Hydrological influence on the evolution of a subtropical mangrove ecosystem during the late Holocene from Babitonga Bay, Brazil

Mangroves are key ecosystems which respond to global changes in tropical and subtropical regions worldwide. We describe late Holocene mangroves that established close to the southernmost limit (28°S) for this type of ecosystem in South America. Our findings are based on a C dated core obtained from Babitonga Bay, Santa Catarina State, Brazil (26°12′S, 48°33′W). Analysis of palynology, sedimentary facies, isotopic and elemental data shows that mangrove establishment took place ~500 yrs. B.C.E., following an increase in humidity, and expanded further during the Roman Warm Period and at the end of Dark Age Cold Period. Mangrove and precipitation proxies records appear to be sensitive to rainfall patterns imposed both by the expansion/retraction of the Intertropical Convergence Zone and also the interaction with the South Atlantic Subtropical Anticyclone which affects coastal region due to sea surface temperature variations.The authors thank the Coastal Dynamic Laboratory (LADIC-UFPA) , C-14 Laboratory of the Center for Nuclear Energy in Agriculture (CENA-USP) , University of Joinville (UNIVILLE) and Radiocarbon Laboratory (LAC-UFF) for all infrastructure and support. We also thank three anonymous Reviewers and Prof. H. Falcon-Lang for their constructive comments. The first and third author thanks Brazilian Council for Technology and Science-CNPq for fellowship (process 131813/2016-1 , 165911/2015-8 and 305074/2017-2 ). This study was financed by CNPq ( 445111/2014-3 , 405060/2013- 0 ) and FAPESP ( 2011/00995-7 , 2017/03304-1, and 2020/13715-1 ). This study also was financed in part by the Coordenação de Aperfeiçoamento de Pessoal Nível Superior – Brazil (CAPES) – Finance Code 001

Holocene palaeoenvironmental reconstruction in northeastern Brazil inferred from pollen, charcoal and carbon isotope records

Soils in the Barreirinhas region, Maranhao State, were sampled for delta(13)C analysis and buried charcoal fragments in the soils were radiocarbon dated. Three soil profiles collected in forested areas around the Lagoa do Caco and one in a woody savanna (mixture of non-arboreal and arboreal species) located approximately 10 km southeast of the Lagoa were studied. A high-resolution pollen record was obtained from lake sediments, showing that forest vegetation was predominant in the area in the early Holocene. From approximately 10 000 C-14 yr BP the pollen spectrum gradually changed, suggesting the dominance of open savanna communities, these were transformed to a more forested landscape ( woody savanna) from approximately 7500 yr BP. The lake sediments also record evidence of fire ( indicated by buried charcoal particles at several soil depths) during the Holocene. The delta(13)C analysis of soil organic matter (SOM) indicates that from between approximately 10 000 yr BP and 9000 yr BP to similar to 4000 yr BP, a woody savanna prevailed at two sites around the lake, probably reflecting a drier climate. From similar to 4000 - 3000 yr BP to the present, the results indicate a moderate and progressive increase in arboreal vegetation around the lake as a result of the return to more humid climate conditions probably similar to the present-day. The carbon isotope results from the site located 10 km from the lake indicate the presence of an open vegetation from the early Holocene. In general, there is agreement between the palaeovegetation patterns inferred from the pollen and carbon isotope data. However, a much less uniform landscape, with a mosaic of different ecosystems at any given time, is inferred from the carbon isotope record

Potential use of winter green manure species for nitrogen recycling by \u2018Niagara Rosada\u2019 grapevines

Green manures have become an important option for recycling nutrients in organic cropping. However, its benefits are often not obtained in the short term. In this context, the study aimed to determine whether the use of cover crops during winter can contribute to N provision in the following spring, in the beginning of the growth of young grapevines. The winter green manure species white lupin (Lupinus albus), forage pea (Pisum arvense), common vetch (Vicia sativa), hairy vetch (Vicia villosa), triticale (Triticale hexaploide), oat (Avena sativa), ryegrass (Lollium multiflorum) and forage turnip (Brassica rapa) were grown until flowering in 4 L pots and fertilized with ammonium sulfate enriched at 10% with 15 N atoms. In the following spring, grapevines cv. Niagara Rosada (Vitis labrusca) grafted on two different rootstocks (IAC-572 'Jales' and IAC 766 'Campinas') were planted in 14 L pots where it was superficially applied one of the five different sources of N. The green manure species employed as N source were forage pea (Pisum arvense), common vetch (Vicia sativa), hairy vetch (Vicia villosa) and oat (Avena sativa). The soil surface was covered with the dry matter from the green manure species (3g dry matter pot-1) or fertilized with ammonium sulfate enriched at 2% with 15N atoms. The results demonstrated that the oat plants showed the highest dry matter content (11.68 g pot-1). The species forage pea, hairy vetch and common vetch had the lowest C/N ratios, with values of 16, 16 and 18, respectively. Hairy vetch was the most efficient (255.1 mg pot-1) for the accumulation of N and oat plants showed the highest N uptake from the mineral fertilizer. The N uptake and accumulation by the \u2018Niagara Rosada\u2019 grapevines varied according to N source and rootstock. Grapevines accumulated N in higher amounts from mineral fertilizer, followed by the N from leguminous species and then lower quantities from the oat plants. Grapevines grafted on the IAC-572 \u2018Jales\u2019 rootstock accumulated higher amounts of N than those grafted on IAC-766 \u2018Campinas\u2019, probably due its higher vigor and, consequently, better soil exploration by the roots. Despite of the rootstock, between the green manure species, the N from forage peas was the most recovered by the grapevines cv. Niagara Rosada, attaining 30.8%, while common vetch 23.1%, hairy vetch 19.0%, and oat only 5.2%

Production of single superphosphate labeled with 34S Produção de superfosfato simples marcado com 34S

Single superphosphate is currently one of the mostly used fertilizers as an alternative source for phosphorus and sulphur. Sulphur presents four stable isotopes (32S, 33S, 34S, and 36S) with natural abundances of 95.00; 0.76; 4.22; and 0.014% in atoms, respectively. Single superphosphate labeled with the 34S isotope was obtained from a chemical reaction in stoichiometric amounts between Ca(H2PO4)2 and Ca34SO4.2H2O. Calcium sulphate (Ca34SO4.2H2O) was enriched with 5.85 &plusmn; 0.01 atoms % of 34S. The Ca(H2PO4)2 reagent was obtained from a reaction between CaCl2.2H2O and H3PO4. The reaction between the Ca(H2PO4)2 thus produced and the labeled Ca34SO4.2H2O compound was then performed to obtain the 34S-labeled single surperphosphate. The thermal decomposition of the labeled superphosphate for the production of gaseous 34SO2 was carried out under a vacuum line at 900ºC in the presence of NaPO3. The isotopic determination of S (atoms % of 34S) was carried out on an ATLAS-MAT model CH-4 mass spectrometer. The production yield of Ca(H2PO4)2 and labeled single superphosphate were approximately 97 and 99% respectively, and the purity level of the labeled single superphosphate was estimated as 96%. No isotopic fractionation was observed in the production process of 34S-labeled single superphosphate.<br>O superfosfato simples é um dos fertilizantes mais utilizados atualmente como fonte de fósforo e uma alternativa para enxofre. O enxofre apresenta quatro isótopos estáveis, 32S, 33S, 34S e 36S, com abundância natural de 95,00; 0,76; 4,22 e 0,014% em átomos, respectivamente. O superfosfato simples marcado com 34S foi obtido a partir da reação química em proporção estequiométrica entre o Ca(H2PO4)2 e o Ca34SO4.2H2O. O Ca34SO4.2H2O foi enriquecido com 5,85 &plusmn; 0,01% em átomos de 34S. O Ca(H2PO4)2 foi obtido a partir da reação entre CaCl2.2H2O com o H3PO4. A decomposição térmica do superfosfato marcado para produção do 34SO2 gasoso foi realizada em linha de vácuo a 900ºC na presença de NaPO3. A determinação isotópica do S (% em átomos de 34S) foi realizada no espectrômetro de massas. O rendimento da produção do Ca(H2PO4)2 e do superfosfato simples marcado foi em média 97 e 99%, respectivamente, e a pureza do superfosfato marcado foi estimada como 96%. Não foi observado fracionamento isotópico no processo de produção do superfosfato simples marcado com 34S