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.

Alterations of chemical composition, construction cost and payback time in needles of Masson pine (Pinus massoniana L.) trees grown under pollution.

Previous studies show that Masson pine (Pinus massoniana L.) stands grown at the industrially-polluted site have experienced unprecedented growth decline, but the causal mechanisms are poorly understood. In this study, to understand the mechanisms of growth decline of Mason pine strands under pollution stresses, we determined the reactive oxygen species levels and chemical composition of the current-year (C) and one-year-old (C + 1) needles, and calculated the needle construction costs (CCmass) of Masson pine trees grown at an industrially-polluted site and an unpolluted remote site.

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.

More nitrogen partition in structural proteins and decreased photosynthetic nitrogen-use efficiency of Pinus massoniana under in situ polluted stress.

Masson pine (Pinus massoniana L.) trees in the Pearl River Delta have shown growth decline since late 1980s, particularly those around industrially polluted regions. As nitrogen is an important nutritional element composing functional proteins, structural proteins and photosynthetic machinery, investigation on nitrogen allocation is helpful to understand nutrient alteration and its regulation mechanism in response to pollution stress.

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.

Structural and physiological responses of two invasive weeds, Mikania micrantha and Chromolaena odorata, to contrasting light and soil water conditions.

To better understand the requirement of light and soil water conditions in the invasion sites of two invasive weeds, Mikania micrantha and Chromolaena odorata, we investigated their structural and physiological traits in response to nine combined treatments of light [full, medium and low irradiance (LI)] and soil water (full, medium and low field water content) conditions in three glasshouses. Under the same light conditions, most variables for both species did not vary significantly among different water treatments. Irrespective of water treatment, both species showed significant decreases in maximum light saturated photosynthetic rate (P (max)), photosynthetic nitrogen-use efficiency, and relative growth rate under LI relative to full irradiance; specific leaf area, however, increased significantly from full to LI though leaf area decreased significantly, indicating that limited light availability under extreme shade was the critical factor restricting the growth of both species.

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.

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.