**4. References**

360 Herbicides – Properties, Synthesis and Control of Weeds

**2,3,7,8-TeCDD** 1 2.32 2.3200 **1,2,3,7,8-PeCDD** 1 51.71 51.7100 **1,2,3,4,7,8-HxCDD** 0.1 0.28 0.0280 **1,2,3,6,7,8-HxCDD** 0.1 16.22 1.6220 **1,2,3,7,8,9-HxCDD** 0.1 6.63 0.6630 **1,2,3,4,6,7,8-HpCDD** 0.01 0.76 0.0076

**OCDD** 0.0001 3.11 0.0003 **2,3,7,8-TeCDF** 0.1 10.69 1.0690 **1,2,3,7,8-PeCDF** 0.05 1.45 0.0725 **2,3,4,7,8-PeCDF** 0.5 1.50 0.7500 **1,2,3,4,7,8-HxCDF** 0.1 0.55 0.0550 **1,2,3,6,7,8-HxCDF** 0.1 4.58 0.4580 **1,2,3,7,8,9-HxCDF** 0.1 3.16 0.3160 **2,3,4,6,7,8-HxCDF** 0.1 0.17 0.0170 **1,2,3,4,6,7,8-HpCDF** 0.01 5.90 0.0590 **1,2,3,4,7,8,9-HpCDF** 0.01 0.00 0.0000

**OCDF** 0.0001 67.75 0.0068

Table 5. Contents of PCDD/F in the cube residue from the destillation of 2,4-DCP (Białek,

Authors have developed the technology of removing catalysts and trace pollutions

2,4-dichlorophenol obtained with the method of phenol chlorination in the presence of catalysts is washed off with mineral acid, it is neutralized to pH >10,5 and dilutes with water to 50%. A suspension of mineral sorbents is introduced to chlorophenolate obtained in this way. Chlorophenolate with sorbents is stirred for 30 minutes and the introduced

> Derivatives DPS [%]

<5 <0.001 0.027

Result in **ng TEQ/g 59.15 ± 0,05** 

PCDD/F [TEQ ng/g]

**Congener content in an specimen, mi** [ng/g]

**Toxicity TEQ mi x TEF**  [ng-TEQ/g]

**Toxicity equivalency factor (TEF)**

**Congener PCDD / PCDF**

2009).

(Moszczyński et al. 2005).

sorbents are filtered, which are then destroyed thermally.

Table 6. Trace pollutions in purified 2,4-dichlorophenol.

Iron contents [ppm]

Trace pollutions in purified 2,4-dichlorophenol are given below in table 6.


**20** 

*California, USA* 

**Vegetative Response to Weed Control** 

Longleaf pine (*Pinus palustris* Mill.) stands once occupied an estimated 24 million ha in the southeastern USA (Stout & Marion, 1993). Fire suppression, timber harvest, and land conversion reduced its extent to around one million ha (Outcalt & Sheffield, 1996). In recent times, widespread interest in restoring longleaf pine ecosystems or planting the species for timber production has motivated private landowners, industrial forest owners, and public agencies to establish more longleaf pine forest. Over 33 million longleaf pine seedlings were produced for the 2005-2006 planting season in the southeastern United States (McNabb &

Longleaf pine ecosystems are fire-adapted and support a diverse understory plant community when ground fires are frequent (Peet & Allard, 1993). Longleaf pine seedlings germinate and develop into a grass-like clump, and later transition from this "grass stage" to become woody saplings. Seedlings in the grass stage resist fire, but become vulnerable to fire upon emergence from the grass stage until height growth elevates their terminal bud beyond reach of fire and their bark thickens (Boyer, 1990). Early fire resistance is thought to be an adaptation to frequent fire. During the grass stage, seedlings invest energy in root development in preparation for rapid shoot extension upon emergence. This strategy for reoccupying disturbed sites gives the slower-growing longleaf pine a competitive advantage over less fire-hardy pines and hardwood competitors (Outcalt, 2000). However, in the absence of fire, longleaf pine seedlings are quickly overtopped by competing vegetation. Therefore rapid restoration of longleaf pine forests will necessarily involve some disturbance of competing vegetation. Hardwood regeneration is usually prolific following disturbances such as removal of forest cover. A suite of hardwood species regenerate as stump sprouts and root suckers, developing quickly from established root systems. Grasses and vines also develop quickly after disturbance in the warm humid climate of southeastern USA. Various forms of above- and belowground competition impact on survival and growth of planted longleaf pine seedlings (Harrington et al., 2003; Pecot et al, 2007) and

Tools available for control of competing vegetation in longleaf pine forest restoration include prescribed fire, mechanical methods, and chemical weed control with herbicides. Prescribed fire most closely mimics the natural disturbance regime in longleaf pine forests,

Enebak, 2008), and 54 million produced in 2008-2009 (Pohl & Kelly, 2011).

other pine species (e.g., Richardson et al., 1996b; Amishev & Fox, 2006).

**1. Introduction** 

**in Forest Restoration** 

*Humboldt State University* 

John-Pascal Berrill and Christa M. Dagley

Moszczyński, W. Ostrowski, T. Tomasik W. (1963). Pat PL 49289.

