Global distribution and drivers of relative contributions among soil nitrogen sources to terrestrial plants.

Soil extractable nitrate, ammonium, and organic nitrogen (N) are essential N sources supporting primary productivity and regulating species composition of terrestrial plants. However, it remains unclear how plants utilize these N sources and how surface-earth environments regulate plant N utilization. Here, we establish a framework to analyze observational data of natural N isotopes in plants and soils globally, we quantify fractional contributions of soil nitrate (f), ammonium (f), and organic N (f) to plant-used N in soils.

Metals and possible sources of lead in aerosols at the Dinghushan nature reserve, southern China.

Rationale: Aerosols play an important role in depositing metals into forest ecosystems. Better understanding of forest aerosols with regard to their metal content and their possible sources is of great significance for air quality and forest health.

Methods: Particulate matter with an aerodynamic diameter less than 2.

Lipid-content-normalized polycyclic aromatic hydrocarbons (PAHs) in the xylem of conifers can indicate historical changes in regional airborne PAHs.

The temporal variation of polycyclic aromatic hydrocarbons (PAHs) concentrations as well as the lipid content in the xylem of Masson pine trees sampled from the same site were determined and compared with the days of haze occurrence and with the historical PAHs reported in sedimentary cores. The patterns of the lipid content as well as the PAH concentrations based on the xylem dry weight (PAHs-DW) decreased from the heartwood to the sapwood. The trajectories of PAHs normalized by xylem lipid content (PAHs-LC) coincided well with the number of haze-occurred days and were partly similar with the historical changes in airborne PAHs recorded in the sedimentary cores.

[Characteristics of rain season atmospheric PM2.5 concentration and its water-soluble ions contents in forest parks along an urban-rural gradient in Guangzhou City of South China].

During the rainy season (April-September) of 2012, the atmospheric particulate matter with a diameter less than 2.5 mm (PM2.5) were sampled from the forest parks in the urban area, suburban area, and rural area of Guangzhou City.

Absorption of hazardous pollutants by a medicinal fern Blechnum orientale L.

A Chinese medicinal fern Blechnum orientale (Linn) was separately collected from polluted and unpolluted sites to determine whether it could accumulate hazardous pollutants or not. Metal concentrations (Cu, Zn, Mn, Pb, Cd, Cr, As, and Hg) both in the fronds and roots and polycyclic aromatic hydrocarbons (PAHs) in the fronds of this fern were quantified. At both sites, roots of B.

Physiological responses and accumulation of pollutants in woody species under in situ polluted condition in Southern China.

Physiological leaf traits and accumulation of pollutants of ten woody species in response to air pollution at seriously polluted site Sanguigang (SGG) and control site Maofengshan (MFS) in Southern China were studied. Net photosynthetic rates of most species at SGG were lower than those at MFS, but stomatal conductance (g(s)) showed opposite trend. The specific leaf area of Aporusa dioica, Sapium discolor, Schefflera octophylla and Toxicodendron succedaneum were significantly, 46.

Analysis of polycyclic aromatic hydrocarbons in tree-rings of Masson pine (Pinus massoniana L.) from two industrial sites in the Pearl River Delta, south China.

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were examined and potential sources of PAHs were identified from the dated tree-rings of Masson pine (Pinus massoniana L.) near two industrial sites (Danshuikeng, DSK and Xiqiaoshan, XQS) in the Pearl River Delta of south China. Total concentrations of PAHs (∑PAHs) were revealed with similar patterns of temporal trends in the tree-rings at both sites, suggesting tree-rings recorded the historical variation in atmospheric PAHs.

Homogeneity of delta(15)N in needles of Masson pine (Pinus massoniana L.) was altered by air pollution.

The present study investigated the changes of delta(15)N values in the tip, middle and base section (divided by the proportion to needle length) of current- and previous-year needles of Masson pine (Pinus massoniana L.) from two declining forest stands suffering from air pollution, in comparison with one healthy stand. At the healthy stand, delta(15)N in the three sections of both current- and previous-year needles were found evenly distributed, while at the polluted stands, delta(15)N values in the needles were revealed significantly different from the tip to the base sections.

Concentrations of sulphur and heavy metals in needles and rooting soils of Masson pine (Pinus massoniana L.) trees growing along an urban-rural gradient in Guangzhou, China.

Current (C) and previous year (C + 1) needles and soils (organic horizon, 0-10 cm and 10-20 cm mineral depth) of Masson pine (Pinus massoniana L.) trees were sampled at four forested sites (Huang Pu industrial district, HP; South China Botanical Garden, BG; Mao Feng Mt., MF; and Nan Kun Mt.

Heavy metals in bark of Pinus massoniana (Lamb.) as an indicator of atmospheric deposition near a smeltery at Qujiang, China.

Goal, Scope And Background: Rapid urbanization and the expansion of industrial activities in the past several decades have led to large increases in emissions of pollutants in the Pearl River Delta of south China. Recent reports have suggested that industrial emission is a major factor contributing to the damages in current natural ecosystem in the Delta area. Tree barks have been used successfully to monitor the levels of atmospheric metal deposition in many areas, but rarely in China.

Acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China.

Barks of Pinus massonianm collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution.

Distribution of elements in needles of Pinus massoniana (Lamb.) was uneven and affected by needle age.

Macronutrients (P, S, K, Na, Mg, Ca), heavy metals (Fe, Zn, Mn, Cu, Pb, Cr, Ni, Cd,) and Al concentrations as well as values of Ca/Al in the tip, middle and base sections, and sheaths of current year and previous year needles of Pinus massoniana from Xiqiao Mountain were analyzed and the distribution patterns of those elements were compared. The results indicated that many elements were unevenly distributed among the different components of needles. Possible deficiency of P, K, Ca, Mn and Al toxicity occurred in needles under air pollution.

Distribution of elements in needles of Pinus massoniana (Lamb.) was uneven and affected by needle age.

Macronutrients (P, S, K, Na, Mg, Ca), heavy metals (Fe, Zn, Mn, Cu, Pb, Cr, Ni, Cd) and Al concentrations as well as values of Ca/Al in the tip, middle, base sections and sheaths of current year and previous year needles of Pinus massoniana from Xiqiao Mountain were analyzed and the distribution patterns of those elements were compared. The results indicated that many elements were unevenly distributed among the different components of needles. Possible deficiency of P, K, Ca, Mn and Al toxicity occurred in needles under air pollution.