] [L = N2C10H7(CHMeC6H4)-6 1 or N2C10H7(CMe2C6H4)-6 2, where N2C10H8 = 2,2′-bipy] with AgBF4 in acetone solution affords the acetonyl derivatives [Au(L){CH2C(O)Me}][BF4], 3 and 4, and the dinuclear oxo-bridged complexes [Au2(L)2(µ-O)][BF4]2, 5 and 6; the crystal structure of complex 6 gives evidence for an unprecedented unsupported Au–O–Au bridge.