Relative importance of multiple environmental variables in structuring benthic macroinfaunal assemblages in chronically metal-polluted salt marshes

In this study, we assessed importance of sediment-associated trace metals in structuring benthic macroinfaunal assemblages along multiple environmental gradients in chronically polluted salt marshes of the Arthur Kill - AK (New York, USA). More than 90% of benthic macroinfaunal communities at the northern AK sites consisted of a considerably large number of only a few polychaete and oligochaete species. Approximately 70% of among-site variances in abundance and biomass of benthic macroinfaunal communities was strongly associated with a few environmental variables; only sediment-associated mercury consistently contributed to a significant proportion of the explained variances in species composition along natural environmental gradients (e.g., salinity). Although sediment-associated copper, lead, and zinc were substantially elevated at some of the AK sites, their ecological impacts on benthic macroinfaunal communities appeared to be negligible. These findings suggest that cumulative metal-specific impacts may have played an important role in structuring benthic macroinfaunal communities in chronically polluted AK ecosystems.     

Zircon U–Pb dating of gabbro and diorite from the Bato pluton,northeast Japan

To constrain the timing of the tectonothermal events and formation process of a plutonic suite, U–Pb dating was carried out by laser ablation inductively coupled plasma mass spectrometry combined with cathodoluminescence imaging on zircon grains extracted from the Bato pluton, northern Yamizo Mountains, Japan. The Bato pluton consists of gabbro and diorite. Zircon grains separated from a gabbro sample had a unimodal ²³⁸U–²⁰⁶Pb age (105.7 ±1.0 Ma). It was interpreted as the solidification age of the gabbro. Cathodoluminescence observation showed that the zircon grains from a diorite sample were characterized by anhedral cores, oscillatory zoned mantles, and dark rims. The ²³⁸U–²⁰⁶Pb age of the anhedral cores ranged from 2 165 Ma to 161 Ma, indicating the assimilation of surrounding sedimentary rocks. The ²³⁸U–²⁰⁶Pb ages of the oscillatory zoned mantles and dark rims are 109.0 ±1.3 Ma and 107.7 ±1.3 Ma, respectively. Observation under polarizing microscopy suggests that the anhedral cores occurred before plagioclase and hornblende, and the oscillatory zones around the anhedral cores had crystallized at the same time as the crystallization of biotite. Moreover, the dark rims formed at the same time as the crystallization of quartz and K‐feldspar. The formation process of the gabbro‐diorite complex in the Bato pluton was inferred as follows. (i) A mafic initial magma intruded into Mesozoic sedimentary rocks, and the assimilation of these sedimentary rocks led to geochemical variation yielding a dioritic composition. Subsequently, plagioclase and hornblende of the diorite were crystallized before 109.0 ±1.3 Ma. (ii) Biotite crystallized in the middle stage around 109.0 ±1.3 Ma. (iii) Quartz and K‐feldspar of the diorite were crystallized at 107.7 ±1.3 Ma. The gabbroic magma solidified (105.7 ±1.0 Ma) after solidification of the diorite.     

Contamination by organochlorine compounds in sturgeons from Caspian Sea during 2001 and 2002

Organochlorine compounds (OCs) were determined in the five species of sturgeons collected from coastal waters of Caspian Sea in Kazakhstan, Azerbaijan, Turkmenistan and Iran during 2001 and 2002 to understand their status of contamination and accumulation features. Among OCs examined, concentrations of DDTs (DDT and its metabolites) were predominant in all the sturgeon samples with concentrations ranging from 73 to 31,000 ng/g on lipid weight basis, followed by PCBs, CHLs, HCHs, HCB, dieldrin, TCPMOH, and heptachlor epoxide in order. The concentrations of OCs in beluga (Huso huso) were the highest among all the five species. When comparing residue levels among same species, OC residues were highest in sturgeons from Azerbaijan and Kazakhstan and lowest in Turkmenistan. However, the concentrations of HCHs, dieldrin, and heptachlor epoxide in sturgeons showed less geographical variability.     

Experiments on the Element Distribution between the Granodiorite JG-1a and 2M NaCl Hydrothermal Solution at Temperatures of 300 to 800°C and a Pressure of 1 kb

Abstract. The distribution of Na, K, Ca, Mg, Mn and Fe between the granodiorite JG-la, one of the geochemical standard rocks, and 2M NaCl aqueous solution was experimentally determined at temperatures of 300 to 800C and a pressure of 1 kb using standard cold seal-type pressure vessels. The solid run products melted partially at 800C. Only K shows a significantly different behavior from the experiments using the basalt JB-la (Uchida and Tsutsui, 2000) due to the presence of ortho-clase in the JG-la. The transition elements tend to be preferably partitioned into the aqueous chloride solutions with increasing temperature. At 800C and 1 kb, the Fe concentration of the aqueous chloride solutions reached up to 5,000 ppm, and the Mn concentration up to 350 ppm. The distribution coefficient, K_{D, i} = C_{i, sol}/C_i, rock, is in the order of Na>K>Mn>Ca> Fe>Mg at 300C, but changed in the order of Mn>N>K>Fe>Ca>Mg at 800C. The distribution coefficients of the divalent cations for the JG-la are higher than those for the JB-1a. The distribution coefficient of the transition elements, Fe and Mn, increases significantly with increasing temperature. The thermodynamic analysis for aqueous speciation revealed that this is attributable to the formation of the tri-chloro complexes of the transition elements at higher temperatures.     

Narratives in REDD+ benefit sharing: examining evidence within and beyond the forest sector

REDD+ was designed globally as a results-based instrument to incentivize emissions reduction from deforestation and forest degradation. Over 50 countries have developed strategies for REDD+, implemented pilot activities and/or set up forest monitoring and reporting structures, safeguard systems and benefit sharing mechanisms (BSMs), offering lessons on how particular ideas guide policy design. The implementation of REDD+ at national, sub-national and local levels required payments to filter through multiple governance structures and priorities. REDD+ was variously interpreted by different actors in different contexts to create legitimacy for certain policy agendas. Using an adapted 3E (effectiveness, efficiency, equity and legitimacy) lens, we examine four common narratives underlying REDD+ BSMs: (1) that results-based payment (RBP) is an effective and transparent approach to reducing deforestation and forest degradation; (2) that emphasis on co-benefits risks diluting carbon outcomes; (3) that directing REDD+ benefits predominantly to poor smallholders, forest communities and marginalized groups helps address equity; and (4) that social equity and gender concerns can be addressed by well-designed safeguards. This paper presents a structured examination of eleven BSMs from within and beyond the forest sector and analyses the evidence to variably support and challenge these narratives and their underlying assumptions to provide lessons for REDD+ BSM design. Our findings suggest that contextualizing the design of BSMs, and a reflexive approach to examining the underlying narratives justifying particular design features, is critical for achieving effectiveness, equity and legitimacy.

Key policy insights

• A results-based payment approach does not guarantee an effective REDD+; the contexts in which results are defined and agreed, along with conditions enabling social and political acceptance, are critical.

• A flexible and reflexive approach to designing a benefit-sharing mechanism that delivers emissions reductions at the same time as co-benefits can increase perceptions of equity and participation.

• Targeting REDD+ to smallholder communities is not by default equitable, if wider rights and responsibilities are not taken into account

• Safeguards cannot protect communities or society without addressing underlying power and gendered relations.

• The narratives and their underlying generic assumptions, if not critically examined, can lead to repeated failure of REDD+ policies and practices.

     

Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses

Climate Dynamics - The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an...     

Numerical simulation of a possible origin of the positive radial metallicity gradient of the thick disk

We analyze the radial and vertical metallicity and [α/Fe] gradients of the disk stars of a disk galaxy simulated in a fully cosmological setting with the chemodynamical galaxy evolution code GCD+. We study how the radial abundance gradients vary as a function of height above the plane and find that the metallicity([α/Fe]) gradient becomes more positive(negative) with increasing height, changing sign around1.5 kpc above the plane. At the largest vertical height(2 |z| 3 kpc), our simulated galaxy shows a positive radial metallicity gradient. We find that the positive metallicity gradient is caused by the age-metallicity and age-velocity dispersion relation, where younger stars have higher metallicity and lower velocity dispersion. Due to the agevelocity dispersion relation, a greater fraction of younger stars reaches |z| 2 kpc at the outer region, because of the lower gravitational restoring force of the disk, i.e.flaring. As a result, the fraction of younger stars with higher metallicity due to the age-metallicity relation becomes higher at the outer radii, which makes the median metallicity higher at the outer radii. Combining this result with the recently observed age-metallicity and age-velocity dispersion relation for the Milky Way thick disk stars suggested by Haywood et al., we argue that the observed(small) positive radial metallicity gradient at large heights of the Milky Way disk stars can be explained by flaring of the younger thick and/or thin disk stars.     

Compositional variations,chemical weathering,and provenance of sands from the Cox’s Bazar and Kuakata beach areas,Bangladesh

The modal and chemical composition of sands from Cox’s Bazar beach (CBB) and Kuakata beach (KB) areas of Bangladesh has been investigated to infer their maturity, chemical weathering, and provenance signatures. The CBB and KB sands are typically high quartz, low feldspar, and lithic fragments, representing a recycled orogen source. Major element compositions of CBB sands are characterized by high SiO₂ (83.52–89.84 wt%) and low Al₂O₃ (4.39–6.39 wt%), whereas KB sands contained relatively low SiO₂ (63.28–79.14 wt%) and high Al₂O₃ (9.00–11.33 wt%) contents. The major, trace and rare earth element (REE) compositions of beach sands display comparable distribution patterns with enriched Th and SiO₂ for both sands relative to upper continental crust (UCC). Pb, Rb, Y, and Fe for KB sands are little higher than UCC and the rest of the elements are marked depleted for both suites reflecting destruction of plagioclase and K-feldspar during fluvial transportation. The CBB and KB sands are compositionally low mature to immature in nature subsequently classified as subarkose and litharenite, respectively. Chondrite-normalized REE patterns for CBB and KB sands show LREE enrichment and nearly flat HREE (La_N/Yb_N, 7.64–9.38 and 5.48–8.82, respectively) coupled with prominent Eu anomalies (Eu/Eu*, 0.51–0.72 and 0.52–0.76, respectively), suggesting felsic source provenance. The provenance discrimination diagrams, immobile trace element ratios (Th/Sc, Zr/Sc, Ce/Sc, and Ti/Zr), and REE (∑LREE/HREE, Eu/Eu* and Gd_N/Yb_N) parameters indicate that CBB and KB sands were largely derived from felsic source rocks, with compositions close to average rhyolite, granodiorite, granite, and UCC.